摘要
钢壳混凝土沉管隧道采用低水胶、胶凝材料用量大的自密实混凝土引起的早期收缩大,容易造成钢壳与混凝土脱空。以深中通道采用的双层钢壳内部填充自密实混凝土设计为背景,配制钢壳沉管自密实微膨胀混凝土以解决此问题。在优化配比的基础上,研究了单掺和复掺矿物掺合料对C50自密实混凝土的工作性能、力学性能和变形性能的影响。得出采用大掺量粉煤灰(42%)与小掺量矿粉(18%)复掺,总胶凝材料为550kg/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,采用内养护剂与氧化镁复合膨胀剂复掺技术对自密实混凝土进行收缩调控,内养护剂和氧化镁复合膨胀剂复合作用下对自密实混凝土具有良好的协同膨胀效应。SEM与MIP分析表明,内养护材料界面区形成了致密水化层,降低了界面过渡区孔隙率,显著改善水泥基体的微观结构,可以有效地对C50钢壳沉管混凝土进行收缩调控。
The steel-shell submerged tunnel used adopts self-compacting concrete(SCC)with low water to blinder ratio incorporating volume cement material,which causes large early shrinkage,which is easy to cause the steel-shell and concrete to void.To this end,the article uses the double-layer steel shell internally filled with self-compacting concrete design used in Shenzhen-Zhongshan bridge as a background,and prepares steel-shell submerged tunnel filled with self-compacting micro-expansion concrete to solve this problem.This paper studies the effects of single and multiple mineral admixtures on the working performance,mechanical properties and deformation properties of C50 self-compacting concrete.It is concluded that a large amount of fly ash(42%)is mixed with a small amount of mineral powder(18%),the total cementitious material is 550 kg/m^(3),the water-binder ratio is controlled at 0.31,and the sand ratio is 50%.Produce a low-shrinkage C50 self-compacting concrete that meets the mechanical performance requirements and effectively meets the working performance requirements of steel shell immersed tube self-compacting concrete;at the same time,the self-compacting concrete shrinkage control is carried out by the composite technology of internal curing agent and magnesium oxide compound expansion agent.Under the combined action of internal curing agent and magnesium oxide compound expansion agent,it has agood synergistic expansion effect on self-compacting concrete.SEM and MIP analysis show that a dense hydration layer is formed in the interface zone of the internal curing material,which reduces the porosity of the interface transition zone,significantly improves the microstructure of the cement matrix,and can effectively control the shrinkage of C50 steel shell immersed tube concrete.
作者
芮伟国
彭英俊
何涛
吴旭东
吴琪锋
RUI Wei-guo;PENG Ying-jun;HE Tao;WU Xu-dong;WU Qi-feng(Shenzhen-Zhongshan Link Management Center,Zhongshan 528400,China;Poly Changda Engineering Co Ltd,Guangzhou 510620,China)
出处
《武汉理工大学学报》
CAS
2021年第4期20-26,56,共8页
Journal of Wuhan University of Technology
基金
广东省重点领域研发计划项目(2019B111105002)。
关键词
钢壳沉管
自密实混凝土
工作性能
体积稳定性
孔结构
steel-shell submerged tunnel
self-compacting concrete
workability
volume stability
pore structure
作者简介
芮伟国(1986-),男,硕士,工程师.E-mail:28018509l@qq.com。
