A laboratory test called the standard Proctor test

COMPACTAION

Purpose:

A laboratory test called the standard Proctor test was developed to deliver a standard amount of mechanical energy (compactive effort) to determine the maximum dry unit weight of a soil. In the standard Proctor test, a dry soil specimen is mixed with water and compacted in a cylindrical mold of volume 9.44 3 1024 m3 (standard Proctor mold) by repeated blows from the mass of a hammer, 2.5 kg, falling freely from a height of 305 mm. The soil is compacted in three layers, each of which is subjected to 25 blows. The water content at which the maximum dry unit weight, (gd)max, is achieved is called the optimum water content (wopt). The soil is invariably unsaturated at the maximum dry unit weight, that is, S < 1. We can determine the degree of saturation at the maximum dry unit weight using Equation (5.1). We know gd =(gd)max and w = wopt from our Proctor test results, If Gs is known, we can solve Equation (5.1) for S. If Gs is unknown, you can substitute a value of 2.7. The objective of the test is determining the relationship between water content and the dry unit weight of soils.

        Equation:  gd= (Gs/1+e) * gw = g/1+W = (Gs/1+W*Gs/S)*gw.
    Materials used:  Sand, Drying Oven, Pans, Balance, Hammer, cylinder mold.

Procedure: Test material that pass through 3/8inche

1. Determine to weight of mold empty and clean on the electronic scale.
2. Add 2000.2 gram of the dry sand in pan, then added 79.9 gram of water, mixed the sand together to ensure uniform distribution of the water content in the material.
3. Add 1/3 of the wet sample in mold, then place the collar over mold to facilitate the placement of the sand.
4. Place the mold on straight floor, and held it steady with operator feet.
5. Using hammer to apply 25 blows per lifting alternating locations to provide uniform coverage.
6. Remove the collar, and trim excess material using straight edge, in order to ensure the final volume is 1/3.
7. Determine the final weight plus wet sand.
8. Determine the masses of tin A and tin B.
9. Put weight sample of the wet sand in A tin from the top of the compactor.
10. Put weight sample of the wet sand in B tin from the bottom of the compactor.
    We repeated the same steps for three times, but by adding 1/3 of wet sample and increasing water content by 40 grams every time.
    Dry unit weight

Sample Solution