Concrete strength and elasticity of precast thin-walled elements

The real mechanical properties of concrete plays an important role in the structural analysis of the behavior of precast, thin-walled elements, especially those without passive reinforcement. The experimental research of the concrete samples of pre-tensioned hollow core slabs have shown that the real strength and elasticity of concrete might be about 30 to 50% lower than the so-called "standard" properties, assigned to a specific class of concrete. Reasons of the strength properties reduction in the narrow ribs of slabs with very heterogeneous microstructure, subjected to the influence of interrelated hydrothermal fields during the process of casting, are presented in the paper.