To study the size effect in lightweight aggregate concrete (LWC), a two‐dimensional (2D) random aggregate numerical model was established based on the parameters of LC30 and applied to LWC specimens with different sizes. The size effect of LWC under static compression was studied based on the macro‐ and micromechanical failure mode of the material and nominal stress–strain relationship. The results show that the distribution of crack zones along the aggregate boundary in LWC is different from that in ordinary concrete. Cracks in LWC specimens eventually develop into an oblique shear crack band with an angle of 45° from the specimen boundary and pass through the aggregate, showing a stronger size effect. Under identical loading strain conditions, increasing specimen size leads to the formation of multiple, more complex oblique cross‐crack zones in LWC specimens. As specimen size increases, the peak strength and the nominal strain at peak strength decrease gradually, while the damage dissipation energy associated with crack propagation increases. In addition, based on the size effect degrees obtained from different specimens, the size‐effect law for LWC was derived, which provides a promising approach for calculating the strength grade parameters of different‐sized LWC specimens.
Sun et al. (Thu,) studied this question.