Effect of Glass Fiber Reinforced Polymer on Mechanical Behavior of High Strength Concrete

Effect of Glass Fiber Reinforced Polymer on Mechanical
Behavior of High Strength Concrete
‫على‬ ‫الزجاجية‬ ‫االلياف‬ ‫تأثير‬‫الميكانيكي‬ ‫السلوك‬‫القوة‬ ‫عالية‬ ‫للخرسانة‬
Mahmoud Mazen Hilles
Supervised by:
Prof. Mohammed Ziara
Professor of Civil Engineering
A Thesis Submitted in Partial Fulfillment of the Requirements for the Degree of Master of
Science in Civil Engineering - Design and Rehabilitation of Structures
November/ 2016
‫الج‬‫ـ‬‫امع‬‫ـــــــــ‬‫اإلس‬ ‫ـة‬‫ـــــ‬‫المي‬‫ــ‬‫ة‬–‫غ‬‫ــ‬‫زة‬
‫شئو‬‫العليا‬ ‫والدراسات‬ ‫العلمي‬ ‫البحث‬ ‫ن‬
‫ك‬‫ـ‬‫ليـــ‬‫ــــــــــــــ‬‫ــ‬‫ة‬‫الهندســـــــــــــــــة‬
‫ماجستي‬‫ــــ‬‫ر‬‫المدنيـــــــــة‬ ‫الهندســــــة‬-
‫المنشات‬ ‫تأهيل‬ ‫و‬ ‫تصميم‬
The Islamic University–Gaza
Research and Postgraduate Affairs
Faculty of Engineering
Master of Civil Engineering- Design
and Rehabilitation of Structures

‫ار‬‫ر‬‫إقــــــــــــــ‬
‫العنو‬ ‫تحمل‬ ‫التي‬ ‫الرسالة‬ ‫مقدم‬ ‫أدناه‬ ‫الموقع‬ ‫أنا‬:‫ان‬
Effect of Glass Fiber Reinforced Polymer on Strength
Properties of High Strength Concrete
‫القوة‬ ‫عالية‬ ‫للخرسانة‬ ‫القوة‬ ‫خصائص‬ ‫على‬ ‫الزجاجية‬ ‫االلياف‬ ‫تأثير‬
‫أ‬‫و‬ ،‫ورد‬ ‫حيثما‬ ‫إليه‬ ‫ة‬‫ر‬‫اإلشا‬ ‫تمت‬ ‫ما‬ ‫باستثناء‬ ،‫الخاص‬ ‫جهدي‬ ‫نتاج‬ ‫هو‬ ‫إنما‬ ‫الرسالة‬ ‫هذه‬ ‫عليه‬ ‫اشتملت‬ ‫ما‬ ‫بأن‬ ‫أقر‬‫هذه‬ ‫ن‬
‫قبل‬ ‫من‬ ‫يقدم‬ ‫لم‬ ‫منها‬ ‫ء‬‫جز‬ ‫أي‬ ‫أو‬ ‫ككل‬ ‫الرسالة‬‫ين‬‫ر‬‫االخ‬‫بحثية‬ ‫أو‬ ‫تعليمية‬ ‫مؤسسة‬ ‫أي‬ ‫لدى‬ ‫بحثي‬ ‫أو‬ ‫علمي‬ ‫لقب‬ ‫أو‬ ‫درجة‬ ‫لنيل‬
.‫ى‬‫أخر‬
Declaration
I understand the nature of plagiarism, and I am aware of the University’s policy on this.
The work provided in this thesis, unless otherwise referenced, is the researcher's own work, and
has not been submitted by others elsewhere for any other degree or qualification.
:‫الطالب‬ ‫اسم‬‫حلس‬ ‫مازن‬ ‫محمود‬Student's name:
:‫التوقيع‬Signature:
:‫يخ‬‫ر‬‫التا‬14/11/2016Date:

I
Abstract
The usage of high strength glass fiber reinforced concrete (HSGFRC) in the construction
applications has been increasing worldwide and will make an impact in Gaza Strip. Due to the
limited land area available for construction, the fast growing population, bad and unstable
political conditions, and the continuing wars in Gaza Strip, strong, relatively cheap, and locally
available repairing and strengthening material should be produced.
The main objective of this investigation is to study the effect of addition of alkali resistant glass
fiber reinforced polymer (AR-GFRP) with various proportions typically 0.3, 0.6, 0.9, and 1.2
by weight of cement on the mechanical behavior of plain HSC (without fiber) with 28 days
cube compressive strength up to 60 MPa using available materials in the Gaza local market.
Results show that it is possible to produce HSGFRC in Gaza strip using materials that are
available at the local markets if they are carefully selected. Based on the experimental results,
the compressive strength, splitting tensile strength, flexural strength and density of HSC is
found to be increases as fiber percentage increases for both ages 7 and 28 days. The compressive
strength of HSC is found to be 57.85, 61.05, 66.01, 66.34 and 66.60 MPa at fiber percentage of
0.0, 0.3, 0.6, 0.9, and 1.2 respectively for 28 days. The 28 days percentage of increasing over
the reference mix is found to be maximum equal to 13.14 percent at 1.2 fiber percentage. The
density of HSC is found to be increases very slightly as fiber percentage increases from 0.0 to
1.2, typically from 2417 to 2441 kg/m3
. The splitting tensile strength of HSC is found to be
4.12, 4.77, 5.53, 5.84 and 6.73 MPa at fiber percentage of 0.0, 0.3, 0.6, 0.9, and 1.2 respectively
for 28 days. The 28 days’ percentage of increasing over the reference mix is found to be
maximum equal to 63.22 percent at 1.2 fiber percentage. The flexural strength of HSC is found
to be 6.35, 7.53, 8.28, 8.79 and 9.68 MPa at fiber percentage of 0.0, 0.3, 0.6, 0.9, and 1.2
respectively for 28 days. The 28 days’ percentage of increasing over the reference mix is found
to be maximum equal to 52.36 percent at 1.2 fiber percentage. The mode of failure is found to
be taken place gradually with the formation of cracks as fiber percentage increase, compared
with plain HSC specimens, the failure was sudden and completely destruction. Hence it is
established that the presence of fibers in the matrix has contributed towards prevent sudden
crack formation.

II
‫الملخص‬
‫كبير‬ ‫بشكل‬ ‫و‬ ‫يتزايد‬ ‫االنشائية‬ ‫التطبيقات‬ ‫في‬ ‫الزجاجية‬ ‫بااللياف‬ ‫المسلحة‬ ‫القوة‬ ‫عالية‬ ‫الخرسانة‬ ‫استخدام‬ ‫ان‬
‫غزة‬ ‫قطاع‬ ‫في‬ ‫اثره‬ ‫له‬ ‫يكون‬ ‫ان‬ ‫المؤكد‬ ‫من‬ ‫و‬ ,‫العالم‬ ‫مستوى‬ ‫على‬‫المتاحة‬ ‫الراضي‬ ‫مساحات‬ ‫ضيق‬ ‫بسبب‬ .
‫االو‬ ‫الى‬ ‫باالضافة‬ ,‫السكان‬ ‫اعداد‬ ‫في‬ ‫الكبير‬ ‫التزايد‬ ‫و‬ ,‫للبناء‬‫حدوث‬ ‫تكرار‬ ‫و‬ ‫مستقرة‬ ‫الغير‬ ‫االمنية‬ ‫ضاع‬
‫تقوية‬ ‫كمواد‬ ‫محليا‬ ‫المتوفرة‬ ‫موادها‬ ‫و‬ ‫نسبيا‬ ‫الرخيصة‬ ‫المواد‬ ‫هذه‬ ‫مثل‬ ‫استخدام‬ ‫يستدعي‬ ‫الذي‬ ‫االمر‬ ,‫الحروب‬
.‫المتضررة‬ ‫للمنشات‬ ‫ترميم‬ ‫و‬‫لهذا‬ ‫االساسي‬ ‫الهدف‬ ‫ان‬‫البحث‬‫هو‬‫دراسة‬‫الزجاجية‬ ‫االلياف‬ ‫اضافة‬ ‫تاثير‬
‫نسب‬ ‫بعدة‬ ‫للقلويات‬ ‫المقاومة‬‫هي‬ ‫و‬ ‫مختلفة‬0.30,0.6,0.9‫و‬ ,1.2‫االسمنت‬ ‫وزن‬ ‫من‬‫القوة‬ ‫خصائص‬ ‫على‬
‫القوة‬ ‫عالية‬ ‫للخرسانة‬)‫الياف‬ ‫بدون‬ ( ‫البحتة‬‫بقوة‬‫للمكعب‬ ‫ضغط‬ ‫تحمل‬‫عند‬28‫تساوي‬ ‫يوم‬60‫باسكال‬ ‫ميجا‬
‫المحلي‬ ‫بالسوق‬ ‫المتوفرة‬ ‫المواد‬ ‫باستخدام‬‫غزة‬ ‫قطاع‬ ‫في‬.
‫النت‬ ‫اظهرت‬‫عالية‬ ‫الخرسانة‬ ‫انتاج‬ ‫يمكن‬ ‫انه‬ ‫ائج‬‫باستخدام‬ ‫غزة‬ ‫قطاع‬ ‫في‬ ‫الزجاجية‬ ‫بااللياف‬ ‫المسلحة‬ ‫القوة‬
.‫بعناية‬ ‫اختيارها‬ ‫تم‬ ‫حال‬ ‫في‬ ‫محليا‬ ‫المتوفرة‬ ‫المواد‬,‫الشد‬ ,‫الضغط‬ ‫قوة‬ ,‫المخبرية‬ ‫النتائج‬ ‫على‬ ‫بناءا‬,‫االنحناء‬
‫الكثافة‬ ‫و‬.‫االلياف‬ ‫نسبة‬ ‫زيادة‬ ‫مع‬ ‫تزيد‬ ‫بانها‬ ‫وجدت‬ ‫القوة‬ ‫عالية‬ ‫للخرسانة‬‫تساوي‬ ‫انها‬ ‫وجدت‬ ‫الضغط‬ ‫قوة‬
57.85,61.05,66.34‫و‬ ,66.60‫باسكال‬ ‫ميجا‬‫تساوي‬ ‫الياف‬ ‫نسبة‬ ‫عند‬0.0,0.3,0.6,0.9‫و‬ ,1.2
‫التوالي‬ ‫على‬‫بعد‬28‫يوم‬‫بعد‬ ‫المرجعية‬ ‫الخلطة‬ ‫عن‬ ‫الزيادة‬ ‫نسبة‬ .28‫القصوى‬ ‫القيمة‬ ‫لتكون‬ ‫وجدت‬ ‫يوم‬
‫تساوي‬13.14‫تساوي‬ ‫الياف‬ ‫نسبة‬ ‫عند‬1.2‫الكثافة‬ ‫اما‬ .‫بعد‬28‫بش‬ ‫تزيد‬ ‫بانها‬ ‫وجد‬ ‫يوم‬‫مع‬ ‫جدا‬ ‫طفيف‬ ‫كل‬
‫من‬ ‫االلياف‬ ‫نسبة‬ ‫زيادة‬0.0‫الى‬1.2,‫من‬ ‫بالضبط‬2417‫الى‬2441‫كجم/م‬3
‫تساوي‬ ‫انها‬ ‫وجدت‬ ‫الشد‬ ‫قوة‬ .
4.12,4.77,5.53,5.84‫و‬ ,6.73‫باسكال‬ ‫ميجا‬‫تساوي‬ ‫الياف‬ ‫نسبة‬ ‫عند‬0.0,0.3,0.6,0.9‫و‬ ,1.2
‫بعد‬ ‫التوالي‬ ‫على‬28‫يوم‬‫بعد‬ ‫المرجعية‬ ‫الخلطة‬ ‫عن‬ ‫الزيادة‬ ‫نسبة‬ .28‫القصوى‬ ‫القيمة‬ ‫لتكون‬ ‫وجدت‬ ‫يوم‬
‫تساوي‬63.22‫تساوي‬ ‫الياف‬ ‫نسبة‬ ‫عند‬1.2‫تساوي‬ ‫انها‬ ‫وجدت‬ ‫االنحناء‬ ‫قوة‬ .6.35,7.53,8.28,8.79‫,و‬
9.68‫باسكال‬ ‫ميجا‬‫تساوي‬ ‫الياف‬ ‫نسبة‬ ‫عند‬0.0,0.3,0.6,0.9‫و‬ ,1.2‫بعد‬ ‫التوالي‬ ‫على‬28‫يوم‬‫نسبة‬ .
‫بعد‬ ‫المرجعية‬ ‫الخلطة‬ ‫عن‬ ‫الزيادة‬28‫يوم‬‫تساوي‬ ‫القصوى‬ ‫القيمة‬ ‫لتكون‬ ‫وجدت‬52.36‫الياف‬ ‫نسبة‬ ‫عند‬
‫تساوي‬1.2.‫مقارنة‬ ,‫االلياف‬ ‫نسبة‬ ‫زادت‬ ‫كلما‬ ‫الشقوق‬ ‫تشكل‬ ‫اثناء‬ ‫تدريجيا‬ ‫يحدث‬ ‫بانه‬ ‫وجد‬ ‫االنهيار‬ ‫شكل‬
‫ان‬ ‫استنتاج‬ ‫تم‬ ‫فانه‬ ‫لذا‬ .‫هش‬ ‫و‬ ‫مفاجئا‬ ‫كان‬ ‫االنهيار‬ ‫شكل‬ ‫ان‬ ‫حيث‬ ‫البحتة‬ ‫القوة‬ ‫عالية‬ ‫الخرسانة‬ ‫عينات‬ ‫مع‬
‫االليا‬ ‫وجود‬‫في‬ ‫يساهم‬ ‫الخرسانية‬ ‫الخلطة‬ ‫في‬ ‫ف‬‫منع‬.‫المفاجئ‬ ‫الشقوق‬ ‫تشكل‬

