Study On Alkali Corrosion Performance Of The Hybrid Fiber Reinforced Self-compacting Concrete In Early Age

Because of its excellent construction performance,working performance and mechanical properties,self-compacting concrete has been widely used in the construction of many cities.It is a hot spot of concrete research.Compared with the traditional concrete,although self-compacting concrete developed currently has more advantages;however,the ratio of material system and application are still have some shortcomings,such as high liquidity will inevitably cause a certain degree of mechanical performance decrease,the porosity increased and the durability of the problem will also highlight.Refer to the above background,this paper in order to investigate the effects of hybrid fiber on the alkali corrosion ability of self-compacting concrete in early age,first,through the mix design and repeated testing,the self-compacting concrete which meets the requirements of performance and strength was prepared successfully.Then the mixed fiber test groups under different curing period under are put into the different concentrations of Na OH for short-term immersion.Finally,the experimental and theoretical studies on the mechanical properties and microscopic properties of the experimental groups before and after corrosion are carried out.The main several aspects of work completed are as follows:(1)The performance of hybrid fiber reinforced self-compacting concrete is tested,and the effect of hybrid fiber on the performance of self-compacting concrete is analyzed.The experimental results show that the incorporation of fiber improves the integrity and anti segregation ability of self compacting concrete,and has the property of 2h.(2)The compressive strength and tensile strength of early age hybrid fiber reinforced concrete before and after alkali corrosion are tested.The effect of alkali solution on the mechanical properties of self compacting concrete at early age is analyzed,and the effect of fiber addition on the mechanical properties is discussed.The test results show that alkali solution inhibited the compressive strength and the tensile strength of self-compacting concrete at early age,and reasonable amount of mixed fiber combination can improve the alkali resistant ability on mechanical properties.(3)Experimental study on pore structure of early age mixed fiber reinforced self-compacting concrete before and after alkali corrosion,the effect of alkali solution on the pore structure of early age self-compacting concrete is analyzed,furthermore,the effect of hybrid fibers on the pore structure in the alkaline environment is analyzed.The experimental results show that the alkali solution destroys the micro pore structure of the self-compacting concrete at early age,but the reasonable amount of hybrid fiber can be used to refine the micro pore structure,improve the impermeability and reduce the penetration of alkali medium,thus improving the damage of alkali solution to the pore structure of self compacting concrete at early age.(4)Micro electron microscope test of early age mixed fiber reinforced self-compacting concrete before and after alkali corrosion is studied.The influence of alkali solution on the interfacial transition zone and cement matrix of early age self-compacting concrete is analyzed,and the influence of hybrid fiber on the two aspects of the early age self compacting concrete in alkali environment is discussed.The experimental results show that the interfacial morphology of the early age self-compacting concrete in alkali environment is obviously changed,the micro cracks are obvious,and the hydration products of cement matrix are uneven,but the incorporation of mixed fiber can effectively prevent the extension of the internal micro cracks in the alkali solution,and enhance the adhesion with the cement matrix.