Internal curing has clearly demonstrated its beneficial effects on the performance of concrete bridge decks. The addition of pre-wetted lightweight aggregates to concrete mixtures can help reduce shrinkage stresses by reducing moisture differentials through the depth of a slab.
From an engineering perspective, Mitch Wyble really likes what he sees when he assesses the value of internally cured concrete (ICC), a concrete mixture where a portion of the fine aggregate is replaced with similar sized prewetted lightweight aggregate (LWA). Wyble first encountered ICC a few years ago while serving on the Technical Committee of the Concrete and Aggregates Association of Louisiana (CAAL).
When the Louisiana Department of Transportation & Development (LADOTD) needed to construct a bridge on U.S. 80 over the Kansas City Southern railroad tracks to accommodate two lanes of northbound and southbound traffic, it decided to incorporate internally cured concrete (ICC) into its completion plan.
It's been a decade since one of the largest internal curing paving projects in the United States kicked off with the placement of over 250,000 cubic yards of concrete paving. Dubbed the Union Pacific Dallas Intermodal Terminal (DIT), this unique project remains an excellent testament of lightweight aggregate's ability to improve the durability, strength, and quality of concrete paving.
Constructing large capacity water storage tank slabs without construction joints is a complex proposition in Colorado's low humidity and often windy climate. One solution that has been successful is to specify low-shrinkage concrete mixtures and monolithic placement of the slab within a prescribed time period to reduce the probability of shrinkage cracking.