Experimental investigation and reliability prediction of high performance concrete based on lightweight aggregate under 4-point bending loading

The damage of lightweight aggregate high performance concrete (LHPC) under four-point bending was experimentally investigated. The effects of stress level and loading age on LHPC damage were elucidated. The research results show that with the increase of stress level, the damage of LHPC is gradually aggravated, but it also stimulates the internal curing effect of lightweight aggregate (LWA). The internal curing effect of pre-wetted lightweight aggregate (PLWA) promotes the formation of hydration products such as C-S-H gel, which can slow down the damage of LHPC under loading. When the stress level is 50%− 70% ultimate load (Pcr), LHPC is partially damaged under continuous bending, and its corrosion resistance coefficient (Kf) and relative dynamic elastic modulus (Erd) are reduced, but it still has a certain carrying capacity. The LHPC under the action of 90% Pcr was completely damaged in 11588 s, and the LHPC under the action of 95% Pcr was completely damaged in 1096 s. Under a given stress level, the fatigue life of LHPC can be simulated by a two-parameter Weibull distribution. Therefore, a reliability evaluation method is proposed to obtain the fatigue life prediction of LHPC under 4-point bending loading.