This document summarizes research on improving tunnel waterproofing performance through the use of a watertight temporary support (WTS) system. It discusses how water infiltrating through soil can absorb corrosive materials and damage tunnel waterproofing membranes. The proposed WTS system involves applying a waterproof concrete/mortar mixture via shotcrete after each excavation to provide a primary barrier before the main membrane. Laboratory tests on mortar specimens with different ratios of acrylic polymer modifier added found reductions in porosity and permeability, with the best results achieving 9.78% porosity. The document concludes the WTS is a cost-effective way to control water infiltration and corrosion in tunnels.
DETERMINING HEIGHT OF BENCHES IN OPEN MINING OF STEEPLY-DIPPING DEPOSITS WITH...IAEME Publication
At present stage of the development of the mineral resource complex, a trend is
seen to deterioration of geological and engineering conditions of mining ore deposits,
which entails increase of losses and dilution of mineral, causing increase of the cost
price of mineral production and processing. With consideration of the specified
limiting conditions, the maximal net present value of deposit mining will be achieved
with minimal economic loss resulted from mineral losses and dilution.
For the conditions of steeply-sloping ore pits, analysis was conducted of the
impact of the bench height on the value of mineral losses and dilution, and necessary
calculations were made to identify the degree of influence of the pit bench height and
the height of the triangle of inmixed waster rocks on the values of losses and dilution
by three possible modes of preparing a new horizon (in mining from the hanging wall
to the bottom wall, in preparation across the ore body).
According to the results of the research, conclusions were made that the economic
loss related to the losses and dilution, increase in direct proportion to the increase of
bench heights; the mode of horizon preparation significantly influences the value of
losses and dilution and the economic losses related to them; the value of losses and
dilution increases with increase of bench height, and the current stripping ratio
reduces. For this reason, for determining the optimal bench height, joint consideration
of the losses and dilution with the current stripping ratio, is required. The conducted
technical and economic calculations result in recommending the bench height in ore
zone, equal to 5 m. with maintaining the rock bench height of 20 meters
Building Materials and Concrete Technology Unit 4DineshGunturu1
Hardened Concrete-Water / Cement ratio – Abram’s law, Gel space ratio, Nature of strength of concrete – Maturity concept, Strength in tension and compression – Properties of Hardened Concrete (Elasticity, Creep, Shrinkage, Poisson’s ratio, Water absorption, Permeability, etc.), Relating between compression and tensile strength, Curing
EFFECT OF SILICA FUME ON RHEOLOGY AND MECHANICAL PROPERTY OF SELF COMPACTING ...IAEME Publication
The usage of an extensive group of industrial mineral residues (silica fume and fly ash) and other products significantly increases the rheological performance of concrete. This research is supposed to take a look at Rheology and Strengthened Properties of Self Compacting Concrete with Silica fume. This examination commenced with 4 groups of Self Compacting Concrete changed with diverse probabilities of Silica fume (5%, 10%,15%, and 20%). The rheological properties of self-compacting concrete are investigated experimentally using the slump flow diameter, the U box test, the V funnel test, and the L box test. Compressive strength and flexural strength are the strengthened properties experimentally examined. In this study, we observed the suitable percent of silica fume, which offers advanced rheological characteristics of Self Compacting Concrete as equated to Conventional Self Compacting Concrete. Our experimental results show, by the replacing 15% of silica fume with the weight of cement will increase both Rheological Properties and strengthened Properties of SCC.
DETERMINING HEIGHT OF BENCHES IN OPEN MINING OF STEEPLY-DIPPING DEPOSITS WITH...IAEME Publication
At present stage of the development of the mineral resource complex, a trend is
seen to deterioration of geological and engineering conditions of mining ore deposits,
which entails increase of losses and dilution of mineral, causing increase of the cost
price of mineral production and processing. With consideration of the specified
limiting conditions, the maximal net present value of deposit mining will be achieved
with minimal economic loss resulted from mineral losses and dilution.
For the conditions of steeply-sloping ore pits, analysis was conducted of the
impact of the bench height on the value of mineral losses and dilution, and necessary
calculations were made to identify the degree of influence of the pit bench height and
the height of the triangle of inmixed waster rocks on the values of losses and dilution
by three possible modes of preparing a new horizon (in mining from the hanging wall
to the bottom wall, in preparation across the ore body).
