Study On Chloride Resistance Of Nano And Micro Particle Modified Cement-based Materials

Large amount of chloride ions exists in the marine environment and decing slat which is widely used in winter. Since the dimater of chloride is very very small, it can penetrate through the concrete, and lead to the corrosion of the reinforcing steel, which will lead to the damage and failure of the concrete structure. How to enhance the durability of concrete structures servicing in the chloride environment has become an engineering challenges, and has attracted much more attention worldwide. It is well known that the mechanical and durability property of the reinforced concrete structure is basically depended on the building materials. The development of a new kind of concrete material that has high chloride resistance property seems to be very important. Based on the systematic investigation in the performance of the modified cement-based materials, a kind of Kaolinite nano caly and Ground Granulated Blast Furnace Slag (GGBS) were applied to modify the chloride resistance of the concrete in this paper. The modification mechanism and the property of the modified cement based materials were investigated. The main contents of this study are listed as follows.Firstly, to achieve a good dispersion of nano-clay in cement based materials, machine mixing, hand mixing and untrasonic dispersion method were taken into consideration herein. The influences of nano-clay on microstructure and pore structure of cement were examined by scanning electron microscopy (SEM) and pressure mercury test respectively. Effects of the influencial factors on the dispersion result of nanoclay in cement based materials are analyzed. The effects of the addition of nano-clay on the microstructure and pore structure of cement were discussed.Then, the performance and durability of nano-clay modified cement-based materials were studied. Performance of the nano-clay modified grout; mechanical properties of nano-clay modified cement-based materials with different additions of nano-clay under various curing periods were studied. The chloride diffusion coefficient and frost resistance of the nano-clay modified cement-based materials with different additions of nano-clay under various curing periods were obtained. The mechanisms of nano-clay on chloride and frost resistance were discussed.Finally, the performance and durability of GGBS modified cement-based materials were discussed. Flexural and compressive strength test were performed. The influence of GGBS on the mechanical property of modified cement at early age was examined. Chloride diffusion coefficients of GGBS modified mortar were obtained. Chloride resistance of mortar with various additions of GGBS was analyzed. The mechanism of GGBS on the performance of cement-based materials was then discussed.