Abstract
Shortly after it was completed in 2 006, a castin- place dam exhibited significant cracking in its concrete slabs. An investigation was undertaken which included laboratory studies, field investigations, petrographic examination of concrete cores, and finite element analysis of the early-age thermal and mechanical behavior of the structure. The root cause of cracking was attributed to thermal effects in the slabs early in the age of each slab. Peak tensile stresses from the analysis were determined to be in excess of the modulus of rupture occur through the thickness of the slab approximately 2 0 days from the date of concrete placement. Cores extracted from the structure showed that the cracks extended through the thicknesses of the slabs. Petrographic examination of the cores did not yield evidence of other possible causes of the observed cracking, namely improper curing, improper mixture proportions, or active deterioration mechanisms such as alkali silica reaction. To prevent similar cracking from occurring in similar construction in the future, it is recommended that a thermal management plan be implemented to mitigate the temperature effects that caused the cracking.