Effect of Portland cement on strength development of Phosphoanhydrite-Pozzolana cement
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Instytut Chemii i Technologii Nieorganicznej Politechniki Krakowskiej
Publication date: 1997-01-01
Physicochem. Probl. Miner. Process. 1997;31(1):137–143
The paper is a part of the research on a complex alternative technology of apatite phosphogypsum (PG) obtained during the production of phosphoric acid from Kola apatite, on rare earth concentrate and phosphoanhydrite cement with the recovery of phosphate compounds. The effect of Portland cement on mechanical properties of phosphoanhydrite-pozzolana cement has been determined. The samples of binder were prepared with phosphoanhydrite and a constant amount of fly ash while the content of Portland cement amounted from 5 to 20%. Maximum strength of the discussed cement was reached for Portland cement addition in the amount of 20 wt. %, after 90 days. The presence of ettringite in the tested samples was confirmed by means of chemical and X-ray analysis. The change of mechanical properties of the above cements is connected with the formation of ettringite and its decomposition during the hydration process of binder. It was found that the change of linear expansion is also connected with the content of the ettringite phase in binders.