Iowa Department of Transportation
Iowa Highway Research Board
Peter Taylorptaylor@iastate.edu email >
Director, CP Tech Center
Kejin Wangkejinw@iastate.edu email >
PCC Engineer, CP Tech Center
About the research
Internal curing is the practice of providing small, well-distributed reservoirs of water throughout a concrete section such that the w/cm of the mixture can be kept low, but the water can later be delivered to hydrating cement as the system dries out. Internal curing has been reported to be effective in reducing shrinkage cracking, improving potential durability of concrete mixtures, and most notably, reducing warping and associated cracking in pavements and slabs on grade.
Currently, the use of light-weight fine aggregate (LWFA) is the most common practice in the US to produce internally cured concrete. This method, however, necessitates pre-saturation of aggregate at concrete batch plants in accordance with a set timeline. This may increase costs related to stockpile management in addition to the costs and emissions associated with production and hauling the LWFA.
The use of superabsorbent polymers (SAP) as a means of internal curing can address such problems, while still promoting hydration and reducing the risk of early age cracking. However, there has been relatively little work conducted in the US on these materials. The aim of the work is to conduct laboratory work to address some remaining questions:
- How should SAP products be specified?
- How much is needed?
- Can SAPs be dry batched with additional water in the mixture without compromising performance?
- How are mixtures affected by their use?