Efficiency of sealers on the scaling resistance of concrete in presence of deicing salts
Abstract The purpose of this paper is to report on the results of a research program carried out to determine the influence of commercially available penetrating sealers on the deicer sal t scaling resistance of different concretes . Thre e sealer s were selected : a silane , a n oligomeric siloxan e an d a polymeric siloxane . The y wer e applie d on the concret e surfaces at a constant dosage of 3 m^/L. Th e double of the recommended dosage of the silane was also used. Differen t types of concrete wer e made: concretes with poor airvoid systems, and air-entrained concretes with good or excellent air-void systems. Th e mixtures were prepared a t water/cementitiou s material s ratio s o f 0,45 (wit h norma l Portland cement an d with silica fume cement) an d 0,35 (wit h silica fume cement). T o simulate application of the sealers to concretes previously exposed t o deicer salts , th e sealers were applied to concrete specimen s previously soaked in 0%, 1% , 5%, and 15% sodium chloride solutions for a period of three days. Th e sealers were also applied to dry as wel l a s humid surfaces. A study of the influence of the application of sealers heated to 40°C and of the influence of weathering of concrete specimens at 40°C before and afte r applicatio n of the sealer s was performed . Th e depth o f penetration o f the sealers, the water and chloride penetration through the sealed surfaces, and the vapour transmission were determined. Th e results of the deicer salt scaling tests performed on the various specimens (according to ASTM C672) clearly indicate that the use of sealers reduces the deterioration of concretes that are not properly air-entrained, although it was found that, after a large number of freezing and thawing cycles, this deterioration could be similar to that of untreated surfaces . Th e results further show that the use of sealers can increase significantly the deterioration of properly air-entrained concretes due to salt scaling. Pre-contaminatio n wit h sal t solutions, even a t low concentrations, wa s found to be very harmful to the performance o f the sealers . Th e sealers , however, ca n b e efficiently applie d on humid or microcracked surfaces. Th e silane was generally found to have the best performance. Keywords: Durability , concretes , deice r salts , scaling , sealers , silanes , siloxanes , conditions of application.