A Study On Properties And Preparation Of High Strength And High Toughness Of Bridge Deck Concrete

Cement concrete has been one of the important bridge deck paving materialsowing to abundant raw materials, high strength, large rigidity and economy. However,tensile strength of concrete was low,brittleness was high. Under combined effects oftraffic loads, natural factors and shrinkage stress, concrete is prone to crack,and it isdifficult to repair once the disease is formed. It would seriously affect the safety anddurability of bridge deck pavement. In this paper, high strength and high toughnesscement concrete was prepared by hybrid fiber reinforced technology and its propertieswere studied.Paper launched from single-fiber reinforcing and toughening. Mechanicalproperties and flexural properties of polyethylene fibers (PE fiber) concrete andcoarse synthetic polypropylene (CPP fiber) concrete was studied. The results showedthat compressive strength of single-fiber concrete was up to60MPa, deformationproperties of single-fiber concrete was improved, load-deflection by rapiddeformation hardening curve becomes brittle failure, concrete has a certain carryingcapacity after cracking, but the flexural toughness of concrete still was poor, thesingle-fiber reinforced concrete could not receive high toughness.Based on structural features of concrete of muti-phase,two different fiber wasused to reinforce concrete, combined with the results of single-fiber toughening, Thedifferent levels of structure and properties of concrete was progressively strengthenedand toughened. Hybrid fiber reinforced concrete with high strength and hightoughness was prepared. Its properties was studied through the strength test, thefour-point bending test, the fiber/matrix interfacial modification trials and abrasionand wear resistance properties test. The results showed that the compressive strengthof concrete was over60MPa, flexural strength was up to8MPa; bending performanceof concrete significantly improved, load-deflection curves was plumper and haddegeneration hardening characteristics, the ability to resistance load was stronger aftercracking. Toughness and residual strength index of hybrid fiber reinforced concretewere improved significantly compared with the ideal elastic-plastic material, themajority of flexural toughness level was3, some up to4; after CPP fiber/matrix interface modified, bond strength was improved, interfacial zone structure was moredense, interfacial microstructure was strengthened, expansion of large cracks anddestruction of concrete was delayed at macroscope, the meso-scale toughening wasassisted, the flexural toughness of concrete was effectively improved; with the coarseaggregate volume levels improve, wear resistance and impermeability of concretereduced, so coarse aggregate level should not be too high.