Experimental Study On High Temperature Mechanical Properties Of Basalt-Polyvinyl Alcohol Fiber High Performance Concrete

At present,with the rapid development of the city,the application of high performance concrete(HPC)will be more and more.HPC has good workability and high strength,but it has the disadvantages of high brittleness,poor fire resistance and easy burst.The main way to improve the fire resistance of HPC is to add fiber.At present,a lot of research results have been obtained,but the research on high temperature or fire performance of hybrid fiber high performance concrete(hfhpc)is less.Hfhpc is a new type of composite material.This topic is to add polyvinyl alcohol(PVA),basalt fiber,fly ash,blast furnace granulated slag and superplasticizer into concrete to obtain a kind of concrete with low water binder ratio,high strength,good fire resistance and more economic and environmental protection.The purpose of this paper is to carry out high temperature experimental research on several factors that have great influence on the mechanical properties of hfhpc,test the cube compressive strength,splitting tensile strength and flexural strength of hfhpc,and carry out range analysis and variance analysis on the data to obtain the calculation model,and discuss the reasons for the performance changes of hfhpc.In this paper,the following work has been done and relevant results have been achieved:(1)This paper studies the influence of basalt fiber,PVA fiber volume fraction and slag powder content on concrete performance,finds out the optimal experimental proportion under the design test conditions through orthogonal test,and finds out the influence degree and significant influence factors of the three factors.The results show that the significant influence factor of cube compressive strength and splitting tensile strength of hfhpc is the content of basalt fiber and slag powder;the significant influence factor of flexural strength is the content of PVA fiber.(2)The effects of different volume fraction of PVA fiber and basalt fiber on the physical and mechanical properties of high performance concrete were studied.The results show that basalt fiber and PVA fiber can enhance the three strength indexes of hfhpc,and the hfhpc strength mixed with basalt fiber and PVA fiber shows positive hybrid effect.(3)Under the condition of different fiber content and different temperature,the influence of temperature change on the mechanical properties of hybrid fiber high performance concrete is studied.The results show that: the compressive strength and tensile strength of the specimens show a trend of small increase first and then decrease with the increase of temperature;the tensile strength of hfhpc is improved most significantly by the influence factors of basalt fiber;the flexural strength of concrete shows a downward trend with the increase of temperature,and the flexural strength of hfhpc is improved most significantly by the influence factors of PVA fiber.(4)Compared with plain concrete,adding basalt fiber,PVA fiber and slag powder can improve the residual rate after high temperature.The plain concrete specimen is seriously damaged,while the concrete mixed with hybrid fiber has obvious omen,and it is relatively complete after damage.It can retain higher strength after high temperature,showing better high temperature resistance.