Three-dimensional meso-scale modelling of geopolymer-based ultra-high performance concrete (G-UHPC) with ceramic ball coarse aggregates under projectile impact

This paper presents three-dimensional meso-scale modelling of geopolymer-based ultra-high performance concrete (G-UHPC) incorporating ceramic ball coarse aggregates subjected to high-velocity projectile impact at normal incidence. Firstly, adopting the spatial octahedral random growth algorithm and the local background grid method, a three-dimensional meso-scale model, which consisted of G-UHPC mortar and randomly distributed ceramic ball coarse aggregates, was established. The applicability of this mesoscopic model was verified by comparing the numerical results of ceramic ball aggregated G-UHPC targets subjected to quasi-static uniaxial compression and high-velocity projectile impact with the relevant test data. With the validated numerical model, effects resulting from the ratio of ceramic ball size to projectile diameter D/d and the volumetric fraction of ceramic balls Pagg on the penetration resistance R of G-UHPC targets were quantitatively investigated. The numerical results revealed that R improved with the increase in D/d and Pagg, with R being more responsive to the changes in Pagg than in D/d. Specifically, as D/d rose from 0.4 to 2, R underwent a roughly 10% increase. Similarly, with an increase in Pagg from 10% to 30%, R exhibited an approximately 15% increase. Furthermore, considering the effect of D/d and Pagg, an updated semi-empirical equation was derived to predict the depth of penetration (DOP) of ceramic ball aggregated G-UHPC targets impacted by the non-deformable projectile at normal incidence.