增黏剂和石灰石粉掺入对喷射混凝土性能影响的试验研究

Experimental study on the effect of adhesives and limestone powder on the performance of shotcrete

基于目前喷射混凝土在施工过程中普遍存在回弹量大、强度保有率低等问题设计石灰石粉和增黏剂复合掺杂混凝土。通过研究新拌混凝土的凝结时间、黏度、扩展度、坍落度、抗压强度和回弹率等因素,发现掺入石灰石粉、并保持增黏剂掺量5%、速凝剂掺量6%时,初凝和终凝时间最短,使混凝土在具有一定黏度的同时,也具有较好的流动性。石灰石粉和增黏剂复合掺入混凝土28 d抗压强度为37.5 MPa,说明一定量增黏剂的掺入可以填充到混凝土的孔隙中,减少了内部水分的流失和蒸发,使混凝土内部水化更加充分,使浆体结构致密,保证后期强度。此外,现场试喷的回弹率为8.6%,从而有效提高喷射效率,降低施工成本。

Based on the problems of large springback and low strength retention rate in shotcrete construction,the composite doped concrete with limestone powder and viscosifier is designed.By studying the setting time,viscosity,expansion degree,collapse degree,compressive strength and rebound rate of freshly mixed concrete,it is found that the initial and final setting time is the shortest when the lime powder is added and the content of viscosifier is 5%and the content of accelerating agent is 6%,so that the concrete has a certain viscosity and good fluidity at the same time.The 28-day compressive strength of concrete mixed with limestone powder and viscosifier is 37.5 MPa,indicating that a certain amount of viscosifier can fill in the pores of concrete,reduce the loss and evaporation of internal water,make the internal hydration of concrete more full,make the structure of slurry compact,and ensure the later strength.In addition,the springback rate of the field test is 8.6%,which effectively improves the injection efficiency and reduces the construction cost.