III
Dedication
To my father’s soul, my mother, and my fiancee

IV
Acknowledgment
I would like to express my sincere appreciation to Prof. Mohammed Ziara, Department of Civil
Engineering, Faculty of Engineering, The Islamic University of Gaza, for their help and
guidance in the preparation and development of this work. The constant encouragement,
support and inspiration they offered were fundamental to the completion of this research.
Special thanks go to the material and soil lab of the Islamic University of Gaza, for their logistic
facilitations and their continuous support. Finally, I would like to thank everyone who gave
advice or assistance that contributed to complete this research.

V
Table of contents
Abstract ..................................................................................................................................... I
‫الملخص‬ .........................................................................................................................................II
Dedication............................................................................................................................... III
Acknowledgment ................................................................................................................... IV
Table of contents......................................................................................................................V
List of Tables....................................................................................................................... VIII
List of Figures ........................................................................................................................ IX
List of Abbreviations............................................................................................................XII
Chapter 1: Introduction...........................................................................................................2
1.1 General Background.........................................................................................................2
1.2 Research Significant.........................................................................................................2
1.3 Research Aim and Objectives...........................................................................................3
1.4 Methodology.....................................................................................................................3
1.5 Thesis Organization..........................................................................................................4
Chapter 2: Literature Review .................................................................................................6
2.1 High Strength Concrete (HSC).........................................................................................6
2.1.1 Definition...................................................................................................................6
2.1.2 Benefits and Limitations of Using HSC in Practice..................................................6
2.1.3 Application of HSC ...................................................................................................7
2.1.4 Materials Selection of HSC.......................................................................................8
2.1.4.1 Cement................................................................................................................8
2.1.4.2 Supplementary Cementitious Materials (SCMs)................................................9
2.1.4.3 Water Reducing Admixtures ............................................................................10
2.1.4.4 Aggregates........................................................................................................12
2.1.4.5 Mixing Water....................................................................................................13

VI
2.1.5 Microstructure of HSC ............................................................................................13
2.1.6 Mix Proportion ........................................................................................................14
2.2 Fiber Reinforced Concrete (FRC) ..................................................................................17
2.2.1 General Background................................................................................................17
2.2.2 Glass Fiber Reinforced Concrete (GFRC)...............................................................21
2.2.3 Applications of GFRC.............................................................................................23
2.3 High Strength Fiber Reinforced Concrete (HSFRC)......................................................24
2.4 Concluding Remarks ......................................................................................................26
Chapter 3: Test Program and Laboratory Works ..............................................................28
3.1 General Description........................................................................................................28
3.2 Test Program...................................................................................................................28
3.3 Materials Selection and Properties .................................................................................29
3.3.1 Cement.....................................................................................................................29
3.3.2 Coarse Aggregates...................................................................................................30
3.3.3 Fine Aggregate ........................................................................................................32
3.3.4 Normal Range Water Reducing Admixture (NRWR).............................................33
3.3.5 Glass Fiber Reinforced Polymer (GFRP)................................................................34
3.3.6 Water .......................................................................................................................34
3.4 Mix Proportioning of HSGFRC .....................................................................................34
3.5 Preparation of HSGFRC and Mixing Procedure ............................................................37
3.6 Testing Procedure...........................................................................................................38
3.6.1 Compressive Strength Test......................................................................................38
3.6.2 Splitting Tensile Strength Test ................................................................................39
3.6.3 Flexural Strength Test .............................................................................................42
3.6.4 Unit Weight .................................................................................................................45
3.7 Curing Procedure............................................................................................................46

VII
Chapter 4: Test Results and Discussion ...............................................................................48
4.1 Compressive Strength and Density Test Results............................................................48
4.1.1 Effect of AR-GFRP on the Compressive Strength of HSC.....................................50
4.1.2 Effect of AR-GFRP on the Strength Gain with Age of HSC ..................................52
4.1.3 Effect of AR-GFRP on the Density of HSC............................................................53
4.1.4 Crack Pattern and Mode of Failure..........................................................................54
4.2 Splitting Tensile Strength Test Results ..........................................................................57
4.2.1 Effect of AR-GFRP on the Splitting Tensile Strength of HSC ...............................58
4.2.2 Crack Pattern and Mode of Failure..........................................................................60
4.3 Flexural Strength (Modulus of Rapture) Test Results....................................................63
4.4 Result Summary .............................................................................................................66
Chapter 5: Conclusions and Recommendations..................................................................68
5.1 Conclusions ....................................................................................................................68
5.2 Recommendations ..........................................................................................................69
The Reference List..................................................................................................................70

VIII
List of Tables
Table (2.1): Chemical Analysis for Normal Portland Cement and Supplementary
Cementitious Materials (Nawy, 2008)......................................................................................10
Table (2.2): Mixture Proportions and Properties of Commercially Available HSC (Steven et
al. 2003)....................................................................................................................................15
Table (2.3): Requirements of Ingredient Materials for HSC (Rashid and Mansur, 2009). .....16
Table (2.4): Properties of Different Types of Fibers (Steven et al. 2003)...............................19
Table (2.5): Chemical Composition of Selected Glasses, (Percent) (ACI Committee 544.1,
2002).........................................................................................................................................22
Table (2.6): Properties of Selected Glasses (ACI Committee 544.1, 2002)............................22
Table (3.1): Test Program........................................................................................................29
Table (3.2): Physical Properties of Cement According to Manufacturer Data Sheet..............30
Table (3.3): Sieve Analysis and Physical Properties of Coarse Aggregate Types. .................30
Table (3.4): Sieve Analysis of Combined Coarse Aggregate According to ASTM C33 (2003)
and Physical Properties.............................................................................................................31
Table (3.5): Grain Distribution of Fine Aggregate and Physical Properties. ..........................32
Table (3.6): Properties of Normal Range Water Reducer. ......................................................33
Table (3.7): Properties of AR-GFRP.......................................................................................34
Table (3.8): Mix Proportioning for 1 m3
of Concrete for The Reference Mixture..................35
Table (3.9): 28 Day Cylinder Compressive Strength Test Result. ..........................................36
Table (3.10): HSGFRC Mixtures for 1 m3
of Concrete...........................................................37
Table (4.1): Cube Compressive Strength and Density Test Results........................................49
Table (4.2): Average Cube Compressive Strength and Density Test Results. ........................49
Table (4.3): Splitting Tensile Strength Test Results................................................................57
Table (4.4): Average Splitting Tensile Strength Test Results. ................................................58
Table (4.5): Flexural Strength (Modulus of Rapture) Test Results.........................................63
Table (4.6): Average Flexural Strength (Modulus of Rapture) Test Results. .........................64

IX
List of Figures
Figure (1.1): Summary of Methodology Flow Chart. ...............................................................3
Figure (2.1): Effect of Superplasticizers on Slump Loss (Mindess, 1988). ............................11
Figure (2.2): Microstructure of NSC (Buyukozturk and Lau, 2007). .....................................13
Figure (2.3): Microstructure of HSC (Buyukozturk and Lau, 2007). .....................................14
Figure (2.4): Steel, Glass, Synthetic and Natural Fibers (Steven et al. 2003).........................17
Figure (2.5): Load–Displacement Curves ...............................................................................21
Figure (2.6): Chopped Strands AR-GFRP (Nippon Electric Glass Co. Ltd. 2007). ...............23
Figure (2.7): Alkali Resistivity of Glass Fiber and ZrO2 Content (Nippon Electric Glass Co.
Ltd. 2007). ................................................................................................................................23
Figure (2.8): Mechanical Behavior of FRC Compared with Plain Matrix (Buyukozturk and
Lau, 2007).................................................................................................................................25
Figure (3.1): Coarse Aggregate Sieve Analysis According to ASTM C33 (2003).................31
Figure (3.2): Grain Distribution of Fine Aggregate. ...............................................................33
Figure (3.3): 150 x 300 mm Cylindrical Specimens. ..............................................................36
Figure (3.4): MATEST C104 Servo Plus 2000 KN Capacity Compression Test Machine....36
Figure (3.5): The Power-Driven Revolving Drum Mixer Used on This Research. ................37
Figure (3.6): (a) and (b) Cube Specimens. ..............................................................................38
Figure (3.7): MATEST C104 Servo Plus 2000 KN Capacity Compression Test Machine....39
Figure (3.8): Cylindrical Specimens........................................................................................40
Figure (3.9): Split Cylinder Test Setup. ..................................................................................40
Figure (3.10): (a), (b), and (c) Failure on Cylindrical Specimen after Split Cylinder Test.....41
Figure (3.11): (a) and (b) Prism Specimens. ...........................................................................43
Figure (3.12): Schematic View for Flexure Test Setup of Concrete by Center-Point Loading.
..................................................................................................................................................44
Figure (3.13): Center Point Loading Flexural Test Machine. .................................................44
Figure (3.14): Fracture on Prism Specimen after Flexural Prism Test....................................45

