Core size and time effects on water absorption values of rock and cement mortar samples

There is no standard size for samples used to establish water absorption (WA) by weight and volume. A total of 150 samples with five different diameters (54, 48, 42, 30 and 21 mm) were cored from sandstone, limestone and cement mortar with a length:diameter ratio between 2.0 and 2.5. The laboratory experiments were continued for 90 days, although some samples reached their maximum absorption at 43 and 60 days. The study has shown that WA values vary significantly with sample dimension and time. NX (54 mm) cores had the lowest WA values while 21 and 30 mm diameter cores gave the highest WA values. The difference between 24-h and 90-day WA values was greatest for the 21 mm cores.