Strength Properties of Fly-Ash Concrete Placed and Cured in the Field

This paper presents compressive and tensile strengths of fly-ash concrete, which is classified as type II in the JIS. Fly-ash concretes were made in different seasons, including summer, autumn and winter. The concretes were made in a ready-mixed concrete plant and were cured in the field to simulate actual construction conditions. To investigate fundamental mechanical properties of the fly-ash concretes, strength tests were conducted at several ages. The paper gives the results of compressive strength, splitting tensile strength and uniaxial tensile strength tests. The study uses the Goral curve for the regression of compressive strength developed with an equivalent age based on the maturity. In the regression result, the coefficient of the Goral curve develops with lower temperatures. The results imply that evaluations using the equivalent age are not always appropriate for predicting the compressive strength of fly-ash concrete. According to comparative results of tensile strengths, the splitting tensile strength of fly-ash concrete can be predicted by using the JSCE design formula. In addition, the results indicate the uniaxial tensile strength of fly-ash concrete is higher than the splitting tensile strength at all test ages. A relationship between splitting strength and uniaxial strength, proposed by Yoshimoto, gives a conservative estimate for the evaluation of fly-ash concrete cracking strength.