X
Figure (3.15): Specimens at Curing Basin. .............................................................................46
Figure (4.1): Effect of AR-GFRP on 28 Days Compressive Strength of HSC. ......................50
Figure (4.2): The Percentage of Increase in Compressive Strength Over the Reference Mix
Due to Addition of AR-GFRP on HSC……………………………………………………….50
Figure (4.3): Comparisons of compressive strength test results with other related researches.
..................................................................................................................................................52
Figure (4.4): Effect of AR-GFRP on the Strength Gain with Age of HSC………………….53
Figure (4.5): Effect of AR-GFRP on %7days / 28days Compressive Strength. .....................53
Figure (4.6): Effect of AR-GFRP on Density of HSC. ...........................................................54
Figure (4.7): Mode of Failure and Crack Pattern of Plain HSC Specimens (Without Fiber). 55
Figure (4.8): (a) and (b): Mode of Failure and Crack Pattern of HSC Specimens with 0.3
Fiber Percentage. ......................................................................................................................55
Figure (4.9): Mode of Failure and Crack Pattern of HSC Specimens with 0.6 Fiber
Percentage.................................................................................................................................56
Percentage.................................................................................................................................56
Percentage.................................................................................................................................56
Figure (4.12): Effect of AR-GFRP on Splitting Tensile Strength of HSC..............................59
Figure (4.13): The Percentage of Increase Over the Reference Mix Due to Addition of AR-
GFRP on HSC: Comparison between Compressive Strength and Splitting Tensile
Strength……………………………………………………………………………………….59
Figure (4.14): Comparisons of splitting tensile strength test results with other related
researches..................................................................................................................................60
Figure (4.15): Mode of Failure of Plain HSC Specimens (Without Fiber).............................61
Figure (4.16): Mode of Failure of HSC Specimens with 0.3 Fiber Percentage. .....................61
Percentage.................................................................................................................................61

XI
Percentage.................................................................................................................................62
Percentage.................................................................................................................................62
Figure (4.20): Effect of AR-GFRP on Flexural Strength (Modulus of Rapture) of HSC.......65
Figure (4.21): The Percentage of Increase Over the Reference Mix Due to Addition of AR-
GFRP on HSC: Comparison Between Compressive, Splitting Tensile and Flexural Strength.
..................................................................................................................................................65
Figure (4.22): Comparisons of flexural strength test results with other related researches. ...66

XII
List of Abbreviations
ACI American Concrete Institute
ASTM American Society for Testing and Materials
AR-GFRC Alkali Resistant-Glass Fibers Reinforced Concrete
AR-GFRP Alkali Resistant-Glass Fibers Reinforced Polymer
CV Coefficient of Variation (%)
Fst Concrete Splitting Tensile Strength
Fr Concrete Flexural Strength or Modulus of Rapture
FRC Fiber Reinforced Concrete
GFRC Glass Fibers Reinforced Concrete
GFRP Glass Fibers Reinforced Polymer
HRWRA High-Range Water-Reducing Admixture
NRWRA Normal-Range Water-Reducing Admixture
HSC High Strength Concrete
HSFRC High Strength Fiber Reinforced Concrete
HSGFRC High Strength Glass Fiber Reinforced Concrete
ITZ Interfacial Transition Zone
NSC Normal Strength Concrete
S Stander Deviation
SFRC Steel Fibers Reinforced Concrete
UHSC Ultra High Strength Concrete
VHSC Very High Strength Concrete
W/C Water / Cement Ratio

2
Chapter 1: Introduction
1.1 General Background
A High Strength Glass Fiber Reinforced Concrete (HSGFRC) it is an advanced form for
concrete technology, which have all advantages of high strength concrete (HSC) and glass fiber
reinforced concrete (GFRC). By using this form of concrete technology, the problems and
disadvantages of each type of concrete alone can be overcome.
Unfortunately, HSC has a brittle behavior at ultimate limit state of loading, so, fibers can be
added to improve the structural properties of concrete. It has been recognized that the addition
of small, closely spaced and uniformly dispersed fibers to concrete would act as crack arrester
and would substantially improve its mechanical behavior. The addition of fibers results in a
product which has higher flexural and tensile strengths as compared with normal concrete
(Gustavo and Parra, 2005).
HSFRC shows an improved performance in the hardened state due to the addition of fibers.
Many types of fibers are available; glass fiber reinforced polymer (GFRP) are preferred than
other type due to high ratio of surface area to weight and high strength properties to unit cost
ratio. However, glass fiber which is originally used in conjunction with cement was found to
be affected by alkaline condition of cement. The alkali resistant glass fiber reinforced polymer
(AR-GFRP), which is used, recently has overcome this defect and can be effectively used in
concrete. (ACI Committee 544.1, 2002).
The use of new form of material such as HSGFRC in practice must be based on actual behavior.
Therefore, the effect of addition of AR-GFRP with various percentages on mechanical behavior
of HSC in compression, split tension and flexure is studied on this research.
1.2 Research Significant
Due to bad and unstable political conditions and the continuing wars in Gaza Strip, strong,
relatively cheap, easy to use and locally available repairing and strengthening material should
be produced for that purposes. For new materials like HSGFRC, studies on mechanical
properties are of paramount important for initializing confidence in engineers and builders.
Most of researches related about the study of strength properties of FRC, were made so far with
steel, carbon, and natural fibers. However, insufficient attempts were made with glass fibers. In
addition, the literature indicates that most of studies are available with normal strength concrete

3
(NSC) reinforced with insufficient proportions of glass fibers. However, this study was
conducted to investigate the mechanical behavior of HSC reinforced with various percentages
of glass fibers. Also, several types of glass fibers are available, the initial studies showed
deterioration of glass fibers due to corrosive alkali environment of the cement paste. The AR-
GFRP, which is used, recently has overcome this defect and can be effectively used in concrete.
1.3 Research Aim and Objectives
The aim of this research is to study the effect of the addition of AR-GFRP with various
proportions on the mechanical behavior of HSC using available materials in the Gaza local
market and to help for use the composite of HSGFRC in practice.
In the present experimental investigation, the following are the objectives:
i. To study the strength characteristics of HSGFRC with various percentages of AR-GFRP
and compare it with plain HSC (without fibers), by performing laboratory tests that are
related to compressive strength, splitting tensile strength, flexural strength, and density.
ii. To compare the mode of failure and cracks pattern between HSGFRC and plain HSC.
iii. To evaluate the strength gain with age of HSGFRC.
1.4 Methodology
In general terms, the following methodology shown in Figure 1.1 has followed
Figure (1.1): Summary of Methodology Flow Chart.
Leterature Review
To conduct comprehensive literature review related to the study.
Materials Selection and Tests
Carfull selection and test of suitable ingredient materials required for the
experimental study.
Mix Proportoning
Determine the relative quantities of materials to obtain the mix design
proportions that achieved the adopted design strength.
Experimental Program
Performing mechanical laboratory tests to achieve the research objectves.
Results and Discussion
Analyzing the experimental output test results to draw conclusions.

4
1.5 Thesis Organization
Chapter 1 (Introduction) This chapter gives general background about HSGFRC, statement
of problem, aim and objectives of the research, and the adopted methodology.
Chapter 2 (Literature Review) This chapter gives general comprehensive literature review
related to HSC and GFRC, in addition of the man constituent materials.
Chapter 3 (Test Program and Laboratory Works) This chapter discusses the materials
properties, adopted mix design, type of laboratory tests and procedures, samples and
specimens that required for tests, and curing condition.
Chapter 4 (Test Results and Discussion)
This chapter includes presentation of the results obtained from testing. Detailed discussion of
results and mechanical properties of each mix also included.
Chapter 5 (Conclusion and Recommendations)
This chapter includes main conclusions and recommendations drawn from this research.

6
Chapter 2: Literature Review
2.1 High Strength Concrete (HSC)
2.1.1 Definition
ACI committee 363 (1997) defined the high strength concrete (HSC) as a concrete with
specified compressive strength for design of 41MPa or greater. Freedman (1970) defined the
HSC as a concrete with the strength of at least 41MPa at 28 days. Iravani and MacGregor (1998)
stated that HSC is typically recognized as concrete with a 28-day cylinder compressive strength
greater than 42MPa. More generally, concrete with a uniaxial compressive strength greater than
that typically obtained in a given geographical region is considered HSC, although the
preceding values are widely recognized. According to Li (2011), Strengths of up to 140MPa
have been used in different applications, laboratories have produced strengths approaching
480MPa.
2.1.2 Benefits and Limitations of Using HSC in Practice
HSC resists loads that cannot be resisted by normal strength concrete (NSC). In addition, it also
increases the strength per unit cost, per unit weight, and per unit volume as well. These concrete
mixes typically have an increased modulus of elasticity, which increases stability and reduces
deflections.
HSC is specified where reduced weight is important or where architectural considerations
require smaller load carrying elements. In high rise buildings, HSC helps to achieve more
efficient floor plans through smaller vertical members and has also often proven to be the most
economical alternative by reducing both the total volume of concrete and the amount of steel
required for a load bearing member. Also, formwork is a large portion of the cost of constructing
a column; smaller column sizes reduce the amount of formwork needed and result in further
cost savings (PCA, 1994).
In general terms, the main benefits of using HSC in practice can be summarized as follow:
1. High compressive and early strength which make HSC resists loads that cannot be
resisted by NSC.
2. High modulus of elasticity, which increases stability and reduces deflections.
3. Enhanced durability characteristics due to extremely low porous volume.
4. Toughness and impact resistance.

