rational proportion for mixture of foamed concrete design

  o^qflk^i=molmloqflk=clo=jfuqrob=lc=cl^jba=`lk`obqb    N=
gìêå~ä=qÉâåçäçÖá, 55 (Sains & Kej.), Mei 2011: 1–12
© Penerbit UTM Press, Universiti Teknologi Malaysia

o^qflk^i=molmloqflk=clo=jfuqrob=lc=cl^jba=
`lk`obqb=abpfdk=
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=C=j^evraafk=o^jif
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^Äëíê~Åí. This paper presents part of the results of laboratory work to design a lightweight
foamed concrete made with Protein Agent 1 as foam, silica fume (SF) mineral admixture and
superplasticizer (SP). Control of foamed concrete mixture made with foam containing only
Ordinary Portland Cement (OPC) and SF, lightweight foam concrete mixture containing 10% of
SF as a replacement for the cement in weight basis was prepared. SF is used to increase the
compressive strength and for economical concerns. The foam concrete was cured at 70% relative
humidity and ± 28°C temperature. The mechanical properties of a lightweight foam concrete with
OPC are presented. The findings indicate that water absorption of aggregate is large in this case.
However, the use of SF seems to be necessary for the production of cheaper and environmentfriendly structural foamed concrete with compressive strength and control structural foamed
concrete containing only OPC.

hÉóïçêÇëW Foam concrete mixed; mortar density; actual density; mechanical properties;
compressive strength
^Äëíê~âK Kajian ini membentangkan sebahagian hasil kerja makmal untuk reka bentuk konkrit
ringan berbusa dengan Protein Agent 1 sebagai busa, silica fume (SF) sebagai bahan tambah dan
ëìéÉêéä~ëíáÅáòÉê (SP). Konkrit ringan berbusa terkawal dicampurkan dengan kandungan simen
Portland biasa (OPC) dan silica fume, campuran tersebut pada kadar 10 peratus, dari berat simen
sebagai bahan tambah akan disediakan. Silica  fume digunakan untuk meningkatkan kekuatan
mampat dan juga menjimatkan kos. Konkrit berbusa diawetkan pada kisaran 70 peratus
kelembapan dan 28 darjah kandungan udara. Sifat mekanikal daripada struktur konkrit ringan
berbusa juga didedahkan. Dapatan kajian menunjukkan bahawa serapan air dalam kajian besar
adanya. Walaupun demikian, silica fume perlu digunakan untuk menghasilkan struktur ringan
berbusa yang murah dan mesra alam, dengan kekuatan mampat dan kawalan struktur ringan
berbusa menggunakan simen Portland biasa (OPC) sahaja

