喷射混凝土用无碱液体速凝剂的制备及其机理研究

Study on Preparation and Mechanism of Alkali-free Liquid Accelerator for Sprayed Concrete

采用常温滴加工艺,以纳米活性氧化铝和改性醇胺为主要原料制备了一种喷射混凝土用无碱液体速凝剂(AFL)。通过贯入阻力研究了速凝剂应用于混凝土,其中早期硬化强度的发展对喷射混凝土回弹量的影响,并通过XRD和SEM微观特征研究,分析了不同类型速凝剂的作用机理。结果表明,无碱液体速凝剂AFL掺量为6%时,初终凝时间满足GB/T 35159—2017《喷射混凝土用速凝剂》检测要求,1 d抗压强度21.8 MPa,28 d抗压强度比111.8%,90 d抗压强度保留率110.4%,30 min内混凝土硬化强度高,应用于喷射混凝土中,隧道拱顶和侧墙的回弹率分别为13.4%和6.4%。

A new alkali-free liquid accelerator for sprayed concrete was prepared through normal temperature drop process by using the nano activated alumina and the modified alcohol amine as the main raw materials.The influence of early hardening strength of concrete mixed with accelerator on the rebound of sprayed concrete was studied by penetration resistance method,and the accelerating mechanism of the different types of alkali-free liquid accelerator were also analyzed via XRD and SEM characterization methods.The results indicate that when the content of alkali-free liquid accelerator is 6%,initial setting time and final setting time meet the testing requirements of accelerant for shotcrete GB/T 35159—2017.The 1 d compressive strength is 21.8 MPa,the 28 d compressive strength ratio is 111.8%,and the 90 d compressive strength retention rate is 110.4%.The hardening strength of concrete is high within 30 min.The resilience of the tunnel vault and side walls is 13.4%and 6.4%,respectively.