Variations of longitudinal wave velocity and modulus of elasticity at different ages of concrete and the effect of mixing ratios on these variations

The real estimation of the mechanical properties of concrete in the analysis and design of reinforced concrete structures plays a key role but mechanical properties of concrete change over time. These changes are due to chemical reactions inside the concrete known as hydration. One of these features is the modulus of elasticity and the ultrasonic wave velocity, which increases with the age of the concrete and its cement setting. In this study, concrete cube specimens were prepared with different mixing ratios and longitudinal wave velocity variations and modulus of elasticity of specimens were monitored during the process of curing at different ages and factors influencing these changes have been investigated. In the theoretical and numerical analysis of structures, as well as in examining the strength of existing structures or their retrofitting, it is necessary to know the variation of mechanical properties of concrete with time. Concrete mixing ratios are factors that are effective in changing the mechanical characteristics of time. In general, reducing the water-to-cement ratio as well as increasing coarse aggregates, the ultrasonic velocity and the modulus of elasticity of concrete at different ages increases.