This test involves studying the water sorptivity index. In other words it measures the amount of moisture the concrete absorbs through its pores. This test can be used to evaluate the mix proportions in the design phase, perform research for further development and for the quality control of concrete on site.
The values obtained from water sorptivity testing are 5mm/hr0.5 for well cured 30-50 grade concretes and the 15-20mm/hr0.5 for poorly cured grade 20 concretes.
The specimen preparation for the water sorptivity test followed a similar procedure to the oxygen permeability index test. Once the OPI test was complete, the same specimens were used to perform the water sorptivity test. A layer of tape was first applied around the curved surface of the specimen in order to prevent the ingress of water on the sides.
Top image shows the sorptivity test in progress.
Bottom image shows the compressor used to create the vacuum for part of the testing procedure.
