Performance of concrete targets mixed with coarse aggregates against rigid projectile impact

Abstract

For effective structure and personnel protection against projectile impact, accurate prediction of the depth of penetration (DOP) of projectile into concrete is essential. Many empirical and semi-empirical formulae have been developed to yield accurate predictions as compared with testing data. In most of these formulae, the concrete target was assumed as homogeneous and the mechanical properties of concrete material were characterized by the compressive strength of concrete. The deviation of DOP predications is identified for the concrete targets mixed with coarse aggregates because of the homogeneous assumption which leads to errors in DOP prediction. In this study, the effects of mortar strength, aggregate strength, maximum size and volume fraction of coarse aggregate on penetration resistance are quantitatively studied by using 3D meso-scale modeling. The applicable condition of the homogeneous assumption and the upper bounds of aggregate size and volume fraction that affect the penetration resistance are determined with respect to the aggregate configurations. The factors dominating the penetration resistance of concrete target are investigated and it is found that the sensitivity of penetration resistance to aggregate size is lower than other mesoscopic factors, i.e., mortar strength, aggregate strength and volume fraction. In addition, a formula incorporating the effect of multi-factors is proposed to predict the DOP of rigid projectile penetration into concrete target mixed with coarse aggregates. The proposed formula, which considers the effects of the mesoscopic factors on the penetration resistance, can give better predictions of DOP into concrete targets.