SprayLock Africa reports that Chloride attack poses a significant threat to reinforced concrete. The outcome of chloride attack is the corrosion of steel reinforcement, leading to concrete cracking and spalling and, in extenuating circumstances, catastrophic structural failure as load bearing capacity is compromised.
There are many factors that contribute to the rate of concrete deterioration due to chloride attack. Chief among these are the physical characteristics of concrete. Concrete is a porous material with most of its strength and durability determined by an array of factors. These include water-to-cement (W/C) ratio, compaction and curing. Considering the action of chloride attack, concrete density has a large influence on the rate of its deterioration. Obviously, concrete with smaller pores and lower pore connectivity will absorb less water or vapour. This inhibits its transport through concrete thus slowing down the ingress of chlorides into the structure.
Three laboratories have tested our unique SCP technology’s ability to significantly deaccelerate the rate of chloride through concrete. Using chloride diffusion testing, chloride concentrations at various depths were ascertained. These informed the calculation of an average diffusion coefficient that predicts the length of time it will take chlorides to reach reinforcing steel and penetrate the passive layer around it. This modelling was undertaken with sophisticated software, including Life 365.
Notably, SCP achieved a 69% reduction in chloride diffusion coefficient for concrete with a W/C ratio of 0,57 and 0,45. For concrete with a W/C ratio of 0,40, a 75% reduction in chloride diffusion coefficient was achieved.
By extending the period it takes for chlorides to reach reinforcing bar, years can be added to the lifecycle of concrete structures.
