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Use of building-related construction and demolition wastes in highway embankment: Laboratory and field evaluations
- Zhang, Junhui, Gu, Fan, Zhang, Yuqing
- Journal of cleaner production 2019 v.230 pp. 1051-1060
- bitumen, cement, chemical composition, clay soils, concrete, deformation, models, prediction, recycled materials, recycling, wastes, China
- This paper aimed at assessing the feasibility of using the recycled building-related construction and demolition (C&D) wastes in highway embankment. First, the recycling of C&D wastes was elaborated, which involved both the manual and mechanical sorting processes. The recycled C&D wastes were classified as an excellent embankment material according to their gradation and Atterberg limits. The physical and chemical composition of recycled C&D wastes were also investigated, which all met the requirements of DB 41/T 1193 in Chinese Standard. Subsequently, the laboratory triaxial tests were conducted to measure the resilient modulus and permanent deformation of recycled C&D wastes. For comparison, one type of embankment clay soil was also evaluated in this study. The triaxial test results indicated that the recycled C&D wastes exhibited stress-dependent and moisture-sensitive characteristics. The existing resilient modulus and permanent deformation models were found to be capable of accurately predicting these characteristics for recycled material. Compared to the embankment clay soil, the recycled C&D wastes had much higher resilient moduli and lower accumulated permanent deformation. This demonstrated that the substitution of recycled wastes for clay soil would improve the structural capacity and reduce rutting damage. Moreover, compared to the clay soil, the recycled material had less moisture sensitivity to resilient modulus and permanent deformation. This characteristic would be beneficial for use of recycled C&D waste in a hot and humid area. Finally, a field project was constructed on G95 Beijing Capital Area Loop Expressway, which utilized 100% recycled C&D wastes to fill embankment. The embankment application were found to utilize much more recycled materials than other potential applications such as asphalt mixture, cement concrete, and base and subbase. The practices of construction of embankment containing recycled C&D wastes were also elaborated in this study. The lightweight deflectometer was used to measure the in-situ resilient moduli of embankment. The measured results indicated that the recycled C&D wastes had significantly higher structural capacity than the clay soil.