Study On The Performance Of Concrete With Fly Ash Instead Of Fine Aggregate

This thesis mainly talks about the concrete with fly ash instead of fine aggregate,the compressive strength,prismatic axis compressive strength,splitting tensile strength,flexural strength,modulus of elasticity,carbonation depth and microstructure of concrete with different age of fly ash instead of fine aggregate under different age were carried out experimental study.The main contents of the study included:1.The effect of fly ash substitution rate on the compressive strength,prismatic axis compressive strength,splitting tensile strength and flexural strength of concrete with fly ash instead of fine aggregate under the same water-cement ratio.2.The effect of age on the compressive strength,prismatic axis compressive strength,splitting tensile strength and flexural strength of concrete with fly ash instead of fine aggregate.3.The modulus of elasticity of concrete with fly ash instead of fine aggregate under different replacement ratio were tested and analyzed;The carbonization depth of ordinary concrete and concrete with fly ash instead of fine aggregate under different replacement ratio were tested and analyzed;The microstructures of concrete with fly ash instead of fine aggregate at different time were tested and analyzed;The cost of ordinary concrete and concrete with fly ash instead of fine aggregate were analyzed,and the cost difference were calculated.4.In order to apply them in the engineering practice and provide the necessary reference materials for the actual project,the test data were analyzed,the optimal substitution rate under the condition of strength and workability were defined.5.The prediction model of compressive strength,splitting tensile strength and flexural strength of concrete with fly ash instead of different amount of fine aggregates were established.The replacement rate weighting factor in the model was only related to the age.The results show that the cube compressive strength,splitting tensile strength and axial compressive strength of concrete with fly ash instead different amount of fine aggregate were better than those of concrete without substituting.However,with the increase of replacement rate,the workability of concrete with fly ash instead of fine aggregate was worse,water-reducing were needed to meet the requirements of workability.In addition,the flexural strength of concrete with fly ash instead of fine aggregate was slightly lower than non-replacement concrete,but still basically meet the engineering requirements.The cube compressive strength,splitting tensile strength,axial compressive strength,flexural strength,elastic modulus and carbonization resistance of concrete with fly ash instead of fine aggregate was optimal at a replacement rate of 45%,and the production cost was far lower than the non-replacement of concrete,it can be used in a large number of practical projects.The strength of concrete with fly ash instead of fine aggregate was mainly due to the second reaction between cement hydration product and SiO2,Al2O3 in the fly ash,the final reaction product of the second reaction resulting in a close combination of various substances,thereby improved the strength of concrete with fly ash instead of fine aggregate.