A study on the calcium chloride resistance of concrete containing an expansive additive[ACI SP-234-26]

The addition of expansive additives to concrete helps to prevent cracks resulting from shrinkage and thermal stress. Chloride based deicing chemicals are used on roads during freezing conditions to prevent wheel slipping. This presentation discussed the damaging effects of salts on concrete prepared with a small amount of expansive additives. This experiment tested the chloride resistance of expansive-cement concrete mixtures made of an ordinary portland cement and a blast-furnace slag cement with and without an expansive additive based on a free CaO hydration as well as ettringite formation. Calcium chloride spray was used as a source of chloride ions. The objective was to determine if the addition of expansive additive had any affect on the chloride resistance of concrete. Details of the experiment were provided with reference to materials used, mix proportions, curing, testing for compression strength, depth of neutralization, measuring for change in length of concrete, pore size distribution, and microstructural observations. The study found that there were no adverse effects on the compressive strength, changes in length, or chloride penetration depth after the concrete was subjected to salt spray between 28 and 56 days of curing. 6 refs., 4 tabs., 4 figs.