Tensile strength of shrinkage-compensating concrete with fly ash.

摘要

In order to evaluate the tensile strength of concrete made with a shrinkage-reducing admixture (SRA) along with fly ash, nine mix designs were prepared and tested at ages of 3, 5, 7, 14, 28, and 56 days under different curing times (3, 7, and 28 days). The compressive strength and the effectiveness of SRA for reducing drying shrinkage of concrete under prevailing conditions in Puerto Rico were also evaluated. The results indicated that the use of partial substitution of Portland cement by Class F fly ash without changing the water or aggregate content reduced the splitting tensile strength and compressive strength of the mixes. Also, the use of shrinkage-reducing admixture and fly ash was effective in reducing the free shrinkage strains for all the concrete mixes tested. It was found that the difference between 3 and 7 days of moist curing was not significant in terms of strength gain of concrete mixes, but it helped to reduce the shrinkage of concrete made with SRA and fly ash.