Recommendation of RILEM TC 260-RSC: using superabsorbent polymers (SAP) to mitigate autogenous shrinkage

This recommendation is devoted to the use of superabsorbent polymers (SAP) in mitigating autogenous shrinkage of concrete and has been prepared by the working group acting within RILEM TC 260-RSC. The recommended procedure for designing mix compositions of concrete with SAP is given. Dry SAP particles of small size should be added to concrete along with additional mixing water that SAP absorb upon mixing. The SAP particles release water during hardening of concrete to compensate for chemical shrinkage and consequently reduce autogenous shrinkage. The procedure for designing mix composition is based on finding a trade-off between mitigation of autogenous shrinkage and possible negative effects on concrete properties (e.g., mechanical properties, workability). A theoretical guideline is provided based on compensating the volume of chemical shrinkage with (additional) internal curing water to be absorbed by the SAP and based on the measured absorption capacity of the SAP.