Performance Evaluation of Recycled Asphalt Mixtures Containing Construction and Demolition Waste Applicated as Pavement Base

Le Ding,Junhui Zhang,Cheng Li,Bowen Feng

doi:10.1155/2020/8875402

Abstract

Construction and demolition waste contain large amount of concrete and bricks. To identify its feasibility of applying in asphalt stabilized gravel mixtures as pavement base, this paper carried out researches on properties of recycled asphalt mixture (RAM) by laboratory testing, under different contents of recycled aggregates (RA) and proportions of bricks to concrete. First, the basic physical properties of each component of the RAM were determined. According to the actual screening passing rate, the Bailey method was used to design and verify the grading of RAM, and then initial asphalt content was estimated. The stability, flow value, voidage, and bulk density were obtained by Marshall Test, and the optimal asphalt-aggregate ratios were determined under different RA contents and proportion of bricks to concrete. Subsequently, the uniaxial compression test, splitting tensile test, immersion Marshall test, freeze-thaw splitting test, and Hamburg rutting test were performed to investigate mechanical properties, water stability, and high-temperature stability of RAM. The results shows that as the content of RA increases from 0% to 100%, the corresponding compressive strength, resilient modulus, and splitting tensile strength all decrease; the same change trend is presented in the residual stability and freeze-thaw splitting test strength ratio and rutting depth. According to the requirement of pavement base of high-grade roads in China’s standards, the recommended RA content and proportion of bricks to concrete were proposed for the design RAM.

Highlights

Extensive urbanization in China has led to the generation of multitudinous construction and demolition wastes (CDW), about 1.7 billion tons in 2019, resulting in many imminent problems to be solved urgently, e.g., occupation of land, overconsumption of resources, and environmental pollution [1,2,3]
The surface of recycled concrete aggregates (RCA) formed rich edges and corners during the crushing process, and they were covered with a large amount of cement mortar, making the surface of recycled aggregates (RA) rougher than natural aggregates (NA)
Laboratory tests were performed to investigate the effect of recycled bricks and concrete on the property of recycled asphalt mixture (RAM). e conclusions that can be drawn from the previous findings and observations are listed below: (1) According to the design of Bailey method, the final proportion of each grading aggregate is 33.3%, 24%, 12.3%, 26%, and 4.4%, close to the recommended median curve; it is helpful to make tested aggregates form a dense skeleton structure

Summary

Introduction

Extensive urbanization in China has led to the generation of multitudinous construction and demolition wastes (CDW), about 1.7 billion tons in 2019, resulting in many imminent problems to be solved urgently, e.g., occupation of land, overconsumption of resources, and environmental pollution [1,2,3]. E composition of CDW is complicated with many sources; waste concrete and bricks are two main parts occupied for 60% and 20% of the whole wastes [6, 7], and they can be processed into RA after crushing and screening. Some studies on the application of CDW have verified its feasibility of using in highway engineering, as pavement base materials [9,10,11,12] or subgrade fillers [13]. Lots of physical methods, including spirals, density and magnetic eddy current, and Advances in Civil Engineering optical and air jigging, have already achieved effective separation of RCA and RCB [24,25,26]. E impact of recycled concrete and bricks on the performance of RAM has not been investigated deeply when it comes to be used as pavement base materials Most existing tests only used waste concrete, and waste bricks were discarded, or the RA were regarded as an integral, and the effect of proportions of internal compositions is often ignored. e impact of recycled concrete and bricks on the performance of RAM has not been investigated deeply when it comes to be used as pavement base materials

Methods

Results

Conclusion