Light Micro-expansion Concrete In Old Bridge Strengthening

Compound of high strength micro-expansive lightweight concrete and the situation that lightweight concrete is applied to the work of bridge rehabilitation are mainly analyzed in this paper. Eight concrete samples of different compound ratio of artificial lightweight aggregate (coarse aggregate of expanded shale) and ordinary aggregate, water-reducing admixture, expanding admixture ,etc ,are compounded firstly, based on the research of main properties such as agitating property ,strength, dry surface density and deformation, an optimum compound ratio of the concrete with high strength(CL40),light density(1800) and slight expand is achieved. Second, design schemes of strengthening arch bridges are put forward and strength computation of which is executed. Because the experimental bridge is an arcade bridge which is comprised of three four-arched bridges, micro-expansive lightweight concrete, micro-expansive ordinary concrete and ordinary concrete are used in each four-arched bridge respectively in order to comprehend the performance of light expanded lightweight aggregate concrete profoundly and contrast effects of different materials. Third, the theory and formulations about the stress redistribution due to creep and shrinkage of composite section and the secondary internal forces which are caused in hyper static structure , the self-stressed force and the secondary internal forces due to expansion, are studied , program is compiled by use of formulations studied above and it is used to analyze sensors that are installed during the course of work. The feasible finite-element model is put forward and it is used to carry out static and dynamic analysis of each four-arched bridge finally. In this paper, high strength micro-expansive lightweight aggregate concrete is compounded successfully and it is firstly applied to the reinforcement of arch ring which is reference to the further compound and usability of lightweight aggregate concrete.