Review on effects of water to cement ratio and chloride penetration in reinforced concrete structure

Abstract

Corrosion become the main concern in structure durability which can result in catastrophic failure. Besides, inadequate or wrong selection of water-cement ratio can cause the insufficient readiness of reinforced concrete structure (RC) to the aggressive environment. This issue might arise due to the material cost saving by reducing the material of concrete and at the same time the quality of concrete might be jeopardized during the construction as the consequences of the acts are untraceable in the early stage. The poor quality of concrete in term of penetrability properties can cause the easiness transport of chloride ions into the internal medium of concrete structure. Therefore, the purpose of this research is to highlight the common and frequent problem on the structure deterioration that often related to the chloride-induced corrosion. The pattern and failure mode of concrete and steel were observed using the secondary data collection method from previous study to analyse the intended various factors that contributed to the corrosion of the RC. After all the possible factors that influence the corrosion was determined, the data comparison were done to study their effect on the chloride penetration that led to the occurrence of corrosion. As a result, water-to-cement (w/c) ratio was the main parameter that highlighted as the main cause of the chloride ions penetration that led to the corrosion of reinforced structure at the first place which eventually end up with structure failure. Different parameters were investigated on the degree of corrosion such as the sodium chloride (NaCl) concentration as aggressive agent, the immersion time, and the intended quality concrete casted. The findings show that the lowest chloride penetration depth was 5 mm with w/c ratio of 0.25, and the highest penetration was at the depth of 33 mm with w/c ratio of 0.55 in 3% NaCl solution for 6 months. It can be seen that when w/c ratio increase by 0.1, the chloride penetration depth will increase to approximately 30 to 60%. This results highly prove that the quality of concrete structure plays a significant role in delaying the chloride-induced corrosion. Moreover, these findings can increase the knowledge and awareness of construction practitioner on the importance of designing the adequate quality of concrete structure and ensure the quality was well-maintained to avoid the economic issue arise in future due to corrosion.