Influence of drying on concrete sorptivity

The experimental programme described in this paper indicated that concrete grade and specimen preconditioning were the major factors influencing sorptivity, whereas specimen size and coating had relatively little effect. The paper recommends that sorptivity be carried out on specimens coated on their side surfaces-that is, the curved surface in the case of cylinders. A 25 mm thick slice incorporating the original cast surface of a cylinder or core could be used as a sorptivity specimen, leaving the rest of the specimen for strength testing. A moderate amount Of oven drying (e.g. 3 days at 50degreesC is also recommended in order to increase the sensitivity of the sorptivity index. This research also demonstrated that sorptivity results from a variety of conditions could be generalised as a function of the desorption ratio; this is an index of the amount of drying that has taken place at the time Of sorptivity testing.