The Applied Research Of Specified Density Concrete And Prestress Technology In Precast Fabricated Pavement

The rapid reparation technology of precast-assemble is a practical technology, which consumes the shortest time and has the minimal impact on road traffic in all reparation technologies at present. The true sense of unimpeded traffic rapid reparation technology has been realized. However, the disadvantage of precast assembly technology was existed——the size problem of precast slab. The weight of road slab and joint processing after assembling were influenced by the size of road slab. Therefore, the technology was gradually improved by solving the size problem of precast slab. In this paper, starting from solving the problem, two solutions were put forward to solve the weight of road slab and joint processing after assembling. The main research contents are as follows:1.The weight of concrete slab was decreased by using lightweight aggregate(shale haydite) partial substitution of the coarse aggregate(gravel). First, the basic performance indices of shale haydite were measured, and then the optimal workability and mechanical properties of specified density concrete was determined by comparing and selecting different substitution rate of shale haydite according to the workability and mechanical properties of concrete. Finally, to verify the degree of reducing weight by using specified density concrete, the dry apparent density and apparent density of specified density concrete were measured, and compared with ordinary concrete. At the same time, the abrasion resistance, drying shrinkages and frost resistance of specified density concrete were measured, to verify the feasibility of specified density concrete used in the rapid reparation technology of precast-assemble.2.The weight of concrete slab was decreased and the concrete amount was reduced by prestress technology, in order to improve its carrying capacity, and can reduce slab thickness. First, the preloading dynamics was determined on the basis of the flexible design principle, and then reinforcement design for whole concrete pavement slab was carried out. Second, this paper put forward a new tension method for the first time and verifies its feasibility through experiment. Finally, in order to study the mechanical properties of precast prestressed concrete pavement and verify its feasibility used in the rapid reparation technology of precast-assemble, scale test was carried out by comparing with the ordinary joint reinforced concrete pavement in carrying capacity.The rapid reparation technology of precast-assemble can get further perfect by applying the specified density concrete and prestress technology, meanwhile, the unimpeded traffic rapid reparation technology of cement concrete pavement has great significance for road maintenance, and has important practical value for the national highway, airport road as well.