7
5. Increases the strength per unit cost, per unit weight, and per unit volume.
6. Reduction in member size, resulting in increase in useable area and direct savings in the
concrete volume saved.
7. Construction of high rise buildings with the accompanying savings in real estate costs
in congested areas.
8. Longer spans and fewer beams for the same magnitude of loading.
9. Reduction in the number of supports and the supporting foundations due to the increase
in spans.
Along with the inherent benefits of HSC, several less clearly defined limitations can
materialize. Most of these limitations are due to a lack of adequate research under field
conditions, although many of the issues are currently being alleviated though the use of
improved admixtures.
In general, the main limitations of using HSC in practice can be summarized as follow:
1. Increased quality control is needed in order to maintain the special properties desired.
2. Careful materials selection is necessary. High quality materials must be used. These
materials may cost more than materials of lower quality.
3. Low water to cementitious materials ratios require special curing requirements.
4. Since serviceability conditions such as deflection can control design, increased capacity
may not be fully utilized.
5. In concrete plant and at delivery site, additional tests are required. This increases the
cost.
2.1.3 Application of HSC
Accordance to ACI committee 363 (2010), the largest application of HSC in buildings has been
for columns of high rise structures. Since 1972, more than 30 buildings in the Chicago area
have been constructed with columns having a design compressive strength of 62MPa. Also
there have been many applications of HSC in pre-cast pre-stressed bridge girders. In tall
building structures, the load plays a very severe effect on structural members, especially the
columns near the ground level which are required to resist a tremendous axial load which is
mainly due to the accumulated load from all the floors above.
It can be imagined that there will be no space in the ground level if NSC is used for a very tall
building (i.e. more than 60 story). Hence, it is a normal trend to adopt HSC in tall building

8
construction due to its advantages (ACI Committee 363, 2010). According to PCA (1994)
concrete compressive strength of 131 MPa have already been batched by a few ready mix
producers, and placed by contractors in some major structures.
2.1.4 Materials Selection of HSC
The selection of suitable cementitious materials for concrete structures depend on the type of
structure, the characteristics of the aggregates, material availability, and method of
construction. The varieties of HSC do not require exotic materials or special manufacturing
processes, but will require materials with more specific properties than conventional concretes.
As the target strength of concrete increases, it becomes increasingly less forgiving to variability,
both material and testing related. Compared with conventional concrete, variations in material
characteristics, production, handling, and testing will have a more pronounced effect with HSC.
Therefore, as target strengths increase, the significance of control practices intensifies
(Caldarone, 2008).
Evaluating cement and other cementitious materials, chemical admixtures, and aggregates from
various potential sources in varying proportions will indicate the optimum combination of
materials. Variations in the chemical composition and physical properties of any of these
materials will affect the concrete compressive strength (ACI Committee 211.4, 2008).
The supplier of HSC should implement a program to ensure uniformity and acceptance tests for
all materials used in the production of HSC. In general term, the composition of HSC usually
consists of cement, water, fine sand, water reducing admixtures, and supplementary
cementitious materials.
However, the key elements of HSC can be summarized as follows:
1. Low water-to-cement ratio.
2. High dosage of water reducing admixtures (superplasticizers).
3. Large quantity of supplementary cementitous material, i.e. silica fume, fly ash (and/or
other fine mineral powders).
4. Smaller aggregates.
2.1.4.1 Cement
Almost any portland cement type meeting the compositional requirements of ASTM C 150 can
be used to obtain concrete with satisfactory workability having compressive strength up to
about 60 MPa.

9
However, within a given cement type, different brands will have different strength development
characteristics because of the variations in compound composition and fineness that are
permitted by ASTM C 150 (ACI Committee 363, 2010).
2.1.4.2 Supplementary Cementitious Materials (SCMs)
Supplementary cementitious materials (SCMs) or mineral admixtures have undeniably played
a significant role in the evolution of HSC. SCMs are important materials that contribute to the
properties of concrete when used in conjunction with portland cement by reacting either
hydraulically or pozzolanically. Pozzolans are siliceous or alumino-siliceous materials that, by
themselves, possess no hydraulic (cementing) value, but will, in finely divided form and in the
presence of water, chemically react with calcium hydroxide to form compounds having
cementitious properties. Examples are fly ashes, silica fumes, and slag cement (Caldarone,
2008).
The major difference between conventional concrete and HSC is essentially the use of mineral
admixtures in the latter. Fly ash, silica fume, and slag, have been the most commonly used
SCMs in HSC (Steven, 2003).
Mineral admixtures like fly ash and silica fume act as puzzolonic materials as well as fine fillers,
thereby the microstructure of the hardened cement matrix becomes denser and stronger.
The use of silica fume fills the space between cement particles and between aggregate and
cement particles. When combined with cement, these materials have been used for
economically producing binary concretes with specified compressive strengths of at least 70
MPa. For higher strengths, particularly above 80MPa, ternary mixtures containing very fine,
paste densifying pozzolans such as silica fume, metakaolin, or ultra-fine fly ash can be quite
advantageous (Caldarone, 2008). Table 2.1 present the chemical analysis for normal portland
cement and supplementary cementitious materials.

10
Table (2.1): Chemical Analysis for Normal Portland Cement and Supplementary
Cementitious Materials (Nawy, 2008).
Normal Portland
Cement (%)
Microsilica
(%)
Fly Ash,
Class F
(%)
Fly Ash,
Class C
(%)
Slag,
Grade
100 (%)
Silica (SiO2) 20.13 94–98 49.00 40.40 27–38
Calcium oxide (CaO) 63.44 0.08–0.30 5.00 25.40 34–43
Magnesium oxide
(MgO)
2.86 0.30–0.90 1.50 4.70 7–15
Ferric oxide (Fe2O3) 2.96 0.02–0.15 6.00 5.90 .2–1.6
Aluminum oxide (Al2O3) 5.10 0.10–0.40 26.00 17.00 7–12
Sulfur trioxide (SO3) 3.00 — 0.50–0.60 2.75 .15–.23
Potassium oxide (K2O) 1.12 0.20–0.70 0.80–0.90 0.27 —
Sodium oxide (Na2O) 0.30 0.10–0.40 0.25 1.60 .6–.9
Loss on ignition 0.80 0.80–1.50 3.50 0.43 —
Silicon carbide (SiC) — 0.20–0.10 — — —
Carbon (C) — 0.20–1.30 — — .78
C4AF 9.00 — — — 8.89
C3S 57.40 — — — 54.00
C2S 14.40 — — — 19
C3A 8.50 — — — 8
Blaine (cm2
g) 3782 100,000+ — — 5360
2.1.4.3 Water Reducing Admixtures
Water reducing admixtures are used to reduce the quantity of mixing water required to produce
concrete of a certain slump, reduce water/cement ratio, reduce cement content, or increase
slump. Water reducers are classified broadly into two categories: normal and high range water
reducers. The normal range water reducers (NRWR) are called plasticizers, while the high range
water reducers (HRWR) are called superplasticizers (Steven et al. 2003).
NRWR meeting the specifications of ASTM C 494 Type A, will provide strength increases
without altering rates of hardening and reduce the water demand by 5–10%. Lignosulfonate
salts of sodium and calcium are an example of NRWR. Their selection should be based on
strength performance (ACI Committee 363, 2010).

11
Increases in dosage above the normal amounts will generally result in significant side effects,
such as decreasing on strength and retardation with some binder blends especially at lower
temperatures (ACI Committee 363, 2010).
HRWR meeting the specifications for superplasticizers which are detailed in ASTM C 494 as
Type F for HRWR with normal set times or Type G for HRWR with retarded setting times.
HRWR are most effective in concrete mixtures that are rich in cement and other cementitious
materials. HRWR help in dispersing cement particles, and they can reduce mixing water
requirements by more than 30%, thereby increasing concrete compressive strengths (ACI
Committee 211.4, 2008).
Reduction in water/cement ratio is against the different water reducers admixtures (See Figure
2.1). While NRWR allow 5-12% reduction of water, HRWR melamine/naphthalene based
admixtures reduces water 16-25 %, and HRWR polycarboxylate ether polymer based admixture
reduces water 20 to 35% (Nawy, 2008).
Figure (2.1): Effect of Superplasticizers on Slump Loss (Mindess, 1988).
In general, according to Collepardi (1984) and Nawy (2008), the main objectives for using
water reducing admixtures are the following:
1. Reduce the water/cement ratio for higher strengths and improved durability while
maintaining the same workability and cement content.
2. Reduce the paste portion of the matrix, water, and cement, for the purpose of reducing
shrinkage and heat development in massive placements; workability, strength, and
durability are maintained at a comparative level.

12
3. Keep water and cement the same and maintain the same strength and durability but
improve flow and workability.
2.1.4.4 Aggregates
In HSC, careful attention must be given to aggregate size, shape, surface texture, mineralogy,
and cleanness. Cubically shaped crushed stone with a rough surface texture appears to produce
the highest strength. For each source of aggregate and concrete strength level there is an
optimum size aggregate that will yield the most compressive strength per unit of cement.
The quantity of coarse aggregate (CA) in HSC should be the maximum consistent with required
workability. Because of the high percentage of cementitious material in HSC, an increase in
CA content beyond values recommended in standards for normal strength mixtures is necessary
and allowable (Steven et al. 2003).
For optimum compressive strength with high cement content and low water-cement ratios the
maximum size of CA should be kept to a minimum, at 12.5 mm or 9.5 mm. The strength
increases were caused by the reduction in average bond stress due to the increased surface area
of the individual aggregate. Smaller aggregate sizes are also considered to produce higher
concrete strengths because of less severe concentrations of stress around the particles, which
are caused by differences between the elastic moduli of the paste and the aggregate. Gradation
of CA within ASTM limits makes very little difference in strength of HSC. Optimum strength
and workability of HSC are attained with a ratio of CA to FA above that usually recommended
for NSC. Also, due to the already high fines content of HSC mixes, use of ordinary amounts of
CA results in a sticky mix (Rashid and Mansur, 2009).
In high strength concretes, the strength of the aggregate itself and the bond or adhesion between
the paste and aggregate become important factors. Tests have shown that crushed stone
aggregates produce higher compressive strength and modulus of elasticity in concrete than
gravel aggregate using the same size aggregate and the same cementing materials content, this
is probably due to a superior aggregate to paste bond when using rough, angular, crushed
material. Smoother faced, uncrushed gravel may be used to produce strengths of up to about 70
MPa but it does not have the bond strength necessary to produce higher strengths (Nawy, 2008).
According to ACI 363R (2010), Rashid and Mansur (2009), Steven et al. (2002), and Peterman
and Carrasquillo (1986), fine aggregates (FA) with a rounded particle shape and smooth texture
have been found to require less mixing water in concrete and for this reason are preferable in

13
HSC. The grading of the FA used in HSC -typically contain such high contents of cementitious
materials- is relatively unimportant. However, it is sometimes helpful to increase the fineness
modulus (FM) as the lower FM of FA can give the concrete a sticky consistency (i.e. making
concrete difficult to compact) and less workable fresh concrete with a greater water demand.
Therefore, sand with a FM of about 3.0 is usually preferred for HSC.
2.1.4.5 Mixing Water
The requirements for water quality for HSC are no more stringent than those for conventional
concrete. Usually, water for concrete is specified to be of potable quality. This is certainly
conservative but usually does not constitute a problem since most concrete is produced near a
municipal water supply. The single most important variable in achieving HSC is the water-
cement ratio. HSC produced by conventional mixing technologies are usually prepared with
water-cement ratios in the range of 0.22 to 0.40, and their 28 days compressive strength is about
60 to 130 MPa when normal density aggregates are used (Rashid and Mansur, 2009).
2.1.5 Microstructure of HSC
The microstructure of concrete can be described in three aspects, namely composition of
hydrated cement paste, pore structure and interfacial transition zone. The hydrated cement paste
is in fact the hydration products when cement is reacted with water which is referred to as
cementitious calcium silicate hydrate (C-S-H) gel. The pore structure refers to the gel pores,
capillary pores and voids, as well as their connections within the hardened concrete. The
interfacial transition zone refers to the boundaries between the cement paste, and aggregates or
particles of admixtures. The composition of NSC is relatively simple, which consists of cement,
aggregate and water (See Figure 2.2) (Buyukozturk and Lau, 2007).
Figure (2.2): Microstructure of NSC (Buyukozturk and Lau, 2007).

