Objective

For determination of specific gravity & water absorption of aggregates.

Reference标准

IS : 2386 (Part 3) – 1963 – Method of test for aggregates for concrete (Part I) Particle size and shape.

Equipment & Apparatus

• Wire basket
• Oven (300⁰c)
• 用于填充水并悬挂篮子的容器
• An air tight container
• Balance[0-10 kg]
• 浅盘和吸收衣服。

Preparation of sample

被测试的样品separated from the bulk by quartering or by using sample divider.

Procedure

1. About 2kg of the aggregate sample is washed thoroughly to remove fines, drained and then placed in the wire basket and immersed in distilled water at a temperature between 22 to 32⁰C with a cover of at least 50 mm of water above the top of the basket
2. Immediately after the immersion the entrapped air is removed from the sample by lifting the basket containing it 25 mm above the base of the tank and allowing it to drop 25 times at the rate of about one drop per second. The basket and the aggregate should remain completely immersed in water for a period of 24±0.5 hours afterwards.
3. The basket and the sample are then weighed while suspended in water at a temperature of 22 to 32⁰C.悬浮在水中时注意重量（W₁） G。
4. The basket and the aggregate are then removed from water and allowed to drain for a few minutes, after which the aggregates are transferred to one of the dry absorbent clothes.
5. The empty basket is then returned to the tank of water, jolted 25 times and weights in water (W₂） G。
6. The aggregates placed in the dry absorbent clothes are surface dried till no further moisture could be removed by this clothe.
7. Then the aggregate is transferred to the second dry cloth spread in a single layer, covered and allowed to dry for at least 10 minutes until the aggregates are completely surface dry. 10 to 60 minutes drying may be needed. The surface dried aggregate is then weighed W₃g.
8. 将聚集体放置在浅托盘中，并保持在保持在110的温度的烤箱中⁰C for 24 hours. It is then removed from the oven, cooled in air tight container and weighed W₄g.

Calculation

饱和聚集体的重量悬浮在水中，篮子= w₁g

Weight of basket suspended in water = W₂g

Weight of saturated aggregate in water = (W₁-W₂)g = W_sg

Weight of saturated surface dry aggregate in air = W₄g

Weight of water equal to the volume of the aggregate = (W₃-W_s) g

Safety & Precautions

• Use hand gloves while removing containers from oven after switching off the oven.
• Thoroughly clean & dry the container before testing.
• Special care should be taken that no outer air enters when using the balance.
• Use apron & safety shoes at the time of testing.
• All parts of the equipment should always be kept clean.