According to the results of the research, conclusions were made that the economic
loss related to the losses and dilution, increase in direct proportion to the increase of
bench heights; the mode of horizon preparation significantly influences the value of
losses and dilution and the economic losses related to them; the value of losses and
dilution increases with increase of bench height, and the current stripping ratio
reduces. For this reason, for determining the optimal bench height, joint consideration
of the losses and dilution with the current stripping ratio, is required. The conducted
technical and economic calculations result in recommending the bench height in ore
zone, equal to 5 m. with maintaining the rock bench height of 20 meters
Building Materials and Concrete Technology Unit 4DineshGunturu1
Hardened Concrete-Water / Cement ratio – Abram’s law, Gel space ratio, Nature of strength of concrete – Maturity concept, Strength in tension and compression – Properties of Hardened Concrete (Elasticity, Creep, Shrinkage, Poisson’s ratio, Water absorption, Permeability, etc.), Relating between compression and tensile strength, Curing
EFFECT OF SILICA FUME ON RHEOLOGY AND MECHANICAL PROPERTY OF SELF COMPACTING ...IAEME Publication
The usage of an extensive group of industrial mineral residues (silica fume and fly ash) and other products significantly increases the rheological performance of concrete. This research is supposed to take a look at Rheology and Strengthened Properties of Self Compacting Concrete with Silica fume. This examination commenced with 4 groups of Self Compacting Concrete changed with diverse probabilities of Silica fume (5%, 10%,15%, and 20%). The rheological properties of self-compacting concrete are investigated experimentally using the slump flow diameter, the U box test, the V funnel test, and the L box test. Compressive strength and flexural strength are the strengthened properties experimentally examined. In this study, we observed the suitable percent of silica fume, which offers advanced rheological characteristics of Self Compacting Concrete as equated to Conventional Self Compacting Concrete. Our experimental results show, by the replacing 15% of silica fume with the weight of cement will increase both Rheological Properties and strengthened Properties of SCC.
Rheology of Fresh Self Compacted Concrete - Concrete Shear Box_ Ajay and Dr.G...ajay nagaraj
Flow characterization and controlling fresh property of SCC is most critical. Even slight variations in ingredients can have adverse effect on fresh properties; strength and durability of hardened concrete. The material science approach to study rheological properties is essential in order to overcome the paucity posed while characterizing mixes by empirical methods such as the slump flow test.
In the present work, the Bingham parameters of SCC were assessed by using the new concrete shear box. The mixes were designed considering volume of paste based on absolute volume concept. Three different volumes of pastes (0.38, 0.40 and 0.42) with water contents of 170 and 190 lt/m3 and cement contents of 300 and 450 kg/m3 along with slag as filler was used. A unique test procedure was followed, by applying low normal stresses of 0.10, 0.20 and 0.30 MPa with three different displacement rates of 1, 5 and 15mm/min under static condition. The results indicate that the new concrete shear box shall effectively put to use, as an additional tool for evaluating the rheological properties of SCC viz., yield stress and plastic viscosity
Study of Mechanical Properties in SCC by Blending Cement Partially With Fly A...IJSRD
The development of self-compacting concrete has been one of the most important materials in the modern building industry. The purpose of this concrete concept is to decrease the risk due to human factor. The use of SCC is spreading worldwide because of its very attractive properties. In the present investigation Blended SCC is the one in which some percentage of cement content used for the concrete is replaced by any of the mineral admixtures. Here, the present study to development of blended self-compacting concrete by replaced in the mineral admixtures using Fly ash 0-30% and metakaolin 0-30% as the weight of cement. Study the rheological properties and mechanical properties of developed blended SCC mixes in the laboratory condition and different curing ages. In recent years, many researchers have established that the use of supplementary cementatious materials (SCMs) like blast furnace slag, silica fume, metakaolin (MK), fly ash (FA) and rice husk ash (RHA) etc. can, not only improve the various properties of concrete both in its fresh and hardened states, but also can contribute to economy in construction costsruning.
This study comparatively evaluated the quality, performance and utilization limits of
three locally manufactured cement brands in Botswana using the laboratory experiments conducted
on mortar and concrete specimens produced from the brands. The study identified the physical
characteristics of three cement brands designated A, B and C, as well as the strength and durability of
the concrete and mortar produced from such cements under varying operational and exposure
conditions to establish a limit of application for each cement considered. The physical tests performed
on cement were loss on ignition (LOI) and particle size distribution. Compressive strength test and
the resistance to carbonate and sulphate attack were investigated on concrete and mortar. Cement
type A had similar physical characteristics to C but proved to be the most workable compared to the
other cements. It however produced the lowest strength in both concrete and mortar but showed
desirable durability limits. Durability assessment of the cement-based products found cement type B
as the best with the most desirable physical properties. Cement type B gave the highest strength in
concrete, while cement type C was found to be the most suitable for mortar.
Development of mix design for high strength Concrete with AdmixturesIOSR Journals
This paper presents the result of mix design developed for high strength concrete with silica fume
and High range water reducing admixture (HRWR). It involves the process of determining experimentally the
most suitable concrete mixes in order to achieve the targeted mean strength. In this research work 53 grade
ordinary Portland cement, the locally available river sand, 10 mm graded coarse aggregate were selected based
on ASTM C 127 standard for determining the relative quantities and proportions for the grade of concrete M60.