14
In order to improve the concrete performance, the following three aspects are considered:
1. The hydrated cement paste should be strengthened. This can be achieved by reducing
the gel porosity inside the paste. By adding suitable admixture (e.g. silica fume)
2. The porosity in concrete should be lowered. This can be achieved by adding suitable
fine admixture which can fill up the empty space inside concrete.
3. The interfacial transition zone should be toughened. This can be achieved by lowering
the locally high water-to-cement ratio and by improving the particle packing in this
zone. Fine admixtures, like silica fume or fly ash, is added as well to improve the particle
packing in the interfacial transition zone.
It is noticed that in order to improve the concrete performance, admixture is a necessary
component which must be added into the design mix in order to generate HSC. Hence, its
microstructure is quite different from that of NSC. Figure 2.3 shows the microstructure of HSC.
Figure (2.3): Microstructure of HSC (Buyukozturk and Lau, 2007).
2.1.6 Mix Proportion
Concrete mix proportions for HSC have varied widely depending upon many factors. The
strength level required, test age, material characteristics, and type of application have
influenced mix proportions.
The main requirements for successful and practical HSC are a low water/cement ratio combined
with good workability characteristics. In the absence of a standard mix design method, the
importance of trial mixes in achieving the desired concrete performance is increased (Newman
and Choo, 2003).
Thus, the trial mixture approach is best for selecting proportions for HSC. Table.2.2 shows
some mixture proportions and properties of commercially available HSC.

15
To obtain high strength, it is necessary to use a low water to cementing materials ratio and a
high cement content. The water requirement of concrete increases as the fine aggregate content
is increased for any given size of coarse aggregate. Because of the high cementing materials
content of these concretes, the fine aggregate content can be kept low. However, even with
well-graded aggregates, a low water-cementing materials ratio may result in concrete that is not
sufficiently workable for the job (Steven et al. 2003).
Table (2.2): Mixture Proportions and Properties of Commercially Available HSC (Steven et
al. 2003).
Units per m3
Mix number
1 2 3 4 5 6
Cement, Type I, kg 564 475 487 564 475 327
Silica fume, kg — 24 47 89 74 27
Fly ash, kg — 59 — — 104 87
Coarse aggregate SSD
(12.5 mm crushed
limestone), kg
1068 1068 1068 1068 1068 1121
Fine aggregate SSD, kg 647 659 676 593 593 742
HRWR Type F, liters 11.6 11.6 11.22 20.11 16.44 6.3
Retarder, Type D, liters 1.12 1.05 0.97 1.46 1.5 —
Water to cementing
materials ratio
0.28 0.29 0.29 0.22 0.23 0.32
Fresh concrete properties
Slump, mm 197 248 216 254 235 203
Density, kg/ m3 2451 2453 2433 2486 2459 2454
Air content, % 1.6 0.7 1.3 1.1 1.4 1.2
Compressive strength, 100 x 200-mm moist-cured cylinders
7 days, MPa 67 71 71 92 77 63
28 days, MPa 79 92 90 117 100 85
56 days, MPa 84 94 95 122 116 —
91 days, MPa 88 105 96 124 120 92
Modulus of elasticity in compression, 100 x 200-mm moist-cured cylinders
91 days, GPa 50.6 49.9 50.1 56.5 53.4 47.9
Drying shrinkage, 75 by 75 x 285-mm prisms
7 days, millionths 193 123 100 87 137 —
28 days, millionths 400 287 240 203 233 —
90 days, millionths 573 447 383 320 340 —

16
The materials proportion of HSC is different from NSC. As described before, for the aggregate
to be used in making HSC, it is better to choose one with a high crushing strength, if possible.
The maximum size of aggregate is usually kept to be minimum. The limitation on maximum
aggregate size is to reduce the influence of the transition zone and to get a more homogeneous
material. The moisture content in aggregates has to be carefully calculated to make sure the
right water/cement ratio is secured. The cement content is usually high, in a range of 400–600
kg/m3
leads to a more homogenous concrete structure. Moreover, water-reducing admixtures
and mineral admixtures such as fly ash, slag, and silica fume are incorporated in the mix for
HSC (Li, 2011).
Requirement of different ingredient materials required for producing HSC can be summarized
as stated in Table 2.3 adapted from Rashid and Mansur (2009).
Table (2.3): Requirements of Ingredient Materials for HSC (Rashid and Mansur, 2009).
Material Requirements
Cement
- Portland cement.
- Higher content.
Water - w/b ratio 0.22 to 0.40.
Fine
aggregate
- Higher FM (around 3.0).
- Smaller sand content or coarser sand.
- Grading is not critical for concrete strength.
Coarse
aggregate
- Smaller maximum size (10 – 12 mm) is preferred.
- Angular and crushed with a minimum flat and elongated particle.
- Type of aggregate depending on the concrete strength targeted.
- Gradation within ASTM limits has little effect on concrete strength.
- Higher CA/FA ratio than that for normal strength concrete.
Admixtures
(chemical and
mineral)
- Type of admixture depends on the property of the concrete to be improved.
- Reliable performance on previous work can be considered during selection.
- Optimum dosage.
Overall basic
considerations
- Quality materials
- Improved quality of cement paste as well as aggregates.
- Denser packing of aggregates and cement paste.
- Improved bond between aggregate surface and cement paste.
- Minimum numbers as well as smaller sizes of voids in the paste.

17
2.2 Fiber Reinforced Concrete (FRC)
2.2.1 General Background
The application of cement concrete is limited due to the characteristics of brittle failure; this
can be overcome by the inclusion of a small amount of short and randomly distributed fibers
such as steel, glass, synthetic and natural. Such concrete can be practiced where there is a
weakness of concrete such as less durability, high shrinkage cracking, etc. (Li, 2011).
Concrete has some deficiencies such as low tensile strength, low post cracking capacity, and
brittleness, highly porous, susceptible to chemical and environmental attack. The above
deficiencies of plain concrete are overcome in the new materials which have unique
characteristics, which make them highly susceptible to any environment. Fiber Reinforced
concrete (FRC) is one of them and relatively a new composite material in which concrete is
reinforced with short discrete uniformly distributed fibers so that it will improve many
engineering properties such as flexural strength, shear strength and resistance to fatigue, impact
and eliminate temperature and shrinkage cracks (Harle, 2014).
Fibers made from steel, glass, and natural materials (such as wood cellulose) are available in a
variety of shapes, sizes, and thicknesses; they may be round, flat, crimped, and deformed with
typical lengths of 6 mm to 150 mm and thicknesses ranging from 0.005 mm to 0.75 mm (see
Figure 2.4) (Steven et al. 2003).
Figure (2.4): Steel, Glass, Synthetic and Natural Fibers (Steven et al. 2003).

18
The main objectives of the modern engineer in attempting to modify the properties of concrete
by the inclusion of fibers are as follows:
1. To improve the rheology or plastic cracking characteristics of the material in the fresh
state or up to about 6 hours after casting.
2. To improve the tensile or flexural strength.
3. To improve the impact strength and toughness.
4. To control cracking and the mode of failure by means of post cracking ductility.
5. To improve durability.
It is generally accepted that the inclusion of any type of short fiber in a three-dimensional
random fiber distribution at practical fiber volumes will not significantly alter the load at which
cracking occurs in hardened concrete. Therefore, the main benefits of the inclusion of fibers in
hardened concrete relate to the post cracking state. In this context, it is worth considering an
understanding of the word ‘reinforcement’. If it is assumed that any loadbearing capacity
greater than zero is described as reinforcement, then all types of fibers at any volume addition
will reinforce hardened concrete. However, if we consider ‘reinforcement’ to mean carrying a
force in excess of the force required to crack the concrete, then less than about 0.4 percent by
volume of short three dimensional random fibers will not generally provide load capacity in
excess of the cracking load in beams and slabs, and two or three times this fiber volume is
required to increase the load capacity in uniaxial tension (Newman and Choo, 2003).
According to Li (2011), the properties of FRC can be influenced by many parameters, such as
fiber type, fiber amount, and matrix variation. In this section, these parameters are discussed as
follow:
(a) Fiber type: The fiber type can be viewed with different criteria. From the size point of view,
fibers can be classified into macro and microfibers. The diameter of macrofibers is in the range
of 0. 2 to 1 mm and for microfibers is in a range of a few to tens of micrometers. Basically,
microfibers are efficient in restraining micro cracks and macrofibers in restraining macroscopic
cracks. From the materials point of view, the fibers that are commonly used in FRC are carbon,
glass, polymeric (acrylic, aramid, nylon, polyester, polyethylene, polypropylene, and poly vinyl
alcohol), natural (wood cellulose, sisal, coir or coconut, bamboo, jute, akwara, and elephant
grass), and steel (high tensile and stainless). Different types of fibers have different values of
Young’s modulus, different tensile strength, different surface texture, and different elongation
ability, as can be seen in Table 2.4 adapted from Steven et al. (2003).

