The limit of water absorption by coarse aggregates is determined so as to calculate the appropriate amount of water to be added to the concrete mix, thus modifying the water cement ratio. A bone dry aggregate would necessitate, while for wet aggregate water contents should be reduced.
Designation of Experiment
BS-812, Part 2: 1975
Balance, Oven, Dry and Soft absorbent cloth, shallow Trays
|Determine the Water absorption of coarse aggregate|
Sample of watered aggregates and water.
Take a sample of coarse aggregates, wash to remove finer particles and dust and then immerse in water for 24+1/2 hours.
After this period, aggregate are taken out and dried with a dry absorbent cloth.
Weigh the aggregates and let this weight be A.
Place the aggregate in the oven at a temperature 100-110 for 24+1/2 Hours.
Remove the sample of aggregates from oven and cool in air, weight them and let this weight be B.
Observations and Calculations
Percentage water absorption =( (A-B)/B ) x 100
A = Mass of saturated surface dry sample
B = Mass of Oven dried sample
A = 2225 gms
B = 2170 gms
Percentage Water Absorption = (55/2225) x 100 =2.47 %
Percentage water absorption of coarse aggregate of given sample is 2.472 %.