For this design ACI 211.4R-93 guidelines were followed. Totally Five mixes were designed one mix was treated
as basic mix with HRWR - 0.5% without silica fume, Four mixes were designed with Micro silica quantities
varied from 5 to 9 percent weight of cementitious materials and HRWR varies between 0.6% to 0.9% with
increment of 0.1% . Each mix 2 numbers of 150mm x 300 mm cylinders were cast then kept in curing tank after
24 hours of time period. After 28 days of curing the specimens were tested and the appropriate mix proportions
were obtained.
To Study the Properties of Self-Compacting Concrete Using Recycled Aggregate ...paperpublications3
Abstract: This paper investigates the study of workability and durability characteristics of Self-Compacting Concrete (SCC) with Viscosity Modifying Admixture (VMA), and containing fly ash. The mix design for SCC was arrived as per the Guidelines of European Federation of National Associations Representing for Concrete (EFNARC). In this investigation, SCC was made by usual ingredients such as cement, fine aggregate, coarse aggregate, water, mineral admixture fly ash and demolished concrete at various replacement levels (5%, 10%, 15%, and 20%). To enhance the property of SCC made with the use of demolish concrete and fly ash, glass fiber has been added to the mix. Glass fiber in various % (i.e. 0.15%, 0.20% 0.30%, of Wt. of cement) has been added in the mix which contain demolish concrete and gave highest strength i.e. (10% demolish concrete).
Rheology of Fresh Self Compacted Concrete - Concrete Shear Box_ Ajay and Dr.G...ajay nagaraj
Flow characterization and controlling fresh property of SCC is most critical. Even slight variations in ingredients can have adverse effect on fresh properties; strength and durability of hardened concrete. The material science approach to study rheological properties is essential in order to overcome the paucity posed while characterizing mixes by empirical methods such as the slump flow test.
In the present work, the Bingham parameters of SCC were assessed by using the new concrete shear box. The mixes were designed considering volume of paste based on absolute volume concept. Three different volumes of pastes (0.38, 0.40 and 0.42) with water contents of 170 and 190 lt/m3 and cement contents of 300 and 450 kg/m3 along with slag as filler was used. A unique test procedure was followed, by applying low normal stresses of 0.10, 0.20 and 0.30 MPa with three different displacement rates of 1, 5 and 15mm/min under static condition. The results indicate that the new concrete shear box shall effectively put to use, as an additional tool for evaluating the rheological properties of SCC viz., yield stress and plastic viscosity
Study of Mechanical Properties in SCC by Blending Cement Partially With Fly A...IJSRD
The development of self-compacting concrete has been one of the most important materials in the modern building industry. The purpose of this concrete concept is to decrease the risk due to human factor. The use of SCC is spreading worldwide because of its very attractive properties. In the present investigation Blended SCC is the one in which some percentage of cement content used for the concrete is replaced by any of the mineral admixtures. Here, the present study to development of blended self-compacting concrete by replaced in the mineral admixtures using Fly ash 0-30% and metakaolin 0-30% as the weight of cement. Study the rheological properties and mechanical properties of developed blended SCC mixes in the laboratory condition and different curing ages. In recent years, many researchers have established that the use of supplementary cementatious materials (SCMs) like blast furnace slag, silica fume, metakaolin (MK), fly ash (FA) and rice husk ash (RHA) etc. can, not only improve the various properties of concrete both in its fresh and hardened states, but also can contribute to economy in construction costsruning.
This study comparatively evaluated the quality, performance and utilization limits of
three locally manufactured cement brands in Botswana using the laboratory experiments conducted
on mortar and concrete specimens produced from the brands. The study identified the physical
characteristics of three cement brands designated A, B and C, as well as the strength and durability of
the concrete and mortar produced from such cements under varying operational and exposure
conditions to establish a limit of application for each cement considered. The physical tests performed
on cement were loss on ignition (LOI) and particle size distribution. Compressive strength test and
the resistance to carbonate and sulphate attack were investigated on concrete and mortar. Cement
type A had similar physical characteristics to C but proved to be the most workable compared to the
other cements. It however produced the lowest strength in both concrete and mortar but showed
desirable durability limits. Durability assessment of the cement-based products found cement type B
as the best with the most desirable physical properties. Cement type B gave the highest strength in
concrete, while cement type C was found to be the most suitable for mortar.
Development of mix design for high strength Concrete with AdmixturesIOSR Journals
This paper presents the result of mix design developed for high strength concrete with silica fume
and High range water reducing admixture (HRWR). It involves the process of determining experimentally the
most suitable concrete mixes in order to achieve the targeted mean strength. In this research work 53 grade
ordinary Portland cement, the locally available river sand, 10 mm graded coarse aggregate were selected based
on ASTM C 127 standard for determining the relative quantities and proportions for the grade of concrete M60.