19
Table (2.4): Properties of Different Types of Fibers (Steven et al. 2003).
Fiber type
Relative density
(specific gravity)
Diameter,
µm
Tensile
strength, MP
Modulus of
elasticity, MPa
Strain at
failure, %
Steel 7.80 100-1000 500-2600 210,000 0.5-3.5
Glass
E 2.54 8-15 2000-4000 72,000 3.0-4.8
AR 2.70 12-20 1500-3700 80,000 2.5-3.6
Synthetic
Acrylic 1.18 5-17 200-1000 17,000-19,000 28-50
Aramid 1.44 10-12 2000-3100 62,000-120,000 2-3.5
Carbon 1.90 8-0 1800-2600
230,000-
380,000
0.5-1.5
Nylon 1.14 23 1000 5,200 20
Polyester 1.38 10-80 280-1200 10,000-18,000 10-50
Polyethylene 0.96 25-1000 80-600 5,000 12-100
Polypropylene 0.90 20-200 450-700 3,500-5,200 6-15
Natural
Wood cellulose 1.50 25-125 350-2000 10,000-40,000
Sisal 280-600 13,000-25,000 3.5
Coconut 1.12-1.15 100-400 120-200 19,000-25,000 10-25
Bamboo 1.50 50-400 350-500 33,000-40,000
Jute 1.02-1.04 100-200 250-350 25,000-32,000 1.5-1.9
Elephant grass 425 180 4,900 3.6

20
(b) Fiber volume ratio: Another important factor that greatly influences FRC properties is the
fiber volume fraction ratio, which is defined as the ratio of the fiber volume to the total volume
of FRC. At low fiber volume ratio, the addition of fibers mainly contributes to the energy-
consuming property. At a higher fiber volume fraction ratio, the tensile strength of the matrix
can be enhanced and the failure mode can be changed.
(c) Matrix variation: The properties of the matrix influence the bond with the fibers and the
mechanical properties of FRC, such as ultimate tensile strength. The FRC matrix can be
modified using mineral admixtures, such as fly ash, slag, silica fume, and metakaolin. It can
also be modified by adding some water soluble polymers. Changing the matrix composition
can increase the bond properties with the fibers, improve the matrix toughness, and enhance the
matrix tensile strength and, hence, the mechanical properties of FRC.
According to Li (2011), the functions of the fibers in cement based composites can be classified
into two categories: shrinkage crack control and mechanical property enhancement. For
shrinkage crack control, usually small amounts of low modulus and low strength fibers are
added to restrain the early age shrinkage and to suppress shrinkage cracking. For mechanical
property enhancement, fiber reinforcement has been employed in various concrete structures to
improve flexural performance, to increase impact resistance, and to change the failure mode.
The amount of fiber added has a significant influence on the mechanical properties and failure
mode of FRC. In conventional applications of FRC, usually with a low volume fraction of
fibers, the function of the fibers is apparent only after a major crack has formed in the
composite. Although there is still only one major crack and the overall behavior of the
composites is still characterized by strain softening after the peak load is reached, the
incorporation of fibers leads to a significant increase in the total energy consumption and overall
toughness of the composites, represented by the area under a stress–strain or load–displacement
curve, as shown in Figure 2.5. In such cases, as long as there is no fiber fracture, the fiber
de-bonding and pullout process can consume a great amount of energy. On the other hand, with
an increase in fiber volume fraction, it is possible that microcracks formed in the matrix will be
stabilized due to the interaction between the matrix and fibers through bonding, hence
postponing the formation of the first major crack in the matrix. Thus, the apparent tensile
strength of matrix can be increased.

21
Figure (2.5): Load–Displacement Curves (Li, 2011).
Moreover, when a sufficient volume fraction of small diameter steel, glass, or synthetic fibers
is incorporated into the cement based matrix, the fiber-matrix interaction can lead to strain
hardening and multiple cracking behavior, changing the failure mode from quasi brittle to
ductile. As a result, not only the composites toughness, but also the matrix tensile strength can
be significantly improved. One of the mechanisms in slowing down growth of a transverse
crack in unidirectional fiber composites can be attributed to development of longitudinal
cylindrical shear micro cracks located at the boundary between the fiber and the bulk matrix,
allowing the fibers to de-bond while transferring the force across the faces of the main crack.
In addition to enhancing the toughness and tensile strength, the addition of fibers can also
improve the bending resistance of cement based composites (Li, 2011).
2.2.2 Glass Fiber Reinforced Concrete (GFRC)
Much of the original research performed on glass fiber reinforced concrete (GFRC) took place
in the early l960s. This work used conventional borosilicate glass fibers (E-Glass) and soda-
lime-silica glass fibers (A-Glass). However, Glass compositions of E-glass and A-glass, used
as reinforcement, were found to lose strength quickly due to the very high alkalinity (PH of
12.5) of the cement based matrix. Consequently, early A-glass and E-glass composites were
unsuitable for long term use. Continued research resulted in the development a new alkali
resistant-glass fiber reinforced polymer (AR-GFRP) that provided improved long term
durability. The chemical compositions and properties of selected glasses are listed in Tables 2.5
and 2.6, respectively (ACI Committee 544.1, 2002).

22
Table (2.5): Chemical Composition of Selected Glasses, (Percent) (ACI Committee 544.1,
2002).
Component A-glass E-glass AR-glass
SiO2 73.0 54.0 61.0
Na2O 13.0 — 15.0
CaO 8.0 22.0 —
MgO 4.0 0.5 —
K2O 0.5 0.8 2.0
Al2O3 1.0 15.0 —
Fe2O3 0.1 0.3 —
B2O3 — 7.0 —
ZrO2 — — 20.0
TiO2 — — —
Li2O — — 1.0
Table (2.6): Properties of Selected Glasses (ACI Committee 544.1, 2002).
Property A-Glass E-Glass AR-Glass
Specific gravity 2.46 2.54 2.74
Tensile strength, ksi 450 500 355
Modulus of elasticity, ksi 9400 10,400 11,400
Strain at break, percent 4.7 4.8 2.5
Metric equivalent: 1 ksi = 1000 psi = 6.895 MPa
AR-GFRP shown in Figure 2.6 containing 16% - 20% zirconia (ZrO2), which protects the fibers
from high alkali attack was successfully formulated (see Figure 2.7). Glass fiber is available in
continuous or chopped lengths. Fiber lengths of up to 35 mm are used in spray applications and
25 mm lengths are used in premix applications.
Compressive strength, flexural strength and split tensile strength for these AR-GFRP are more
as compared to other glass fibers (ACI Committee 544.1, 2002).
Glass fiber has high tensile strength (2 – 4 GPa) and elastic modulus (70 – 80 GPa) but has
brittle stress-strain characteristics (2.5 – 4.8% elongation at break) and low creep at room
temperature. Claims have been made that up to 5% glass fiber by volume has been used
successfully in sand-cement mortar without balling (Concrete institute, 2013).

23
Figure (2.6): Chopped Strands AR-GFRP (Nippon Electric Glass Co. Ltd. 2007).
Figure (2.7): Alkali Resistivity of Glass Fiber and ZrO2 Content (Nippon Electric Glass Co.
Ltd. 2007).
2.2.3 Applications of GFRC
By far, the single largest application of GFRC has been the manufacture of exterior building
facade panels. Since the introduction of AR-GFRP in the 1970s, growth in applications has
been appreciable. Over 60 million square feet of GFRC architectural cladding panels have been
erected from 1977 to 1993 (ACI Committee 544.1, 2002).
It is suitable for use in direct spray techniques and premix processes and has been used as a
replacement for asbestos fiber in flat sheet, pipes and a variety of precast products. GFRC
products are used extensively in agriculture; for architectural cladding and components; and for
small containers (Concrete institute, 2013).

24
In Gaza strip, the GFRC is recently used in large scale as an architectural material for building
faces. However, because of the lack of data on long term durability, GFRC has been confined
to non-structural uses where it has wide architectural applications in Gaza strip.
2.3 High Strength Fiber Reinforced Concrete (HSFRC)
HSC is brittle and has very steep descending branch of the stress-strain curve. These causes
explosive failure after peak and make it difficult to get descending part because the strain
change is small. To overcome brittle characteristic of HSC, fiber has been used. Fiber has been
used to reinforce the brittle materials since ancient times, such as straw in sunbaked bricks and
horsehair in reinforced plaster. Nowadays, fibers have been produced from steel, plastic, and
glass in various shapes and sizes. The capacity of a structure to absorb energy, with acceptable
deformation and without failure is essential in seismic design. So sufficient ductility is needed
and can be achieved using HSFRC. Currently, steel fiber is used widely in HSC, including
highway, airport pavement, and hydraulic structures. However, sufficient literature is
unavailable on the structural behavior of HSC reinforced with glass fiber (Lee, 2002).
According to Buyukozturk and Lau (2007), it is known that the ductility can be improved by
applying a confining pressure on HSC. Besides confinement, the ductility of HSC can be
improved by altering its composition through the addition of fibers in the design mix. The
conventional FRC made by adding fibers in NSC only exhibits an increase in ductility compared
with the plain matrix, whereas HSFRC made by adding fibers in HSC exhibits substantial strain
hardening type of response which leads to a large improvement in both strength and toughness
compared with the plain matrix as shown in Figure 2.8. Because of this increased improvement
in terms of ductility, HSFRC is referred to as ultra-ductile concrete as well. In order to examine
the scope of HSFRC, it is useful to identify two performance related parameters: elastic limit,
and strain hardening response. The elastic limit refers to the point of first cracking. The strain
hardening response refers to the plastic region. Traditionally, it was assumed that the elastic
limit of FRC is influenced by the tensile strength of the matrix itself and that the fibers primarily
control deformation after cracking. Recently, it was reported that fibers can enhance the elastic
limit provided that they effectively bridge the matrix microcracks. The effectiveness of the
fiber-bridging action will depend on volume fraction, length, diameter, and distribution of
fibers, as well as the properties of the fiber matrix.

25
It was found that the inherent tensile strength and strain capacity of the matrix itself was
enhanced when small fibers were used. When 4% (by volume) of fibers were added, the first
cracking, indicating the elastic limit, was observed at about 30% of the maximum tensile load
(Buyukozturk and Lau, 2007).
Figure (2.8): Mechanical Behavior of FRC Compared with Plain Matrix (Buyukozturk and
Lau, 2007).
Strain hardening is caused by the process of multiple cracking which occurs after the start of
the first crack. In the post-peak region, the number of cracks remains constant while crack
widths increase. Failure is obtained by fiber pullout and fiber rupture. Uniform distribution of
the fibers affects the stress distribution in the matrix and hence, higher stress is required to
propagate the crack. After the first crack starts, distributed multiple matrix cracking follows.
The width of the cracks is usually between 1-3 mm. The multiple cracking process exhibits a
ductile behavior which causes strain hardening phenomenon of the HSFRC. To increase the
elastic limit of HSFRC and achieve strain hardening response, the volume content of the fibers
should be increased as well. Meanwhile, the fibers should be closely spaced and well
distributed. It was found that the decreasing fiber length significantly enhances the tension and
flexure response of HSFRC. In general, short fibers are advantageous because they are easier
to handle during mixing and result in less broken fibers and better dispersion. It was also found
that the distribution of the smaller fibers was more homogeneous than that of larger fibers
(Buyukozturk and Lau, 2007).

26
2.4 Concluding Remarks
Through surveying the literature, concluding remarks that are related and could help on this
research work can be drawn as follow:
i. In HSC, materials selection and mix proportioning can consider the most significant
stage to get higher strength.
ii. In the absence of a standard mix design method for HSC, the importance of trial and
error basis in achieving the desired concrete performance is increased.
iii. Several types of fiber are existed; glass fiber can prefer than other type due to high ratio
of surface area to weight and high strength properties to unit cost ratio.
iv. Glass fiber which is originally used in conjunction with cement was found to be affected
by alkaline condition of cement. The alkali resistant glass fiber reinforced polymer (AR-
GFRP), which is used, recently has overcome this defect and can be effectively used in
concrete.
v. To understand how can fiber work and enhance the mechanical behavior of HSC; two
level of cracks should be defined, micro and macro level. The micro level starts when
the first micro crack occurs (at elastic limit), and then in the plastic region multiple
cracking occur. In the macro level, the number of cracks remain constant while crack
width increased and propagate until formation of the first major crack in the matrix that
cause the failure.
vi. Fiber can enhance the mechanical behavior by control and stabilized of micro cracks
and postponing the crack transformation from micro to macro, hence, increase the
energy absorption capacity result in enhancing the mode of failure. At macro level fiber
can make a bridge action to control and stabilized macro cracks propagation and
postponing the formation of the first major crack in the matrix that cause the failure.
Hence increase the tensile strength and enhance the mode of failure from brittle to quasi-
ductile.
vii. While plain HSC have a very brittle behavior at failure, HSGFRC could have all
advantages of HSC and GFRC. By using this form of concrete technology, the problems
and disadvantages of each type of concrete alone can be overcome.

