This study investigated using foamed concrete as infill material in reinforced concrete beams to reduce weight. Beams were tested under shear loading. Reinforced concrete beams with foamed concrete infill were 14% weaker in shear strength but experienced 78% lower deflection compared to normal reinforced concrete beams. While lighter, beams with foamed concrete infill still maintained adequate strength and failure behavior. This composite design has potential to improve structural design through reduced weight.

1. In structural design, an ideal situation of material saving is to reduce the weight of structure without having to compromise on its strength and serviceability. This study presents a novel used of foamed concrete as infill for
reinforced concrete beam. The beams were designed and prepared with dimension 1100mm x 150mm x 200mm, while foamed concrete infill has size 1000mm x 50mm x 125mm. All beams were tested under shear using
four-point load method. Meanwhile, cube specimens were also casting and tested under compression. The compressive strength for normal concrete and foamed concrete are 21.3MPa and 8.3MPa respectively. The ultimate
shear strengths of reinforced concrete beam, reinforced concrete beam with foamed concrete infill and reinforced foamed concrete are 62.07kN, 53.11kN and 27.84kN, while the deflections are 9.6mm, 2.1mm and 1.9mm.
Although the strength of reinforced concrete beam with foamed concrete infill is lower than normal reinforced concrete, but it poses high serviceability in term of cracking and mode of failure. Thereof, reinforced concrete
beam with foamed concrete infill has the high potential to be used as structural component, consequently leads to improved design.
i. To design reinforced concrete beams with foamed concrete infill using relevant standard.
ii. To study the strength, deflection and failure mode of reinforced concrete beams with foamed concrete infill
under shear tests.
iii. To compare the strength, deflection and failure mode between reinforced concrete beams with foamed
concrete infill, normal reinforced concrete beam and reinforced foamed concrete beam.
METHODOLOGY
RESULTS
STRUCTURAL BEHAVIOUR ON SHORT-SPAN OF REINFORCED CONCRETE BEAMS WITH FOAMED CONCRETE
INFILL
Ismail Mat, Dr. Zainorizuan Jaini and Mr. Koh Heng Boon
Department of Structural and Material Engineering, Faculty of Civil and Environmental Engineering
University Tun Hussein Onn Malaysia, 86400 Parit Raja, Batu Pahat, Johor.
ismailma42@gmail.com
In reinforced concrete structure, the material properties, weight and structural geometric are put into the
indicator of performance and serviceability. Basically, concrete is highly designed to carry compression while
steel reinforcements transfer tension stress and loadings, especially in the beam. The relationship between
transfer tension stress and strain in a normal concrete cross-section is almost linear at small values of stress.
Figure 1: Strain, stress, and force diagrams of a reinforced concrete section.
Concrete has low tensile strength, therefore, when a reinforced concrete structure is subjected to flexure or
shear, the concrete area under the neutral axis of the cross-section is considered ineffective when it is in
tension at ultimate limit states . Therefore, the ineffective volume of reinforced concrete can be replaced by
another material, in many-sided and interests, the foamed concrete block or prefabricated lightweight concrete
is highly likely to be used in the ineffective volume. Consequently, produces lighter reinforced concrete
structure with expectation of lower weight around 30% of normal reinforced concrete structures. However, the
extensive investigations on the structural behaviours and serviceability of reinforced concrete with foamed
concrete infill are paramount important in order to deeply understand the ability of this structure under load
actions.
Literature review
Beam design
Laboratory work
1
2
3
Material
preparation4
Specimen casting5
Compressive and
shear test6
Results and
analysis7
Figure 3: Detailing for normal reinforced
concrete and reinforced foamed concrete
beams.
Figure 4: Detailing for reinforced concrete
beam with foamed concrete infill.
2
Grade Cement
Content (kg)
Coarse
Aggregate
(kg)
Fine
Aggregate
(kg)
Maximum w/c
Ratio
Maximum Size of
Aggregate (mm)
Slum and
Tolerance (mm)
20 25 97 79 0.65 20 70 ± 10
Table 1: Mixture of normal concrete.