h~í~= âìåÅáW Campuran konkrit berbusa; ketumpatan mortar; ketumpatan sebenar; sifat
mekanikal; kekuatan mampat
1&2
School of Housing, Building and Planning, Universiti Sains Malaysia, 11800 USM
Pulau Pinang, Malaysia
*
 Corresponding author : fahrizal_zulkarnain@ymail.comO=================================c^eofw^i=wrih^ok^fk=C=j^evraafk=o^jif=
NKM= fkqolar`qflk=
Foam concrete is either a cement paste or mortar classified as lightweight concrete,
in which air-voids are entrapped in mortar by a suitable foaming agent. It possesses
high flowability, low self-weight, minimal consumption of aggregate, controlled low
strength, and excellent thermal insulation properties. With proper control in
dosage of foam, a wide range of densities (1600–400 kg/m
3
) of foamed concrete
can be obtained for application to structural, partition, insulation, and filling grades
(Ramamurthy Éí=~äK, 2009).
  Foam concrete is a lightweight material consisting of Portland cement paste or
cement filler matrix (mortar), with a homogeneous void or pore structure created
by introducing air in the form of  small bubbles (Nambiar and Ramamurthy,
2007a).
  Foam concrete consists of cement paste and voids, and the properties of both
components have a measurable effect on the properties of the combined materials
(Kearsley and Wainwright, 2001).
  Foam concrete is produced under controlled conditions from cement, filler,
water and a liquid chemical, that is diluted with water and aerated to form the
foaming agent (Vine-Lott, 1985).
  The first comprehensive review on cellular concrete was presented by Short
and Kinniburgh in 1963, summarizing the  composition, properties, and uses of
cellular concrete, irrespective of the method of formation of the cell structure.
Recently, Jones and McCarthy reviewed the history of uses of foam concrete,
constituent material, its properties, and construction application, including some
projects carried out worldwide. These reviews included functional properties such
as fire resistance, thermal conductivity,  and acoustical properties. However, data
on fresh state properties, durability, and  air-void systems of foam concrete are
rather limited (Short and Kinniburgh, 1978).
  The production of stable foam concrete mix depends on many factors such as
selection of foaming agent, method of foam preparation and addition for uniform
air-voids distribution, material section and mixture design strategies, production of
foam concrete, and performance with respect to fresh and hardened state are of
greater significance (Ramamurthy Éí=~ä., 2009).
  According to Kearsley and Wainwright, 2001, both the 28-days and one year
results indicate that the compressive strength of foam concrete  is primarily a
function of dry density and is little affected by the percentage cement replaced by   o^qflk^i=molmloqflk=clo=jfuqrob=lc=cl^jba=`lk`obqb    P=
ash. Based on the results of this investigation, it can therefore be concluded that
replacing high proportions of cement with fly ash does not significantly affect the
long-term compressive strength of well-cured foamed concrete.
  Objective of this research such as to design and selection lightweight foam for
housing construction and construction industry, to determine the percentage of
foam and superplasticizer also the criteria for construction industry, and to define
and testing structure lightweight foam based on the semi load bearing
performance.
  In this paper, studies and classifications of foam concrete related to
proportional mix design foamed concrete are also discussed.
OKM= _^`hdolrka=
In addition to Ordinary Portland Cement (OPC), Rapid Hardening Portland
Cement (High Alumina and Calcium Sulfoaluminate) has been used for reducing
the setting time and to improve the early strength of foam concrete. Fly ash and
ground granulated blast furnace slag have been used in the ranges of 30%−70%
and 10%−50%, respectively, as cement replacement to reduce the cost, enhance
consistency of mixture, and reduce heat of hydration, while contributing towards
long-term strength. Silica fume (SF) of up to 10% by mass of cement has been
added to intensify the strength of cement (Ramamurthy Éí=~äK, 2009).
  The water requirement for a mixture depends upon the composition and use
of admixtures, and is governed by the consistency and stability of the mixture (Karl
and Worner, 1993). At lower water content, the mixture would be too stiff,
causing bubbles to break, while a high water content would make the mixture too
thin to hold the bubbles, leading to separation of bubbles from the mixture and,
thus, segregation (Nambiar and Ramamurthy, 2006a). Though super plasticizers
are sometimes used (Jones, 2001), its use in foamed concrete can cause instability
of the foam (Jones and McCarthy, 2006). Hence, compatibility of admixture with
foam concrete is of paramount importance.
  Foam concrete is produced either by pre-foaming method or mixed foaming
method. Pre- foaming method comprises  production of base mix and stable
preformed aqueous foam separately, and then thoroughly blending foam into the
base mix. In mixed foaming, the surface active agent is mixed with base mixture
ingredients; foam is produced, resulting in cellular structure in concrete during the Q=================================c^eofw^i=wrih^ok^fk=C=j^evraafk=o^jif=
process of mixing (Byun Éí=~äK, 1998). The foam must be firm and stable so that it
can resist the pressure of the mortar until the cement takes its initial set and a
strong skeleton of concrete is built up around the void filled with air
(Koudriashoff, 1949). The preformed foam  can be either wet or dry foam. The
wet foam is produced by spraying a solution of foaming agent over a fine mesh,
has bubbles 2–5 mm in size, and is relatively less. Dry foam is produced by forcing
the foaming agent solution through a series of high-density restrictions and
simultaneously forcing compressed air  into mixing chamber. Dry foam is
extremely stable and has size smaller than 1 mm in size, which makes it suitable
for easier with the base material for  producing a pump able foam concrete
(Aldridge, 2005).  