For this design ACI 211.4R-93 guidelines were followed. Totally Five mixes were designed one mix was treated
as basic mix with HRWR - 0.5% without silica fume, Four mixes were designed with Micro silica quantities
varied from 5 to 9 percent weight of cementitious materials and HRWR varies between 0.6% to 0.9% with
increment of 0.1% . Each mix 2 numbers of 150mm x 300 mm cylinders were cast then kept in curing tank after
24 hours of time period. After 28 days of curing the specimens were tested and the appropriate mix proportions
were obtained.
To Study the Properties of Self-Compacting Concrete Using Recycled Aggregate ...paperpublications3
Abstract: This paper investigates the study of workability and durability characteristics of Self-Compacting Concrete (SCC) with Viscosity Modifying Admixture (VMA), and containing fly ash. The mix design for SCC was arrived as per the Guidelines of European Federation of National Associations Representing for Concrete (EFNARC). In this investigation, SCC was made by usual ingredients such as cement, fine aggregate, coarse aggregate, water, mineral admixture fly ash and demolished concrete at various replacement levels (5%, 10%, 15%, and 20%). To enhance the property of SCC made with the use of demolish concrete and fly ash, glass fiber has been added to the mix. Glass fiber in various % (i.e. 0.15%, 0.20% 0.30%, of Wt. of cement) has been added in the mix which contain demolish concrete and gave highest strength i.e. (10% demolish concrete).
International Journal of Engineering and Science Invention (IJESI)inventionjournals
International Journal of Engineering and Science Invention (IJESI) is an international journal intended for professionals and researchers in all fields of computer science and electronics. IJESI publishes research articles and reviews within the whole field Engineering Science and Technology, new teaching methods, assessment, validation and the impact of new technologies and it will continue to provide information on the latest trends and developments in this ever-expanding subject. The publications of papers are selected through double peer reviewed to ensure originality, relevance, and readability. The articles published in our journal can be accessed online.
EFFECT OF SILICA FUME ON RHEOLOGY AND MECHANICAL PROPERTY OF SELF COMPACTING ...IAEME Publication
The usage of an extensive group of industrial mineral residues (silica fume and fly ash) and other products significantly increases the rheological performance of concrete. This research is supposed to take a look at Rheology and Strengthened Properties of Self Compacting Concrete with Silica fume. This examination commenced with 4 groups of Self Compacting Concrete changed with diverse probabilities of Silica fume (5%, 10%,15%, and 20%). The rheological properties of self-compacting concrete are investigated experimentally using the slump flow diameter, the U box test, the V funnel test, and the L box test. Compressive strength and flexural strength are the strengthened properties experimentally examined. In this study, we observed the suitable percent of silica fume, which offers advanced rheological characteristics of Self Compacting Concrete as equated to Conventional Self Compacting Concrete. Our experimental results show, by the replacing 15% of silica fume with the weight of cement will increase both Rheological Properties and strengthened Properties of SCC.
IJRET : International Journal of Research in Engineering and Technology is an international peer reviewed, online journal published by eSAT Publishing House for the enhancement of research in various disciplines of Engineering and Technology. The aim and scope of the journal is to provide an academic medium and an important reference for the advancement and dissemination of research results that support high-level learning, teaching and research in the fields of Engineering and Technology. We bring together Scientists, Academician, Field Engineers, Scholars and Students of related fields of Engineering and Technology
An experimental study on durability of high strength self compacting concrete...eSAT Journals
Abstract The basic philosophy in the construction of every structure is it should perform its intended functions successfully through the expected and anticipated life time, irrespective of external exposure conditions. The ability of the concrete is to resist and withstand any environmental conditions that may result in early failure or severe damages and it is a major concern to the engineering professional. Out of all the deteriorating agents acid attack is one of the phenomena that plays a vital role in disintegrating concrete structures depending on the type and concentration of the acid. Certain acids are harmless. The present investigation focused on the effect of H2 So4 and HCL on High Strength Self Compacting Concrete. Keywords: Self Compacting Concrete, Durability, deterioration, Compressive strength, viscosity modifying agent, Workability
EXPERIMENTAL INVESTIGATION ON BEHAVIOUR OF NANO CONCRETEIAEME Publication
The influence of Nano-Silica on various properties of concrete is obtained by replacing the cement with various percentages of Nano-Silica. Nano-Silica is used as a partial replacement for cement in the range of 2.5%, 3%, and 3.5% for M25 mix. Specimens are casted using Nano-Silica concrete. Laboratory tests were conducted to determine the compressive strength, split tensile and flexural strength of Nano-Silica concrete at the age of 7 and 28 days. Results indicate that the concrete, by using Nano-Silica powder, was able to increase its compressive strength. However, the density is reduced compared to standard mix of concrete. The replacement of cement with 3% Nano-Silica results in higher strength and reduction in the permeability than the controlled concrete. The replacement of cement with Nano-Silica more than 3% results in the reduction of various properties of Nano-Silica concrete.
