Experimental Investigation on the Mechanical and Durability Properties of Sustainable Bricks Manufactured Using Waste Plastic and River Sand

Abstract

The increasing generation of waste from plastic creates a persistent solid-waste management challenge, while traditional clay brick production consumes natural resources and can impose environmental burdens. This study investigates the feasibility of converting selected waste plastics into sand-based masonry units and evaluates their physical and mechanical performance against conventional clay bricks. Waste compact discs and post-consumer plastic water bottles were cleaned, dried, reduced in size, heated, and combined with river sand. The reported experimental program used a plastic-to-sand proportion of 1:1.5 by weight for specimen preparation, with moulded specimens cooled before testing. Bulk density, water absorption, apparent porosity, and strength were also evaluated. The waste-plastic specimens showed lower density and substantially lesser water absorption and apparent porosity than the normal clay-brick specimen. In the reported comparison, the plastic-bottle specimen achieved a compressive strength of 10.6 MPa, compared with 1.77 MPa for the normal clay brick, while the compact-disc specimen reached 10.0 MPa. A separate set of project results also reported compressive strengths of 4.78 MPa and 4.65 MPa for plastic-sand bricks at 1:2 and 1:3 ratios, respectively. Overall, the findings indicate that waste-plastic–sand composites have potential as an alternative brick material, particularly where reduced water absorption, lower unit weight, and effective utilization of plastic waste are desirable. Further standardized testing is recommended before structural application.

Introduction

The text presents an experimental study on producing sustainable bricks by combining waste plastic with river sand. The main aim is to reduce plastic waste, minimize the use of natural resources and energy required for conventional clay bricks, and develop a useful construction material.

Materials and Methodology

The study used waste compact discs (CDs), plastic water bottles (PBs), and river sand. The plastic was cleaned, dried, cut into small pieces, and heated to approximately 200°C so that it could act as a binder for the sand.

The main plastic-to-sand ratio was 1:1.5 by weight. The heated mixture was placed into moulds of 70.7 × 70.7 × 70.7 mm, cooled, and then tested. Additional plastic-sand ratios of 1:2 and 1:3 were also investigated.

The specimens were evaluated for:

• Bulk density
• Water absorption
• Apparent porosity
• Compressive strength

Their performance was compared with conventional clay, burnt, and fly-ash bricks.

Main Results

The plastic-sand bricks showed promising performance compared with conventional clay bricks.

• Bulk density: PB brick = 14.38 kN/m³, CD brick = 15.27 kN/m³, while normal clay brick = 20.43 kN/m³. Thus, plastic-sand bricks were lighter.
• Water absorption: CD = 4.5%, PB = 6.5%, compared with 9.42% for the clay brick.
• Apparent porosity: CD = 7.98%, PB = 12.04%, while clay brick = 22.24%.
• Compressive strength: PB = 10.6 MPa, CD = 10.0 MPa, compared with 1.77 MPa for the reported clay brick.

The additional dataset showed compressive strengths of 4.78 MPa for the 1:2 ratio and 4.65 MPa for the 1:3 ratio, demonstrating that the plastic-to-sand ratio affects performance.

Advantages

Plastic-sand bricks can:

• Reuse waste plastic that would otherwise enter landfills or water bodies.
• Reduce dependence on conventional clay and firing processes.
• Produce lighter construction units.
• Reduce water absorption and apparent porosity.
• Provide relatively high compressive strength.
• Offer a potentially economical and environmentally friendly construction material.

Limitations and Future Scope

The study notes that performance depends on plastic type, plastic-sand ratio, heating temperature, mixing, compaction, and cooling conditions. More research is needed on fire resistance, long-term durability, dimensional stability, environmental safety, repeatability, energy consumption, and life-cycle cost.

Conclusion

This study presents an experimental assessment of bricks produced by combining waste plastic with river sand. On the basis of results reported in the source paper, the following conclusions are drawn: 1) Waste plastic can be incorporated with river sand to produce a rigid brick-like composite without relying on conventional clay firing. 2) The reported bulk density of the plastic-bottle specimen (14.38 kN/m³) was lower than that of the compact-disc specimen (15.27 kN/m³) and the normal clay brick (20.43 kN/m³). 3) Water absorption of the CD and PB specimens was reported as 4.5% and 6.5%, respectively, compared with 9.42% for the normal clay brick. 4) Apparent porosity was reported as 7.98% for CD, 12.04% for PB, and 22.24% for the normal clay brick, indicating fewer accessible voids in the plastic-sand specimens. 5) The PB specimen achieved the highest reported compressive strength of 10.6 MPa, while the CD specimen reached 10.0 MPa and the normal clay brick reached 1.77 MPa. 6) The additional project dataset reported compressive strengths of 4.78 MPa and 4.65 MPa for plastic-sand ratios of 1:2 and 1:3, respectively, indicating that mix proportion influences performance. 7) Waste-plastic–sand bricks therefore show potential as a sustainable construction material, but broader standardized testing is required before recommending them for specific structural applications.

References

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Copyright

Copyright © 2026 Harish Sharma, Er. Lucky Thakur. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.