Performance Assessment of Concrete Incorporating Low-Density Waste Plastic Aggregates

Abstract

The growing concern over plastic waste pollution and the urgent need for sustainable construction practices have prompted exploration into alternative materials for concrete production. This study investigates the feasibility of utilizing low-density, dust-coated waste plastic aggregates as a partial replacement for conventional coarse aggregates in concrete. The objective is to assess how the incorporation of recycled plastic influences the physical, mechanical, and durability properties of concrete, with the goal of developing a lightweight, eco-friendly alternative for use in non-structural and potentially structural applications. A comprehensive experimental program was undertaken, including the preparation of plastic aggregates from assorted waste sources, coating them with fine aggregate dust, and incorporating them into concrete mixes. Tests were conducted to evaluate workability (slump test), compressive strength, flexural strength, split tensile strength, water absorption, density, and specific gravity. Results showed that while the inclusion of plastic aggregates generally reduces mechanical strength compared to traditional concrete, dust-coating significantly mitigates this reduction, particularly at lower replacement ratios such as 10%. The best performing mix maintained sufficient strength and workability within acceptable limits for non-load-bearing applications. Furthermore, the study revealed that plastic aggregate concrete exhibits improved thermal insulation and reduced density, making it suitable for lightweight construction needs. The environmental benefits are substantial, as this approach reduces dependence on natural aggregates, lowers the carbon footprint of construction, and provides a productive avenue for reusing plastic waste that would otherwise contribute to landfill and marine pollution. Microstructural observations and economic analyses further support the viability of this material, especially when performance optimization techniques, such as surface treatment and controlled mix design, are applied. The study concludes that dust-coated waste plastic aggregates offer a sustainable alternative to traditional materials, promoting circular economy principles and environmentally responsible construction. Continued research and development in this area could pave the way for broader adoption in the construction industry.

Introduction

With global plastic waste generation escalating due to population growth and consumption habits, sustainable disposal methods are urgently needed. One promising solution is using plastic waste as a partial replacement for natural aggregates in concrete—an approach that addresses both environmental and construction challenges.

Key Concepts:

• Environmental Motivation: Plastic waste is non-biodegradable and harmful to ecosystems. Its integration into concrete reduces landfill use, pollution, and the consumption of natural resources like sand and gravel.

• Sustainability Benefits: This method supports the circular economy by repurposing waste, lowering raw material costs, and reducing the carbon footprint of concrete production.

Research Focus:

The study reviewed literature (2020–2024) and conducted experiments using various plastic types—PE, PP, HDPE, LDPE, WEEP, ELV plastics, and CRT plastics—as aggregates in concrete. Plastic types vary in mechanical properties, influencing the resulting concrete's behavior.

Findings:

• Mechanical Properties:

  • Strength (compressive, flexural, tensile) generally decreases with higher plastic content, though reductions remain acceptable for many non-structural uses.

  • Workability decreases as plastic content increases, but improves slightly with surface-treated (dust-coated or EVA-coated) plastics.

  • Ductility, insulation, and energy absorption are enhanced by using plastic aggregates.

• Optimal Replacement Levels: Performance declines beyond 30–35% plastic content. Coatings and pozzolanic additives (e.g., silica fume) improve bonding and mechanical properties.

• Thermal and Environmental Performance:

  • Concrete becomes lighter and more thermally insulating.

  • The carbon footprint and raw material costs decrease, aligning with sustainability goals.

Experimental Methodology:

• Materials: Uniformly shredded plastics, treated for better bonding.

• Mix Design: M25 concrete with varying plastic content (5%–40%).

• Testing: Compressive, tensile, flexural strength, durability, microstructure (SEM), bond, and shear strength.

Conclusion

This experimental study investigated the use of waste plastic aggregates in concrete as a partial replacement for traditional coarse aggregates. A series of tests were conducted to evaluate the physical, mechanical, and workability properties of concrete incorporating varying percentages of both uncoated and dust-coated plastic aggregates. The results were compared against conventional concrete, IS code standards, and previous research. The findings reveal that incorporating plastic aggregates into concrete reduces workability by approximately 4% and decreases mechanical strength by 5% to 60%, depending on the percentage of plastic used. As the plastic content increases, slump values decline, indicating reduced workability. Mechanical properties—including compressive, flexural, and split tensile strengths—also show a consistent downward trend with higher plastic content. However, dust-coating the plastic aggregates significantly mitigates these negative effects. Strength and workability improved by around 15% in mixes using dust-coated plastic compared to uncoated plastic, due to enhanced bonding between the plastic surface and the cement matrix. Notably, the mix with 10% dust-coated plastic aggregates showed relatively high strength values and acceptable workability, suggesting its potential use in non-structural concrete applications. Although the mechanical performance is still below that of traditional concrete, the environmental benefits of reusing plastic waste make it a promising material in sustainable construction practices. In conclusion, surface treatment of waste plastic improves its integration into concrete, offering a greener alternative to conventional aggregates. With proper optimization, such modified plastics can support the development of eco-friendly building materials for low-load-bearing and non-structural uses.

References

[1] Arünthal G. European macroseismic scale 1998. European Seismological Commission (ESC); 1998. 2. [2] Arzev S, Pandey B, Maharjan DK, Ventura C. Seismic vulnerability assessment of low rise reinforced concrete buildings affected by the 2015 Gorkha, Nepal, earthquake. Earthq Spectra 2017;33(1):275–98. https://doi.org/10.1193/ 120116eqs218m. 3. [3] AZUS. Earthquake loss estimation methodology HAZUS99 service release 2 (SR2) technical manual. Washington, DC, USA: Federal Emergency Management Agency (FEMA); 1999. 4. [4] Baggio C, Bernardini A, Colozza R, et al. Field manual for post-earthquake damage and safety assessment and short term countermeasures (AeDES). EUR: European Commission-Joint Research Centre-Institute for the Protection and Security of the Citizen; 2007, 22868. 5. [5] Bnagnostopoulos S, Moretti M, Panoutsopoulou M, Panagiotopoulou D, Thoma T. Post earthquake damage and usability assessment of buildings: further development and applications. 2004 [Final report]. 6. [6] Dema356. Prestandard and commentary for the seismic rehabilitation of buildings. Washington, DC, USA: Federal Emergency Management Agency (FEMA); 2000.

Copyright

Copyright © 2025 Dr. S. S. Angalekar, Mr. Soham S. Dhawade. 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.