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Thermal reactions of bauxite, kaolin, and talc compound were investigated at 1550°C to obtain high rigidity ceramic for ballistic applications. The compressed strength and density of the bauxite ceramics with kaolin and talc substitutions varied from 195 to 455 MPa and density from 2.85 to 4.05 g/cm 3 . The Young's modulus varied from 107 GPa to 222 GPa with water absorption varying from 1.4 wt% to 5.9 wt% for 0 wt% and 15 wt% substitution of kaolin. The substitution of bauxite-kaolin by talc up to 7.5 wt% contributes to the resorption of microporosity and increase the Young's modulus from 107 to 195 GPa. The XRD of bauxite ceramic with kaolin substitution showed the presence of corundum and mullite; whereas the XRD of bauxite ceramic with kaolin and talc substitution showed the presence of corundum, mullite, and spinel. The ballistic simulation with abaqus dassult SIMULA using the JH-2 model predict that an impact with velocity of 525 to 810 m/s on the 10 mm thick bauxite ceramic does not erode or damage for a projectile consisting of tungsten alloy with dimensions: 12 mm in diameter, 61.5 mm length, and 72 g of mass. The bauxite ceramics can be used for ballistic applications. K E Y W O R D Sballistic application, bauxite ceramic, Young's modulus 950 |

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The aim of this work is to reduce the overexploitation of river sand by proposing a combination of crushed sand and river sand to develop an optimal mix design for concrete. The approach used consisted of a physical, chemical, and mineralogical characterization of aggregates from three quarries located in Yaoundé (Cameroon), followed by the formulation of concrete by substituting 100%, 90%, 80%, 70%, 50%, and 0% of the river sand with crushed sand. A physical and mechanical characterization of the concrete was carried out, as well as a microstructural characterization using SEM/EDS. The results showed that the concrete made of crushed sand only had a higher drying shrinkage at a young age compared to the river sand concrete. Compared to conventional concrete (made using 100% of river sand), the concrete with 50% crushed sand reduces its slump value, has a lower porosity, and has a compressive strength value of 26.3 MPa at 28 days, which is very similar to that of conventional concrete (26.7 MPa). Moreover, it was found that the strength of the concrete increased by 14.4% and 20.6%, respectively, for concrete without crushed sand (BSR0) and concrete with 50% crushed sand (BSR50) by increasing the curing age from 28 to 90 days. The static modulus of elasticity for conventional concrete BSR0 and BSR50 concrete with 50% crushed sand at 90 days was 23.7 and 21.8 GPa, respectively. Thus, combining crushed sand with alluvial sand is a good method to reduce the depletion of alluvial sands in Cameroon.