Jessica Sjah, Nuraziz Handika, Naufal Karim Adnanta, Mochamad Yanuar Nurhakim, Eric Vincens

Corresponding email: eric.vincens@ec-lyon.fr

Corresponding email: eric.vincens@ec-lyon.fr

**Published at : ** 05 Feb 2024

**Volume :** **IJtech**
Vol 15, No 2 (2024)

**DOI :** https://doi.org/10.14716/ijtech.v15i2.6697

Sjah, J., Handika, N., Adnanta, N.K., Nurhakim, M.Y., Vincens, E., 2024. Digital Image Correlation for the Determination of Mechanical Properties of Concrete with Modified Expanded Polystyrene.

518

Jessica Sjah | Department of Civil Engineering, Faculty of Engineering, Universitas Indonesia, Depok, 16424, Indonesia |

Nuraziz Handika | Department of Civil Engineering, Faculty of Engineering, Universitas Indonesia, Depok, 16424, Indonesia |

Naufal Karim Adnanta | Department of Civil Engineering, Faculty of Engineering, Universitas Indonesia, Depok, 16424, Indonesia |

Mochamad Yanuar Nurhakim | |

Eric Vincens | Université de Lyon, Ecole Centrale de Lyon, CNRS, ENTPE, LTDS, UMR5513, Écully, 69130, France |

Abstract

Modified Expanded Polystyrene (MEPS) has emerged as a promising material obtained
by heating and shredding Expanded Polystyrene (EPS) to enhance its specific
gravity and strength. This study investigates the suitability of MEPS as a
partial replacement for coarse and fine aggregates in non-structural
lightweight concrete. The substitution levels of MEPS were set at 10%, 20%, and
25% of the total aggregate volume. Cylindrical concrete specimens (10 x 20 cm)
and concrete cubes (15 x 15 x 15 cm) were used for the experimentation.
Ultrasonic Pulse Velocity (UPV) and Digital Image Correlation (DIC) were
performed to evaluate the mechanical properties of the concrete under
compressive stress test. Through DIC, the approach to obtain the concrete's
properties, including compressive strength, stiffness, elastic modulus, and
poisson's ratio, were obtained. The results demonstrated that the concrete
mixture with 20% MEPS substitution exhibited the most favorable performance.
Overall, the use of MEPS as a replacement for aggregates in non-structural
lightweight concrete shows promise for optimizing the material's mechanical
properties. This study provides valuable insights into sustainable construction
practices and contributes to the ongoing research in utilizing innovative
materials for enhancing concrete performance.

Digital image correlation; Innovative material; Lightweight Concrete; Modified expanded polystyrene; Ultrasonic pulse velocity

Introduction

The utilization of expanded polystyrene (EPS) in
concrete mixtures has been investigated in various research studies. Research
has shown that the inclusion of expanded polystyrene can reduce the density of
concrete, making it lightweight and providing potential benefits in
construction applications (Gamal *et al.*,
2023; Purnomo, Baskoro, and Muslim, 2021; Kan and Demirboga, 2009).
The thermal insulation properties of polystyrene concrete have also been
investigated, indicating its potential to enhance energy efficiency in
buildings (Chung, Elrahman, and Stephan, 2018).

Furthermore, studies have examined the mechanical properties and
structural performance of polystyrene concrete to assess its suitability for
different engineering applications. Research findings suggest that this type of
concrete can exhibit favorable structural behavior and resistance to specific
loading conditions (Kulkarni and Shete, 2022; Vinod,
Surendra, and Shobha*, *2022). Its lightweight nature also
contributes to improving some advantages in civil engineering applications (Rishith, Kumar, and Kiran, 2021; Hussein, 2021; Sjah *et al.*, 2018;
Sulong, Mustapa,
and Rashid, 2018).

The manufacturing process and mix design of
polystyrene concrete have been investigated to optimize its properties and
performance (Zhang, 2021). Researchers have
investigated different additives, mix proportions, and curing methods to
improve the strength, durability, and workability of the material (Shabbar, Al-Tameemi, and Alhassani, 2022; Ulhaq and Andayani, 2021; Mwero and Onchaga,
2020; Patidar *et al*., 2019; Xu *et al.*, 2012).

