Effects of termiticides on the properties and microstructure of termite-resistant cement-based materials and their residuals characteristics

Abstract

Cement mortars and pastes containing different concentrations of termiticides and/or contents of technical materials were prepared to investigate their effects on cement-based materials. The mortar and pastes were then tested for strength and other physical properties. Afterwards, the cement pastes were characterized by X-ray diffraction (XRD) and scanning electron microscopy (SEM). Additionally, the residual termiticides and technical materials in the cement pastes were examined by gas chromatography (GC). Results show that the paste's strength decreased with the increase of the concentration of termiticides or the content of technical material. The termiticide and technical material did not change the hydration products and almost did not affect the development of the microstructure of cement pastes. Results of residue detection show that bifenthrin cannot be well stored in cementitious materials. In the early stage, the recovery rate of chlorpyrifos was relatively stable, while in the late stage, the recovery rate decreased sharply. In conclusion, the termite-resistant concrete prepared by traditional methods had a strong termite resistance in a short time rather than in a long time. Hence, it is not feasible to directly use termiticide or technical material to prepare termite-resistant concrete.