The water absorption test using rectangular specimens
were cut with the dimensions of 30 · 28 mm (length · -
wide). The experiments were performed using test samples
unsealed on the sides (ASTM D570), in an attempt to replicate
the most aggressive in-use water absorption condition.
The sample was oven dried at 50 C for 24 h to a
constant weight (M0). The specimens were then periodically
taken out from tank; surface dried with absorbent
paper and weighed using an analytical balance with
0.1 mg precision (M1). The percentage weight gain at any
time t (percent water absorb, Mt), as the result of water
absorption was determined by using Eq. (2). The specimens
were immersed until saturated by averaged from four specimens
for each composite system.