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Influence of fly ash on leaching behavior of cement paste under environment of soft water


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Influence of fly ash on leaching behavior of cement paste under environment of soft water
Chen ShuaiZuo XiaobaoYin Guangji
School of Science,Nanjing University of Science and Technology,Nanjing 210094,China
emironment of soft water fly ash cement paste calcium leaching microstructure morphology
In order to investigate influence of fly ash on leaching behavior of cement paste in soft water,the cement paste slice specimens with different fly ash content are prepared to perform their leaching experiments in deionized water. By using the saturation-drying weighing method,the ethylene diamine tetraacetic acid(EDTA)titration,and the scanning electron microscope(SEM/EDS)measurement,the changes of porosity,calcium dissolution,Ca-Si ratio and microstructure morphology in the specimens with fly ash content and leaching time are analyzed. Results show that,the addition of fly ash can increase the initial porosity and leaching depth of the slice specimens,and accelerate leaching process of cement pastes.However,the fly ash can also reduce the content of calcium hydroxide and calcium dissolution in the cement paste,and the dense C-S-H gel formed by the pozzolanic reaction can effectively fill the pores in cementpaste resulting in slowing down the increase of porosity and the decrease of compactness in the specimens in its leaching process,so the fly ash can reduce the leaching degree of cement pastes.


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Last Update: 2020-04-20