AN ADDITIVE FOR THE OBTAINING OF RAPID-HARDENING PORTLAND CEMENT AND A METHOD OF IS APPLICATION

摘要

Additive for mfg. rapid setting cement, and contg. (a) Ca-SO4, (b) CaO, (c) active Al2O3 added as dialuminium-pentahydroxy-chloride (DAPO), using a wt. ratio (R) of Al2O3: CaSO4: CaO of 1:3.5-4.3, 1.3:1,8 and (d) 2 pts.wt. max. nitrite, esp. an alkali- or alkaline earth-nitrite. 4-16 Pts.wt. of mixt. (a,b,c) plus 2 pts.wt. max. nitrite, are pref. mixed at max 90 degrees C with water and 100 pts.wt. Portland cement (grade not smaller than '350'). The mixt. is then used to make cement pastes, cement-sand mortar or concrete, which are hardened at max. 100 degrees C. Alternatively, the additive may be dry mixed with cement, esp. by milling. Rapid hardening of cement, mortar or concrete in monolithic- and assembled-structures, which may be reinforced with steel, which is corroded by Cl in the additive. The nitrite neutralises the chlorine and also increases strength.