EFFECT OF POLYCARBOXYLATE ON COMPRESSIVE STRENGTH OF PERVIOUS CONCRETEIAEME Publication
Pervious Concrete which is also known as porous Concrete is motley of cement,
body of water and a particular sized coarse aggregate combined to form a porous
structural material. Application of pervious concrete in pavements mainly focuses on
storm water ascendency mostly in urban areas where scarcity of land is high gear.
Permeable Pavement allows water from precipitation and other informant to liberty
chit through it and therefore reduces the runoff from a site which final result in the
recharge of land water and increase the level. This Pavement is made using coarse
sum with no fine aggregates. The main objective is to study about the applications of
pervious concrete and also develop a strong and durable Pervious cement
concrete mix using additive polycarboxylate as addition
IRJET - Comparative Study of Chloride Absorption in Pre-Conditioned Concrte C...
ATS11-05415
1. 1
ATS11-05415
1. INTRODUCTION
Underground infrastructures including macro and micro
tunnels such as subway tunnels, mining tunnels, water, gas &
oil supply tunnels, sewer and culverts are always expensive to
build, repair and maintain but are essential for the wealth
creation and development of the nations. Therefore, they must
be built with a long term design life which is related to
structural and waterproofing stability of tunnel.
The soil which is covered the underground tunnels
contain a variety of corrosive materials [10], [12]. Thus, when
groundwater penetrates towards the tunnel it can absorb all
these aggressive materials from the soil. Hence, direct contact
between this aggressive water with the main waterproofing
membrane causes major damages to waterproofing system of
the tunnel (Figure 1). Then, after seepage through the main
waterproofing membrane, this corrosive water by penetrating
into fabric of the tunnel final lining can cause steel
reinforcement corrosion and concrete cracks (Figure 2). As a
result, the water leakages start to damage the final concrete
structure just a few years after construction of the tunnel.
As we can see in Figures 1 and 2, the common problem in all
existing underground tunnels is the lack of a primary water
reducing system.
ABSTRACT
According to investigations conducted on the existing underground tunnels, one of the most primary
problems observed in these infrastructures is water leakage due to the penetration of water through
damaged waterproofing system and final lining. While the water infiltrate through the soil, there is a high
probability that corrosive materials such as acids and sulfates may dissolve in the water. As a result,
waterproofing membrane starts corrosion after contact with corrosive water and tunnel will experience
irreparable structural damages such as steel reinforcement corrosion and concrete cracks. Hence, the major
problem in all existing underground tunnels is the direct contact between high volumes of aggressive water
with the main waterproofing membrane without any defense opportunity. Execution of a watertight
temporary support (WTS) right after each partial excavation can be a proper solution to this problem. The
objective of this paper is to demonstrate the positive roll of WTS in improvement of tunnel waterproofing
performance. In this study the standard test method ASTM C 642 has been carried out to estimate the
porosity and pore volume in concrete specimens. Furthermore, a cement based polymer was added to test
mortar mixture to reduce the porosity and permeability of hardened specimens. According to the final
results, percentage of volume of permeable pore space or porosity (ɸ) less than 11% was achieved for
mortar specimens which were contained 7.5% to 20% acrylic polymer modifier (APM) while the porosity
of reference specimen was 14.42%. Additionally, the best result was obtained for the test mortar specimen
which was contained 12.5% APM, with 9.78 % porosity.
KEYWORDS
Corrosion; Permeability; Porosity; Shotcrete; Temporary support; Tunnel waterproofing membrane.
Improvement of Tunnel Waterproofing Performance by Execution
of Watertight Temporary Support (WTS)
N. Ghafari
Department of Civil & Environmental Engineering, Mapúa Institute of Technology, Manila, Philippines
2. 2
Figure 1: Water infiltration through the soil and temporary support
Figure 2: Water penetration through the final lining structure
This paper recommends the use of watertight temporary
support (WTS) system as an innovative waterproofing method
(Figure 3) to control the corrosion and leaking in underground
tunnels in future. This method employs a waterproof
concrete/mortar mixture to spray on the excavated parts of the
tunnel by shotcrete operation and provide a primary water
reducing barrier before execution of the main waterproofing
membrane and final lining. This is to reduce the volume of
aggressive water before contact with the main waterproofing
membrane.
In construction of underground spaces such as highway or
subway tunnels, except in shield tunneling method, the soil
around the excavated parts of tunnel should be protected by
execution of a temporary support immediately after each
excavation process. This is to prevent the falling of any debris
and reduce the risk of settlement before the execution of
tunnel final lining. This will be a good opportunity to provide
a primary water resistant barrier by adding a suitable concrete
waterproofing admixture to the shotcrete mixture. In fact, the
greatest advantage of this proposed waterproofing system is
that, there is no additional shotcrete operation cost for
execution of watertight temporary support (WTS).
