Quantitative Characterization of the Microstructure of Cementitious Repair Materials
The aim of this study is to investigate the effects of nanosilica(NS)and polyvinyl alcohol fiber(PVA)on the flow and mechanical properties of cementitious ternary repair materials,and to reconstruct the pore structure of the repair materials in three dimensions and quantitatively characterize them using computed tomography(CT)technology and DRAGONFLY image processing platform.Ordinary silicate cement(OPC),cement aluminate(CAC)and gypsum dihydrate(CS)were selected as cementitious materials for the study,and their effects on the properties of the repair materials were analyzed by changing the dosage of NS and PVA.The results showed that the optimal dosage of NS was3%,at which the28 days compressive strength of the repair material increased by9.4%compared with the ternary system,while the optimal dosage of PVA was0.75%,which could significantly improve the flexural and compressive strength of the repair material.CT scanning and three-dimensional reconstruction revealed the spatial distribution characteristics of the internal pore structure of the specimens under different dosages,in which the addition of NS significantly reduced the porosity,while the addition of PVA increased the porosity.The addition of NS significantly decreased the porosity,while the addition of PVA increased the porosity.This study provides an experimental basis for the optimization of cementitious repair materials and a new perspective for understanding the relationship between the internal structure and macroscopic properties of materials.
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