AIM:-
- To determine of specific gravity of coarse aggregate,
APPARATUS:-
- A weight balance of capacity not less than 3 kg & accuracy 0.5 gm.
- Thermostatically controlled oven to maintain temperature at 100°c - 110°c.
- Basket — perforated container made of not more than 6.3 mm mesh.
- A stout watertight container in which the basket may be freely suspended.
- Two dry soft absorbent cloth (75×45) cm.
- A shallow tray of area not less than 650cm2
Sample:-
- A sample not less than 2 kg of the aggregate shall be tested.
TEST PROCEDURE:-
- First wash the sample to remove finer particle & dust.
- Then place the sample in the basket and immerse in water at a temperature between 22°C - 32°C.
- Immediately after immersed remove entrapped air by jolting the basket.
- Keep the basket and aggregate immersed in water in same position for period of 24± ½ hours.
- The take weight of basket and aggregate (Al) in the water after jolting properly.
- The basket and aggregate are than to be removed from water and allowed to drain off for few minutes.
- The gently empty the aggregate and again place the basket ip to water and take weight (A2).
- The aggregate then is to be placed on a dry cloth and made dry with another cloth, then after some time to be weighed (B).
- Aggregate shall Then be placed in the oven shallow tray, at a temperature of 100°C to 110°C Maintained at this temperature for 24±½ hours. It shall then be removed from the oven, cooled in the airtight container and weight (C).
CALCULATIONS:-
- Specific gravity = C / (B-A)
- Apparent specific gravity= C / (C-A)
- A= The weight in gm of the aggregate in water (A1 - A2)
- B= The weight in gm of the saturated surface dry aggregate in air.
- C= The weight in gm of the oven dry aggregate in air.