Chloride attack evaluation on concrete compositions according to Brazilian standard ABNT NBR 6118 specification

Abstract

One of the factors that affect the concrete structures durability is the corrosion in reinforcement steel. This phenomenon does not occur because of the physical and chemical protection that concrete offers. Among the factors that cause the degradation of reinforced concrete, the ingress of chloride ions stands out. This phenomenon reproduction in laboratory is difficult because of its time for natural occurrence. Therefore, researchers created tests that accelerate the ingress of ions inside concrete in order to simulate how this process will occur in real situations. The Salt Spray test, showed by ASTM B117 standard, is one of these tests, which has been widely utilized in the analysis of metal materials, but it is rare in concrete. Thus, this paper aims to evaluate the chloride ions attack behavior on the four concrete mixes showed by ABNT NBR 6118. The samples are prismatic and the ions attack geometry was observed through the longitudinal rupture of the samples, silver nitrate chemical indicator aspersion and image analysis using the softwares, AutoCAD and Arc Map 10.3. The samples with and without protection in its ends and two different sizes were utilized. On samples without protection, the combined effect of the ingress by the end and the sides of the samples was observed, adding to its influence on maximum penetration of the chloride ions. The maximum penetrations increased to twice in the analysis by longitudinal rupture, compared to the analysis by the transversal rupture in four heights, because of the heterogeneous profile showed in samples.

Proposed variations in nominal reinforcement cover based on the environmental aggressivity class (EAC) of concrete exposure

“…Figure 2 shows the salt spray chamber. The base and top of the plaques were sealed with epoxy-based paint applied in 3 coatings as instructed by Rissardi et al [27]. To further differentiate the grey and brown tonalities of the silver nitrate marker, images were digitally post-processed on Arc Map 10.3 software.…”