Concrete undergoes a number of volume changes during its service life. In engineering terms this volume change is generally expressed as “strain”, which is defined as the change in length per unit length. Under conditions of constraint this strain results in an applied stress, which can lead to cracking.

Drying shrinkage occurs when concrete in a saturated condition is dried in air. The source of this drying shrinkage is the loss of the adsorbed water and water held in small capillary pores of the hydrated cement paste.

Drying shrinkage of slag blended cements have been reported to be considerably higher than concretes made with ordinary Portland cement but this reported shrinkage difference is not always consistent. This variability in reported drying shrinkage results is due to the many factors that influence drying shrinkage.

This project has been designed to reduce the number of factors and seeks to determine the effect of ground granulated iron blast furnace slag by comparing drying shrinkage of a standard concrete produced with a range of cement blends. In addition, a modified shrinkage test is proposed which will provide critical information on the shrinkage behaviour during the first seven days of curing.

• Comprehensive report
• Paper to be delivered at Concrete 05