钢壳沉管自密实混凝土制备及其收缩调控技术

Preparation of Steel-concrete Sandwitch Immersed Tunnel Used Self-conpacting Concrete of Low-shrinkage and the Regulation of Shrinkage Technology

基于深中通道采用双层钢壳内部填充混凝土的钢壳混凝土三明治结构形式,为解决混凝土自密实填充和良好体积稳定性的技术难题,通过一系列自密实混凝土的正交试验,得出采用大掺量粉煤灰(30%)与小掺量矿粉(30%)复掺,总胶凝材料为550 kg/m^3,水胶比控制在0.31,砂率为50%,制备出满足力学性能要求且有效应对钢壳沉管自密实混凝土工作性能要求的低收缩的C50自密实混凝土;同时提出掺入MgO膨胀剂,有效地对C50钢壳沉管混凝土进行收缩调控,防止混凝土的脱空和抑制裂缝的产生;并且通过分析其微结构从机理上探讨了该体积稳定性调控技术的可行性和优异性。

The structure of Steel-concrete Sandwitch with double layer steel shell was adopted to the project of ShenZhen-ZhongShan Bridge.In order to solve the technical problems of concrete filling and good volume stability,large dosage(30%)and small dosage of fly ash mineral powder(30%),total gelled material of 550 kg/m^3,water/cement ratio controlled in 0.31,sand rate of 50%were prepared,a series of orthogonal experiment of self-compacting concrete were conducted.The steel shell submerged tunnel used self-conpacting concrete of low-shrinkage was prepared to meet the requirement of strength and effectively deal with the work performance requirement.At the same time,the process of adding MgO expansion agent were proposed.It effectively carries out the regulation of shrinkage in C50 steel shell concrete,and prevents the steel shell from being empty and inhibits the crack.What’s more,the feasibility and superiority of the stability control technique were discussed by analyzing its microstructure.