process for the preparation of cement with magnesium sulphate with mechanical resistance mile installment

摘要

Prepn. of magnesium sulphate cement with increased strength, the novelty being the mixing, at or below ambient temp. of (a) an aq. soln. of (NH4)2CO3 and/or (NH4)HCO3, with (b) a soln. contg. by wt. 10-20%, esp. 12-14% MgSO4, the resulting soln. (c) is mixed as quickly as possible with the amt. of caustic magnesia or semi-roasted dolomite necessary for the setting of the cement and, if required, aggregates, then allowed to set in a closed, hot space, esp. at a temp. up to 100 degrees C. The concn. in soln. na) is pref. 5-18%, esp. 10%, and the pref. aggregates are organic cellulose materials such as wood flour or shavings, or straw, or inorganic materials such as rock wool, asbestos, glass fibres or expanded minerals. Normally, the caustic magnesia used must contain 60% min. free MgO, the invention permits the use of lower grade magnesite materials, esp. in mfg. high-strength products.