Durability of Concrete Containing an Ester-Amine Admixture Exposed to Sulfate and Sulfuric Acid Solutions

An investigation is presented to evaluate the effect an ester-amine admixture (EA) has on the durability of concrete exposed to sulfate and sulfuric acid solutions traditionally detrimental to concrete. Prisms were exposed to a MgSO4 environment under cyclic wet/dry conditions for 336 days. Other prisms were exposed to a H2SO4 environment at pH=1 for 100 days. During the sulfate exposures, the concrete specimens were evaluated by appearance and length change over time. During the sulfuric acid exposures, the concrete specimens were evaluated by the pH changes of the test solution. The ester-amine admixture was shown to be beneficial in reducing the initial susceptibility of concrete exposed to both environments. This benefit was also observed to improve the resistance of already low permeability concrete containing pozzolans such as fly ash and silica fume. The behavior was explained by the admixture's reaction products which line the concrete pore matrix. A mechanism that differentiates the action of the EA from other permeability reducing materials (e.g., pozzolans) is proposed.