Professor LONG Guangcheng, Principal Investigator of NEXCEL 2024 TDA project "Fiber reinforced concrete and its surface strengthening for novel transportation infrastructure" from Central South University，has published a paper entitled "Acoustic emission-based flexural fracture analysis of polyethylene fiber reinforced ultra-high performance concrete under low vacuum environment" in "Construction and Building Materials" (SCI) recently.

 

 

Abstract：

This study systematically investigates the flexural behavior and damage mechanisms of polyethylene fiber reinforced ultra-high performance concrete (PEFRC) under low vacuum conditions. Based on the dense particle packing model, PEFRC specimens were designed with different fiber contents (0.75–1.50 vol%) and coarse aggregate replacement ratios (ARR: 0, 20%, 40%). Through three-point bending tests combined with acoustic emission (AE) technology, a comparative analysis was conducted on the effects of atmospheric drying (AD) and low vacuum drying (VD) on the mechanical properties and damage evolution of PEFRC. The results indicate that the low vacuum environment reduces the post-peak toughness of the specimens. The synergistic effect of fiber (1.5%) and coarse aggregate substitution (ARR 20%-40%) allows PEFRC to retain superior fracture toughness under VD conditions while maintaining cost advantages. AE analyses (ringing counts, AE energy, b-values, and AF-RA images) reveal that VD-induced shrinkage exacerbated fiber pullout behavior, leading to an increase in AE signals, a rise in the proportion of shear cracks, and a shortening of the b-value warning period. The establishment of a stable fiber-matrix-aggregate synergistic structural system can effectively mitigate VD-induced embrittlement of PEFRC. This study provides critical theoretical and technical support for the development of high-performance concrete with low-vacuum resistance.