IJERD – International Journal of Environmental and Rural Development (2019) 10-2

Research article
erd

Properties of Lightweight Concrete Using Expanded
Polystyrene as Aggregate
EIJI MATSUO*
Faculty of Architecture and Civil Engineering, Kyushu Sangyo University, Fukuoka, Japan
Email: ematsuo@ip.kyusan-u.ac.jp
Received 7 December 2018

Accepted 10 July 2019(*Corresponding Author)

Abstract When large structures are built on the soft ground such as paddy field, thedemand for lightweight concrete will be high. However, issues related to quality control oflightweight aggregates, decline in the tensile strength of lightweight concrete, the economicproblems, and so on, have been inhibiting the promotion of its development. There aresome conventional methods of construction to cast the large size of expanded polystyrene(EPS) blocks near the surface of soft ground. But there is concern that the EPS block will
float up by liquefaction in case of earthquake. In this study, the strength properties oflightweight concrete which uses EPS waste as fine aggregate have been investigated. Theabove-mentioned concern could be wiped out by mixing EPS as aggregate in concrete
aggregate. This EPS aggregate is manufactured product, but there is extremely little numberof the factories. The volume of this aggregate was reduced by being irradiated the extreme
infrared radiation to utilize the stockyards effectively. This aggregate is ecological because
its origin is the industrial waste of EPS. That the absorption of water is zero is one of themerits as the aggregate for concrete. The author has obtained experimentally the mix
proportions for the concrete that have the compressive strength enough to be used asstructural material. As the results, the treatment of EPS using extreme infrared radiation
was found to be effective in improving the strength of EPS concrete.
Keywords lightweight concrete, expanded polystyrene, strength, density

INTRODUCTION
In Japan, the annual discharge of industrial waste is over 400 million tons which is about 8 times
that of general wastes (Japan Environmental Sanitation Center, 2000). About 80 million tons ofthem are discharged from the construction industry. After the recycling law was enforced,development of technologies for effective use of the waste has been much desired.
The main objective of this study is the successful utilization of expanded polystyrene waste(EPS for short) as fine aggregate to produce lightweight structural concrete. The quantity of EPS
production in Japan is about 200,000 tons, which accounts for about 10% of the total global
production. Only 64% of them have been recycled, the rest being incinerated or reclaimed. Various
technologies have been developed for the reduction of EPS volume. Although structurallightweight concrete can be produced using artificial lightweight aggregates, the major drawback isthe high cost of these aggregates. Using EPS as aggregate makes the production of lightweight
concrete economical and environmentally friendly. In addition to the lightweight property, EPS hasother beneficial properties such as high thermal insulation, high sound absorption, and super low
water absorption.
There are extremely few studies on EPS concrete except the case study as non-structurematerial (Nagase et al., 2000). There are some studies on structural lightweight concrete whichwere confirming the basic properties and trying a multifunctionality, however the artificial
aggregate is expensive (Kuku et al., 2000), (Onishi et al., 2000). Then the originality of this study
is to use this EPS for structural concrete, and the objective of this paper is to quantify the basicproperties of density and strength.

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IJERD – International Journal of Environmental and Rural Development (2019) 10-2

METHODOLOGYa) Property of EPS Aggregate
Fig.1 shows the EPS used in this study and a section of an EPS concrete cylinder. Table 1 gives
various physical properties of EPS aggregate. Methods of reducing the volume of EPS waste areextreme infrared ray irradiation processing, a new technology, has been performed on this EPS. In
this method, firstly the EPS is roughly crushed, and inorganic powders are sprinkled on its surface
using small amount of resin adhesive. Then, the volume is reduced to about 1/20 by irradiation ofextreme infrared rays before being ground again into fine pieces. With this processing, the strengthand the Young's modulus accompanying the increase of density is more than that of theconventional EPS. Because the processing is done in a low temperature of 120-130 degrees-C,generation of unpleasant odour is limited. Loss percentage of mass was 0.55% as shown by thestability examination (Test method for soundness of aggregates using sodium sulphate, JIS A1122). The resistivity against aging deterioration was confirmed to be as high as that of aggregatesfor normal concrete.
In the case of conventional lightweight concretes, the limit of weight reduction has been about
1.5t/m3. ALC (Autoclaved Lightweight Concrete) has been put into practical use to advance furtherweight reduction. In this case, if water from rain etc. is absorbed into air spaces, the density will
increase greatly. There is little study on using EPS as aggregate for concrete (Matsuo et al., 1994,1995, 1996, 1997).
b) Experimental Details
The key points in using a lightweight material like EPS are suppression of segregation, evaluationof fresh condition, and to control the decrease of strength. In the experiments, the relation between
the density and the strength of specimens accompanying the change in the quantity of EPS andwater cement ratio (W/C) was investigated first. The mix proportions were selected based on theresult anticipating a compressive strength of 30N/mm2 in the super lightweight domain.
Segregation must be prevented in order to stabilize the strength. For this, adequate mix proportionsof EPS concrete that could control the segregation and have good workability were established byobtaining the relationship between the segregation and viscosity of the cement paste prior to thestrength tests.

