Detailed Analytical EPMA Study of the OPC Pastes Prepared with the Addition of Raw and Milled Fly Ashes

Concrete and cement pastes belong to the most used building materials in human history and represent a solidified mixture of ordinary Portland cement (OPC), water, course and fine-grained aggregates. Fly ash is used as a pozzolanic additive to improve concrete properties. The fly ash property can also be modified by various treatments such as milling or size reduction with sieving. It was suggested that a beneficial pozzolanic reaction with fly ash gives high mechanical properties. Such pozzolanic reaction results in calcium silicate hydrate (C-S-H) phase formation. In this research comparative analytical EPMA study of the paste samples prepared with the addition of the milled and non-milled fly ashes has been performed to elucidate the pozzolanic reaction of the OPC with the milled and non-milled fly ashes. A higher pozzolanic reaction with CSH phase formation was observed in milled fly ash added paste.