The dynamic responses of calcareous sand at high strain rates, closely relating to geotechnical and ocean engineering, are still not fully understood. This paper reports a series of split-Hopkinson pressure bar tests on porous calcareous and solid silica sands, with particle sizes of 0.15-0.30 mm, 030-0.60 mm, 0.60-1.18 mm and 1.18-2.00 mm. The particle size affects the impact stress-strain behaviour during particle crush, which mainly occurs at the final strain-hardening stage for silica sand, but occurs in the entire loading process for calcareous sand. The natural crushability of calcareous sand, quantified by fractal dimension, is approximately 1.2 times that of silica sand. The two sands show opposite responses for particle size in confined/bulk modulus and capability of energy absorption. This is because, as the particle size increased, calcareous and silica sands have opposite changes in terms of the void ratio and friction angle due to inter-particle voids and mineral composition. (C) 2019 Elsevier B.V. All rights reserved.