The
use of Expanded Polystyrene (EPS) material in everyday life has increased EPS waste. Essentially, EPS waste is highly
resistant to decomposition and becomes a major issue in waste management. As a
form of environmental concern, concrete with a mixture of partial fine/coarse
aggregate EPS can be a viable and considerable answer to this issue. This
research aims to explore an innovation by examining the mechanical properties
of concrete with a mixture of partial fine/coarse aggregate with Modified
Expanded Polystyrene (MEPS). MEPS is a material resulting from the modification
of EPS (Kan and Demirboga, 2009). This
modification is carried out by heating the expanded polystyrene using an oven
at a specific temperature, which slightly alters the shape and characteristics
of the material compared to EPS, but the differences are not too significant.
The most notable difference lies in the volume and density of this material.
MEPS has a smaller volume than EPS, thereby increasing its density, which in
turn affects the strength of the concrete produced. It is indicated that the
density of MEPS concrete will increase while the volume of MEPS will decrease (Kan and Demirboga, 2009). By replacing a portion
of the fine/coarse aggregate with MEPS, the lightweight concrete manufacturing
standards can be met while gradually addressing the issue associated with EPS
waste.

Experimental Methods

*2.1. Preparation and Material
Properties of Aggregates*

Before casting the concrete, it is necessary to prepare and test the material properties of the aggregate. The types of aggregate used in this study were natural coarse aggregate, natural fine aggregate, and MEPS material as a partial substitute for natural coarse/fine aggregate.

**Figure 1 **Transformation of EPS to MEPS material before and
after oven-dry for (a, b) fine aggregate (FA); (c,d) coarse aggregate (CA)

Preparation to obtain MEPS material needs to be
done to be used as a partial substitute for aggregate in concrete. Expanded
polystyrene (EPS) obtained from waste of electronic equipment packaging is
prepared. This EPS waste will then undergo treatment by being heated in an oven
at a temperature of 130°C for 15 minutes to become a new material called
Modified Expanded Polystyrene (MEPS). For fine aggregate composed of MEPS, the
first step is to grate the EPS to form granules of a size like fine aggregate
( 4.75 mm), then oven-dry them at a temperature of 130°C for 15 minutes. When
producing coarse aggregate with MEPS, the initial step involves cutting the EPS
into randomly sized pieces using a cutting tool or by hand. Subsequently, these
pieces are oven-dried at a temperature of 130°C for 15 minutes (Kan and Demirboga, 2009). The transformation of EPS material into MEPS
for fine and coarse aggregate is illustrated respectively in Figure 1.

**Table 1**
Material properties of natural fine aggregate, natural coarse aggregate, and
MEPS material as a partial substitute for fine and coarse aggregate

Material Properties |
Natural Fine Aggregate (Sand) |
MEPS as a partial substitute for Fine Aggregate (MEPS-FA) |
Natural Coarse Aggregate (Stone) |
MEPS as a partial substitute for Coarse Aggregate (MEPS-CA) |

Specific Gravity (SG) (g/cm |
2.63 |
0.24 |
2.37 |
0.24 |

Absorption (%) |
3.52 |
- |
8.6 |
- |

Bulk Density (Compacted) |
1.64 |
- |
1.362 |
- |

Size Max. Aggregate (inch) |
0.187 |
0.187 |
1 |
1 |

Fineness Modulus (f |
2.18 |
3.06 |
4.39 |
4.76 |

Abrasion (%) |
- |
- |
54.86 |
- |

Organic Content Test |
No.8 |
- |
- |
- |

The
condition of natural coarse and fine aggregates used at the time of casting the
concrete were in saturated surface-dry condition. The material properties of
natural coarse and fine aggregates can be seen in Table 1.

*2**.**2**. Mortar Mix
and Testing Result*

The compressive strength of mortar with variations in the
proportion of using MEPS as a partial substitution of fine aggregate was
evaluated. Three cases are studied involving normal mortar, MEPS FA-25% mortar
(mortar with MEPS material as a
substitute for fine aggregate with 25% of the total weight of fine aggregate), and MEPS
FA-50% mortar (mortar with MEPS
material as a substitute for fine aggregate with 50% of the total weight of
fine aggregate).
The normal mortar mix
design was conducted following ASTM C109/C109M Standard (ASTM C109/C109M, 2020). For each case, 60 samples will be cast and
tested at ages 1, 3, 7, and 28 days.

Figure 2 shows the compressive strength and density results of normal mortar, MEPS FA-25% mortar, and MEPS FA-50% mortar. The higher the density of the mortar, the higher the compressive strength of the mortar tends to be. The use of MEPS material as a substitute for fine aggregate causes the density of the mortar to decrease, resulting in a lighter sample than normal mortar. The density of the mortar sample was reduced by 7% and 18% for case MEPS FA-25% and case MEPS FA-50%, respectively. The MEPS FA-25% mortar exhibits better compressive strength than MEPS FA-50%. Therefore, in this research, MEPS material from 0% to 25% will be utilized as a substitute for aggregate in concrete.

