Specific Gravity and Absorption of Coarse Aggregate

Purpose: To determine the specific gravity (bulk and apparent) and absorption capacity of coarse aggregate (AGG-5)

Related Standard: ASTM C127

Definitions:

Specific gravity is the ratio of weight in air of a unit volume of a material to the weight of an equal volume of water.

Bulk specific gravity is the ratio of the weight in air of a unit volume of aggregate (including the permeable and impermeable voids in the particles, but not including the voids between the particles) to the weight of an equal volume of water.

Apparent specific gravity is the ratio of the weight in air of a unit volume of the impermeable portion of aggregate to the weight of an equal volume of water.

Absorption is the increase in weight of aggregate due to water in the pores, but not including water adhering to the outside surface of the particles, expressed as a percentage of the dry weight.

Equipment: Balance, wire basket (of 3.35-mm or finer wire mesh) water tank, oven

Sample: A minimum of 4000 grams (8.8 lb) test sample for aggregate of maximum nominal size 1-inch (25-mm). The sample should not have particles of size less than 0.187-in (4.75-mm).

Procedure:1. Weigh the test sample2. Immerse the aggregate in water at room temperature for a period of 24 ± 4 h.3. Remove the sample from the water. Roll it in a large absorbent cloth until all

visible films of water are removed. The sample is now in saturated surface dry (SSD) condition.

4. Weigh the sample and obtain its saturated surface dry weight, B (g).5. Place the SSD sample in the wire basket and determine its weight in water: C (g).

Note that the wire basket should be immersed to a depth sufficient to cover it and the test sample during weighing.

6. Remove the sample from the wire basket.7. Dry the sample to constant weight at a temperature of 110 ± 5 oC (approximately

24 h), and weigh: D (g)8. Calculate specific gravity and absorption.

Bulk specific gravity, dry = A/(B-C)

Bulk specific gravity, SSD = B/(B-C)

Apparent specific gravity = D/(D-C)

Absorption = (B-D)/D x 100

Report: report the specific gravity and absorption values for ¾-inch gravel, ¾-inch crushed stone, and ½-in. crushed stone in tabular form.