Use of crystalline waterproofing to reduce capillary porosity in concrete

Abstract

The use of different technologies have contributed to the increase in durability facing the aggressive agents that damage the concrete structures. Therefore, it is possible to reduce the capillary porosity in concrete lowering the ratio water/binder; using pozzolan, hydrophobic or waterproofing products in the mixture; applying hydrophobic products or waterproofing in the concrete surface; replacing pure cements for compounds cements, pozzolanic cements or cements with blast furnace slag; among other actions. The waterproofing has the function to prevent the water or fluid passage in liquid or steam state, thereby protecting structures. The waterproofing creates a barrier when coating is applied to close surface pores with the aim of preventing the water pervasion by any transport mechanism. This paper has evaluated the use of crystalline waterproofing as admixtures, as well as a coating, sanding and no-sanding, in order to know the benefits it can bring to the concrete water absorption, comparing their performance with other concretes with or without silica fume admixture. Developed tests were: total absorption, under pressure water penetration (30 kPa) and compressive strength test. The results have showed that the silica fume admixture is more efficient than the analyzed crystalline waterproofing, as it has contributed to the compressive strength increase and decrease of water absorption and penetration. The crystalline waterproofing admixture has contributed to compressive strength increase; however, there was also an increase in the absorption and penetration. On the other hand, the coating waterproofing has not influenced the compressive strength, but reduced absorption and penetration when sanded.