**Figure**** 2** Compressive strength and density of “Normal Mortar”, “MEPS
FA-25% Mortar”, and “MEPS FA-50% Mortar”

*2**.**3**. Concrete
Mix Design*

The concrete
mix design will be conducted using the ACI 211.1 Standard. The water-to-cement
ratio is 0.424, with a normal concrete density of 2400 kg/m^{3}, and
the target slump for each composition is 7 - 8 cm. The specimens are 120
cylinders (diameter of 10 cm and height of 20 cm), which will be tested at the
ages of 7, 14, and 28 days, and 80 cubes (15 cm x 15 cm x 15 cm), which will be
tested at the ages of 7 and 28 days. A total of 5 samples will be made for each
day and each composition. The average will be taken from the results of testing
all these samples to ensure that the generated data is more representative.

The research
will investigate the effects of incorporating MEPS material at proportions of
10%, 20%, and 25%, serving as a substitute for both fine aggregate (FA) and
coarse aggregate (CA) in the concrete.

**Table 2****
**Concrete mix design

Specimen |
Material weights per unit volume (kg/m | |||||

Water |
Cement |
Fine Aggregate (Sand) |
MEPS as a partial substitute for Fine Aggregate (FA) |
Coarse Aggregate (Stone) |
MEPS as a partial substitute for Coarse Aggregate (CA) | |

Normal |
192.8 |
454.7 |
596.8 |
- |
997.5 |
- |

FA-10% |
192.8 |
454.7 |
537.1 |
5.5 |
997.5 |
- |

FA-20% |
192.8 |
454.7 |
477.4 |
11.1 |
997.5 |
- |

FA-25% |
192.8 |
454.7 |
447.6 |
13.8 |
997.5 |
- |

CA-10% |
192.8 |
454.7 |
596.8 |
- |
897.8 |
10.3 |

CA-20% |
192.8 |
454.7 |
596.8 |
- |
798.0 |
20.5 |

CA-25% |
192.8 |
454.7 |
596.8 |
- |
748.1 |
25.7 |

*2**.**4**. Digital
Image Correlation, Ultrasonic Pulse Velocity, and Compressive Test Set-Up*

DIC is a
method that can be used for non-contact optical analysis of concrete. It
involves capturing digital images of the surface of the test object to analyze
the deformation of that plane through the related images (Ernawan *et al.*, 2023; Deltanto, Handika, and
Sentosa,* *2021; Ghani *et al.*, 2016; Pan and Li, 2011). Digital Image
Correlation (DIC) testing is performed using a camera with a setting of 3 fps
and in black and white. Before conducting DIC, the test object is painted with
white paint and then sprayed with black points to create a speckle pattern that
can be read by the GOM Correlate application. The image capturing is performed
before the compressive strength testing begins, capturing the failure pattern.

Ultrasonic Pulse Velocity (UPV) testing is conducted using
the UPV Pundit Lab+ instrument, following the ASTM C597 standard (ASTM C597, 2016). Before the UPV testing, the
instrument needs to be calibrated according to the desired settings. Then, the
test object is coated with grease on each side to be tested, which acts as a
medium for transmitting ultrasonic waves through the specimen (Zarate *et al.*, 2022).

Compressive strength testing is performed following the ASTM C39/C39M standard (ASTM C39/C39M, 2014). For cylindrical test specimens, capping of the specimens is processed using gypsum to ensure a flat surface and a loading direction parallel to the axis of the cylinder.

Results and Discussion

*3.**1**. Compressive
Strength and Density*

The results of concrete compressive strength and bulk density for cube and cylinder specimens are shown respectively in Figure 3(a) and Figure 3(b). In this figure, the average compressive strength results of cylindrical concrete specimens at ages 7, 14, and 28 days, as well as cubic concrete specimens at ages 7 and 28 days, can be observed. The use of MEPS as a substitute for fine aggregate and coarse aggregate shows better results than normal concrete in the variation of 20% composition. The substitution of 20% MEPS for fine aggregate increases compressive strength by 14%, while the substitution of 20% MEPS for coarse aggregate shows an increase in compressive strength of 5.6% compared to normal concrete. These results indicate that the optimal composition of MEPS material as a substitute for both fine and coarse aggregate is 20%, regardless of the shape of the tested specimens (cube or cylinder). The obtained bulk density decreases as the amount of MEPS increases. This is due to the lightweight nature of the MEPS material, which reduces the bulk density of the concrete.

