Study On Performance And Microstructure Of Basalt Fiber Asphalt Mixture With Different Types Of Sizing Agent

In recent years,basalt fiber asphalt mixture has been paid more attention for its superior road performance and the ease of construction.The application of basalt fiber in asphalt mixture has carried out a lot of research,mostly focusing on the performance study of asphalt mixture,and most of the micro-mechanisms were inferred from the performance test results.Few people study its influence on the performance and microstructure of the asphalt mixtures from the fiber-sizing agent itself.Therefore,on the basis of studying the road performance of basalt fiber asphalt mixtures treated with different sizing agent,the mechanism of three types of basalt fiber reinforced asphalt mixtures of A-type,B-type and C-type were analyzed.Firstly,micro-morphology and chemical components of the basalt fiber treated by three different kinds of sizing agent were analyzed by field emission scanning electron microscope and X-ray spectrometer.It was found that there are irregular bulges on the surface of three kinds of fibers,and the A-type and C-type were more prominent.The content of Si and Fe in the bulge was relatively more.Compared with three different types of basalt fibers,the content of Si is the highest in the A-type basalt fiber.Secondly,the AC-20 grade paired with three different types of basalt fiber asphalt mixture and ordinary asphalt mixture were selected to design the mix ratio.The best asphalt ratio of the four asphalt mixture was determined,and the Marshall index was analyzed.It shows that the ratio of bitumen and the stability were increased by the addition of these three types of basalt fiber.Then,the road performances of the four asphalt mixture were tested by the rutting test,low temperature bending test,water immersion Marshall test,freezing and thawing splitting test and four-point bending test.The results showed that the high temperature stability,low temperature crack resistance and fatigue resistance of asphalt mixture were improved by adding basalt fiber of A-type,B-type and C-type.Among them,A-type had the best improvement effect.Finally,by means of microscopic testing,the fracture morphology characteristics of asphalt mixture including hole,crack and interface between fiber and asphalt were compared and analyzed,and the properties of basalt fiber to improve the performance of asphalt mixture were discussed.The failure modes of three different types of basalt fiber asphalt mixture were discussed,and the microstructure of the fiber in the asphalt mixture was further studied by microstructural analysis.The results show that the internal pore structure was optimized,although the number of holes in the asphalt mixture was increased.The average crack width of basalt fiber asphalt mixture A was the smallest,only 1/6 of the ordinary,followed by the addition of C-type basalt fiber,about 1/4 of the ordinary.It shows that both A-type and C-type basalt fiber had good effect on asphalt mixture.In addition,the A-type and C-type basalt fibers had better infiltration compared with B type,and most of the fiber belonged to pull-off when the basalt fiber was damaged in asphalt mixture A and C,and only a small part was pulled out,The B-type basalt fiber was mostly pulled out.It shows that the A-type and C-type basalt fibers and the bitumen had the better interfacial wettability,and the external load can be effectively transferred from the bitumen matrix to the fiber.The fiber was subjected to more load and was broken.However,the bond between the B-type basalt fiber and the asphalt was poor,and the tensile strength of the fiber itself was not fully utilized.Therefore the fiber was easy to pulled out.