INFLUENCE OF SILICA FUME AND FLY-ASH ON CHLORIDE DIFFUSION AND PH VALUES IN CEMENT PASTE

The diffusion rate for chloride in cement paste is a parameter of major significance for the resistance of concrete structures to seawater environments. The results of this investigation show that an addition of silica fume or flyash in ordinary Portland cement paste considerably reduces the diffusion rate for chloride. Measurements of pH values in pore solution pressed out of cement paste show that mineral additions reduce the pH value and this has a negative effect on the capacity of the cement paste to resist reinforcement corrosion.