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Effective uses of Light Weight Concrete

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Journal of Civil Engineering and Environmental Technology
p-ISSN: 2349-8404; e-ISSN: 2349-879X; Volume 3, Issue 3; January-March, 2016, pp. 208-211
© Krishi Sanskriti Publications
http://www.krishisanskriti.org/Publication.html

Effective uses of Light Weight Concrete

Ningombam Thoiba Singh
Dept. of Civil Engineering, Assam Don Bosco University (ADBU)
Azara, Guwahati -781017, ASSAM, INDIA.
E-mail: ningombam.singh@dbuniversity.ac.in

Abstract—Light weight concrete (LWC) is the building material and the fundamental way using concrete is ultimately to shape
used in the construction of building using latest technology to reduce the infrastructure of the modern world. It is difficult to
the self weight of the building. By reducing the self weight or dead overstate the role this material plays today.
load of the building or prismatic dimensions, it can minimize the
destruction or casualties during the earthquake or any environmental 3. NOMINAL MIX CONCRETE AND ITS
impact. Light weight concrete can be produced using light weight BEHAVIORS
aggregates (Pumice stone) or volcanic stone or by using admixture
aluminum powder as an air entraining agent to the normal mix
There are many types of concrete, designed to suit a variety of
concrete with or without coarse aggregate. This paper presents the
light weight concrete of nominal mix of M20 grade using admixture purposes coupled with a range of compositions, finishes and
aluminum powder mixed with various quantities and water cement performance characteristics. The choice of the concrete
ratios. After curing for 7, 14 and 28 days, the compressive strength depends upon the type of the construction project. These
developed in the concrete cubes and weights were measured and requirements considered the weather conditions that the
compare with the various quantities of aluminum added in concrete will be exposed, and the required design strength.
percentage. By observing, the light weight concrete using the The compressive strength of a concrete is determined by
nominal size of the aggregate still can be effectively used as they are taking standard molded and cured cylindrical or cube samples.
lighter in weight, greater in compressive strength but limit to the
quantity of aluminum powder beyond which they are useless. A 50 kg cement bag has a volume of 0.035 cum, a batch box
of aggregate is made of size 35 x 25 x 40cm which
1. INTRODUCTION corresponds to one bag of cement. Nominal mix concretes
with Cement (C) : Fine aggregate (FA): Coarse aggregate
Concrete is a composite element composed of coarse (CA) ratio of 1:5:10, 1:4:8, 1:3:6, 1:2:4 and 1:1.5:3 roughly
aggregate, fine aggregate (sand), cement and water. Often, correspond to M 5, M 7.5, M 10, M 15 and M 20 grades of
additives and reinforcements are included in the mixture to concrete as mentioned in the IS Code 456 in regard to their
achieve the desired strength of the concrete. When these compressive strength is concerned.
ingredients are mixed together, they form a fluid mass that is
easily molded into any shape. After few hours, the cement Use of finely powdered aluminum with the slurry and reaction
forms a hard matrix which binds the rest of the ingredients caused with the calcium hydroxide liberated during the
together into a durable stone-like material with various uses. hydration process to give out large quantity of hydrogen gas as
Some plasticizer are added as ingredients which may speed up mentioned by Keertana et al. (2011). [1]. Radhakrishna et
or slow down the rate at which the concrete hardens, and to al. (2011) [2] explained about the re-proportioning of light
impart other useful properties including increased tensile weight concrete with pumice stone along with fly ash as per
strength and water resistance. ACI method as coarse aggregate by law of mixtures known as
Abrams law. The fracture of the concrete cubes was found
2. IMPACT AND USE OF MODERN CONCRETE through the pumice aggregate and the characteristic strength
of pumice was the same irrespective of age and other
Concrete is widely used for making architectural structures, parameters. Desai D. (2012) [3] also explained about
foundations, brick or block walls, pavements, bridges or development of two types of lightweight concrete using
overpasses, highways, runways, parking structures, dams, lightweight aggregate (Pumice stone) and water floating type
pools or reservoirs, pipes, fences, poles, even boats etc.. stone using aluminum powder as an air entraining agent. The
Concrete is used in large quantities for development of paper shows the importance of water/cement ratio as in first
infrastructures. The amount of concrete used worldwide by type of concrete relate to the smoothness of the concrete
weight is twice that of steel, wood, plastics, and aluminum surface and in second type is detailed about major factor
combined. So, manufacturing concrete is become a large which controls the expansion of concrete.
commercial industry. Giving the size of the concrete industry,
Effective uses of Light Weight Concrete 209

