Effect of coarse aggregate characteristics on hardened properties of concrete

The effects of coarse aggregate properties and characteristics on the properties of hardened concrete were examined in this experimental program. Tests were performed to determine effects on modulus of elasticity, compressive strength, splitting tensile strength, modulus of rupture, shrinkage, and coefficient of thermal expansion. The effects of varying coarse aggregate type, volume of coarse aggregate, cement content, and maximum size of coarse aggregate on the hardened properties of concrete were also studied. The results of this study show that coarse aggregate properties and characteristics do have a marked effect on the properties of hardened concrete. Modulus of elasticity is influenced by type of rock and the amount of rock present. Compressive strength is affected by surface texture of the rock. Coefficient of thermal expansion is mainly influenced by mineralogical compostion of the rock. Splitting tensile strength and modulus of rupture both are affected by type and surface texture of the rock. Drying shrinkage also seems to be influenced by the type of rock and volume of rock present. Recommendations are made regarding the incorporation of aggregate characteristics in concrete mixture design.