Study And Application On High Performance Concrete For Bridge Deck Overlays

It is high concerned that cement concrete bridge deck overlays are seriously damaged at early ages, the phenomenon often occurred greatly affect communication. This research funded by the Western Communication Construction Project of Communication Ministry of China-Study on Massive Concrete and High Performance Concrete for Badong Yangtze River Highway Bridge. On the basis of investigating the reason causing the destruction of cement concrete bridge deck overlays and finite element analysis, the technical requirements of bridge overlay concrete and interfacial adhesive have been presented. To solve the cracking and debonding of cement concrete bridge deck overlays, the high performance bridge deck overlay concrete (BDO-HPC) — micro-expansion polypropylene fiber reinforced concrete has been prepared, and a new inorganic interfacial adhesive has been developed to strengthen cementation of bridge slabs and deck overlays by using some inorganic materials and functional components, which has similar linear expansion coefficient with concrete and excellent bond performance.The effects of polypropylene fibers, expansion agents and fly ash on mechanical properties, ductility and durability of BDO-HPC have been studied. It is indicated that BDO-HPC combines the merits of polypropylene fiber reinforced concrete, shrinkage-compensating concrete and high performance concrete, and it sufficiently exploits each effect of the three components, namely anti-cracking and enhancing ductility from polypropylene fibers, compensating shrinkage from expansion agents and retarding and water-reducing from retarding superplasticizers and their superimposed effect. The BDO-HPC has good ductility, flexural strength, anti-cracking, impermeability, impact resistance and wearing resistance. The effects of polypropylene fibers, expansion agents and fly ash on the cracking resistance of cement mortar under plastic and drying curing conditions and the effect of expansion agents on the drying shrinkage of cement mortar under different curing have been studied, too. The results show that there have excellent anti-cracking capabilities for polypropylene fibers and the blending of polypropylene fibers and expansion agents or fly ash, while it is only under the moisture curing conditions that the expansion agent has good anti-cracking.The technical measurements to improve construction quality of cement concrete bridge deck overlays has been established, and the methods and technologies of roughening, cleaning and wetting of bridge slabs, spraying interfacial adhesive, strengthening moisture curing of BDO-HPC at early ages and cutting gutter have been put forward.