Chapter 3
Test Program and
Laboratory Works

28
Chapter 3: Test Program and Laboratory Works
3.1 General Description
This chapter presents the experimental program and the materials selection and its properties
used to produce HSGFRC associated with this research work. The laboratory investigation
consisted of testing strength properties which included compressive strength tests, splitting
tensile strength tests, flexural strength tests, and unit weight tests was carried out to achieve the
aim of this research. The test procedures, details and equipment used to assess concrete
properties are illustrated in the following sections.
3.2 Test Program
In order to achieve the research objectives, the test program illustrated in Table 3.1 was carried
out. Tests which include compressive strength test, splitting tensile strength test, flexural
strength test, and density were carried out to evaluate the strength properties of HSGFRC. Five
fiber percentages were chosen, typically, 0.0, 0.3, 0.6, 0.9, and 1.2 by weight of cement led to
five mixtures including the reference mixtures (without fibers) made to evaluate the effect of
AR-GFRP on the mechanical behavior of plain HSC. These percentages were chosen in a range
that can give better observation and evaluation on the mechanical behavior of HSGFRC when
contain a small amount of fiber and when contain a large amount of fiber. Each test is
determined at ages 7 and 28 days, except for the density which determined at 28 days. 150 x150
x150 mm cube specimens were prepared for compressive strength test and density. The test of
compressive strength was made according to BS 1881, Part 108 (1993) standard test method.
150 x 300 mm cylinder specimens were prepared for splitting tensile strength test in accordance
to ASTM C496 (2004) standard test method. 100 x 100 x 500 mm prism specimens were
prepared for flexural strength test in accordance to ASTM C293 (2002). For each mix, three
specimens were made for testing for each test for period of 28 days and two specimens were
made for testing for each test for period of 7 days, the mean value of the specimens was
considered as the test result of the experiment. A detailed description of test procedures,
equipment, and curing conditions will be discussed in the following sections.

29
Table (3.1): Test Program.
Test
Mixture
Designation
M50 F0 M50 F1 M50 F2 M50 F3 M50 F4
% GFRP by
Weight of Cement
0.0 0.3 0.6 0.9 1.2
CompressionTestand
Density
Ages (day) 7 28 7 28 7 28 7 28 7 28
NO. of Specimens 2 3 2 3 2 3 2 3 2 3
Specimen Type and
Dimension (mm)
Cube
150 x150
x150
Cube
150 x150
x150
Cube
150 x150
x150
Cube
150 x150
x150
Cube
150 x150
x150
SplittingTensile
StrengthTest
Ages (day) 7 28 7 28 7 28 7 28 7 28
NO. of Specimens 2 3 2 3 2 3 2 3 2 3
Specimen Type and
Dimension (mm)
Cylinder
150 x 300
Cylinder
150 x 300
Cylinder
150 x 300
Cylinder
150 x 300
Cylinder
150 x 300
FlexuralStrengthTest
Ages (day) 7 28 7 28 7 28 7 28 7 28
NO. of Specimens 2 3 2 3 2 3 2 3 2 3
Specimen Type and
Dimension (mm)
Prism
100 x 100
x 500
Prism
100 x 100
x 500
Prism
100 x 100
x 500
Prism
100 x 100 x
500
Prism
100 x 100 x
500
3.3 Materials Selection and Properties
HSGFRC constituent materials used in this research include ordinary portland cement, course
aggregate, fine aggregate, normal range water reducer (NRWR), in addition to GFRP.
Proportions of these constituent materials have been chosen carefully in order to optimize the
packing density of the mixture.
3.3.1 Cement
On this research, ordinary portland cement CEM II 42.5R produced from local market was used
for the production of HSGFRC.

30
The cement met the requirements of ASTM C150 (2007) specifications. Table 3.2 shows the
physical properties of cement according to manufacturer data sheet.
Table (3.2): Physical Properties of Cement According to Manufacturer Data Sheet.
Properties Cement
ASTM C150-07
Requirements
Fineness (cm2/gm.) 3500 Min. 2800
Setting Time, Vicat Test (hr:min)
Initial 2 hr 5 min ≥ 45 min
Final 5 hr ≤ 375 min
Mortar Compressive Strength (MPa)
3 days 25 > 10
28 days 58 > 42.5
3.3.2 Coarse Aggregates
According to the local market surveying, two types of coarse aggregate are used on this
research, natural crushed lime stone of 12.5 mm nominal maximum size was used as coarse
aggregate in the mix proportions. Table 3.3 illustrate the sieve analysis and the physical
properties of these types.
Table (3.3): Sieve Analysis and Physical Properties of Coarse Aggregate Types.
Sample Description Type (1) Type (2)
Sieve Size (mm) % Passing % Passing
25 100 100
19 100 100
12.5 91.11 100
9.5 32.28 96.12
4.75 3.018 31.33
2.36 0.40 6.46
1.18 0.12 2.11
Dry unit weight (Kg/m3) 1504 1488
Dry specific gravity 2.63 2.61
Saturated specific gravity 2.67 2.64
Absorption % 2.4% 3.1%

31
To achieve the ASTM C33 (2003) standard requirements for coarse aggregate, a mix design of
these two types by 70% of type 1 and 30% of type 2 was prepared as shown in Table 3.4 and
Figure 3.1
Table (3.4): Sieve Analysis of Combined Coarse Aggregate According to ASTM C33 (2003) and
Physical Properties.
Sieve Size (mm) %Passing %Passing (Min.) %Passing (Max.)
19.00 100.00 100 100
12.50 94.67 90 100
9.50 57.82 40 70
4.75 14.35 0 15
2.36 2.83 0 5
Unit Weight (KG/m3) 1499.2
Dry Specific Gravity 2.624
Saturated Specific Gravity 2.661
Moisture Content % 0.14
Absorption % 2.60
Figure (3.1): Coarse Aggregate Sieve Analysis According to ASTM C33 (2003).
-5.00
15.00
35.00
55.00
75.00
95.00
115.00
1.00 5.00 25.00
%Passing
Sieve Size (mm)
Combined Coarse Aggregate ASTM min. Limits ASTM max. Limits

32
3.3.3 Fine Aggregate
According to the local market surveying, the available fine aggregate is dune sand type which
is finer than required by standard specifications of ASTM C33 (2003) and its gradation does
not fall within the limits. However, as mentioned before in chapter two, many researchers
mentioned that the role of FM and gradation of the fine aggregate in HSC is not as crucial as in
conventional strength mixtures.
In spite of the FM does not necessary to comply with the requirements of ASTM C33 (2003),
higher FM or coarser fine aggregate may be highly desirable in HSC, since HSC typically
contain high volumes of cementitious material. However, this problem is largely related with
workability of concrete, to overcome this problem, many researchers recommend to use higher
CA/FA ratio and water reducing admixtures, and the fine aggregate content can be kept low.
Figure 3.2 and Table 3.5 illustrate the grain distribution of fine aggregate used on this research
and its properties.
Table (3.5): Grain Distribution of Fine Aggregate and Physical Properties.
Sieve Size (mm) % Passing
4.75 100
2.36 100
1.18 95.99
0.6 87.33
0.425 73.14
0.3 39.33
0.15 1.50
0.075 0
Fineness Modulus FM 1.75
Dry Unit Weight (Kg/m3) 1635.14
Dry Specific Gravity 2.61
Saturated Specific Gravity 2.632
Absorption (%) 0.71

33
Figure (3.2): Grain Distribution of Fine Aggregate.
3.3.4 Normal Range Water Reducing Admixture (NRWR)
According to the local market surveying the available water reducers type is NRWR confirming
ASTM C494(2004) Type “A” specification which is used on this research with dosage of
2Lit./m3
based on manufacturer’s suggestion. Table 3.6 illustrate the properties of used NRWR
according to manufacturer data sheet.
It should be noted that NRWR, when used with upper the dosage range suggested by the
manufacturer’s, often result in very significant secondary effects, such as decreasing on strength
and retardation with some binder blends especially at lower temperatures. As a result of this
low dosage of NRWR, the amount of water reduction and workability performance is limited
and less good than for HRWR.
Table (3.6): Properties of Normal Range Water Reducer.
Type Property
Appearance Dark brown liquid
Specific Gravity Approx. 1.2
Basis Lignosulfonate salts of calcium
Dose 0.2 to 0.6 lit./100 kg of cement
Toxicity Non-Toxic under relevant health and safety codes
-5
15
35
55
75
95
115
0.05 0.5 5
%Passing
Sieve Size (mm)

34
3.3.5 Glass Fiber Reinforced Polymer (GFRP)
On this research, alkali resistant glass fiber reinforced Polymer (AR-GFRP) is used, the
available AR-GFRP in the Gaza local market has a hybrid length, typically ranged from 8 mm
to 30 mm. According to manufacturing data sheet, the properties of AR-GFRP used on this
research are shown in Table 3.7.
Table (3.7): Properties of AR-GFRP.
3.3.6 Water
Potable tap water without any salts or chemical was used in the study for the experimentation
and for the curing process. The water source was the laboratory of the Islamic University of
Gaza.
3.4 Mix Proportioning of HSGFRC
The reference concrete mixture (without GFRP) was developed on a trial and error basis to
obtain 28-day cylinder compressive strength for design of 50 MPa. The first trail mixture was
based on Steven et al. (2003), then modifications were applied to obtain the best determinable
mix design proportions that achieved the target design strength which illustrated in Table 3.8.
The following factors were considered when designing a HSC mixture.
i. Usually, for the aggregate to be used in making HSC, it is better to choose one with a
high crushing strength, if possible. The maximum size of aggregate is usually limited to
Fiber Properties Quantity
Fiber Length Hybrid 8 to 30 mm
Diameter 14µ
Specific Gravity 2.68 g/cm3
Density 2.7 t/m3
Modulus of Elasticity 72 GPa
Tensile Strength 1,700 MPa
Chemical Resistance Very high
Electrical Conductivity Very low
Softening Point 860 °C
Zro2 Content 15-20 %
Material Alkali Resistant Alkali Resistant Glass

35
12.5 mm. The limitation on maximum aggregate size is to reduce the influence of the
transition zone and to get a more homogeneous material.
ii. The quantity of coarse aggregate in HSC should be the maximum consistent with
required workability.
iii. The water requirement of concrete increases as the fine aggregate content is increased
for any given size of coarse aggregate. Because of the high cementing materials content
of these concretes, the fine aggregate content can be kept low.
iv. The cement content is usually high, in a range up to 600 kg/m3
. The higher cement
content is the result of limiting the maximum aggregate size and the need for workability
under the smaller water/cement ratio condition. Moreover, the higher cement content
also leads to a more homogenous concrete structure.
v. The appropriate free water/cement ratio should be selected as minimum as possible
either from reference to published data or on a trial and error basis.
vi. The workability of concrete mix should be enough to obtain good compaction using
suitable chemical admixtures such as water reducer.
Table (3.8): Mix Proportioning for 1 m3
of Concrete for The Reference Mixture.
Material Type Units / m3
Cement (kg) 600
Fine Aggregate (kg) 484
Coarse aggregate (kg) 1068
NRWR (Lit.) 2
W/C 0.37
The compressive test carried out in the trial mix stage was according to ASTM C39 (2003)
standard test method. The average 28-day cylinder compressive strength of three 150 x 300 mm
cylinder specimens (See Figure 3.3) was 51.149 MPa as shown in Table 3.9. The rate of loading
was constant for the specimens equal 0.34 MPa/sec. confirming the standard requirements.
Before testing, cylinders are capped from the faces of specimens that will be in contact with the
bearing plate of the testing machine. The testing machine used on this research for compressive
strength is MATEST C104 Servo Plus 2000 KN capacity showed in Figure 3.4.

