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ABSTRACT

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.

5. Conclusions

The following conclusions can be drawn from the results and analysis: 1. The limits of total chloride could be violated even though the limits of chloride content in concrete ingredients are satisfied. 2. The effect of chloride content in mixing water on total chloride is minimal to moderate up to a w/c equal to 0.4. 3. Aggregate is the critical ingredient on total chloride. 4. Mix design that has the lowest w/c ratio is preferable as far as chloride is concerned. 5. The proportions of any mix design are an important factor to be considered in order to specify the chloride limits in mix ingredients. 6. It is important to investigate empirically the relationship between total chloride and chloride content in mix ingredients to define precise chloride limits in mix ingredients. 7. Chloride content in mixing water could be higher than the ASTM limits with low water cement ratios and should be lower than the ASTM specified limits with high water cement ratios.