Effects of particle characteristics of lightweight aggregate on mechanical properties of lightweight aggregate concrete

Particle characteristics of lightweight aggregates (LWAs) have great influences on the mechanical performance of the corresponding concrete. In this research, particle characteristics of LWAs were measured through digital image processing (DIP), including particle sizes, gradation and shape properties, and the effects of LWA particle characteristics on mechanical performances of lightweight aggregate concrete (LWAC) were investigated through grey correlation analysis methods. The LWAC interfacial roughness was investigated with fractal theory, and the effects of LWA particle characteristics on the LWAC interfacial roughness were also investigated through grey correlation analysis methods. The results show that LWAC interfacial fractal dimension and mechanical performance exhibit good linear correlation. LWA particle specific surface area and LWA particle aspect ratio take greater effects on LWAC mechanical strength and interfacial roughness. LWAC mechanical strength would be greater when LWA specific surface area (SV) was within 586.4-633.7 m2/m3 and LWA aspect ratio was within 1.3262-1.3308. LWAC interfacial fractal dimension (D) would be greater when LWA specific surface area (SV) was within 539.1-633.7 m2/m3 and LWA aspect ratio was within 1.3262-1.3354. It is proposed that the change of the contact area between LWA particles and mortar phases will change the occlusal structures on the LWAC interface, which consequently changes the interfacial roughness, the interfacial bond strength and hence the LWAC mechanical strength.