Influence of mineral admixture on strength and impermeability of shotcrete under high temperature environmentt
Aiming at the problems of later strength decline and durability deterioration of shotcrete under high temperature tunnel environment,investigates the influence of different mineral admixtures(fly ash,slag powder,silica fume)on the long-term strength stability,resistance to water penetration and chloride penetration of shotcrete under 80 ℃ dry-hot curing condition in the case of single doping,binary and ternary compound doping.The improvement mechanism of mineral admixtures is revealed by analyzing the bubbles structural parameters of hardened concrete.The experimental results indicate that the long-term strength stability and impermeability of shotcrete can be improved significantly by single adding 5％silica fume or double adding 10％slag powder and 5％silica fume,meeting the 56 d compressive strength without shrinkage and the seepage height only is 78 mm and 101 mm respectively.The three-component compound system(10％fly ash+10％slag powder+5％silica fume)has the best chloride ions penetration resistance,and the chloride ions diffusion coefficient of 28 d and 56 d are reduced to 6.4×10-12m2/s and 13×10-12m2/s,respectively.
high temperaturemineral admixtureshotcreteimpermeabilitypore structure
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维普
