Research on the Influence of Mix Ratio on Rebound Rate of Shotcrete
2021
YANG Yongmin
Shotcrete often has the disadvantages of high rebound rate and serious construction loss. By optimizing the mix ratio of shotcrete, and considering the three factors of water-cement ratio, sand ratio and cementitious material content, this paper designs the orthogonal test to investigate the influence of the three factors on the rebound rate of shotcrete. The results show that: The most important factor influencing the rebound rate of shotcrete is the sand ratio, followed by the water-cement ratio and the cementitious material content. Three representative mix ratios are selected for on-site trial mixing and spray construction. All the slump, expansion degree, and air content of the shotcrete meet the design requirements. The state of the mixture is good, and there is no concrete disintegration. The slump loss is very small after being placed for 1 h; the measured strength generally is greater than 30 MPa; and the shotcrete with the optimal ratio selected in the orthogonal test has the smallest on-site rebound rate.
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