PKM molmloqflkfkd= ^ka= mobm^o^qflk= lc= cl^j=
`lk`obqb=
The trial and error process is often adopted to achieve foam concrete with desired
properties (Nehdi Éí= ~äK, 2001). For a given mixture proportion and density, a
rational proportion method based on solid volume calculation was proposed by
McCormick (1967). ASTM C 796-97 provides  a method of calculation of foam
volume required to make cement slurry of known w/c ratio and target density. For
a given 28 days compressive strength, filler-cement ratio, and fresh density, typical
mixture design equations of Nambiar and Ramamurthy (2006b) determine
mixture constituents (i.e., percentage  foam volume, net water content, cement
content, and percentage fly ash replacement). Most of the methods help in
calculation of batch quantities if the mixture proportions are known. Even though
the strength of foam concrete depends on its density, the strength can be increased
by changing the constituent materials for a given density. In addition, for a given
density, the foam volume requirement  depends on the constituent material
(Nambiar and Ramamurthy, 2006b). Hence, for a given strength and density
requirement, the mixture design strategy should be able to determine the batch
quantities.   o^qflk^i=molmloqflk=clo=jfuqrob=lc=cl^jba=`lk`obqb    R=
QKM= j^qbof^ip=
These tests have shown that the production of foamed concrete with predictable
densities and strengths is only possible with protein foam. This investigation was
therefore conducted using only this type of foaming agent. All the materials used
were produced in Malaysia, and only one source of protein agent, cement, and
superplasticizer was used.  
  Foam concrete is produced under controlled conditions from cement, filler,
water, and a liquid chemical (Vine-Lott, 1985) diluted with water and aerated to
form the foaming agent. The foaming agent used was “NORAITE PA-1”,
manufactured in Malaysia, and which consists of additive agent. The foaming
agent was diluted with water with a ratio of 1:33 (by volume), and aerated to a
density of 75–80 g/L.
  OPC from Cement Industries of Malaysia Berhad (CIMA Group), Kangar,
Perlis Indera Kayangan, Malaysia, was used. The cement can be classified as MS
522, as well as BSEN 196. The OPC Type I cement produced by CIMA is
packed under the brand name “Blue Lion” cement. The product is available in 50
kg/bag and in bulk form. Cement is a hydraulic binder and is defined as a finely
ground inorganic material which, when mixed with water, forms a paste which sets
and hardens by means of hydration reactions and processes which , after
hardening retains its strength and stability even under water. Ordinary Portland
Cement (OPC) is one of several types of cement being manufactured throughout
the world.
  The cement quality and particles size distribution of all samples are shown in
Table 1 and Figure 1.
q~ÄäÉ=N Cement quality
fqbj `ifkhbo=B `bjbkq=B=
lñáÇÉ=`çãéçëáíáçå= == ==
SiO2 21.04 19.98
Al2O3 5.24 5.17
Fe2O3 3.41 3.27
CaO 63.31 63.17
MgO 0.85 0.79
SO3 0.41 2.38
   S=================================c^eofw^i=wrih^ok^fk=C=j^evraafk=o^jif=
`çåíáåìÉÇ q~ÄäÉ=N
Total Alkalis 0.9 0.9
Insoluble Residue 0 0.2
Loss of Ignition 0.5 2.5
jçÇìäìë  
Lime Saturation Factor 0.93 0.96
Silica Modulus 2.39 2.37
Iron Modulus 1.9 1.58
jáåÉê~ä=`çãéçëáíáçå=EBF  
C3S 55.4 59.9
C2S 18.53 12.71
C3A 8.59 8.18
C4AF 10.36 9.94
Free CaO (lime) 1.9 0
`çãéêÉëëáîÉ=píêÉåÖíÜI=
kLãã
O
= kLãã
O
 
