Recycled GFRP Aggregate Concrete Considering Aggregate Grading: Compressive Behavior and Stress-Strain Modeling

Area of Science:

• Materials Science
• Civil Engineering
• Sustainable Construction

Background:

• Growing volumes of fiber-reinforced polymer (FRP) composite waste pose environmental challenges.
• Recycling FRP waste into concrete aggregates offers a sustainable disposal method with potential for new material development.
• Natural coarse aggregates (NCA) can be replaced by recycled FRP aggregate (RFA) to create recycled FRP aggregate concrete (RFAC).

Purpose of the Study:

• To investigate the feasibility of using waste glass FRP (GFRP) bars as coarse aggregates in concrete.
• To evaluate the influence of varying RFA volume replacement ratios on the compressive performance of RFAC.
• To develop a suitable stress-strain model for RFAC.

Main Methods:

• Waste GFRP bars were processed into recycled FRP aggregate (RFA) with particle sizes graded to match natural aggregate (NAC).
• Uniaxial compression tests were conducted on 15 standard concrete cylinders with RFA replacement ratios of 0%, 30%, 50%, 70%, and 100%.
• Existing stress-strain models for NAC and recycled aggregate concrete (RAC) were assessed for applicability to RFAC.

Main Results:

• RFAC exhibited different failure modes compared to NAC.
• Compressive strength and elastic modulus of RFAC decreased with increasing RFA ratio, while post-peak brittleness was significantly reduced.
• Poisson's ratio of RFAC increased with RFA content but remained lower than that of NCA concrete.
• Existing stress-strain models were inadequate for RFAC.

Conclusions:

• RFAC demonstrates potential for waste FRP utilization, offering enhanced ductility at the cost of reduced strength.
• A new, modified classical stress-strain model was developed and validated for RFAC, showing good agreement with experimental data.
• This research provides a foundation for the structural application of RFAC and sustainable waste management in the construction industry.