Determination of modulus of elasticity of two and three phase composites

In this study, the experimental and theoretical results of mechanical properties of two- and three-phase composites are presented. It was investigated whether the existing equations in the literature describe the experimentally obtained elastic moduli and compressive strengths for these materials. Some equations that do not fit these results have been modified. The calculations performed with the modified Sherban equation show that this equation is very successful in predicting the porosity-dependent mechanical properties of ordinary and silica fume cement pastes. The reductions in compressive strength of concretes containing epoxy emulsion can be minimized by adding silica fume to the mixture. The proposed equations explain the changes in the compressive strength of concrete depending on both the water to cement ratio and the aggregate to cement ratio. From the results obtained, it was understood that the maximum compressive strengths of Portland cement concretes containing epoxy emulsion and silica fume can be calculated by these equations. In addition, Çolak model has been proposed to define the stress and strain behaviour of these types of concretes. This model reflects all the properties of the curve up to the strain corresponding to the peak stress. Thus, the area under the curve was calculated by the finite difference method and the fracture toughness of the concretes was determined. The modulus of elasticity of two- phase composites, consisting of a mixture of white Portland cement and gypsum were determined precisely by Reuss, modified Paul, modified Ishai and Popovics models. Elasticity modules of three-phase composites containing white Portland cement, gypsum and lime were calculated precisely with Çolak model. The agreement between theoretical and experimental results proves the correctness of the assumptions used to derive and modify the equations.