A study on properties, static and dynamic elastic modulus of recycled concrete under the influence of modified fly ash

The effects of modified fly ash (MFA) on the replacement rate of cement, the quality and replacement rate of recycled fine aggregates (RFA), the mechanical properties of concrete, such as compressive strength (f(c)), static elastic modulus (E-c), dynamic elastic modulus (E-d), and durability, i.e., drying shrinkage (epsilon), were investigated in this study. Based on the data and discussion of the results, different linear correlations were found between E-c and E-d, and the concrete's age was found to be an important influencing factor. A new equation about E-c and f(c) of concrete was proposed, as well as the relationship between E-d and f(c), and the correlation coefficients were analyzed by the quality and substitution of recycled fine aggregates, and it was confirmed that they were two important influencing factors. Finally, the correlation between E-d and e and the pore volume in the pore diameter interval of concrete was investigated under the influence of the quality and replacement rate of aggregates and the replacement rate of MFA, and it was found that the variation of E-d and epsilon on the pore volume correlation coefficient was highly consistent.

Automated summary

This study investigated the effects of modified fly ash on the mechanical properties and durability of concrete, proposed a new equation relating the elastic modulus and compressive strength of concrete, and confirmed the importance of the quality and substitution rate of recycled fine aggregates in these effects.