Effect of Mineral Admixture on Hydration Behavior and Mechanical Properties of Shotcrete at Different Temperatures

Abstract

Abstract: The effects of fly ash, slag and silica fume on hydration behavior and mechanical properties of shotcrete at different temperatures are still unclear. The effects of three mineral admixtures on the hydration behavior of shotcrete at different temperatures and ages were characterized by XRD quantitative analysis, thermogravimetric analysis and SEM test, and the compressive strength of mortar was tested. The results show that silica fume and slag can improve the early and late strength of shotcrete at different temperatures, while fly ash is not conducive to the development of early strength. The 6 h compressive strength of fly ash mortar is lower than reference value at 20 ℃. At 6 h and 1 d ages, the effect of temperature on the compressive strength of test blocks is very significant, and the 6 h compressive strength of silica mortar at 60 ℃ is as high as 13.39 MPa. With the increase of age, the strengthening effect of temperature on the strength of test block decreases. The increase of temperature stimulates the pozzolana effect of mineral admixture, generates C-S-H gel to fill the internal pores and improve the compressive strength of mortar test block. At the same temperature and age, the content of C-S-H gel in hydration products of silica fume system is high, resulting in the highest compressive strength.The slag system has the highest degree of hydration, resulting in higher compressive strength. Although AFt content of fly ash system is the highest, C-S-H gel content is low, resulting in the lowest compressive strength.This paper provides guidance for the application of mineral admixtures in shotcrete under special environment.

Key words: shotcrete, mineral admixture, alkali-free accelerator, temperature, hydration

CLC Number:

TU528.53

YUAN Jian, WANG Qin, ZENG Fanchao, GUO Zhixiang, WANG Hongwei. Effect of Mineral Admixture on Hydration Behavior and Mechanical Properties of Shotcrete at Different Temperatures[J]. BULLETIN OF THE CHINESE CERAMIC SOCIETY, 2024, 43(2): 407-417.

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