Figure 3: WTS waterproofing system
In this study a cement based polymer was used to produce
a water resistant mortar mixture for test specimen preparation.
Different ratios of acrylic polymer modifier (APM), as a
typical waterproofing admixture, were added to the mortar
mixture to determine the optimum amount of APM for
achieving the lowest porosity and permeability. Since,
underground temporary structures (supports) are always
covered by the final lining structure during construction of
tunnel; preparation of specimens from a real underground
shotcrete structure was not possible. The methodology section
of this paper was focused on the laboratory concrete test
(ASTM C 642) [9] on cylindrical mortar specimens (5 × 10
cm) prepared in accordance with ASTM C 1438 [5], C 1439
[6], C 192 [7], and C 470[8].
2. REVIEW OF RELATED LITERATURE
Waterproofing of underground structures has been a
subject of concern to many professionals for thousands of
years [22]. Recent researches in the field of tunnel
waterproofing methods and materials can be divided into two
different categories [11], [14], [15], [17], [20], [23]:
2.1. Developments in the field of waterproofing materials
and membranes
The first group of researchers study on the new
waterproofing materials for execution of tunnel waterproofing
system. This group believes that they can achieve a secure
tunnel waterproofing system by developing in the field of
waterproofing materials such as epoxy, liquid and sprayed
waterproofing materials or sheet membranes like PVC sheets.
2.2. Developments in the field of concrete waterproofing
admixtures
The second group of researchers study on the new concrete
admixtures to attain a proper waterproof concrete for
execution of tunnel final lining. This group believes that they
can produce a secure waterproof concrete that could be able to
cover the tunnel as a suitable waterproofing system without
3. 3
any need of other waterproofing materials and membranes.
However this method should not be generalized for any
condition related to depth below water table and chemical
aggressivity of the ground water. Waterproof concrete method
is primarily used in Asia and has been used in Singapore on
the MRT.
3. CONCRETE LABORATORY TEST
The ASTM C 642, standard test method for density,
absorption, and voids in hardened concrete, is recommended
by the National Concrete Pavement Technology Center at
Iowa State University (2008) to determine the porosity of a
portland cement concrete structure. The porosity and
permeability of reinforced concrete structures are the major
factors for long-term durability particularly in underground
spaces. ASTM C 642 estimates the volume of permeable pore
space as well as the porosity (ɸ) of hardened concrete
specimens by determining the density of specimens in three
different states of oven dry, saturated and saturated-boiled. A
chart has been provided (Figure 5) which shows the test
processes from specimen preparation to the final calculations.
3.1. Mortar specimen preparation
A total number of 27 specimens (nine different mortar
mixtures and from each mixture three specimens) in the form
of cylinder (5 × 10 cm) were provided (Figure 4). Moreover,
different ratios of acrylic polymer modifier (APM) were added
to test mortar mixtures as a concrete admixture for preparation
of test mortar specimens.
Figure 4: Specimen preparation
The specimen preparation established according to ASTM
C 1439 (Standard test methods for evaluating polymer
modifiers in mortar and concrete) [6], ASTM C 192 (Standard
practice for making and curing concrete test specimens in the
laboratory) [7], and ASTM C 470 (Standard specification for
molds for forming concrete test cylinders vertically) [8]. Table
1 is provided below to show a summary of mixture proportion
for each prepared mortar specimen.
Figure 5: Concrete test processes
Table 1: Summary of mixture proportion of each specimen
Specimen APM W/C Sand
Portland
Cement
Water
S1 0% 70%
1210
(61.80%)
440
(22.47%)
308
(15.73%)
S2 2.5% 70%
1210
(60.29%)
440
(21.92%)
308
(15.35%)
S3 5% 70%
1210
(61.80%)
440
(22.74%)
308
(14.98%)
S4 7.5% 70%
1210
(57.49%)
440
(20.90%)
308
(14.63%)
S5 10% 70%
1210
(56.18%)
440
(20.43%)
308
(14.30%)
S6 12.5% 70%
1210
(54.93%)
440
(19.98%)
308
(13.98%)
S7 15% 70%
1210
(56.18%)
440
(20.43%)
308
(13.68%)
S8 17.5% 70%
1210
(52.59%)
440
(19.13%)
308
(13.39%)
S9 20% 70%
1210
(51.50%)
440
(18.73%)
308
(13.11%)
4. 4
3.2. Determination of Oven-Dry Mass
After the mass determination all 28 day specimens were
placed in the electrical oven and the temperature was set on
104°C to oven dry the specimens for 24 hours (Figure 6). After
the first 24 hours, oven dried specimens were removed from
the oven and they were allowed to cool in dry air to a
temperature of 22 to 24°C. Then the mass of each specimen
was determined and recorded.
