Laboratory investigation on effects of microwave heating on early strength of cement bitumen emulsion mixture

Effects of microwave heating time, microwave power, water-cement ratio (W/C) and bitumen-cement ratio (B/C) on early strength of cement bitumen emulsion mixture (CBEM) were studied in this work. Environment scanning electron microscopy (ESEM) and Fourier Transform infrared spectroscopy (FT-IR) were adopted to analyze microstructures and compositions of CBEM. The most important factors affecting CBEM strength were putting forward based on multiple linear regression analysis (MLRA) and grey correlation analysis (GCA). The results show that the total microwave energy is composed of microwave power and microwave radiation time. The higher the total microwave energy, the higher the surface temperature of CBEM. The effect of W/C on CBEM temperature is more significant than that of B/C. Microwave heating time and microwave power can evidently influence strength of CBEM. Microwave heating can promote cement hydration, which is beneficial to improve strength of CBEM. However, excessive microwave time can result in the decrease of CBEM strength. Temperature model based on MLRA can show linear correlation between different factors. Strength model shows quadratic correlation to microwave parameters. In summary, reasonable microwave heating is an effective technique to improve early strength of CBEM.