Literature Review: Sand Plastic Composite HDPE

• This review explores the use of sand-plastic composites in construction, particularly in sustainable building materials.
• It examines recent advancements, challenges, sustainability, and economic impacts of reducing plastic waste through sustainable construction.
• Sources are from 2024-2025 for the most current insights.

Keywords terms (KWT)

1. sand plastic composites
2. sustainable construction
3. recycling
4. plastic waste
5. HDPE

Strategies

1. Searched Google Scholar using KWT1, KWT2, KWT3, KWT4 and KWT5
2. Focused on recent publications to ensure up-to-date information

• Definition and composition: Ratio of sand to plastic, types of plastic used (ie: recycled polycarbonate, HDPE).
• Applications: Bricks, pavement, tiles.

• Material Science Perspective: Properties of plastic-sand composites (durability, thermal resistance, water absorption).
• Engineering Perspective: Structural integrity compared to conventional bricks/building material.
• Sustainability Perspective: Environmental impact and carbon footprint reduction.

• Environmental Impact: Reduce landfill & ocean-bound waste, lower carbon emissions compared to traditional building materials (cement)
• Economic Impact: Recycled plastic & sand is cheaper than concrete, a cost-effective alternative, and expands the market for recycled plastic applications
• Structural Advantages: Higher durability

• Limited research on high-density polyethylene (HDPE) sand-plastic composites, with most studies focusing on polyethylene terephthalate (PET), polypropylene (PP), and polystyrene (PS). The potential of HDPE for structural applications remains underexplored.
• Success with other plastics: Studies on recycled polycarbonate (PC) composites demonstrate high strength, durability, and thermal stability, suggesting potential for future applications of HDPE in sand-plastic composites.

• Researchers & Engineers: Innovating sustainable composite materials
• Construction Industry: Adopting alternative building materials
• Government & Policy Makers: Regulating and incentivizing eco-friendly materials
• Environmental Organizations: Promoting circular economy strategies

• Urban Construction: Lightweight bricks, interior textured panels, decorative facades
• Road & Pavement Infrastructure: Durable paver blocks and pavement tiles
• Low-Cost Housing: Affordable construction in developing regions
• Recycling Industry: Integration into circular economy initiatives
• Focused on London Ontario, Canada (North America)

Zotero citation field with the URL (DOI preferred).

• • Diverse Industrial Applications
    • Recycled plastics are increasingly used in construction (roof tiles, pavement, curbs), automotive parts, electronics, agriculture, household goods, and energy sectors.
    • Example: Pavements reinforced with plastic strips (PP, PET, HDPE) show improved strength and durability. Building Materials & HDPE-Based Composites
    • Sand + Recycled HDPE has been explored for roof tiles and curb designs, replacing up to 20% of natural coarse aggregate without compromising strength.
    • PET-based mixtures showed higher abrasion resistance than PP alternatives. Waste Management & Sustainability
    • Non-biodegradable plastics accumulate in landfills and marine environments, turning into microplastics.
    • Recycling reduces environmental impact and supports sustainability. Economic & Social Benefits
    • Recycled plastics contribute to employment opportunities, particularly in developing regions, where individuals earn livelihoods through plastic repurposing. Future Outlook & Research Gaps
    • Need for policy-driven incentives to increase adoption of recycled plastic materials. Further research on mechanical properties & long-term performance in high-load applications is required.

https://doi.org/10.3390/su17030839^[2]

Material Selection & Performance

• Used recycled polycarbonate (rPC) instead of HDPE for higher compressive strength (71 MPa)—outperforming traditional concrete (23–30 MPa).
• Maintained stiffness and durability, making it viable for structural applications.

Life Cycle Emissions Reduction

• Brick-scale production resulted in 45–54% lower CO₂ emissions compared to concrete.
• Replacing 26 Mt of concrete with sand–rPC composites could save 4.5–5.4 Mt of CO₂ annually.

Energy Source Dependence

• Carbon footprint reduction varied from 3% to 98% based on electricity source.
• Renewable energy integration would further lower emissions.

Scalability & Sustainability Benefits

• Composites can repurpose plastic waste, addressing pollution and carbon emissions in construction.
• Offers a low-carbon alternative for large-scale building applications, especially in developing regions.

Design Gap & Research Contribution

• Prior studies focused on mechanical properties but lacked in-depth LCA (life cycle assesment).
• This study quantifies carbon savings and energy demand, bridging a key research gap.

Future Considerations

Optimize manufacturing to reduce emissions in small-scale production.

Regulatory approval needed for widespread use in construction.

https://doi.org/10.1007/s12649-022-01708-x^[3]

Plastic-Sand Composites as a Recycling Solution

• LDPE and HDPE plastics were tested as binding agents for sand-based composites.
• Offers an alternative while mitigating plastic waste challenges in developing nations.

Optimal Processing Conditions

• Temperature Range: 250 °C – 325 °C ensures maximum compressive and flexural strength. Higher temperatures (>325°C) degrade plastics, reducing material integrity.

Mechanical Properties & Strength

• HDPE composites exhibited higher compressive strength (37.1 MPa) than LDPE (27.2 MPa).
• Plastic-bonded sand composites outperform C20/25 concrete and sandcrete in strength, toughness, and ductility.

Environmental Considerations

• Thermal degradation risk: Plastic breakdown occurs at 250°C in air, emitting toxic gases.
• Recommended processing in low-oxygen environments to minimize emissions.

Future Research & Challenges

• Long-term durability of plastic-sand composites under various climate conditions.

Further studies on structural applications and cost-benefit analysis needed for large-scale adoption.

https://doi.org/10.1177/09673911251318542^[4]

Methods & Design:

• Reviewed waste plastics (thermoplastics, thermosets) for composite production.
• Processing: melt blending, compression molding, extrusion, injection molding.
• Reinforcements: natural fibers, sand, fly ash, synthetic fibers.

Key Findings:

• Composites improve mechanical, thermal, and chemical properties.
• Supports circular economy & waste reduction.

Gaps:

• Limited long-term durability & recyclability studies.
• Need for standardization in processing methods.

Future Directions:

• Optimization for large-scale applications.
• Improved life cycle analysis for sustainability assessment.

https://doi.org/10.1016/j.jobe.2025.112025^[5]

Methods

• Used liquid-fed pyrolysis (breaking down plastic with heat in liquid form) to remove contaminants.
• Collected retentate (filtered waste residue) for composite production.
• Processed material using hot compression molding (pressing heated material into shape).

Findings:

• Strength: The new material has a compressive strength of 10–12 MPa, which is stronger than traditional bricks (7 MPa).
• Weight: 57.3% lighter than clay bricks and 12.5% lighter than lightweight bricks, making it easier to transport and use.
• Safety: Displays ductile fracture behavior (bends before breaking), which makes failures more predictable and safer in construction.
• Needs more testing on durability, weather resistance, and fire safety.
• Environmental and economic impact not yet fully analyzed.

Future Directions

• Conduct life cycle assessment (LCA) to measure environmental impact.
• Perform technoeconomic analysis (TEA) to determine cost-effectiveness.
• Investigate alternative manufacturing techniques (e.g., additive manufacturing / 3D printing).
• Test material in real-world construction projects for feasibility and performance validation.