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Specific gravity test of aggregates is washed to mensurate the strength or quality of the cloth while water absorption test determines the h2o holding chapters of the coarse and fine aggregates. The principal objective of these examination is to,

  1. To measure the force or quality of the material.
  2. To determine the water absorption of aggregates.

Aggregate Sample

Specific Gravity is the ratio of the weight of a given volume of aggregate to the weight of an equal volume of water. Information technology is the measure of strength or quality of the specific material. Aggregates having low specific gravity are by and large weaker than those with college specific gravity values.

Contents:

  • Process of Water Assimilation and Specific Gravity Test on Aggregates
    • Appliance Required
    • Process
    • Observations of Examination
    • Formulas:
  • Recommended Values of Specific Gravity and Water Absorption for Aggregates

Procedure of Water Absorption and Specific Gravity Examination on Aggregates

At that place are three methods of testing for the determination of the specific gravity of aggregates, according to the size of the aggregates larger than 10 mm, 40 mm and smaller than ten mm. For Samples larger than 10 mm, 40 mm, the below given test method is used and for samples smaller than x mm Pycnometer test is washed.

Apparatus for testing Specific Gravity and Water Absorption of Aggregates

Apparatus Required

  1. A rest of capacity nearly 3kg, to weigh accurate 0.5g, and of such a type and shape as to permit weighing of the sample container when suspended in water.
  2. A thermostatically controlled oven to maintain temperature at 100-110° C.
  3. A wire basket of not more than 6.3 mm mesh or a perforated container of convenient size with thin wire hangers for suspending it from the remainder.
  4. A container for filling water and suspending the basket
  5. An air tight container of chapters similar to that of the handbasket
  6. A shallow tray and two absorbent clothes, each not less than 75x45cm.

Procedure

  1. About 2 kg of aggregate sample is washed thoroughly to remove fines, tuckered and placed in wire basket and immersed in distilled water at a temperature betwixt 22- 32º C and a encompass of at least 5cm of water in a higher place the top of basket.
  2. Immediately after immersion the entrapped air is removed from the sample by lifting the basket containing it 25 mm higher up the base of the tank and allowing it to drib at the charge per unit of about one drop per second. The basket and aggregate should remain completely immersed in water for a catamenia of 24 hour afterwards.
  3. The basket and the sample are weighed while suspended in water at a temperature of 22° – 32°C. The weight while suspended in water is noted = W1g.
  4. The basket and aggregates are removed from water and allowed to drain for a few minutes, subsequently which the aggregates are transferred to the dry absorptive apparel. The empty basket is then returned to the tank of water jolted 25 times and weighed in water= Due westtwo grand.
  5. The aggregates placed on the absorbent clothes are surface dried till no further wet could be removed by this material. Then the aggregates are transferred to the second dry cloth spread in single layer and immune to dry for at least 10 minutes until the aggregates are completely surface dry out. The surface dried aggregate is then weighed = W3 one thousand
  6. The amass is placed in a shallow tray and kept in an oven maintained at a temperature of 110° C for 24 hrs. It is then removed from the oven, cooled in an air tight container and weighted=W4 k.

Observations of Examination

Weight of saturated aggregate suspended in water with basket = Wig Weight of basket suspended in water = W2 g Weight of saturated surface dry aggregate in air = Wiii g Weight of oven dry aggregate = Westfour grand Weight of saturated aggregate in water = W1  – Westwardtwo g Weight of water equal to the volume of the aggregate = W3 –( West1 –Due west 2 )g

Formulas:

(1) Specific gravity = Westwardiii / (W3 – (W1 – W2 )) (two) Apparent specific gravity = West4 / (Due west4 – (West1 1– Westward2 )) (three) Water Absorption = ((W3 – Wiv ) / W4 ) X 100 ** The size of the aggregate and whether it has been artificially heated should be indicated. ** Though high specific gravity is considered as an indication of high strength, it is not possible to judge the suitability of a sample aggregate without finding the mechanical backdrop such as aggregate crushing, affect and chafe values.

Recommended Values of Specific Gravity and Water Assimilation for Aggregates

The specific gravity of aggregates normally used in route construction ranges from near 2.v to 3.0 with an average of virtually 2.68. Water absorption shall non be more than 0.six per unit of measurement by weight. Read more than :  Specific Gravity of Fine Aggregates