Void structure of concrete with superabsorbent polymers and its relation to frost resistance of concrete

Superabsorbent polymers (SAP) can be used to control air void formation in concrete. However, due to surfactant left on suspension polymerized SAP particles during production, they may not only create SAP voids but also entrain extra air. In the present investigation, a method is tested to remove surfactant prior to concrete mixing. The method comprises rinsing of the SAP with ethanol. This effectively removes the surfactant. Freeze–thaw testing of concrete with rinsed and non-rinsed SAP shows that for equal dosages of SAP, the extra air entrained due to surfactant is considerable and can make the difference between poor and satisfactory frost-resistance. Furthermore, the results indicate that voids created directly by SAP protect concrete against frost deterioration just like other air voids; if the concrete contains enough SAP voids, these alone can provide sufficient frost resistance.