Effect Of Coarse Aggregate Shape On The Physicomechanical Properties Of Concrete

First, a systematical study was made on the physicomechanical properties of cement paste, cement mortar and ordinary aggregates concrete. Emphasis was then put on the effect of coarse aggregate shape on the physicomechanical properties of concrete. Finally, analytical solutions for the chloride diffusivity of cement paste and aggregates concrete were presented.It was showed that, as the water/cement ratio increases, the compressive strength, splitting tensile strength and elastic modulus of cement paste, cement mortar and manufactured aggregate concrete decrease obviously, but the chloride diffusivities increase. For cement mortar and ordinary aggregate concrete, the addition of aggregates has little influence on the compressive strength and splitting tensile strength, but increases the elastic moduli and decreases the chloride diffusivity to a large extent. For manufactured aggregate concrete, aggregate shape has no significant effect on the mechanical properties when the aggregate content is smaller than a certain value. The more the ratio between the major axis and minor axis is close to unit, the higher the compressive strength and elastic modulus of concrete are. However, this is not true for the splitting tensile strength. Coarse aggregate shape has a significant influence on the chloride diffusivity of concrete. The chloride diffusivity decreases with the increase of the ratio between the major axis and minor axis.In the theoretical aspect, an analytical solution for the chloride diffusivity of cement paste was presented. The validity of the solution was verified with two independent sets of experimental data. The effects of the degree of hydration and water/cement ratio on the chloride diffusivity of cement paste were evaluated in a quantitative manner. The analytical method for the interfacial transition zone volume fraction was discussed. A simple analytical solution for the chloride diffusivity of concrete was derived by the differential effective-medium approximation. Finally, the validity of the proposed analytical solution was verified with two independent of sets of experimental data.