In 2012, ASTM published the Standard Specification for Lightweight Aggregate for Internal Curing of Concrete, a guideline for using pre-moistened lightweight, porous aggregate to achieve high-level hydration.
Concrete producers are using expanded lightweight clay aggregate such as Riverlite to produce mix designs that meet high-performance specifications for bridge decks.
The amount of wetted lightweight aggregate needed is based on the absorption and desorption of the aggregate being used.
Although the concept of internal curing may still be somewhat new to many in the concrete industry, since 2003, more than 2 million cubic yards of IC normal weight concrete, including 1.3 million cubic yards in low slump pavements, have been placed.
A high-performance concrete deck with internal curing has a predicted service life of 63 years with a life cycle cost of $292 per square meter, a 63% reduction compared to a normal concrete deck.
The ASTM Standard Specification for Lightweight Aggregate for Internal Curing of Concrete has begun to impact concrete projects contracted by the U.S. Federal Highway Administration and state departments of transportation as well as architects, contractors, producers, and engineers.