For the sound absorption coefficient test,
cylindrical specimens were made and the specimen sizes were determined according
to the specification, which will be given in the next subsection For each individual
test for pervious concrete of a specific mixture, five specimens were made.
Therefore, every data point represents the average value of five specimens. After casting, specimens were demolded in 1 day. The specimens then were embedded in
saturated lime water for 27-d curing. As the age of specimens reached 28 days, the
specimens then were removed from the curing pool and all experiments were conducted
afterwards which meant the age of pervious concrete was 28 days.