50mm

W/C=40%，V=50%
W/C=40%，VEPS
EPS=50%

Fig.1 EPS and the section of an EPS concrete cylinder
Table 1 Properties of EPS
Density (g/cm3)
Maximum size of sieve (mm)Percentage of solid volume (%)
Fineness modulus
Water absorptivity (%)
Quantity loss of aggregate (%)Ⓒ ISERD

90.53
4.064.8
3.02
00.55

IJERD – International Journal of Environmental and Rural Development (2019) 10-2

Strength properties and the density of EPS concrete were investigated and compared with paststudies (Matsuo et al., 1994, 1995, 1996, 1997). Mix proportions that can control segregation wereselected based on the results mentioned previously. The variation in the strength of EPS concrete
was also examined. Admixtures were not used so that the most fundamental properties could beinvestigated. Additionally, the effect of a super plasticizer was also confirmed. It was also
confirmed from preliminary experiments that segregation could be controlled even without thethickening agent (thickner, or viscosity increasing agent).
c) Mix Proportion and Casting Method
The material used here is the same as the one mentioned previously. The representative mix
proportions are shown in Table 2 which can control segregation and have a small density difference.
VEPS means the volume ratio of EPS in concrete. Mixing was done using a mortar mixer/force
mixer. Experiments were carried out using EPS concrete prisms (4×4×16cm) and cylinders(φ10×20cm). The prisms were compacted 40 times in two layers, and the cylinders werecompacted 25 times in 3 layers. A table vibrator was used as required. Specimens were removed
from the molds one day after casting and they were cured in water until the strength test.
Table 2 Representative Mix Proportions

W/C VEPS Unite Weight (kg/m3)

Name(%) (%)
30 4040 50ABC972697

W292279

TheoreticalEPS Density (g/cm3)
212
1.48
265
1.24

RESULTS AND DISCUSSIONa) Relation between VEPS and Strength
An instance of density change of EPS concrete with the increase of VEPS is shown in Fig. 2. The
density decreases linearly as VEPS increases. Since the difference of theoretical density and actual
density is very small in all mix proportions, it can be inferred that EPS waste had not been
compressed with cement paste during the mixing and hardening.
Fig. 3 shows the relationship between VEPS and the compressive strength. The compressivestrength decreased with the increase of VEPS. Even if VEPS is about 50%, a compressive strength of15-30N/mm2 can be obtained with small water cement ratio. The fact that a compressive strength of
19-45N/mm2 can be obtained for VEPS as small as 20-30% suggests that EPS concrete can bebroadly used as structural materials as well as non-structure materials.
W/C=30% Actual
W/C=35% Actual
W/C=50% Actual
W/C=60% Actual

Concrete Density (g/cm3)

2.2
2.0

W/C=30% Theoretical
W/C=35% Theoretical
W/C=50% Theoretical
W/C=60% Theoretical

1.81.61.41.2

1.00102030VEPS (%)

405060Fig. 2 Relationship between VEPS and concrete densityⒸ ISERD10Compressive Strength by Cubic (N/mm2)

IJERD – International Journal of Environmental and Rural Development (2019) 10-2

W/C=30%
W/C=35%
W/C=50%
W/C=60%7060504030201000102030
VEPS (%)

405060Fig. 3 Relationship between VEPS and compressive strengthb) Density and Strength
Fig. 4 shows the relationship between concrete density and compressive strength for cubic EPS
concrete specimens. The results for every VEPS and compared with a previous study (Matsuo et al.,1994). For given concrete density, the strength of EPS concrete is larger than that of the previous
beads-type EPS for all VEPS. This reflects the effectiveness of the volume reduction method using
extreme infrared ray to EPS is relatively more effective regarding the strength. Furthermore, it isalso estimated that the increase in the strength can be attributed to the increase of adhesion strength
between the paste and EPS due to the complexity of the surface shape of EPS.

2Compressive Strength (N/mm )6050

Thin Lines : Past Study
Thick Lines : This Study(without Agent)Line with Mark : This Study(with Agent)

4030201000.8

1.0

1.2

1.4

1.6

1.8

2.0

2.2

3Density (g/cm )Fig. 4 Relationship between concrete density and compressive strength
Bache’s equation was used in order to determine the mix proportion which can utilize thestrength of EPS more effectively (Bache, 1967). Bache expressed the strength of concrete as Eq.
(1) in case that the strength of aggregates is weaker than the matrix. This is empirical and has thegeneral tendency to underestimate the strength of the aggregate to be calculated. The effective
mixing ratio of the aggregate is said to be in the range of 0-0.5. There are various views regarding
the effective range concerning the strength ratio of the aggregate and the matrix (Murata et al.,1968).

