Compressive strength and modulus of elasticity of freshly compressed concrete

This paper is going to offer an interesting solution to enhance the compressive behavior of concrete in terms of strength and modulus of elasticity. In the presented method, by compressing the fresh concrete in a fabricated pressure apparatus, the excess water of concrete is expelled and the percent void is remarkably decreased. Applying this technique without needing the additive materials, external vibration and workability control, a significant enhancement in the strength and modulus of elasticity of the freshly compressed concrete (FCC) is observed. A parametric study is conducted to investigate the effect of various reference concrete (RC) strengths, different pressure levels and pressure duration on the behavior of FCC. Based on the regression analysis of the experimental data, this study provides empirical equations to predict the percentage increase in the compressive strength and modulus of elasticity of FCC specimens. A relationship between the modulus of elasticity and compressive strength for both the compressed and uncompressed concretes is statistically derived and then the results are compared with those calculated by the prediction models given in ACI 318, ACI 363 and EN 1992-1-1 codes. Finally, the code-compliant expressions for RC are modified for FCC.

► We offered an interesting solution to enhance compression behavior of concrete.
► Compressive strength and modulus of elasticity of compressed concrete were investigated.
► Code-compliant expressions for uncompressed concrete were modified for compressed one.
► Applying long-term pressure to fresh concrete has no economic justification in comparison with short-term pressure.
► Exerting minimum pressure is sufficient to reach ultimate limit of mechanical properties.