Study of a cement with low environmental impact from sulfoaluminate clinker and phosphogypsum

Abstract

The possibility of using industrial residues as raw materials for construction products has increased its importance for the environment and has also created new technological challenges. This article describes a study in which phosphogypsum, a by product of the phosphoric acid manufacturing industry, has been used for producing cement as a replacement for gypsum. The aim was to develop a cement with low environmental impact, with minimal consumption of clinker and maximum use of phosphogypsum (calcium sulfate). The sulfoaluminate clinker was used, which requires larger quantities of calcium sulfate in relation to Portland cement. Six combinations of phosphogypsum and clinker were tested, ranging between 70%-95% and 30%-5%, respectively. The performance of the low environmental impact was assessed, in terms of mechanical resistance, and durability tests for the standard mortar. (NF EN 196-1). The interactions between phosphogypsum and clinker were investigated by using XRD and DTA techniques. In the analysis of the standard mortar, with a proportion of 1:3 (cement: sand), the proportion of 70% phosphogypsum and 30% clinker resulted in a compressive strength higher than 20 MPa after 28 days.