The Resistance of Cements to Ammonium Nitrate Attack

The durability of different types of cement to ammonium nitrate attack was studied. The tests were conducted on mortar prisms kept in ammonium nitrate solutions at different concentrations, ranging from 0.0 percent to 50.0 percent. Five types fo cement were used: ordinary portland, pozzolanic, blastfurnace, aluminous and supersiliceous. Changes in length and weight were registered during 14 years; also determined were the mechanical strength and changes in composition. Initially, the most concentrated solution was the most aggressive, but owing to crystallization of the ammonium nitrate in the pores of the mortar, its relative aggressivity diminished with time, so that it was the 0.5 and 5.0 percent solutions that showed the greatest aggressivity. The aluminous cement showed the best resistance to ammonium nitrate attack. Of the other cements, the blastfurnace cement was the one that best resisted that attack.