The Cement Stabilized Recycling Technology Research Of Reclaimed Semi-Rigid Base Materials

In the process of highway construction,the maintenance of asphalt pavement with semi-rigid base produces a lot of waste materials stabilized by cement and lime-fly ash,which can't get a good use;On the other hand,highway construction consumes a large amount of aggregates and is increasingly faced with the lack problem of aggregates.As a thick course,Semi-rigid base consumes a lot of mineral resources and produces a large amount of waste materials.Recycle of these waste materials into road base construction will produce huge economic,social and environmental benefits.This paper aims to research the impact of grading design,dosage of waste materials and blending mode on cement stabilized recycling materials,exploring the design method of recycling utilization and performance evaluation method of waste materials.Firstly,the physical and mechanical properties of waste materials stabilized by cement and lime-fly ash were evaluated.The test results show that: on the contrast to new limestone,the density of aging coarse aggregate is smaller,and the crushing value is larger.The fineness modulus of aging fine aggregate and the water absorption rate is larger.From 2.36 mm to 13.2mm,the content of mortar on the surface of the lime-fly ash old material decreases with the increase of particle size.From 13.2mm to 26.5mm,the content of mortar on the surface of the lime-fly ash old material is basically unchanged with the increase of particle size.From 2.36 mm to 26.5mm,the content of mortar on the surface of the cement old material is basically unchanged with the increase of particle size.Secondly,according to the specifications of coarse and fine aggregate performance requirements and grading requirements,the applicable road grade and traffic level conditions of different size old materials is determined.Thirdly,the dosage range of cement and lime-fly ash is determined in the whole blending mode and split file utilization mode.According to the dosage range the grading design range is determined and furthermore the design grading is determined in the whole blending mode and split file utilization mode.Besides,the optimum moisture content and maximum dry density is determined by static pressure method.Through performance comparison and verification,it is found that in the whole blending mode cement stabilized crushed stone utilizing cement and lime-fly ash old materials of 3.5% cement dosage is above 3.5Mpa,Both in the whole blending mode and split file utilization mode cement stabilized crushed stone utilizing cement and lime-fly ash old materials of 4.5% cement dosage is above 4Mpa.The performance of cement stabilized recycled crushed stone in the comprehensive recycle mode of cement and lime-fly ash materials is better than that of utilizing only cement or lime-fly ash old materials.It is suggested that the intermediate size materials should be new aggregates.Through the research of split file utilization mode,we can conclude that the materials of 0-4.75 mm size exerts a larger influence on 7d unconfined compressive strength,7d splitting strength and 7d compressive resilient modulus than coarse aggregates of 4.75-9.5mm and 9.5mm-19 mm size.Special attention should be paid to the selection of fine aggregate in the design of cement stabilized crushed stone.Finally,the drying shrinkage performance of cement mortar with different materials and different dosage of cement was evaluated,it is found that the optimum cement dosage of cement mortar with different fine aggregate is not the same.The dry shrinkage strain of cement mortar and the fineness modulus of fine aggregate have a good linear correlation,the dry shrinkage coefficient of cement mortar and the fineness modulus of fine aggregate have a good exponential correlation.The erosion and wear resistance performance evaluation shows that cement stabilized new aggregates is better than cement stabilized crushed stone utilizing aging materials.The erosion and wear rate of experimental group utilizing lime-fly ash old fine materials is higher than experimental group with cement old fine materials,higher than experimental group with new fine aggregates.