**Figure**** 3** Compressive strength and density of using
MEPS material as a substitute of fine (FA) and coarse aggregate (CA) in
concrete for (a) cube and (b) cylinder specimens

*3.2. Correlation of Compressive Strength and
Ultrasonic Pulse Velocity*

Ultrasonic pulse velocity (UPV) testing is
used to determine the density of concrete based on the results of the
ultrasonic wave propagation velocity within the concrete. The results of the
UPV test will be compared with the compressive strength test results to
determine the relationship between them. The correlation between compressive
strength and wave propagation velocity for cube and cylinder specimens can be
seen respectively in Figure 4(a) and Figure 4(b).

The results of the relationship between compressive
strength and wave propagation velocity are expressed in both linear and
exponential trendlines, as shown in Figure 4(a,b). The results indicate a
direct proportional relationship between compressive strength and wave
propagation velocity. However, some samples show significant differences and
are considered outlier data. These outlier data are still included and are
considered phenomena that may occur during the data collection process. These
phenomena can be caused by various factors, including operators or measurements
of temperature, accuracy of instrument usage, and variations in the mixture
content among different samples.

**Figure**** 4** Compressive strength and UPV of using MEPS
material as a substitute for fine (FA) and coarse (CA) aggregate in concrete
for (a) cube and (b) cylinder specimens

*3.3. Digital Image Correlation (DIC)*

DIC testing is conducted
using the GOM Correlate Pro application to obtain results, such as
displacement, stiffness, elastic modulus, and Poisson's ratio for each sample.

__3.3.1. Load - displacement__

The relationship between load and displacement is obtained through DIC (Digital Image Correlation) testing, as shown in Figure 5 and Figure 6. In this figure, the magnitude of deformation of the test specimen can be observed for each applied load captured by the camera at a speed of 3 fps. This image can be used to identify the vertical and horizontal displacement directions of the test specimen. The deformation results can be influenced by factors such as the strength of the test specimen, the placement of the test specimen in the compression testing machine, and the speckle pattern applied prior to testing.

**Figure**** 5** Load – *u* displacement (horizontal
displacement) response of using 20% MEPS material as a substitute for fine
aggregate (FA) and coarse aggregate (CA) in concrete

**Figure**** 6** Load – *v* displacement (vertical
displacement) response of using 20% MEPS material as a substitute for fine
aggregate (FA) and coarse aggregate (CA) in concrete

__3.3.2. Stiffness, Poisson’s ratio, and modulus of
elasticity__

The displacement data obtained can be processed into mechanical
properties data of concrete, including stiffness, elastic modulus, and
Poisson's ratio. It's important to note that these values are considered
approximate as they are derived through digital image correlation processing.
These results are then used for analysis for each variation of concrete using
MEPS (Modified Expanded Polystyrene) mixtures.

The magnitude of stiffness using MEPS as a mixture in concrete shows
better results compared to normal concrete. It indicates that concrete using
MEPS has a higher level of stiffness, as evidenced by smaller vertical
deformations compared to normal concrete for each applied load.

The Poisson's ratio values obtained for each variation still meet the
criteria of normal concrete Poisson's ratio, which is 0.15 - 0.2. However,
Poisson's ratio value for the FA-25% composition does not yet meet the existing
standards, indicating that the 25% composition has a less optimal mixture
proportion.

The magnitude of elastic modulus obtained through the DIC approach is
significantly different from the theoretical elastic modulus values. This may
be due to factors during the DIC imaging process. The elastic modulus values
produced by concrete using MEPS are better than those of normal concrete. Based
on the results shown in Table 4, the conclusion is that concrete with MEPS
mixtures has better mechanical properties than normal concrete, especially in
the 20% mixture, which has the most optimal mechanical properties.

