CHEMICAL EFFECTS OF HEAVY-METALS ON THE HYDRATION OF CALCIUM SULFOALUMINATE 4CAO-CENTER-DOT-3AL(2)O(3)CENTER-DOT-SO3

The system 4CaO . 3Al(2)O(3) . SO3-CaSO4 . 2H(2)O-Ca(OH)(2) was hydrat ed in the presence of ten dopants, specifically soluble salts of heavy metals. When added in 10% amount, the effect of each salt is strongly evident at shorter curing times, the hydration kinetics being more fa voured in the order Pb(NO3)(2)<K2CrO4<Cd(NO3)(2)< Zn(NO3)(2) approxima te to Mn(NO3)(3) approximate to 2MoO4<Ni(NO3)(2)<Cu(NO3)(2)<Cr(NO3)(3) <Fe(NO3)(3). At longer curing times the differences among the systems decrease significantly. The 28-day compressive strength is almost the same for all the systems except those containing Pb(NO3)(2), K2MoO4 an d K2CrO4.