4. LIGHT WEIGHT CONCRETE 5. PREPARATION OF THE SAMPLES

Lightweight concrete generally include an expanding agent Experiments were conducted on production of light weight
that increases the volume of the mixture while reducing the concrete by using Aluminum powder as an air entraining
dead weight. It is lighter than the conventional concrete. The agent. In order to examine the compressive strength of
main specialties of lightweight concrete are its low density and lightweight concrete, we prepared 18 nos. of light weight
low thermal conductivity. There are many types of lightweight concrete cube samples of size 150 mm x 150 mm x 150 mm of
concrete which can be either by using :- grade M20 (nominal mix) with varying water-cement ratio in
addition to varying percentage of Aluminum powder by
a). Lightweight aggregate b). Air entraining agent (Aluminum
weight of cement. We also prepared 9 nos normal concrete
Powder or foaming).
cube samples of grade M20 (nominal mix) of the same size
4.1 Light weight concrete using light weight aggregate with varying water-cement ratio. Table-1 shows the
experimental data conducted in the concrete lab.
Light weight concrete using light weight aggregates can be of
two type depending upon the type of the aggregate uses such Table 1: Samples prepared for test
as : (a) using Pumice stone as an aggregate and (b) using
volcanic rock as lightweight aggregates. In pumice stone, the
stone aggregates are having low specific gravity, highly
porous material with high water absorption percentage.
When using the volcanic rock, the aggregate are expanded
clay therefore, they are lighter than normal aggregates (bulk
density in the range of 880 kg/m3)
4.2 Lightweight concrete by using Aluminum powder
Light weight concrete is also made of introducing air or gas
entraining into slurry composed of Portland cement, coarse
aggregate and sand and the mix is set and harden with uniform
cellular structure. Fine powder of Aluminium can be used as
air entraining agent mixed with the slurry and reacts with the
calcium hydroxide present in slurry, thereby producing After casting the concrete samples in the lab, the samples were
hydrogen gas. This hydrogen gas contained in the slurry form kept inside the water tank for curing in three phases. 1st phase
cellular structures and thus makes the concrete lighter than the is for 7 days curing, 2nd phase is for 14-days curing and 3rd
conventional concrete. phase is 28-days curing.

Light weight concrete is also produced by addition of a 6. RESULTS AND DISCUSSIONS

foaming agent in cement mortar. They create a fine cement
matrix which has air voids throughout its structure. Aerated The results obtained from the experiments mentioned above
cement mortar is produced by the introduction gas into are categorized in to three (3) groups following the norms as
cementations slurry so that after hardening a cellular structure mentioned in the IS-Code 456, 2000. This can be grouped in
is formed. to 7days curing, 14 days curing and 28 days curing. Thus the
results can be examined and discussed as follows:-
4.3 Properties of light weight concrete
6.1 7- Day compressive strength
The LWC density ranges from 650 Kg/m3 to 1850 Kg/m3 as
compared to 1800 kg/m3 to 2400Kg/m3 for conventional brick NC- Normal concrete, LWC-Lightweight concrete
and concrete respectively. Despite millions of tiny air filled
cells, it is strong and durable. They are excellent in acoustic
performance, earthquake resistant, good insulation,
workability, long life span due to termite and fire resistance,
weather proof and, material savings, low modulus of elasticity
(0.5%– 0.75%) than that of the normal concrete and therefore
they are more pronounced to deflection. Good eenvironmental
impact due to thermal efficiency and thus it makes a major
contribution to environmental protection by heating and
cooling in buildings. However, light weight concrete cannot
be used as reinforced concrete as it has a cellular structure and Fig. 1: Variation of LWC weight due to variation in
therefore rusting to steel reinforcement is quite proactive. percentage of Al powder

Journal of Civil Engineering and Environmental Technology

p-ISSN: 2349-8404; e-ISSN: 2349-879X; Volume 3, Issue 3; January-March, 2016
210 Ningombam Thoiba Singh

Fig. 2: Comparison of Compressive strength Fig. 6: Effect of Aluminum content

6.3 28-Day compressive strength

Fig. 3: Effect of Aluminum content

Fig.7: Variation of LWC weight due to variation in
6.2 14-Day compressive strength percentage of Al powder

Fig. 4: Variation of LWC weight due to variation in

Fig. 8: Comparison of compressive strength
percentage of Al powder

Fig. 5: Comparison of compressive strength Fig. 9: Effect of Aluminum content

Journal of Civil Engineering and Environmental Technology

p-ISSN: 2349-8404; e-ISSN: 2349-879X; Volume 3, Issue 3; January-March, 2016
Effective uses of Light Weight Concrete 211

7. CONCLUSION
Light weight concrete using normal aggregates are having
19% to 28% less weight than that of the normal concrete. The
compressive strength of the light weight concrete is greater
than the normal same grade concrete. When started placing the
slurry mixed with Aluminum powder in cube mould, the
expansion in the volume was observed along with evolution of
gas forming pores inside to expel the hydrogen gas from the
mixture in the concrete. Because of the pores, it is become a
good insulator, sound absorbent and less weight. It can be
used in place of conventional bricks or at the places. However,
LWC is contained cellular structure and pores; it may not
advisable for used as reinforced concrete. Lightweight
Fig. 10: Preparation of concrete mix concrete must also be coated with some form of protective
material, as it tends to degrade over time because of its porous
nature.
REFERENCES

[1] Keertana, B. Sini, S. Mani, and M. Thenmozhi. Utilization of

Eco sand and fly ash in aerated concrete for a richest mix
design” in International Journal of Engineering Science and
Technology (IJEST), 299-304, Vol. 3 No. 1 Jan 2011, ISSN:
0975-546.
[2] Radhakrishna, Prithviraj P, Abhishek P.V., “Re-proportioning of
Light Weight Concrete with Pumice as Coarse Aggregate by
Law of Mixtures”, in International Journal of Engineering
Sciences Research-IJESR Vol 02, Issue 04; August2011.
[3] Desai, D. “Development of light weight concrete” Civil
Engineering portal.
[4] Bomhard. H., “Lightweight concrete structures, potentialities,
Fig. 11: Removal from cube mold and ready for curing limits and realities”, The Concrete Society, The Construction
Press, Lancaster, UK, pp. 227–290, 1980.

Fig. 12: Effect of Aluminum powder (effervescence)

Journal of Civil Engineering and Environmental Technology

p-ISSN: 2349-8404; e-ISSN: 2349-879X; Volume 3, Issue 3; January-March, 2016

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