| Summary: | 碩士 === 國立高雄應用科技大學 === 化學工程系碩士班 === 92 === Microstructures and compressive strength of concrete and superplasticizing concrete pastes prepared by nano-technology were investigated by scanning electron microscope (SEM) and universal compressive tester.
In Part A, an inorganic cluster of polysilsesquioxane (POSS) in nano-scale was prepared by sol-gel method and was subsequently added into cement pastes. POSS was formed via the hydrolysis and the condensation reaction of methyltrimethoxysilane (TMOS) or /and 3-glycidoxypropyltrimethoxysilane (GPOS) with polyethylenimine linear (PEI) and identified by the fourier transformation infra-red (FTIR) spectrum. In-situ developing microstructure and compressive strength of various cement pastes with different level of POSS (1, 3, 5 and 10 phr based on weight of cement) were monitored and tested at the different curing time. The densification effect is not apparently observed when POSS content is less than 5 phr in the concrete paste. Whereas, the densification effect is gradually promoted to a plateau level when POSS content reaches 10 phr in the concrete paste. Microstructures of superplasticizing concrete paste with inorganic clusters of POSS are densification because of superplasticizer. The POSS content in concrete or superplasticizing concrete pastes is less than 3 phr, the compressive strength of early period is low strength, but the compressive strength of later period increases progressively. The absorption capacity and permeability of concrete or superplasticizing concrete pastes decreased with the content of POSS increased.
In Part B, montmorillonite clay was modified by the cetylpyridinium chloride (CPC) and was subsequently added into cement pastes. The organoclay (MMT-C) is identified that the interlayer spacing is increase from 1.41 nm to 1.98 nm by X-ray Diffractometer (XRD). In-situ developing microstructure and compressive strength of various cement pastes with different level of MMT-C (1, 5 and 10 phr based on weight of cement) were monitored and tested at the different curing time. The densification effect is obviously observed when MMT-C content reaches 10 phr in the concrete paste. Microstructures of superplasticizing concrete paste with MMT-C are densification because of superplasticizer. The compressive strength of concrete paste with MMT-C is high strength when MMT-C content is 1 phr. The compressive strength of superplasticizing concrete paste with MMT-C decreases progressively with the content of MMT-C increased. The absorption capacity and permeability of concrete or superplasticizing concrete pastes decreased with the increasing amount of MMT-C.
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