Exposure to water in the form of rain or high humidity conditions
can also adversely affect the quality of the densified
product. Hence immersion tests were performed to assess the
effects resulting from exposure to water. As advised by
Richards [39], the water resistance was defined as 100 minus
the percentage of water absorbed by the densified product
after it has been immersed in water at room temperature for
1800 s (30 min), removed, wiped clean of surface water, and
weighed.