Investigation of Fineness and Calcium-Oxide Content in Fly Ash from ASEAN Region on Properties and Durability of Cement–Fly Ash System

Abstract

Fly ash is a ubiquitously used pozzolan in cementitious material. Its technical knowledge has been widely studied for several decades and seems very well-established. However, a practical challenge currently exists. Different fly ash, even in different batches produced from similar power plant, has a wide variation of properties. To better control the wide variation of properties, this study aims to assess the effects of cementitious mixtures containing different fly ash properties (degree of fineness and CaO content) on heat release, flow, compressive strength, chloride ion penetration resistance, and carbonation resistance. Results from statistical analysis of 270 tested data of fly ash in various ASEAN countries indicate that the fineness of fly ash particle influences on the compressive strength, chloride ion penetration resistance, and carbonation resistance. Whereas, the CaO content of fly ash only statistically impacts on the compressive strength, but not on the chloride ion penetration resistance and carbonation resistance. To reduce the current practical challenge of the wide variation of cement–fly ash composite properties, their durability properties can be improved by adding smaller fly ash particle in cement system. The control of fly ash production by delivering its optimal degree of fineness is more important than selecting the optimal CaO content of fly ash. The study offers a deep technical value differentiating between effects of its fineness and CaO content such that the fly ash producers and consumers can realize and offer the optimized fly ash for good product quality.