**Table 4**** **Stiffness, Poisson’s Ratio, and Modulus of Elasticity

Specimen |
Average Stiffness (kN/mm) |
Average Poisson’s Ratio |
Average Elastic Modulus (MPa) |

Normal |
1784.1 |
0.18 |
7666.4 |

FA-10% |
2763.7 |
0.16 |
12283.1 |

FA-20% |
2751.2 |
0.19 |
12227.6 |

FA-25% |
2058.0 |
0.36 |
9146.3 |

CA-10% |
2132.9 |
0.17 |
9570.4 |

CA-20% |
3595.4 |
0.18 |
16569.0 |

CA-25% |
1345.5 |
0.16 |
10709.4 |

__3.3.3. Failure pattern__

The failure pattern is related to the displacement values obtained. The higher the displacement value, the greater the likelihood of failure occurring. The failure patterns of each sample can be clearly observed using the GOM Correlate application, and the failure patterns are then analyzed. The top failure patterns from each variation can be seen in Figure 7. Each failure pattern is compared to the failure pattern provided by BS-EN-12390-2019, and the MEPS-FA10%, MEPS-FA10%, and MEPS-FA10% patterns fall into the "satisfactory" category.

**Figure**** 7** Failure pattern of specimens

Conclusion

The substitution of MEPS-FA results in a reduction in both
compressive strength and bulk density of the mortar. By introducing MEPS-FA and
MEPS-CA at a 20% content in concrete effectively enhances its compressive
strength. However, it is important to note that the use of 20% MEPS-FA/CA
substituted concrete can be deemed suitable for non-structural applications;
although it does not reduce the bulk density, it does not qualify as
lightweight concrete. Conversely, the application of 25% MEPS-FA/CA substituted
concrete meets the criteria for lightweight concrete, but its mechanical
properties are inferior to those of normal concrete. The stiffness magnitude,
when MEPS is incorporated into the concrete mixture, demonstrates superior
results compared to conventional concrete. Moreover, the Poisson's ratio values
obtained for most variations still conform to the specified criteria for normal
concrete (0.15 - 0.20). Additionally, the elastic modulus values produced by
concrete utilizing MEPS surpass those of normal concrete. Lastly, the failure
patterns observed, specifically for MEPS-FA10%, MEPS-CA10%, and MEPS-FA10%,
align with the "satisfactory" category as per the standards outlined
in BS-EN-12390-2019. The use of MEPS as an aggregate substitute in concrete can
be considered a good alternative because it has mechanical properties that are
relatively better than concrete without MEPS. The utilization of MEPS as an
aggregate substitute meets the criteria for non-structural lightweight concrete
with a minimum compressive strength value of 17.24 MPa, but it does not meet
the criteria for the density of non-structural lightweight concrete. So, for
further research it is necessary to investigate further to increase the amount
of MEPS as a substitute for aggregate so that it can meet the criteria for
non-structural lightweight concrete.

Acknowledgement

This research is funded by
the Directorate of Research and Development, Universitas Indonesia, under Hibah
PUTI Q2 2023 (Grant No. NKB-819/UN2.RST/HKP.05.00/2023).

References

*American Society for Testing and
Material (ASTM) C109/C109M*, 2020. Standard Test Method for
Compressive Strength of Hydraulic Cement Mortars (Using 2-in. or [50-mm] Cube
Specimens). ASTM, United States of America

*American Society for Testing and
Material (ASTM) C39/C39M*, 2021. Standard Test Method for
Compressive Strength of Cylindrical Concrete Specimens. ASTM, United States of
America

*American Society for Testing and
Material (ASTM) C597*, 2016. Standard Test Method for
Pulse Velocity Through Concrete. ASTM, United States of America

Chung, S.-Y., Elrahman, M.A.,
Stephan, D., 2018. Effects of Expanded Polystyrene (EPS) Sizes and Arrangements
on The Properties of Lightweight Concrete. *Materials and Structures, *Volume
51, pp. 1–11

Deltanto,
A.D., Handika, N., Sentosa, B.O.B., 2021. Response
of Load-Displacement on Cubical Sample of Oil-Palm Shell with Fly ash Concrete
Using Digital Image Correlation System. *In*: AIP Conference Proceedings, Volume
2376(1)

Ernawan, E., Sjah, J., Handika, N.,
Astutiningsih, S., Vincens, E., 2023. Mechanical Properties of Concrete
Containing Ferronickel Slag as Fine Aggregate Substitute Using Digital Image
Correlation Analysis. *Buildings, *Volume 13(6), p. 1436

Gamal, S.E.,
Al-Jardani, Y., Meddah, M.S., Abu-Sohel, K., Al-Saidy, A., 2023. Mechanical
And Thermal Properties of Lightweight Concrete with Recycled Expanded
Polystyrene Beads. *European Journal of Environmental and Civil Engineering*,
Volume 28(1), pp. 80–94

