Study On Fatigue Performance Of Recycled Concrete And Brick Aggregate Applicated In Cement Stabilized Macadam Base

Recycling of construction and demolition waste is a hot issue in recent years.The demand for natural aggregates required in road engineering far exceeds China’s supply capacity.Construction and demolition waste can be used to obtain recycled aggregates for applying in cement stabilized crushed stone base layer,which will effectively alleviate environmental pollution and the problem of resources depletion."Turning waste into treasure" and green recycling are conducive to a good start in the first year of the "14th Five-Year Plan" and the building of a modern socialist country.Based on this,this article launches a study on the fatigue performance of cement stabilized recycled mixtures under different cement dosages,different recycled aggregate content and brick-concrete ratios.This paper is aimed to obtain the fatigue life equation under different recycled aggregate content and brick-concrete ratio.Firstly,it carried out some basic performance tests of recycled aggregate and natural aggregates.Subsequently,unconfined compressive strength tests,flexural strength and fatigue life were undertaken in five contents of RA(0%,25%,50%,75%,100%).In each grade of RA content,three different ratios of RCB/RCA(1:9,3:7,5:5)were considered.The effects of recycled aggregate content and brick-concrete ratio on the performance of cement stabilized recycled mixtures are explored,and the recommended material schemes for the base course and the subbase course under different levels of roads and different traffic levels are obtained.Research shows that with the increase of cement dosage,recycled aggregate content and brick-concrete ratio,the maximum dry density of cement-stable recycled mixture decreases and the optimal moisture content increases.In the most unfavorable case,the 4%cement dosage can meet the requirements of the sub-base layer of the second and lower roads under heavy traffic loads.For the 5%cement dosage,it meets the requirements of highways and first-class highways under medium and light traffic.With the increase in the content of recycled aggregates and brick-concrete ratio,the difference in fatigue life gradually increases.By applying two fitting methods of Bayesian Ridge regression and Gaussian process,the curve of recycled aggregate content and brick-concrete ratio on the fatigue life of cement-stabilized recycled mixture shows great linear relationship.And the fatigue life equation under different recycled aggregate content and brick-concrete ratio is obtained,which provides important references and suggestions for the refined use of recycled aggregates.