瓦斯隧道气密性机制砂混凝土的配制与研究

Preparation and research of air tightness machine-made sand concrete for gas tunnel

通过掺入气密剂,配制适用于瓦斯隧道的气密性机制砂混凝土,并研究其对水泥水化的影响,运用等温量热仪、X射线衍射仪、热重分析仪、扫描电镜和压汞法对水泥水化放热及水化产物进行分析。结果表明:相较未掺时,掺入气密剂混凝土表观渗透率由497.50×10^(-18) m^(2)减小为29.16×10^(-18) m^(2),抗氯离子渗透系数减小了54.96%,56 d干燥收缩减小了8.63%,56 d抗压强度提高了11.2%。掺加气密剂对水泥净浆水化产物的生成无不利影响,同时明显减少了水泥净浆水化产物内部的大毛细孔(100~1000 nm)数量,使水化产物更密实,并改善了混凝土界面过渡区结构,从而提高了混凝土的强度、气密性及耐久性。

Air tightness machine-made sand concrete suitable for gas tunnel was prepared by adding air-tight agent and its influence on cement hydration was studied.The heat release and hydration products of cement were analyzed by isothermal calorimeter,XRD,thermogravimetric analyzer,scanning electron microscope and mercury injection method.The results show that,compared with the concrete without air tightness,the apparent permeability of concrete decreases from 497.50×10^(-18) m^(2) to 29.16×10^(-18) m^(2),the chloride permeability coefficient decreases by 54.96%,the drying shrinkage decreases by 8.63%,and the compressive strength increases by 11.2%at 56 d.According to the analysis,the addition of air-tight agent has no adverse effect on the generation of cement hydration products,compared with the sample without adding air-tight agent significantly reduces the large capillary pores(100~1000 nm)inside the cement hydration products,makes the hydration products more dense,and improves the structure of the transition zone of the concrete interface,so that the strength,air tightness and durability of the concrete can be improved.