Effect Of Basalt Fiber On Properties Of Cement Stabilized Macadam

Cement-stabilized macadam is widely used because of its advantages of convenient sampling,high strength and strong integrity.However,the excessive exploitation of natural sand and stone leads to the destruction of ecological environment.Mining of natural sand and gravel is banned in many areas of the country.So the phenomenon of aggregate shortage appeared in the project construction.In some stone shortage areas,it has good economic and social benefits to use excavating stone as the raw material of pavement base engineering.In this paper,according to the actual situation of highway construction in Anhui Province,the porous basalt obtained from excavation is broken into gravel with different particle sizes instead of ordinary gravel.Cement-stabilized porous basalt macadam was prepared by mixing basalt staple fiber with different content.Firstly,the mineral composition,basic physical properties and mechanical properties of porous basalt were studied and analyzed by thin section analysis,density test,CT scan and mechanical test.Then through gradation design,the porous basalt crushed rock is used as aggregate in cement stabilized crushed rock.The effect of basalt chopped fiber on the road performance and crack resistance of the mixture was studied.Finally,through the test section.the influence of fiber on road performance of cement-stabilized porous basalt macadam in test section was studied.The main contents and conclusions are as follows:(1)The physical and mechanical properties of porous basalt are studied.The experimental results show that the porous basalt is mainly composed of olivine,plagioclase and pyroxene,and the olivine generally turns into iddingsite.The rock is rich in micro pores and high bibulous rate.The mechanical strength of saturated rock is much lower than that of dry rock.(2)The effect of adding basalt staple fiber on the performance of cement-stabilized porous basalt macadam road was studied.The results show that adding fiber can improve the mechanical strength of the mixture at different curing time.The splitting strength of the fiber to the mixture increased obviously.After curing the specimen for 7 days,the increase effect of 18 mm fiber on the strength of the mixture is better than that of 12 mm and 24 mm fiber.As for the mixture with fiber length of 18 mm,the enhancement effect of mechanical properties is the best when the dosage is 0.1%.At the same time,adding fiber can reduce the compressive modulus and splitting modulus of the mixture.And fiber can improve the freezing resistance of the mixture.(3)The effect of short cut basalt fiber on the shrinkage resistance of cement-stabilized porous basalt macadam was studied.Experiments show that adding fiber can improve the dry shrinkage and warm shrinkage deformation properties of the mixture.During the first 15 days,the increase of dry shrinkage coefficient of the mixture slowed down by10.2%.When the temperature range is 20-10 ℃,the basalt short-cut fiber has the best improvement effect on the temperature shrinkage phenomenon of the mixture,and the temperature shrinkage coefficient of the group with the fiber content of 0.1% is 28.6%lower than that of the group without fiber.(4)Through the test section,the fiber can enhance the road performance of cementstabilized porous basalt macadam.