Calcium Sulfo Aluminate Cement (CSA)

CSA binder is a hydraulic binder made from calcium aluminate sulphate. It has a quicker setting time than ordinary Portland cement (OPC) and doesn’t release free lime during hydration, which reduces efflorescence. CSA binder accelerates the setting time and strength of Portland cement, compensates for shrinkage, and adapts the rheology to suit various applications. CSA binder commonly forms part of a ternary binder system which also contains Portland Cement and a source of calcium sulphate (usually anhydrite).

CSA binder has several key characteristics. It is resistant to sulphate attack, impermeable, freeze-thaw resistant, and requires a short curing phase. These qualities make CSA cement useful in a range of applications, including airport runways, concrete road repairs, and bridges—especially in cases where fast reuse is necessary. Its properties also make it suitable for self-smoothing and self-levelling compounds, tile adhesives, casting mortars, rapid-hardening screeds, non-shrink grouts, mining roof support materials, and glass-fibre-reinforced concrete.

The benefits of CSA binder are numerous. It promotes rapid strength development in mortars and concrete, achieving in 24 hours the same strength that OPC would take 28 days to reach. It also bonds quickly, with many formulas having an initial set which starts after just 20 minutes and the final set being completed after 30 minutes, although retarders can extend processing time. Unlike other binders, CSA remains reactive even in low temperatures.

CSA binder is also known for compensating for shrinkage. It requires more water than Portland cement, but since all the water becomes chemically bound, there is no surplus to cause shrinkage, warping, or cracking. During the hardening phase, there is stable expansion that prevents gradual shrinkage, and the tension during hydration builds up more rapidly than in other cement types.

Additionally, CSA binder has a low carbon footprint. It is softer than Portland cement, requiring less energy during grinding. It is also calcined at 1232°C compared to Portland cement’s 1480°C. Portland cement production is said to be responsible for about 8% of global carbon dioxide emissions, with around 579 kg of CO₂ emitted for every 1000 kg produced. In contrast, CSA binder produces lower emissions than alternatives such as calcium aluminate cement.