DESIGN OF FLY ASH CONCRETE

A method for the design of flyash concrete to achieve a specified compressive strength at 7 and 28 days is presented. The method is simple and easy to use. The validity of this method has been tested by comparing the actual and the predicted strength for a number of mixes. Abram's law is used in this method to develop design charts; the law is found to hold good for flyash concrete when the water cement ratio is replaced by the water cementitious ratio. The constants of the equations are found to vary according to a cubic polynomial of the flyash cement ratio. The reduction in the water demand with the increase in the flyash cement ratio is also included. It is shown that the contribution to the compressive strength due to the pozzolanic reaction is related to both the curing period and the flyash cement ratio. The paper also includes a typical design example. (Author/TRRL)