Properties of concrete containing fly ash and temperature control measures used during construction

Abstract

In recent years, fly ash cement has been applied in engineering with the continuous application of concrete admixtures. Although we have been using fly ash concrete and have done a lot of experimental research, but the understanding of its thermophysical properties was not complete, and further research was needed. This paper presented results of a study into important fundamental thermal and physical properties of both fly ash mortar and fly ash concrete. Different replacement percentage of OPC by FA ranging from 0 to 60% by mass were devised. Increasing fly ash content was found to delay the initial setting time and final setting times, decrease both compressive and flexural strengths and reduce hydration heat. It also can effectively reduce the hydration heat evolution of cement-fly ash binder. The adiabatic temperature rise of cement fly ash material in engineering can be estimated by reduction coefficient k. In fly ash concrete tests, thermal properties, including thermal diffusivity, conductivity, specific heat, ultimate tensile strain and static elasticity modulus were also measured and reported. There also appeared the relationship between compressive strength and flexural strength showed similar linear change with the replacement rate of fly ash rising from 30% to 60%. Most importantly, pipe cooling tests of fly ash concrete were carried out and from the perspective of temperature control of mass concrete, dynamic pipe cooling measures were investigated.