| Taking the waste rice husk ash produced by biomass power plant as the research background,a new type of rice husk ash(E-RHA)concrete was prepared by adding it into concrete,which insteads of part of cement.Contrast with the performance of ordinary concrete,the working performance,mechanical and durability of E-RHA concrete are investigated.Moreover,according to the macro and micro test results,such as the mechanical and physical parameters,XRD,microstructure,the mechanical strength and sulfate resistance of concrete reinforced by E-RHA are analyzed.The main research results are as follows:(1)The addition of E-RHA can reduce the workability of concrete.According to the fluidity test of cement mortar,it is determined that 0.8ng water should be added on the basis of the original water consumption to replace n g cement with E-RHA to make up for the adverse effects of E-RHA on the working performance of concrete.(2)The mechanical properties of E-RHA concrete are tested,including the tests of the unconfined compressive strength and splitting tensile strength of E-RHA concrete with different content.The result shows that the mechanical strength of concrete increases first and then decreases with the content of E-RHA,the macro mechanical properties of concrete reach the best when the content of E-RHA is 9%,and the compressive strength and splitting tensile strength are increased by 30.5%and 31.4%respectively coMPared with ordinary concrete.Besides,according to the XRD diffraction test of E-RHA,it is found that E-RHA has a large number of non qualitative SiO2,producing the calcium silicate hydrate(C-S-H)gel with cementation strength,which is the main reason for the improvement of the strength of the E-RHA concrete.(3)Based on the tests of natural erosion of sulfate solution and dry wet cycle with a total age of 270 days on 9%E-RHA concrete and ordinary concrete,the compressive strength,splitting tensile strength,effective porosity and relative dynamic modulus of elasticity of the two kinds of concrete at different erosion ages are obtained.The results show that with the increasing erosion time,the mechanical parameters and main physical parameters of the two kinds of concrete show a downward trend after a short increase.However,the initial period of strength decline of E-RHA concrete under the two erosion mechanisms are both later than that of ordinary concrete,which indicates that E-RHA concrete has better resistance to sulfate.Besides,the damage constitutive models of E-RHA concrete and ordinary concrete in sulfate solution erosion environment are established based on the micro damage micro element hypothesis and Weibell distribution,,which can play a reference role for the damage assessment of two kinds of concrete under sulfate erosion,and also provide a prediction method for the practical application of E-RHA concrete in sulfate erosion environment.(4)According to the SEM microscopic test,,the degradation of E-RHA concrete and ordinary concrete under two sulfate erosion mechanisms are analyzed,it can be observed the expansive corrosion products such as ettringite,gypsum,and C-S-H gel,which made E-RHA concrete carry a better sulfate resistance.Combined with the macro parameters and micro morphology,it is analyzed that E-RHA can improve the sulfate resistance of concrete from reducing the Ca(OH)2 content of concrete,improving the coMPactness of concrete and reducing the evaporation shrinkage of concrete surface.figure[48]table[23]reference[62]... |
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