𝜎𝑐 = 𝜎𝐸𝑃𝑆 𝑉𝐸𝑃𝑆 ⋅ 𝜎𝑝 1−𝑉𝐸𝑃𝑆(1)Ⓒ ISERD

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IJERD – International Journal of Environmental and Rural Development (2019) 10-2

Here,  is the compressive strength (N/mm2), c means concrete and p means paste.
Eq. (1) can be expressed as𝜎𝐸𝑃𝑆 = 𝑒𝑥𝑝 {log 𝜎𝑐 −(1−𝑉𝐸𝑃𝑆 ) log 𝜎𝑝𝑉𝐸𝑃𝑆}(2)

Estimaed Compressive Strengthof EPS (N/mm2)

Substituting the result of Fig. 3 in Eq. (2) the compressive strength of EPS for all mix
proportions can be found. In practice, since the strength of EPS is constant, the authors think that
this calculation value is the resistance which EPS shares with the cement paste matrix to the acting
compressive stress. Here, it is called “estimated strength”. Change of estimated strength of EPS
with VEPS is shown in Fig. 5 for different water cement ratio of paste. The estimated strength ofEPS changes not only with the paste matrix strength but also with VEPS. Mix proportions with VEPS
about 40-50% and high paste strength can use the EPS strength advantageously. These mix
proportions are closely in agreement to the ones which control segregation discussed previously.
Stress-strain curves for various VEPS are shown in Fig. 6 with 35% of water cement ratio. The
elastic modulus obtained from this figure is shown in Fig. 7. It is observed that the elastic modulus
decreases linearly with VEPS, a trend similar to that shown by the compressive strength.
3.5

3.0
2.5
2.0

1.5

W/C=30%
W/C=35%
W/C=50%
W/C=60%1.00.50.010203040
VEPS (%)

50

60

70Fig. 5 Estimated compressive strength of EPS

50

W/C=35%Stress (N/mm2)

4030
20

EPS20%EPS30%EPS40%EPS50%

10001000

2000

3000
Strain (μ)

Fig. 6 Stress-strain curvesⒸ ISERD

1240005000

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Elastic Modulus (kN/mm2)

161412108620253035404550VEPS (%)

Fig. 7 Relationship between VEPS and elastic modulus
CONCLUSION
In this study, fundamental strength properties of lightweight concrete using EPS as fine aggregate
were investigated. The main conclusions are as follows.
(1) Irradiation of EPS by extreme infrared rays is effective in improving the strength of EPS
concrete.
(2) The mix proportions which authors propose are "W/C=40% and V EPS=50%" for weight
reduction, and "W/C=30% and VEPS=40%" for high strength.
Drying shrinkage is the subject for a further study in case of the applicability of this concrete
in a large scale. It is necessary to quantify the adequate amount of shrinkage reducing agent.
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Bache, H.H. 1967. Testing and design methods of lightweight aggregate concretes. Proceedings of RILEM
International Symposium, Budapest.
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Matsuo, E., Makizumi, T. and Sakamoto, Y. 1995. Control of segregation of polystyrene beads concrete. JCA
Proceedings of Cement & Concrete, 49, 826-831.
Matsuo, E., Matsushita, H. and Makizumi, T. 1996. Study on mix proportion of super lightweight concrete.
JCA Proceedings of Cement & Concrete, 50, 364-369.
Matsuo, E., Matsushita, H. and Makizumi, T. 1997. Property of super lightweight concrete using expanded
polystyrene beads as coarse aggregate. JSCE, Journal of Materials, Concrete Structures and Pavements,571, 36, 37-48.
Matsuo, E., Sakamoto, Y. and Makizumi, T. 1994. Effect of the chopped fiber reinforcement on thepolystyrene-bead concrete. JCA Proceedings of Cement & Concrete, 48, 774-779.
Murata, J. and Kamiyama, Y. 1968. Study on the testing method for strength of aggregate. Japan Cement
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Nagase, K., Tanaka, H., Jinnai, H., Ookida, K., Yamada, T. and Goto, K. 2000. Use of lightweight andthermally insulating exterior wall concrete panels containing EPS waste as aggregate. Proceedings of JCI
Symposium on High Performance Structural Lightweight Concrete, Japan Concrete Institute, 159-164.
Onishi, T., Toda, Y., Takemura, G. and Nakamizu, T. 2000. Fundamental properties of concrete using
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Lightweight Concrete, Japan Concrete Institute, 23-28.

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