Effect of bauxite aggregate in cement composites on mechanical properties and resistance against high-velocity projectile impact

This paper investigates the effect of the bauxite sand and coarse aggregate on the quasi-static mechanical properties and resistance against high-velocity projectile impact of cement composites with 28-day compressive strengths from 34.2 to 197.2 MPa, in comparison to that of the siliceous sand and granite coarse aggregate. Mechanical properties investigated include compressive strength, elastic modulus, compressive stress-strain behavior, splitting tensile strength, and effective hardness index. Impact resistance was evaluated using 8.0 mm-diameter, 7.8-g-mass, conical-nosed projectiles at velocities of approximately 400 m/s. The results indicate that the bauxite sand and coarse aggregate are beneficial for enhancing mechanical properties and impact resistance of cement composites compared to the siliceous sand and granite coarse aggregate. The concrete incorporating both bauxite sand and coarse aggregate exhibits compressive strength of about 200 MPa and elastic modulus of about 105 GPa at 28 days under ambient curing conditions, and better impact resistance than a granite rock specimen. This study will provide insights into the development of advanced cement composites with superior mechanical properties and impact resistance for protective structures.