Research On The Method And Experiment Of Performance Enhancement Of Resource Concrete

Recycled concrete is a kind of resource concrete,which is characterized by recycling and sustainable development of resources,but its mechanical properties are relatively poor.In this paper,by adding calcined kaolin and blending calcined kaolin with PVA fiber,basalt fiber,steel fiber,etc.,the mechanical properties of recycled concrete are studied.From the aspects of macro mechanical properties and micro pore structure,the effects of adding calcined kaolin,calcined high coagulation + one-way fiber,calcined kaolin + two-way mixed fiber on recycled concrete are studied The main work and contents of strengthening effect of soil mechanical properties are as follows:(1)research on macro mechanical propertiesThe mechanical properties of 594 test blocks were tested,including compressive strength,flexural strength and splitting tensile strength.The effects of adding calcined kaolin,calcined kaolin + one fiber,calcined kaolin + two fiber on the performance of recycled concrete were studied.The results show that:(1)When calcined kaolin is added alone,the cube compressive strength increases first and then decreases with the increase of the replacement rate of calcined kaolin,but it is higher than that of the reference group without calcined kaolin,which has a reasonable range of adding value;on the basis of calcined kaolin,PVA fiber,basalt fiber and steel fiber are added separately,and the cube compressive strength is higher than that of calcined kaolin alone On the basis of calcined kaolin,the compressive strength of recycled concrete is also improved by adding binary fiber.(2)When the content of calcined kaolin is less than 20%,the cleavage tensile strength increases positively with the increase of the content.When the content of calcined kaolin is more than 20%,the relationship between the content of calcined kaolin and cleavage tensile strength is inverse.When the content of calcined kaolin is less than 15%,PVA fiber can enhance the cleavage tensile strength better.When the content of calcined kaolin is more than 20%,basalt is added respectively Compared with the splitting tensile strength of calcined kaolin alone,the splitting tensile strength of some binary mixed fibers increases and some decreases with different content of calcined kaolin.(3)Under different calcined kaolin content,the flexural strength of resource-based concrete from high to low is: calcined kaolin content 20% >calcined kaolin content 25% > calcined kaolin content 10% > calcined kaolin content15% > calcined kaolin content 5%.It can be seen that the flexural strength of the concrete with 20% calcined kaolin is obviously improved,but the flexural strength of the concrete with each content is higher than that of the reference group When the content of calcined kaolin is added with one fiber and two fiber,the flexural property of recycled concrete can be improved due to the existence of fiber,but the degree of improvement is different.(2)micro pore studyIn this paper,the micro void structure of the recycled concrete reinforced with calcined kaolin and calcined kaolin + monofiber was studied by NMR.The results show that:(1)The peak value of NMR T2 spectrum curve of performance-enhanced resource-based concrete increases first and then decreases with the increase of calcined kaolin content.In T2 spectrum curve,the area enclosed by the first peak spectrum curve and coordinate axis is the largest.Compared with the reference group,the area enclosed by the first peak spectrum curve,the second peak spectrum curve and coordinate axis are all decreasing under each calcined kaolin content,while the area enclosed by the calcined kaolin is decreasing When the content of kaolin is more than 20%,the area around the first peak,the second peak and the coordinate axis increases,but they are smaller than the reference group.(2)Different content of calcined kaolin + monobasic fiber,T2 The peak value of the spectrum curve is smaller than the peak value of the undoped fiber when the content of calcined kaolin is equal,and the area of the first peak spectrum curve when the content of calcined kaolin is equal is larger than the area of the first peak spectrum curve when the content of calcined kaolin is less than 15% When the content of PVA and basalt fiber is more than 15%,the total area of the three peak spectrum curve is the smallest when PVA and basalt fiber are 5:5;when PVA and basalt fiber are more than 15%,the total area of the three peak spectrum curve is the smallest when PVA and basalt fiber are 7:3,indicating that the material is relatively dense,the internal pores are smaller and the strength is higher.(3)grey relation researchBased on the grey correlation theory,the mechanical properties of the recycled concrete are evaluated when calcined kaolin + PVA fiber + steel fiber,calcined kaolin +PVA fiber + basalt fiber,calcined kaolin + basalt fiber + steel fiber are mixed.The results show that:(1)When calcined kaolin,PVA fiber and steel fiber are mixed,the mechanical properties of recycled concrete can be enhanced from high to low: PVA fiber content > calcined kaolin content > steel fiber content.(2)When calcined kaolin,PVA fiber and basalt fiber are mixed,basalt fiber has the greatest influence on compressive strength,PVA fiber has the greatest influence on splitting tensile strength and flexural strength,and PVA fiber and basalt fiber have little influence on their performance enhancement.(3)When calcined kaolin,basalt fiber and steel fiber are mixed,the correlation degree of compressive strength and flexural strength of recycled concrete is: steel fiber content > basalt fiber content > calcined kaolin content,and the correlation degree of splitting tensile strength is: basalt fiber content > steel fiber content > calcined kaolin content,which can be used for reference in preparing such concrete and engineering application.