Study on the properties and microstructure of polymer modified waste printed circuit board cement-based materials

Abstract

Waste printed circuit boards (WPCB) are solid waste, and the current disposal of WPCB in landfills has raised environmental concern. Existing studies used ground WPCB as a replacement of fine aggregate in cement-based materials, but the performances of those materials were notably decreased. This paper aims to improve the performance of WPCB-bearing cementitious materials using styrene butadiene rubber (SBR) latex and chloroprene rubber (CR) latex. For this purpose, cement-based materials with ground WPCB as fine aggregates were prepared, and the effects of SBR latex and CR latex on the mechanical properties of WPCB-bearing samples with varying dosages were studied. The influence mechanism was studied using SEM, hydration heat, XRD, and FTIR tests. The results showed that the incorporation of ground WPCB tends to significantly reduce the compressive strength of cement-based materials, while the addition of SBR and CR latex can prevent the strength loss. For instance, with the optimal dosage of 5 % for SBR latex or 7.5 % for CR, the 28-d compressive strength of the latex-modified sample was 42.6 MPa and 45.3 MPa, which was 26.78 % and 34.82 % higher than that of the unmodified samples. Through microstructure analysis, it was found that the incorporation of WPCB had a negative impact on the densification of cement-based materials. SBR latex and CR latex promoted the hydration reaction and formed continuous film products inside the structure, which improved the bonding performance of WPCB cement-based materials.