Concrete structures such as bridge decks, with large surface area relative to volume, shrink and crack, thus reducing service life performance and increasing operation costs.

The project evaluated the early, first 24 hours, and long-term, 180 days, shrinkage of Virginia Department of Transportation overlay and A4 general bridge deck concrete mixtures. A modified ASTM C157 prism was developed to measure the early-age shrinkage, as was a unique hygral cylinder test.  Long-term shrinkage was measured using the ASTM C157 prism test.  In addition, scaled bridge deck overlay specimens were cast to assess cracking potential.  Overlay mixtures tested were latex modified mixtures using portland cement, Type K cement, an expansive mixture and portland cement, fly ash and microsilica blend.  Deck concrete mixtures evaluated were fly ash, slag, Type K cement and an expansive mixture.

Recommendations for controlling shrinkage at 3, 7, and 28 days were developed for all overlay and A4 concrete mixtures.