Analysis of total chloride content in concrete

• Total chloride limits could be violated while the limits in mix materials are satisfied.
• The effect of chloride in mixing water on total chloride is minimal up to w/c = 0.4.
• Mix design with the lowest w/c ratio is preferable as far as chloride is concerned.
• Mix proportions are an important factor to specify chloride limits in mix materials.
• Chloride in mixing water could be higher than the ASTM limits with low w/c ratios.

This research paper presents an analysis of total chloride contents in concrete. The concrete mixtures that were approved by the municipality of Riyadh city in Saudi Arabia for a main ready mix concrete plant were considered in this study. The analysis was based on an experimental investigation of chloride levels in mixing water, aggregates, and concrete. The analysis also used the maximal total chloride limits of British Standards for the concrete in conjunction with other ingredients required for the mix.The results obtained suggest that the effect of chloride content in mixing water has minimal to moderate influence upon the chloride content of concrete up to w/c equal to 0.4. It also shows that aggregate is the critical ingredient in terms of determining the presence of chloride in concrete. Critically, the limits of chloride content in any concrete mix could be violated even though the limits of chloride content still meet some standards for their content within concrete ingredients. The proportions of any mix design are also an important factor to be considered when attempting to specify the limits of chloride content of the ingredients of concrete mixtures for any type of concrete. It is vital to investigate empirically the relationship between total chloride and chloride contents in ingredients in order to precisely define the limits of chloride content in concrete mix ingredients. Mix design that has the lowest w/c ratio is preferable as far as the chloride content is concerned. Finally, water chloride content could be higher than ASTM specified limits with mix designs that have low water cement ratios and should be lower than the ASTM limits with high water cement ratios.