Performance evaluation of cement stabilized recycled mixture with recycled concrete aggregate and crushed brick

Abstract

This paper presents an experimental investigation on the performance of cement stabilized recycled mixture containing recycled concrete aggregate (RCA) and crushed brick (RCB), which are separated from recycled aggregate. Firstly, basic material performance tests were conducted to establish a comparison among natural aggregate and recycled aggregate (RA). To reveal the mechanism of cement stabilized mixtures in strength formation, Scanning Electron Microscope (SEM) and Energy Dispersive Spectrometer (EDS) tests were carried out in specimens of 3 different ages (9 d, 28 d, 90 d). Subsequently, unconfined compressive strength tests, splitting strength and compressive modulus tests, were undertaken in five contents of RA by weight (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. Afterward, the fuzzy set method was used to rank these schemes and evaluate the mechanical property of specimens. It can be found that the mechanical properties of cement-stabilized mixtures change linearly with the proportion of RA at 25% and 50%, sharply decreased from 50% to 75%. With the RA content increasing, the effect of RCB content on pavement performance gradually decreases. Finally, by taking the results of dry and temperature shrinkage testes into consideration, it was concluded that the amount of RA should not exceed 50%, the ratio of RCB/RCA should not exceed 3:7 in the road construction. In that way, it can meet the requirements of the sub-base of expressways and first-class highways in China when the cement dosage is setting to 4%.