2.5. Water absorption measurement
The small pieces of samples (dimensions 15151 mm) were
stored at 55% RH for 7 days and 45 days before testing, then were
dried in the oven at 105C for 24 h. These small pieces of sample
were weighed immediately after being removed from the oven.
The water absorption can be calculated using equation[22,23]:
Water absorptionð%Þ¼½ðw1w2Þ=w2100 ð1Þ
wherew1was the weight of sample before drying andw2was the
weight of sample after drying. All measurements were performed
in triplicate.