22.3.6. Specific Gravity and Water Absorption

Try these first

1. 1.

   What is specific gravity?

   Hint

   Think about how it relates materials of different densities.

2. 2.

   What does water absorption measure?

   Hint

   What could happen to concrete if aggregates absorb too much water?

3. 3.

   What is the apparent specific gravity formula?

   Hint

   Remember which dimensions we leave out.

4. 4.

   Water absorption values in aggregates typically range from?

   • 0.01 to 0.5%
   • 0.1 to 2.0%
   • 2.1 to 3.0%

   Hint

   Think about the impact of higher absorption on durability.

5. 5.

   An aggregate sample has a dry weight of 1.5 kg and weighs 1.7 kg when saturated. Calculate the water absorption and discuss its potential impact on concrete performance.

   Hint

   Use the water absorption formula and think about long-term performance.

6. 6.

   If a bulk specific gravity of an aggregate is found to be 2.7 and apparent specific gravity is 2.5, what can you infer about the water-permeable voids?

   Hint

   Look at the relationship between the two specific gravities.