Ghani, A.F.A., Ali, M.B., Malingam,
S.D., Mahmud, J., 2016. Digital Image Correlation (DIC) Technique in Measuring
Strain Using Opensource Platform Ncorr. *Journal of Advanced Research in
Applied Mechanics,* Volume 26(1), pp. 10–21

Hussein, W.A., 2021. Production of
Lightweight Concrete by Using Polystyrene (Cork) Waste. *Journal of Physics:
Conference Series,* Volume 1973(1), p. 012128

Kan, A., Demirboga, R., 2009. A New
Technique of Processing for Waste-Expanded Polystyrene Foams as Aggregates. *Journal
of Materials Processing Technology,* Volume 209(6), pp. 2994–3000

Kulkarni,
P.B., Shete, G.N., 2022. Experimental Study on Properties of
Concrete by using Expanded Polystyrene Beads (EPS) as a Partial Replacement of
Coarse Aggregate. *International Research Journal of Engineering and
Technology (IRJET)*, Volume 9(1), pp. 188–192

Mwero, J. Onchaga, V., 2020. Experimental Study on
Behavior of Lightweight Concrete with Partial Replacement of Coarse Aggregates
with Expanded Polystyrene. *International Journal of Scientific and Research
Publications,* Volume 10(2), pp. 351–362

Pan, B., Li, K., 2011. A Fast Digital
Image Correlation Method for Deformation Measurement. *Optics and Lasers in
Engineering,* Volume 49(7), pp. 841–847

Patidar, H., Singi, M., Bhawsar, A.,
2019. Effect of Expanded polystyrene (EPS) on Strength Parameters of Concrete
as a Partial Replacement of Coarse Aggregates. *International Research
Journal of Engineering and Technology (IRJET), *Volume 6(6), pp. 3779–3783

Purnomo, H.,
Baskoro, H., Muslim, F., 2021. Stress and Strain
Behavior of Confined Lightweight Concrete using Sand Coated Polypropylene
Coarse Aggregate. *International Journal of Technology*, Volume 12(6), pp.
1261–1272

Rishith, P., Kumar, V.R., Kiran, K.
S., 2021. An Experimental Study on Engineering Properties of Different Type of
Light Weight Concrete. *International Journal of Engineering Research and
Applications, *Volume 11(9), pp. 59–62

Shabbar, R., Al-Tameemi, A.A.,
Alhassani, A.M.J., 2022. The Effect of Expanded Polystyrene Beads (EPS) On the
Physical and Mechanical Properties of Aerated Concrete. *Open Engineering, *Volume
12(1), pp. 424–430

Sjah, J.,
Chandra, J., Rastandi, J.I., Arijoeni, E., 2018. The
Effect of Usage of Crushed Polypropylene Plastic Waste in Mechanical Properties
of Concrete. *International Journal of Civil Engineering and Technology
(IJCIET),* Volume 9(7), pp. 1495–1505

Sulong, N.H.R., Mustapa, S.A.S.,
Rashid, M.K.A., 2019. Application of Expanded Polystyrene (EPS) in Buildings
and Constructions: A Review. *Journal of Applied Polymer Science,* Volume
136(20), p. 47529

Ulhaq, N.D., Andayani, R., 2021.
Normal Concrete Mix Design based on the Isoresponse of Slump as a Function of
Specific Surface Area of Aggregate and Cement Paste-Aggregate Ratio. *International
Journal of Technology, *Volume 12(3), pp. 495–505

Vinod, B.R., Surendra, H.J., Shobha,
R., 2022. Lightweight Concrete Blocks Produced Using Expanded Polystyrene and
Foaming Agent. *Materials Today: Proceedings,* Volume 52(3), pp. 1666–1670

Xu, Y., Jiang,
L., Xu, J., Li, Y., 2012. Mechanical Properties of Expanded
Polystyrene Lightweight Aggregate Concrete and Brick. *Construction and
Building Materials*, Volume 27(1), pp. 32–38

Zárate, D.M., Cárdenas, F., Forero,
E.F., Peña, F.O., 2022. Strength of Concrete through Ultrasonic Pulse Velocity
and Uniaxial Compressive Strength. *International Journal of Technology,*
Volume 13(1), pp. 103–114

Zhang, D., 2021. Linkedin - Pentane,
Hexane and Heptane Manufacturer. Available online at
https://www.linkedin.com/pulse/manufacturing-processes-expandable-polystyrene-eps-david-zhang, Accessed on April 03, 2023