Figure 6: Specimens in electrical oven for oven drying process
The recorded mass of specimens showed that specimens
were still wet and need redrying since the differential in the
determined mass was more than 0.5% of the lesser value.
Therefore the specimens were returned to the oven for an
additional 24 hours drying process. A same procedure was
applied for the second oven drying. This time the differential
in the determined mass was not exceeded 0.5% of the lesser
value. Hence, this last value was designated “A”.
3.3. Determination of Saturated Mass after Immersion
At the second step, all specimens were immersed in the
potable water at approximately 21°C for three times (Figure 7).
Figure 7: Immersing the specimens in water
In the first immersion specimens were immersed for 48
hours. Then, specimens removed from the container and after
mass determination were returned to the water for the second
immersion (24 hours). Finally after the third immersion (24
hours) increase in the determined mass was not exceeds 0.5%
of the larger value. The specimens were immersed in the water
for the total time of 96 hours (48 + 24 + 24 = 96) and the last
determined value was designated “B”.
3.4. Determination of Saturated Mass after Boiling
After the last immersion, surface drying and mass
determination all specimens were boiled in a steel container
for 5 hours (Figure 8).
Figure 8: Boiling the specimens in steal container
After 5 hours boiled specimens were removed from the
container and allowed to cool by natural loss of heat for 18
hours to achieve a final temperature of 22°C. The surface
moisture was removed and the mass of each specimen was
determined. This soaked, boiled, surface-dried mass
designated “C”.
3.5. Determination of Immersed Apparent Mass
After immersion and boiling the specimens were
suspended in the water using a suitable wire to determine the
apparent mass of each specimen (Figure 9).
Figure 9: Suspending the specimens in water
To achieve the adequate values of apparent mass an
especial technique was used in this part of test. First a small
deep bowl filled with tap water and placed on the electronic
5. 5
scale and then, scale was set on the zero. Specimens one by
one suspended in the water by a wire and weights were
recorded and designated “W”. The following equation has
been used to determine the apparent mass for each specimen:
Apparent mass (g) = C (g) – W (g) (1)
where C is the recorded weight of each specimen after boiling
and before suspending and W is the recorded weight during
suspension of specimens in the water.
For example, for specimen number 1-1 (S1-1) we have:
Apparent mass of S1-1 (g) = C1-1 (g) – W1-1 (g) (2)
where C₁ˍ₁ is the recorded weight of S₁ˍ₁ after boiling and
before suspending and W₁ˍ₁ is the recorded weight during
suspending the S₁ˍ₁ in the water.
3.6. CALCULATIONS
By using the values of determined mass in accordance with
the procedures described above, the following calculations [9]
have been applied for all specimens separately and the results
of porosity are cited in Table 2.
Absorption after immersion, % = [(B – A) / A] × 100 (3)
Absorption after immersion & boiling, % = [(C – D)/A] × 100 (4)
Bulk density, dry = [A / (C – D)].ρ = g1 (5)
Bulk density after immersion = [B / (C – D)].ρ (6)
Bulk density after immersion and boiling [C / (C – D)].ρ (7)
Apparent density = [A / (A – D)].ρ = g2 (8)
Porosity, % = [(g2 – g1) / g1] × 100 (9)
Or:
Percentage of voids, % = [(C – A) / (C – D)] × 100 (10)
4. RESULTS AND DISCUSSION
The results of calculations show reduction in porosity of
mortar specimens (ɸ) from S1 to S6 and a little increase from
S6 to S9. Note that all specimens had a same w/c ratio (0.7)
and same materials (except ratio of APM) and tested in same
environmental conditions. S1 was the reference (ordinary)
concrete specimen which was not contained any waterproofing
admixture while S2, S3, S4, S5, S6, S7, S8 and S9 were test
specimens which were contained the amounts of 49 to 391.60
g acrylic polymer (2.5% to 20% of (cement + sand + water)).
The results show an adequate reduction in porosity of concrete
for S6 compare with S1. The mass determination charts in
different steps of concrete test have been provided for
specimen number 1 (S1) as the reference specimen and
specimen number 6 (S6) as the test specimen with the best
result (lowest porosity) in Figures 10 and 11.
Porosity reduction = ∆ɸ = ɸ (S1) – ɸ (S6) (11)
∆ɸ = 14.42 % – 9.78 % = 4.64 % (12)
In fact, S6 had the most porosity reduction and it has shown
the best result in this laboratory test compare with other test
specimens between S2 to S9 (Figure 12). Therefore, the amount
of 12.5% of concrete/mortar mixture (11.11% of total mass of
mixture) is the optimum usage for the APM (Acrylic Polymer
Modifier) to achieve the best results for waterproofing
stability of a shotcrete coating with thickness of approximate
average of 100 mm (Figure 13).
