Can Microplastics (MPs) Replace Conventional Mineral Aggregates? A Brief Review

Area of Science:

• Materials Science
• Environmental Engineering
• Civil Engineering

Background:

• Microplastics (MPs) are a pervasive pollutant with potential for waste valorization.
• Using MPs as partial replacements for mineral aggregates in cementitious composites is of growing interest.

Purpose of the Study:

• To critically assess the technical feasibility and implications of using MPs as aggregate replacements in cementitious composites.
• To evaluate the impact of MPs on the mechanical properties and durability of cementitious materials.

Main Methods:

• Review of current experimental and analytical evidence on MP-aggregate substitution in cementitious composites.
• Analysis of the fundamental differences between MPs and natural aggregates (stiffness, density, surface chemistry).

Main Results:

• MP-aggregate substitution typically reduces workability, compressive strength, and durability (resistance to chloride ingress, carbonation, freeze-thaw).
• Adverse effects generally increase with higher replacement levels.
• Isolated benefits like reduced unit weight are occasionally reported, but MPs often act as inactive inclusions.

Conclusions:

• Microplastic incorporation as aggregate replacement presents significant challenges to material performance.
• Long-term durability and secondary MP release risks require further investigation.
• MP-based aggregate replacement is a conditional, application-specific strategy, best suited for non-structural uses under defined criteria.