3 days   38
7 days 46
28 days 56
 
cáÖìêÉ=N Particle size distribution
0
20
40
60
80
100
0.1 1 10 100
Percentage Passing
Particle diameter (mm)
Particle Size Distribution
Sand
Silica fume  o^qflk^i=molmloqflk=clo=jfuqrob=lc=cl^jba=`lk`obqb    T=
RKM= `ljmlpfqflk=^ka=jfuqrobp=
Based on the BS 812-103.1:1985, method for determination of particle size
distribution, types of particle size distribution of sand and silica fume vary by
sieving. All samples were cast with cement, sand, water, and foam content. The
volume of mixture design, dry density, wet density, and mixture cement ratios are
shown in Table 2. The first three mixtures contained only cement, sand, water,
and superplasticizer with same w/c ratios. These mixtures were used to determine
the cementing efficiency of the silica fume. Mixtures numbers 4 to 18 contained
cement  classified  and  SF  with  different  percentages,  Table  2.  For  each  day,  only
one mixture (0.05 m
3
) was prepared. In one mixture, a little amount of mortar
underwent slump test to determine the  mortar suitable for good bonding and
mortar density. A good slump is approximately 18 to 20 cm, as shown in Figure 2.
For this test, all of the sand used was approximately 1.0 m
3
. After sieving, a storage
tank was used to prevent water and chemical contamination prior to testing.
q~ÄäÉ=O Composition of the mixtures
jáñíìêÉ= q~êÖÉí=aÉåëáíó==
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=kç= EâÖLã—F `ÉãÉåí p~åÇ t~íÉê= EiáíêÉF= EpcF==
1 1150 0.45 18.88 28.32 8.5 0 0
2 1150 0.45 18.88 28.32 8.5 0 0
3 1150 0.45 18.88 28.32 8.5 0 0
4 1150 0.45 18.88 28.32 8.5 0.5 10%
5 1150 0.45 18.88 28.32 8.5 0.5 10%
6 1150 0.45 18.88 28.32 8.5 0.5 10%
7 1150 0.45 18.88 28.32 8.5 0 10%
8 1150 0.45 18.88 28.32 8.5 0 10%
9 1150 0.45 18.88 28.32 8.5 0 10%
10 1150 0.45 18.88 28.32 8.5 0.75 10%
11 1150 0.45 18.88 28.32 8.5 0.75 10%
12 1150 0.45 18.88 28.32 8.5 0.75 10%
13 1150 0.45 18.88 28.32 8.5 0 15%
14 1150 0.45 18.88 28.32 8.5 0 15%
15 1150 0.45 18.88 28.32 8.5 0 15%
16 1150 0.45 18.88 28.32 8.5 0.5 15%
17 1150 0.45 18.88 28.32 8.5 0.5 15%
18 1150 0.45 18.88 28.32 8.5 0.5 15% U=================================c^eofw^i=wrih^ok^fk=C=j^evraafk=o^jif=
SKM= qbpq=`lkar`qba=
The proportion of the control mixture with foam was 1:1.5:0.45 by mass of OPC,
sand, and water respectively. The approximate quantity of OPC was 18.88 kg for
one mixture foam concrete. For structural concrete, the control concrete was
modified using 10% SF as OPC replacement. Table 3 presents the composition of
the concrete mixtures produced and tested. For control mixture, fresh density was
around 2025 kg/m³. Slump workability value was 19.0 cm. After using the foam,
the new fresh density decreased to 1263 kg/m³.
= = The compressive strength of foamed concrete was determined from 100 mm
cubes. The cubes were cast in steel moulds, demoulded after 24 h, wrapped in
polythene wrapping, and stored in a room with constant temperature room of ±
28° C up to the day of testing. Before testing, each cube was unwrapped and
weighed.
cáÖìêÉ=O Slump test
7.0 obpriqp=^ka=afp`rppflk=

