Penetração de cloretos em concretos compostos com cimento Portland branco e escória de alto forno, ativados quimicamente

Abstract

The consumption of white Portland cement (WPC), in structural concretes, has been growing lately. Thus, targeting diffuse its use, and confirm its quality and durability as structural cement, this work has the aimed to investigate the effect of concretes compounds with WPC, slag and chemical activator (Na2SO4), on its behavior against chloride ion penetration. Besides reference mixture (100% WPC), were analyzed blends containing slag replacements of 50% and 70%. A content of activator was 4% of the binder, in which, 50% were slag. The water/binder (w/b) ratios were 0.30, 0.42 and 0.55, and submitted at ages of cure 3, 7, 28 and 91 days. For analysis of chloride penetration, were evaluated the penetration coefficient (by the immersion test, in chloride solution) and the total charge passed (according ASTM C1202/05). Essays of Compressive strength, mercury intrusion porosimetry and composition of pore solution, also been made. Results showed that replacements of WPC by slag provide excellent performance in chloride penetration tests, in all ages tested, manly, in higher w/b ratios. In spite of, the compressive strength of slag concretes not have been greater than reference mixture, this type of concrete attained good results, excepted for essay with three days. Chemical activator efficiency, to accelerate the improvement of slag concrete properties, at initial ages, were verified. Its efficacy was greater as higher w/b ratio and visible until cure of 28 days. The slag addition was beneficial also for de cost, present best results in uniformity of compressive strength and penetration coefficient. Correlations between immersion test and ASTM s essay, analyzed together other tests, show that results of test described by ASTM C1202/05 aren t trustful for practical in concretes with slag additions.