Document Type : Research Paper
Authors
1
Department of Chemistry, Isfahan University of Technology, Isfahan 84156-83111, Iran. Sepahan Cement Company, Isfahan, 8499186111, Iran
2
Department of Chemistry, Isfahan University of Technology, Isfahan 84156-83111, Iran
3
Cement Research Center, School of Chemical Engineering, Iran University of Science and Technology, Tehran, Narmak 1684613114, Iran
Abstract
Composite cement has several technical, environmental, and economic advantages. Thus, we investigated the properties of a new composite cement composed of four components, including ground granulated blast-furnace slag from Isfahan Steel Co., pozzolan from Rafsanjan Mine, Portland cement from Sepahan Cement Co., and limestone. The chemical and physical properties and activity of the above components were determined. Eight composite cements were prepared and their physical and chemical properties were characterized. After compressive strength test, measurement of flowability and setting time, a composite cement made of 20% slag, 10% pozzolan, and 2.5% limestone was selected for additional investigations. After 120 days of curing, SEM, XRD, and TGA testing on cement pastes made of the proposed blend, the control cement, Portland-blast-furnace slag cement (30% slag), and Portland-pozzolan cement (30% pozzolan) were investigated. The blast-furnace slag improved the long-term compressive strength of the composite cement, provided a greater flow to the mortar, and displayed less permeability. In contrast, the pozzolan offered essential benefits, including proper initial strength, suitable setting time, and good grind-ability. The standard quality tests do not evaluate the durability of concrete containing a composite cement, while our study is based on the hydration reactions that occurred in the composite cement for four months. The XRD results indicated that the slag had few crystals, whereas numerous crystals were observed in the pozzolan, potentially reducing the compressive strength in the composite cement. The experimental results revealed that the slag and pozzolan positively affect the properties of composite cement and improve its capabilities.
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