The compressive strength of paste mixtures containing SF is plotted as function of
time  in  Figure  3.  This  graph  clearly  shows that the compressive strength of SF
mixtures increased over a much longer period than the mixture containing no SF.
The gain in strength for 3 and 7 d is 2.81 N/mm² and 3.40 N/mm², respectively,
and 4.87 N/mm² for 28 d. For control, the strength for 3 and 7 d is 3.15 N/mm²   o^qflk^i=molmloqflk=clo=jfuqrob=lc=cl^jba=`lk`obqb    V=
and 2.81 N/mm², respectively, with 3.41  N/mm² for 28 d. This difference in
strength remains approximately the same for all ages of testing. These results show
a trend similar to the observation for the mixtures containing SF.
cáÖìêÉ=P Compressive strength of paste containing silica fume
As far as ultimate compressive strength is concerned, there is no apparent
significant difference between the mixture with SF and the control. These results
indicate that the classification of the SF does not improve its effectiveness as far as
contribution towards compressive strength is concerned. This test used 10% SF for
increasing the strength. The SF should comprise more  than  10%  to  show  a highly
different in compressive strength.
Compressive Strength with Different Days
0
1
2
3
4
5
6
3 days 7 days 28 days
Testing Age (days)
C o m p r e s s i s v e   S  t r e  n g t h  (N / m m 2 )
Silica fume
ControlNM=================================c^eofw^i=wrih^ok^fk=C=j^evraafk=o^jif=
  q~ÄäÉ=P Mixture design sheet for foam concrete
kçK= aÉëÅêáéíáçåë= s~äìÉ= råáíë kçíÉ=
1 Volume   MKMR m
3

2 Dry density NMRM kg/m
3

3 Density difference  NMM kg/m
3

4 Wet density NNRM kg/m
3

5 Solid Mass  RTKR kg
6 Estimated foam mass  NKU kg
7 Actual Mixture Mass  RRKT kg
8 Mixture cement ratio  N=W=NKR=W=MKQR
9 Cement   N
10 Sand  NKR
11 Water  MKQR
   
12  qçí~ä=ê~íáç= OKVR
   
13  `ÉãÉåí== NUKUU kg
14  p~åÇ= OUKPO kg
15  t~íÉê= UKRM kg
16 Additional water  J L
17 Total mortar weight   RRKT kg
päìãé NVKM cm
18 Mortar density OMOR kg/m
3
 As Measured
19 Mortar volume  MKMOU m
3

20 Estimated foamed volume  MKMOO m
3

21 Estimated foam volume  OO liters
22 Foam density (Actual)  TUKO g/L
23 Foam weight in mixture  TR¥UM g/L
24 Actual density NOSP kg/m
3
 As Measured
   
25 Foam flow rate  TKQM L/s
26 Time of foaming  UKNR s
   
27 Percentage of foam   QPKON %




   o^qflk^i=molmloqflk=clo=jfuqrob=lc=cl^jba=`lk`obqb    NN=
8.0 `lk`irpflkp
The results for the 28 days test indicate that the compressive strength of foamed
concrete is primarily a function of dry density, and only minimally affected by the
percentage  of  cement  replaced  by  SF.  Based on the results of this investigation, it
can be concluded that replacing high proportions of cement with SF does not
significantly affect the long-term compressive strength (in this case, 28 days) of
well-cured foamed concrete. The results can be used to predict the strength of
foamed concrete of different densities and ages.
= = The results presented in this paper show that although the foamed concrete
mixtures with high silica fume content might need a longer period to reach their
ultimate strength, this strength was observed for all samples. Similar results for SF
indicate that the cost of foamed concrete mixtures could be reduced by replacing
large volumes of cement without significantly affecting the long-term strength.
^`hkltibadbjbkqp
We extend our gratitude to the Universiti Sains Malaysia for Postgraduate
Research Grant Scheme (USM-RU-PRGS)  for funding this research, the USM
Fellowship, and Dean School of Housing, Building and Planning, Universiti Sains
Malaysia. Specials thanks are also given to those who rendered their timely help to
the successful completion of this paper.