Microstructure of Cement Paste Blended with Micronized Sand (MS)

Abstract

In this article, micronized sand is selected as filler to partially replace Portland cement in order to reduce the global warming potential, i.e. CO2 emission. It is necessary to figure out the effects of micronized sand on the properties of cement paste. Microstructure, especially the pore structure, influences the transport properties, which are widely recognized as the most important factors to determine the durability of cementitious materials. In this study, it focused on the microstructure of cement paste blended with micronized sand in comparison with the reference ordinary Portland cement paste. Non-evaporable water test was carried out to calculate the degree of hydration of cement. By means of mercury intrusion porosimetry measurements and electronic scanning electron microscope, the pore structure of cement pastes blended with micronized sand as well as interfacial transition zone between micronized sand and hydration products have been investigated. Parameters, including the Portland cement replacement percentages: 10, 20 and 30 % and fineness of micronized sand: M6, M300 and M600, have been taken into account. The results show that although micronized sand is considered as inert filler, it can indirectly modify the hydration kinetics by increasing the degree of hydration of cement and influence the porosity and pore size distribution of the paste. There is a clear interfacial zone between micronized sand and hydration products. This interfacial zone caused by the micronized sand is considered as the decisive factor which influences the transport properties of the material.