An Investigation Into The Mechanism Of Silane Coupling Agent On Interfacial Transition Zone Between Granite And Cement Paste

Several mechanical experimental researches have indicated that the bond strength of granite/silane coupling agent (SCA)/cement paste interfaces is much higher than that of the granite /cement interfaces obtained using existing granite surface modification methods. Hence SCA surface modification is likely to be a superior means to improve the strengths and durability of the billions of tons of concrete used worldwide. This is a new method to improve the bond strength between aggregates and cement paste. It is hence necessary to investigate the bond mechanisms.The influence of SCA/aggregates reaction time and temperature was investigated through an experimental study. Spectrophotometry and contact angle measurements were used to investigate the formation of the granite/SCA interfaces. Fourier transform infrared spectrometer (FTIR) and X-ray Photoelectron Spectroscopy (XPS) experiments had revealed that strong chemical bonds (even in room temperature) have formed on the modified surfaces of the granite. The results of all the experiments showed that physical adsorption, chemical adsorption and chemical bonds were formed between the SCA and the aggregates. The longer time and higher temperature at reaction, the more chemical adsorption and chemical bonds are formed. However, mechanical experiments indicated that higher aggregate/cements bond strengths were obtained at room temperation with short reaction time. The author investigated the formation of the granite/SCA/cement paste interfacial layers with respect to physical and chemical considerations. A mechanism describing the formation of the modified interfacial transition zone and its improvements to the aggregates/cement paste bond strength was proposed. Finally, propositions of future research were brought forward.