混凝土回弹抑制剂对提升现场喷射混凝土施工效率及降低混凝土用量具有重要意义。采用室内及现场原位试验方法对外掺新型纳米型回弹抑制剂的喷射混凝土开展试验研究,探究了抑制剂对喷射混凝土力学性能及回弹抑制效果的影响规律。结果表明:新型纳米回弹抑制剂降低了喷射混凝土的流动性能,添加抑制剂后的喷射混凝土砂浆稠度增大11.4%,扩展度减少6.7%;室内砂浆试验测得试件在1 d、3 d、7 d、14 d抗压强度相比未添加抑制剂的分别增大19.5%、31.5%、17.1%、19.6%,未添加速凝剂的混凝土的抗压强度受回弹抑制剂影响较不明显;现场回弹率测试表明回弹抑制剂可降低约42%的回弹量,且回弹抑制剂的加入对抑制粉尘粒子数量有着显著效果,随掌子面距离增大,实验组相较对照组分别小39.1%、40.7%、44.6%、50.9%、52.4%、45.9%。

The application of concrete rebound inhibitors is of great significance for enhancing the construction efficiency of on-site sprayed concrete and reducing the consumption of concrete. This study employed a combination of laboratory and field tests to investigate the effects of a new nano-scale rebound inhibitor on shotcrete. The research focused on how the admixture influences the mechanical properties and rebound rate of the concrete. The research results indicate that the addition of the new nano-scale rebound inhibitor slightly reduces the flowability of wet sprayed concrete. The consistency of the sprayed concrete mortar after adding the inhibitor increases by 11.4%, while the expansion degree decreases by 6.7%. In the indoor mortar test, the compressive strengths of the specimens measured at 1d, 3d, 7d, and 14d increase by 19.5%, 31.5%, 17.1%, and 19.6%, respectively, compared to those without the addition of the inhibitor. However, the compressive strength of the concrete without the addition of the accelerator is less affected by the rebound inhibitor. In the on-site rebound rate test, the rebound inhibitor can reduce the on-site construction rebound by approximately 42%. The addition of the rebound inhibitor on the construction site shows a significant difference in the number of dust particles. With the increase in the distance from the tunnel face, the experimental group is 39.1%, 40.7%, 44.6%, 50.9%, 52.4%, and 45.9% smaller than the control group, respectively.