Creepy and Shrinkage Properties in Concrete Containing Fly Ash

The creep and shrinkage of concrete containing fly ash subjected to different conditions were investigated in this research program. One Type-A and two Type-B fly ashes were used at 0, 20, 27.5, and 35 percent replacement of cement by volume. Test specimens were heat cured at 160°F and 100% relative humidity for 12 hours and moist cured under standard moist curing conditions. The tests performed included creep, shrinkage, creep recovery, and strength gain due to sustained loading.

The creep tests were begun at early age for a duration of 120 days followed by 14 days of creep recovery tests. The shrinkage tests were conducted for a duration of 135 days under a constant environment of 75°F and 40% relative humidity. The strength gain tests were performed on loaded and companion unloaded specimens after the recovery period to determine the sustained load effect on the strength.

The test results reveal that creep and shrinkage of concrete are affected by the use of fly ash and curing conditions. Heat curing was found to reduce both creep and shrinkage and also to reduce residual deformation due to sustained loading. Sustained loading was found to increse the strength of conventional and fly ash concrete.