36
Figure (3.3): 150 x 300 mm Cylindrical Specimens.
Table (3.9): 28 Day Cylinder Compressive Strength Test Result.
NO.
Failure
Load
(KN)
Compressive
Strength
(Mpa)
Rate of
Loading
(Mpa/sec)
Average
Compressive
Strength (Mpa)
S CV
1 976.36 55.251
0.34 51.149 3.67 7.172 884.45 50.05
3 850.84 48.148
Figure (3.4): MATEST C104 Servo Plus 2000 KN Capacity Compression Test Machine.
To achieve the objectives of this research, varying percentages of AR-GFRP are added to the
reference mixture to produce HSGFRC mixtures, typically 0.0, 0.3 0.6 0.9, 1.2 by weight of
cement as shown in Table 3.10.

37
Table (3.10): HSGFRC Mixtures for 1 m3
of Concrete.
Designation
% AR-GFRP
by Weight of
Cement
Cement
(kg)
Fine
Aggregate
(kg)
Coarse
Aggregate
(kg)
NRWR
(Lit.)
W/C
M50 F0 0 600 484 1068 2 0.37
M50 F1 0.3 600 484 1068 2 0.37
M50 F2 0.6 600 484 1068 2 0.37
M50 F3 0.9 600 484 1068 2 0.37
M50 F4 1.2 600 484 1068 2 0.37
3.5 Preparation of HSGFRC and Mixing Procedure
After selection of all needed constituent materials and amounts to be used (mix proportioning);
all materials are weighed properly. Then mixing with a power-driven revolving drum mixer
showed in Figure 3.5 started to ensure that all particles are surrounded with each other.
Figure (3.5): The Power-Driven Revolving Drum Mixer Used on This Research.
For the reference mixture M50 F0 (without fibers), mixing procedures was applied in
accordance with ASTM C192 (2002). However, for addition of the glass fibers; careful
attention must be given when mixing the glass fibers. The glass fibers are always added last
and mixed for the minimum time required to achieve uniform dispersion. It is important to
ensure that minimum time is spent mixing the fibers because they can be damaged by excessive
mixing. In addition, mixing the glass fibers at the higher speed would also damage the fibers.

38
3.6 Testing Procedure
In this section, testing procedures to evaluate the strength properties of HSGFRC are
presented.
3.6.1 Compressive Strength Test
A significant portion of this research focused on the behaviors of HSGFRC cube specimens
under compressive loading. The compressive tests discussed on this section were all completed
nominally according to BS 1881, Part 108 (1993) standard test method. Total of 25 cubes were
manufactured. For each batch of HSGFRC made, 150x150x150 mm cube specimens were
prepared, (See Figure 3.6). The cubes were filled with fresh concrete and then compacted by
rod method in accordance to the standard, after preparing the specimens, cubes were covered
with plastic sheets for about 24 hours to prevent moisture loss prior to the curing stage.
(a)
(b)
Figure (3.6): (a) and (b) Cube Specimens.

39
After 24 hours; Cubes extracted from forms and stored in water (curing phase) up to the time
of test. Before testing, any loose sand grains or incrustations from the faces of specimens that
will be in contact with the bearing plate of the testing machine are removed. The testing
machine used on this research for compressive strength is MATEST C104 Servo Plus 2000 KN
capacity shown in Figure 3.7.
Figure (3.7): MATEST C104 Servo Plus 2000 KN Capacity Compression Test Machine.
The cubes then placed in the testing machine so that the load is applied through flat and parallel
sides. The rate of loading was constant for the tests of compression strength equal 0.34 MPa/sec.
confirming the standard requirements. The compressive strength of the specimen, (in MPa), is
calculated by dividing the maximum load carried by the cube specimen during the test by the
cross-sectional area of the specimen.
The compressive strength was determined at different ages 7, and 28 days. Three cubes were
tested for each mix for period of 28 days and two cubes were tested for each mix for period of
7 days, the mean value of the specimens was considered as the compressive strength of the
experiment.
3.6.2 Splitting Tensile Strength Test
The splitting tensile strength of HSGFRC was measured based on ASTM C496 (2004) standard
test method. This test often referred to as the split cylinder test, indirectly measures the tensile
strength of concrete in which a cylindrical specimen (See Figure 3.8) is placed on its side and
loaded in diametrical compression as shown in Figure 3.9, so to induce transverse tension.

40
Figure (3.8): Cylindrical Specimens.
Figure (3.9): Split Cylinder Test Setup.
The load applied (compressive force) on the cylindrical concrete specimen induces tensile and
shear stresses on the aggregate particles inside the specimen, generating the bond failure
between the aggregate particles and the cement paste (See Figure 3.10). The failure of concrete
in tension is governed by micro-cracking, associated particularly with the interfacial region
between the aggregate particles and the cement, also called interfacial transition zone (ITZ).
However, the most important advantage is that, when applying the splitting procedure, the
tensile strengths are practically independent of either the test specimen or of the test machine
sizes, being only a function of the concrete quality alone. Thus, much inconvenience is
eliminated.

41
(a)
(b)
(c)
Figure (3.10): (a), (b), and (c) Failure on Cylindrical Specimen after Split Cylinder Test.

42
Total number of 25 cylinder of 300 x 150 mm were manufactured. The cylinders were filled
with fresh concrete and then compacted by rod method in accordance to the standard, after
preparing the specimens, cylinders were covered with plastic sheets for about 24 hours to
prevent moisture loss prior to the curing stage. All cylinder specimens were tested after 28 days
from casting. The rate of loading was constant for the tests equal 1.4 MPa/min. The testing
machine used on this research for split tensile strength is MATEST C104 Servo Plus 2000 KN
capacity, the same that used for compression test.
The split tensile strength was determined at different ages 7, and 28 days. Three cylinders were
tested for each mix for period of 28 days and two cylinders were tested for each mix for period
of 7 days, the mean value of the specimens was considered as the split tensile strength of the
experiment.
The maximum fracture strength can be calculated based on Eq. 3.1 according to ASTM C496
(2004).
Fsp =
𝟐𝑷
𝝅𝑫𝑳
(3.1)
Where:
Fsp = Splitting tensile strength in MPa
P is the fracture compression force acting along the cylinder in N;
D is the cylinder diameter in mm;
π = 3.14;
L is the cylinder length in mm.
3.6.3 Flexural Strength Test
Total number of 25 prisms were manufactured. The specimens are prisms 100 x 100 x 500 mm
(See Figure 3.11). The flexural strengths or the modulus of rapture of concrete specimens are
determined by the use of simple beam with center point loading in accordance to ASTM C293
(2002) as shown in Figure 3.12. The mold is filled with fresh concrete and then compacted by
rod method in accordance to the standard. After preparing the specimens, they are covered with
plastic sheets for about 24 hours to prevent moisture loss. After 24 hours, the specimens are
extracted from the molds and placed in water for curing up to time of test. At the time of testing,
and because the flexural strengths of the prisms are quickly affected by drying which produces
skin tension, they are tested immediately after they are removed from the curing basin.

43
The flexural strength was determined at different ages 7, and 28 days. Three prisms were tested
for each mix for period of 28 days and two prisms were tested for each mix for period of 7 days,
the mean value of the specimens was considered as the flexural strength or the modulus of
rapture of the experiment.
(a)
(b)
Figure (3.11): (a) and (b) Prism Specimens.

44
Figure (3.12): Schematic View for Flexure Test Setup of Concrete by Center-Point Loading.
The casted beam specimens to be tested, turned on their sides with respect to their position as
molded. This should provide smooth, plane and parallel faces for loading. The pedestal on the
base plate of the test machine shown in Figure 3.13 is centered directly below the center of the
upper spherical head, and the bearing plate and support edge assembly are placed on the
pedestal. The center loading device is attached to the spherical head. The test specimen is turned
on its side with respect to its position as molded and it is placed on the supports of the testing
device.
Figure (3.13): Center Point Loading Flexural Test Machine.
The longitudinal center line of the specimen is set directly above the midpoint of both supports.
The center point loading device is adjusted so that its bearing edge is at exactly right angles to
the length of the beam and parallel to its top face as placed, with the center of the bearing edge
directly above the center line of the beam and at the center of the span length. The load contacts
with the surface of the specimen at the center.

45
The specimen is loaded continuously and without shock at until rupture occurs (See Figure
3.14). Finally, the maximum load indicated by the testing machine is recorded.
Figure (3.14): Fracture on Prism Specimen after Flexural Prism Test.
The flexural strength of the beam, Fr (in MPa), can be calculated by using Eq. 3.2 according to
ASTM C293 (2002):
Fr =
𝟑𝑷𝑳
𝟐𝒃𝒅 𝟐 (3.2)
Where:
Fr = Flexural strength or modulus of rapture in MPa:
P = maximum applied load indicated by the testing machine in N;
L = span length in mm;
b = average width of specimen in mm, at the point of fracture;
d = average depth of specimen in mm, at the point of fracture.
3.6.4 Unit Weight
On this research, the unit weight of the concrete cube specimen is the theoretical density. The
density is calculated by dividing the weight of each cube by the volume. The same cube
specimens which are used to determine the compressive strength was used to determine the
density.

46
3.7 Curing Procedure
Curing is an important process to prevent the concrete specimens from losing of moisture while
it is gaining its required strength. Lack of curing will tend to lead the concrete specimens to
perform less well in its strength required. All concrete samples were placed in curing basin after
24 hours from casing (See Figure 3.15). All samples remained in the curing basin up to time of
testing at the specified age. Curing water temperature is around 25oC. The curing condition of
lab basin followed the ASTM C192 (2004).
Figure (3.15): Specimens at Curing Basin.

Chapter 4
Test Results and Discussion

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