Title: Sulfate Resistance of Ternary Blend Concretes: Influence of Binder Composition on Performance

Author(s): R. Brett Holland, Kimberly E. Kurtis, and Lawrence F. Kahn

Publication: Symposium Paper

Volume: 317

Issue:

Appears on pages(s): 1--14

Keywords: Sulfate Attack, Concrete Durability, Ternary Blend Concrete

DOI: 10.14359/51700841

Date: 6/1/2017

Abstract:
Due to the increasing costs of maintaining deteriorating infrastructure, there has been an increased importance placed on the durability of new concrete structures. For marine structures and structures constructed in sulfate rich soils, sulfate attack can cause the structure to degrade over time. Historically, sulfate attack resistance has been evaluated using an expansion test method. However, in addition to expansion during sulfate attack, concrete can exhibit strength degradation without expansion. Resistance to sulfate attack was assessed using both expansion and strength degradation test methods for thirteen binder compositions. Results were compared to established criteria for expansion and proposed criteria for change in strength and were correlated to overall binder composition, considering the combination of three cement types and five supplementary cementitious materials (SCMs). Compressive strength degradation testing demonstrated that mix designs with a high initial CaO content, determined through oxide analysis of the cement and SCMs, performed well, presumably due to the formation of calcium hydroxide (CH) which served as a buffer to the decalcification of calcium-silicate-hydrate (C-S-H) in the formation of gypsum. However, high CaO contents led to poor performance on expansion testing due to the availability of large amounts of calcium hydroxide to react with sulfate ions to form expansive ettringite. Slag mix designs containing metakaolin performed well on both criteria.