Improvement of water resistance of magnesia stone for hardening of filling mixtures from man-made dolomite

The paper considers the applicability of magnesia binding materials on the basis of mining wastes as an alternative material for production of filling mixtures. The main advantages of such mixtures in comparison with well-known Portland cement mixtures are shown. It’s found out that low water resistance of magnesia binding materials hampers its use in this field. The authors examine ways of improving water resistance of magnesia binding materials from man-made dolomite in order to create on its basis a qualitative filling mixture. The effect of various mineral admixtures on properties of dolomite is studied. The comparative analysis of strength and water resistance of the obtained dolomite with these additives is conducted. The phase constitution of the obtained compositions is examined with the help of X-ray analysis. The influence of additives on water resistance and regularity of dimensional change in case of dolomite hardening is determined. Based on the research results the most efficient admixture, i.e. nickel slag and its dosage for obtaining dolomite binders, which meet the requirements imposed for water resistance of filling mixtures, is chosen.