Water Absorption (Fine Aggregate)

A sample of sand is soaked for 24 hours, brought to a saturated surface-dry (SSD) condition, weighed, then oven-dried and weighed again. The difference in mass, expressed as a percentage of the dry mass, is the water absorption.

This value is used to correct the free water content of a concrete mix — aggregate with high absorption will pull water out of the paste unless the mix design allows for it — and is also a general indicator of porosity and quality.