Effects of Change in Fineness of Fly Ash on Air-Entrained Concrete

Abstract

In order to make clear of the effects of the change in fineness of fly ash on air-entrained concrete, 2 series of laboratory experiments were carried out using 6 kinds fly ash with the specific surface area in the range from 2500 to 4400cm2/g. The test results indicated higher slump and lower air-entraining content and higher dosage of air-entraining agent for fly ash with higher specific surface area. Compressive strength was found to increase with the increases of specific surface area of fly ash, while drying shrinkage and carbonation were found to show different tendency with change in fineness of fly ash.

Research on Durability of High Volume Fly Ash Concrete

“…Recently, production of coal ash in Japan is rapidly increasing with the increase of coal-fired power stations, and the annual production of coal ash was 10 million tonnes [1]. But the use of fly ash as cementitious materials in concrete is still limitted for various reasons, such as difficulty in quality control of air-entrained fly ash concrete [2]. Japanese Industrial Standard, JIS A 6201, Fly Ash for Use in Concrete, specifies 4 type of fly ash depending on fineness, ignition loss, flow value ratio and activity factor [3].…”

Research on Improving the Durability of Fly Ash Concrete

“…Many studies have been made to find ways to make efficient use of fly ash, but the use of fly ash in building construction is still limited [1]. The main reasons are the decreased of the initial compressive strength and increased carbonation in fly ash concrete [2]. Also, in order to ensure resistance to freezing and thawing action, it is necessary to mix a amount of air in the concrete, but the air-entraining agent is adsorbed by the unburned activated carbon in fly ash, which reduces the air-entraining capability of fly ash concrete [3].…”