Experimental investigation on fracture behavior of high-ductility cementitious composites with recycled PET fine aggregate
Jia-Ying Su, Rui-Hao Luo, Shijia Chen, Guo-Wei Ruan, Dongyang Li, Minyang Jiang, Yixian Wu, Jia-Xiang Lin
Abstract
The integration of polyethylene terephthalate (PET) aggregates into high-ductility cementitious composites (HDCC) has potential benefits for sustainability, yet its effects on fracture performance remain poorly understood. In this study, PET aggregates were used to replace quartz powder at varying replacement ratios (0 %, 25 %, 50 %, 75 %, 100 %) to investigate the influence on the fracture performance of HDCC. The analysis was conducted through failure modes and fracture parameters , including mode-I fracture energy G F , and ductility index D u . Double- K and double- J parameters were introduced to further analyze the fracture process. And scanning electron microscope tests were conducted to observe microstrcture of HDCC. Results indicated that PET aggregates acted as intentionally added flaws, contributing to decreased compressive strength but enhanced tensile ductility and delayed fracture . The ductile fracture behavior of PET-modified HDCC was demonstrated, involveing extensive off-crack-plane and on-crack-palne energy absorption due to expanded zone of matrix cracking surrounding the crack tip. The difference between initial crack fracture energy J IC and failure fracture energy J IF swell distinctively with PET incorporation, highlighting a growing buffer zone between crack initiation and unstable failure. Interface transition zone (ITZ) between PET and cement paste exhibited the lowest crack resistance, exacerbated by the hydrophobic nature of PET. This ITZ acted as a stress concentration area, making it more susceptible to crack initiation, which was advantageous for the ductility enhancement based on the design theory of HDCC. The mechanisms identified in this study may also apply to the effects of introducing various inert aggregates on the axial compressive, tensile, and fracture performance of HDCC.