Effects of Impure Water Sources on the Early-Age Properties of Calcium Sulfoaluminate (CSA) Cement

One of the benefits of calcium sulfoaluminate (CSA) cements is that these materials gain strength rapidly, and strength development is often measured in hours instead of days. This property makes these materials desirable for use in temporary, nonreinforced repairs of roadways, airfields, and navigable locks. The rapid repair of these infrastructure elements is critical to transporting supplies into regions devastated by disaster. In these austere environments, potable water may not be available in sufficient quantities to make vital repairs, and the use of impure water in the production of CSA cement–based concrete would be advantageous. However, the hydration products formed by CSA cement are significantly different from those formed by portland cement and may react differently to alkalis, chlorides, sulfates, and other contaminates that these impure water sources may contain. This article investigates the impact of calcium, sodium, potassium, and magnesium chloride and calcium, sodium, and magnesium sulfate on the early-age unconfined compressive strength development of commercially available CSA cement–based concrete. Of these salts, calcium chloride had the greatest effect on early-age concrete properties, retarding unconfined compressive strength development. The strength results obtained from CSA cement–based concrete mixed with these saline solutions are compared with those obtained from potential real-world sources of mixing water, including seawater and greywater.