Pozzolanic Reaction of Supplementary Cementitious Materials and Its Effects on Strength of Mass Concrete

The present study aims to investigate the opportunity to largely substitute low heat Portland cement of mass concrete with supplementary cementitious materials. The pozzolanic reaction of two types of supplementary cementitious materials, phosphorous slag powder and fly ash, were determined by X-ray diffraction, differential thermal analysis-thermogravimetry and scanning electron microscopy from 28 to 90 days. The properties of mortar and mass concrete containing 30% of supplementary cementitious materials were also investigated. Results showed that supplementary cementitious materials could decrease the amount of calcium hydroxide, fill the capillary pores, thus making the mortar and mass concrete more compact and durable. Long-term strength of mass concrete containing 30% of supplementary cementitious materials were comparable (or even better) than the control concrete (without supplementary cementitious materials) at constant workability, while the Young's modulus was lower than the control concrete.