Density
(kg/m3)
Maximum
w/c ratio
Cement
(kg)
Fine Aggregate
(kg)
Foam Agent
(liter)
Water
(liter)
1400 0.5 50 100 0.250 31.25
Table 2: Mixture of foamed concrete.
4
6
A complete set of methodology that was used in this study can be
referred in Figure 2 to Figure 5, also in Table 1and Table 2.
Compressive Strength
Shear Strength-Deflection
0
10
20
30
40
50
60
70
-5 0 5 10 15 20 25
Load(kN)
mid-span deflection (mm)
NFCR
NCR
FCR
27.84kN,1.90mm
53.11kN,2.10mm
62.10kN,9.56mm
0
10
20
30
40
50
60
70
-5 0 5 10 15 20 25
Load(kN)
Point Load deflection (mm)
NFCR
NCR
FCR
27.84kN,1.43mm
53.11kN,1.85mm
62.10kN,7.88mm
Mode of Failure
 The target compressive strength for both normal concrete and foamed concrete has successfully been achieved.
 The strength of reinforced concrete beam with foamed concrete infill is 14% lower than normal reinforced concrete,
however, this composite-based-concrete beam has advantage in weight saving approximately 30% and lower
deflection almost 78%.
 The density of foamed concrete 1000kg/m3 is used in casting the infill block, the weight saving can possibly achieve
as high as 30%.
 The failure behaviour of reinforced concrete beam with foamed concrete infill is in the moderate range, however, the
failure of foamed concrete infill is still ambiguous and need further investigations.
[1] Vanissorn,V., Ade S.W. and Hamid,N. Reinforced Concrete Beams with Lightweight Concrete Infill. Scientific Research and Essay. 2012.7(27); pp.2370-2379.
[2] Jones, M. R. and McCarthy, A. Preliminary Views on the Potential of Foamed Concrete as a Structural Material. Magazine of Concrete Research. 2005. 57(1); pp.21-31.
[3] Sohel, K. M. A. Impact Behaviour of Steel-Composite Sandwich Beams. Master Thesis. National University of Singapore. 2003.
[4] Mosley, B., Bungey, J. and Hulse, R. Reinforced Concrete Design to Eurocode 2. 6th Edition. Palgrave MacMillan. New York. 2007.
a) Normal reinforced concrete beam (NCR)
b) Reinforced concrete beam with foamed
concrete infill (NFCR)
c) Reinforced foamed concrete beam (FCR)
50mm 333.3mm 333.3mm 50mm166.69mm 166.69mm
Figure 9: Final failure mode for beam specimens.
Shear strength-deflection profiles are shown in Figure 7 and Figure 8 below.
Figure 7: Shear strength and mid-span deflection. Figure 8: Shear strength and point-load deflection.
INTRODUCTION
ABSTRACT
CONCLUSSION
REFERENCE
OBJECTIVE
Figure 6: Compressive strength .
Two types of cube specimens from normal concrete and foamed concrete were tested under
compression loading. The results for both type concrete specimens at 7 days, 14 days and 28
days are shown in Figure 6. It was found that the strength of concrete fulfilled the requirement
of grade C20 and density 1400kg/m2 for normal concrete and foamed concrete respectively.
Figure 2: Flow of methodology.
Figure 5: Compressive and four point load bending tests.
6
Beam
Specimen
Mode of Failure Load at First Crack
(kN)
NCR Dowel cracks and Diagonal tension crack from flexure-shear
crack
21.53
NFCR Flexure tension cracks and Flexure – shear cracks 29.23
FCR Flexure tension cracks 7.69
0
4.3
5.3
8.3
12.5
19.5
21.3
0
5
10
15
20
25
0 7 14 21 28
CompressiveStrength(MPa)
Time (Day)
Normal concrete
Foamed concrete