Theeffects Of Nano-modified Composite Waterproofing Agent On The Properties Of Concrete

Seepage control is closely related to structural safety, normal use and service life of concrete engineering. The anti-seepage performance of concrete can be improved with incorporating waterproofing agent, while other properties will be affected, such as early strength. Meanwhile, nano-materials have unique size effect, quantum effect and interface effect, which are quite different from traditional materials. Thus nano-materials can be used to optimize the performance and expand the application field of traditional building materials. Therefore, nano-modified composite waterproofing agent, which is created by incorporating nano-materials with waterproofing agent, can help to significantly improve the anti-seepage performance of concrete.Through macro performance test, the performance of concrete incorporating the waterproofing agent KIM and nano-SiO2was studied, including flowability, mechanical and impermeability, anti-carbonation properties. Combined with microanalysis, such as XRD, SEM, MIP, the effect of KIM waterproofing agent and nano-SiO2on the properties of concrete was investigated in order to develop a high-quality waterproof material, which is characterized with good impermeability and no side effect concerning other properties.The result showed that:(1) Incorporating composite waterproofing agent and nano-SiO2has some influence on the flowability of concrete, which can be ensured hrough appropriate technical measures, such as increasing the dosage of superplasticizer.(2) Incorporating KIM waterproofing agent alone has a significant influence on the properties of concrete, with a decrease of14.81%for the compressive strength and a reduction of71.6%for seepage height at3days, and the carbonation depth at28days was37.3%lower. On this basis, the incorporation of1-2%of nano-SiO2increased the compressive strength by about30%and reduced seepage height by12-19%at3days, and increased the resistance to chloride ion penetration (electric flux value decreased13.4-23.4%) at28days, compared with the concrete incorporating KIM waterproofing agent. At the same time, the incorporation of polymer Powder A was not conducive to the improvement of mechanical and anti-carbonation properties of concrete.(3) From microanalysis, the mechanism of nano-SiO2would probably be filling the pores within concrete, resulting in a better microstructure; and the absorption and refinement of Ca(OH)2crystals, resulting in an improvement of concrete interface.