Analysis of Water Absorption in the Utilization of Plastic Waste as a Mixed Material for Making Environmentally Friendly Paving Blocks

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FORMOSA NEWS - Jakarta - Plastic Waste PET Improves Water Resistance and Strength of Eco-Friendly Paving Blocks. A 2026 study by Sudarno P Tampubolon, Deviana Pratiwi Munthe, Medyawanti Pane, Irene V Simanjuntak, Bintang Sri Rejeki Panjaitan, Antonius D. Tyas Prasetyo dari Indonesian Christian University dan Manado State University demonstrates that plastic waste specifically PET (Polyethylene Terephthalate) can be effectively used to produce environmentally friendly paving blocks with lower water absorption and solid structural strength. Published in the Formosa Journal of Applied Sciences, the research highlights a practical solution to Indonesia’s growing plastic waste problem while offering a viable alternative construction material. The findings matter because plastic waste remains one of the most persistent environmental challenges in Indonesia, accounting for nearly one-fifth of total waste. Transforming this waste into construction materials not only reduces pollution but also supports sustainable infrastructure development.

Plastic Waste Crisis Drives Material Innovation
Indonesia continues to face mounting environmental pressure from plastic waste, driven largely by single-use consumption. Plastic does not easily decompose and can persist in ecosystems for decades. When broken down into microplastics, it enters water systems and food chains, posing risks to human health and biodiversity. At the same time, the construction sector depends heavily on natural resources such as sand and cement, both of which contribute to environmental degradation and carbon emissions. These dual challenges have encouraged researchers to explore alternative materials that are both sustainable and functional. His research team positioned plastic waste as a resource rather than a liability. By incorporating PET plastic into paving blocks, they sought to reduce environmental impact while maintaining engineering performance.

Simple Experimental Design with Practical Focus

The research combined laboratory experiments with a review of existing studies on plastic-based construction materials. The team collected PET plastic waste from community sources and processed it using a custom-built shredding machine. The plastic was cut into small fragments ranging from 0.1 to 2 centimeters. These plastic fragments were then mixed into paving block materials at a proportion of 5% of the fine aggregate (sand). The mixture also included cement and water, following Indonesian National Standards (SNI) for concrete production. A total of 20 paving block samples were produced and tested. Each sample underwent a 48-hour water immersion test to measure water absorption. The team also evaluated compressive strength to determine whether the material met construction standards.

Key Findings: Stronger Performance with Lower Water Absorption

The results show that adding PET plastic significantly improves the water resistance of paving blocks while maintaining structural strength.

Key findings include:

• Water absorption ranged from 4.3% to 6.4%, with an average of 5.2%.
• Lower than conventional paving blocks, which typically absorb 8–12% water.
• Compressive strength ranged from 26.5 MPa to 32.0 MPa, averaging 29.3 MPa.
• All samples met SNI Class B standards, suitable for medium-load applications.
• Applicable for sidewalks, residential roads, and light parking areas.

The lower water absorption is attributed to the hydrophobic nature of plastic, which resists water penetration. This characteristic helps reduce internal moisture buildup, improving durability and resistance to weathering. The study also identified a consistent pattern: paving blocks with lower water absorption tended to have higher compressive strength. This relationship suggests that controlling porosity is critical to optimizing performance.

Real-World Impact: Sustainable Construction and Waste Reduction

The implications of this research extend beyond laboratory results. The use of plastic waste in paving blocks offers a scalable solution for both waste management and construction industries. For local governments and policymakers, this innovation supports circular economy strategies by converting waste into valuable infrastructure materials. It also aligns with sustainability goals by reducing reliance on natural aggregates and lowering carbon emissions. For communities, especially in urban areas, the approach creates opportunities for waste collection, recycling, and small-scale manufacturing. This could generate new income streams while addressing environmental concerns. His Research emphasized the broader significance of the findings. She noted that integrating plastic waste into construction materials can “increase the added value of waste while maintaining product quality that meets national standards.”

Author Profiles

Sudarno P. Tampubolon, S.T., M.T. – Indonesian Christian University; expert in civil engineering and construction materials

Deviana Pratiwi Munthe, S.T., M.T. – Manado State Universityo; specialist in environmental engineering

Medyawanti Pane, S.T., M.T. – Indonesian Christian University; researcher in material engineering

Irene V. Simanjuntak, S.T., M.T. – Indonesian Christian University; focus on sustainable construction

Bintang Sri Rejeki Panjaitan, S.T., M.T. – Manado State University; expertise in eco-friendly materials

Antonius D. Tyas Prasetyo, S.T., M.T. – Indonesian Christian University; civil engineering specialist

Sources

Tampubolon, S.P., Munthe, D.P., Pane, M., Simanjuntak, I.V., Panjaitan, B.S.R., & Prasetyo, A.D.T. (2026). Analysis of Water Absorption in the Utilization of Plastic Waste as a Mixed Material for Making Environmentally Friendly Paving Blocks. Formosa Journal of Applied Sciences, Vol. 5(3), 871–884.
DOI: https://doi.org/10.55927/fjas.v5i3.24
URL: https://journalfjas.my.id/index.php/fjas