Enhancement of Copper Ion Adsorption and Compressive Strength of Foam Concrete by Modified Recycled GFRP Powder

To enhance the recycling value of waste glass-fiber-reinforced plastics (GFRP), improve the environmental benefits of recycled glass-fiber-reinforced polymer powder (rGP), and enhance the mechanical properties of foam concrete, the surface modification of rGP was performed using KH560 and diethylenetriamine, resulting in the synthesis of a modified material denoted as K-N-rGP. K-N-rGP and unmodified rGP were utilized as sand replacements in the fabrication of two types of foamed concrete: modified recycled GFRP foamed concrete (K-N-rGP-FC) and unmodified rGP foamed concrete (rGP-FC). An integrative approach combining experimental and microstructural analyses using scanning electron microscopy (SEM), Fourier-transform infrared spectroscopy (FT-IR), and X-ray photoelectron spectroscopy (XPS) was conducted to validate the modification efficacy of K-N-rGP. Mechanisms underpinning Cu 2 + adsorption enhancement and compressive strength improvement were systematically investigated. Findings revealed that K-N-rGP exhibits increased surface functional group density and roughness, correlating with enhanced Cu 2 + adsorption capacity. Compared to rGP-FC, K-N-rGP-FC demonstrates a 24% improvement in compressive strength (1.03 MPa), representing an 80% increase relative to foamed concrete without powder addition. Additionally, K-N-rGP-FC outperforms rGP-FC in Cu 2 + adsorption efficiency (52% maximum enhancement), although the post-adsorption Cu 2 + concentration difference is marginally lower at a 4% replacement level. This study advances the environmental valorization of rGP while offering novel insights into the functional reuse of such material in sustainable construction applications.