Design And Performence Stduy Of Solid Waste High Performence Concerte

High performance concrete（HPC,UHPC）has superior compressive performance compared to traditional concrete and has broad development prospects in various engineering fields,but usually has low toughness.At present,most high-performance concrete has the problem of being environmentally unfriendly and costly during the preparation process.The preparation method of high-performance concrete using solid waste admixtures such as slag and fly ash instead of cement has lower comprehensive properties such as compressive strength and toughness compared to traditional preparation methods.Therefore,this article studies the method of modifying cementitious materials with external modifiers to improve the performance of solid waste admixtures in concrete,while meeting the compressive performance and toughness of high-performance concrete while also considering environmental friendliness.Through corresponding mechanical performance experiments and microscopic experiments,the failure morphology and corresponding microscopic mechanism of the specimens under the comprehensive effects of different water cement ratios,external modifiers,and fiber types were analyzed.Based on social and economic benefits,the following conclusions were drawn:（1）By using slag,fly ash,and silica fume as solid waste admixtures and using spatial grid theory to optimize aggregate particle size parameters,higher packing density cementitious materials and aggregate proportions can be obtained.On this basis,14 groups of control groups were set up with different water-binder ratios,modification conditions,and fiber types as variables for the experiment.Through FTIR testing and flowability testing,it was found that the amino functional groups provided by modifier KH550 can effectively combine with solid waste cementitious materials,improving material dispersibility;The modifier has improved the flowability of different ratios of cementitious materials,with an increase in the order of 0.16,0.18,and 0.20 water cement ratios,which are 63.8%,17.5%,and 2.4%,respectively.The lower the water cement ratio,the more obvious the effect.（2）Based on the above experimental results,design the mix ratio of solid waste high-performance concrete and prepare the sample.At a water cement ratio of 0.18,high-performance solid waste concrete with a maximum compressive strength of 121 MPa,ultimate tensile strain of 3.44%,and flexural strength of 24.98 MPa was prepared.From the three aspects of modifier,fiber type,and water cement ratio,combined with corresponding mechanical experimental data,it can be concluded that after adding modifier,the average strength of the specimen increases by 17.8%.When other conditions are the same,the average strength of the specimen increases by 27.32%and 27.13%for PE fiber compared to PVA fiber and without adding fiber;Under the condition of 0.18 water cement ratio,the modifier and fiber have improved the overall mechanical properties of the specimen.At 0.2water cement ratio,the fiber and KH550 exhibit a reverse improvement in the performance of concrete.Based on experimental data,provide reference suggestions for the mix ratio during actual construction.（3）Through macro and micro experiments,combined with the hydration products and corresponding mechanical properties of solid waste concrete,the following conclusions are drawn from three aspects:modifier,fiber type,and water cement ratio.The following conclusion is drawn:after modification,the hydration degree of solid waste cementitious materials increases,and more hydration products such as Ca Mg（CO₃）₂and Ca（OH）₂are produced in the later stage,which to some extent improves the micro morphology and pore structure of concrete specimens,Improving the compactness of the matrix helps to enhance the compressive strength and initial crack strength of the toughness experiment of the specimen;When the density of the matrix is higher,the PE fiber,which mainly consumes energy through pulling out,is more conducive to improving the compressive strength of the specimen.After the specimen is damaged,it can maintain good integrity,help to form the phenomenon of multiple cracks and cracks in the specimen,and improve the toughness of the specimen.