Table 2: Summary of test results and porosity for S1 to S9
No. A (g) B (g) C (g) D (g)
porosity
(ɸ)
S1 400.02 441.35 431.83 211.29 14.42%
S2 382.79 419.05 411.61 196.91 13.42%
S3 400.57 434.82 427.32 206.49 12.11%
S4 389.25 419.74 412.54 199.52 10.93%
S5 383.96 411.85 405.69 194.81 10.30%
S6 378.30 404.14 398.20 194.69 9.78%
S7 380.95 407.36 400.88 197.49 9.80%
S8 381.61 408.48 401.57 198.42 9.83%
S9 387.36 414.97 407.65 201.73 9.85%
Figure 10: Mass determination chart for S1 in different conditions
0
50
100
150
200
250
300
350
400
450
500
Massofspecimen(g)
Different parts of the concrete permeability test
Specimen 1-1
Specimen 1-2
Specimen 1-3
6. 6
Figure 11: Mass determination chart for S6 in different conditions
Figure 12: Different percentages of porosity achieved for S1 to S9
Figure 13: Different porosities achieved for different APM content
As shown in last two charts increase in the ratio of APM
does not correspond to porosity reduction for S7, S8 and S9. In
this case always the optimum ratio of admixture should be
determined for the concrete/mortar mixture to achieve the best
result (lowest permeability) with the lowest cost of materials.
The figure 12 shows that using the ratios above 12.5% APM
will just increase the cost of WTS system without any positive
effect.
5. CONCLUSION
According to the final results of concrete test, the porosity
(ɸ) less than 11% were achieved for the mortar specimens
which were contained 7.5% to 20% acrylic polymer modifier
while the porosity for reference specimen was 14.42%. In
addition, the best result (lowest porosity) was obtained for the
test mortar specimen which was contained 12.5% APM, with
9.78 % porosity. The percentage of volume of permeable pore
space (porosity) below or equal to 12% is desirable to achieve
a long-term durability for concrete structures such as
underground temporary supports.
By comparing the porosity of polymer modified specimens
with the porosity of reference specimen, this study has
demonstrated the positive effects of using acrylic polymer
modifier (APM) as an appropriate admixture for porosity and
permeability reduction in the hardened concrete/mortar
structures such as tunnel‟s temporary support and final lining.
The test results show that we cannot expect a continuous
reduction in porosity of concrete structures by increasing the
ratio of APM in the concrete/mortar mixture. In this case, the
optimum ratio of APM should be determined for the concrete
mixtures by conducting the appropriate concrete test. This is
to reduce the cost of tunnel waterproofing projects (cost of
admixture) and also achieve to the lowest porosity and
permeability for tunnel concrete structure at the same time.
The results of this study demonstrate that the WTS
waterproofing system can minimize the volume of aggressive
water before contact with the main waterproofing membrane
and final concrete structure in underground tunnels. As a
result, the performance of underground tunnels will improve
and their service life will become longer.
The cost of execution of WTS system is reasonable since in
underground tunneling methods, except shield tunneling
method, execution of a temporary support right after each
partial excavation is always a part of these conventional
tunneling methods. Hence, by adding an appropriate amount
of admixture (optimum amount) to the shotcrete mixture we
can simply replace the conventional method by the new WTS
waterproofing system without any additional execution and
labor costs.
6. ACKNOWLEDGMENT
I would like to express my deep and sincere gratitude to
Dr. Jonathan W.L. Salvacion the dean of graduate school at
Mapúa Institute of Technology for all helps and supports
during the preparation of this paper.
0
50
100
150
200
250
300
350
400
450
Massofspecimen(g)
Different parts of the concrete permeability test
Specimen 6-1
Specimen 6-2
Specimen 6-3
14.42%
13.42%
12.11%
10.93%
10.30%
9.78% 9.80% 9.83% 9.85%
0%
2%
4%
6%
8%
10%
12%
14%
16%
S1 S2 S3 S4 S5 S6 S7 S8 S9
Porosity(ɸ)
Specimens
14.42%
13.42% 12.11%
10.93%
10.30%
9.78%
9.80%
9.83%
9.85%
0%
2%
4%
6%
8%
10%
12%
14%
16%
0 0.025 0.05 0.075 0.1 0.125 0.15 0.175 0.2
Porosity(ɸ)
Ratio of APM
7. 7
I would also like to thank Prof. Bernard Villaverde the
faculty of the Civil & Environmental Engineering Department
and also the coordinator of the material laboratory at MIT.
And I would like to thank my dear friends Iman Mir and
Farkam Mohebi who were always beside me in the material
laboratory to help me in conducting the concrete test.
And finally special thanks to my dear family who always
support and help me to achieve my goals and wishes in my
life.
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