Soil Compaction Test

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STANDARD PROCTOR COMPACTION TEST OBJECTIVE For determination of the relation between the water content and the dry density of soils using light compaction.

INTRODUCTION This laboratory test is performed to determine the relationship between the moisture content and the dry density of a soil for a specified comp active effort. The comp active effort is the amount of mechanical energy that is applied to the soil mass. The Proctor compaction test is a laboratory geotechnical testing method used to determine the soil compaction properties, specifically, to determine the optimal water content at which soil can reach its maximum dry density. In general, the soil bearing capacity will be increased simultaneously with the increment of density or unit weight of the soil. The increment of soil density can be obtained via compaction process THEORY The Proctor compaction test consists of compacting soil samples at a given water content in a standard mould with standard compaction energy. The standard Proctor test uses a 4inch-diameter mould with the compaction of three separate layers of soil using 25 blows by a hammer falling. In the Proctor test, the soil is first air dried and then separated into 6 samples. The water content of each sample is adjusted by adding water (3% - 5% increments or more depending on the type of the soil). The soil is then placed and compacted in the Proctor compaction mould in three different layers where each layer receives 25 blows of the standard hammer. Before placing each new layer, the surface of the previous layers is scratched in order to ensure a uniform distribution of the compaction effects. At the end of the test, after removing and drying of the sample, the dry density and the water content of the sample is determined for each Proctor compaction test. Based on the whole set of results, a curve is plotted for the dry unit weight (or density) as a function of the water content. From this curve, the optimum water content to reach the maximum dry density can be obtained. The test consists of compacting the soil or aggregate to be tested into standard mold using a standardized comp active energy at several different levels of moisture content. The maximum dry density and optimum moisture content is determined from the results of the test .Soil in place is tested for in-place dry bulk density,

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And the result is divided by the maximum dry density to obtain a relative compaction for the soil in place. In the other hand, soil compaction test is carried out in the laboratory in determining the ideal volume of water To be poured while compaction the soil on site so that the required compaction degree can be obtained. The important characteristics of soil compacted with an ideal compaction degree are: a) High shear strength b) Low permeability coefficient and capacity c) Reduce settlement when additional load is applied

MATERIALS AND APPARATUS 1) Cylindrical metal mould, which is fitted with a detachable base plate and removable extension 2) Metal rammer with 50mm diameter face, weighing 24.4kN, sliding freely in a tube that controls the height of drop to 300mm 3) Sample extruder (jack) for removing compacted material from the mould 4) Metal tray 5) Balances sensitive to 0.1g and 0.01g 6) Drying oven with temperature ranges from 105 0C to 110 0C 7) Desiccator 8) Trowel or scope 9) Straight edge 10) No. 4 sieve (4.75mm) 11) Water sprayer

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PROCEDURE AND PREPARATION 1) Small soil sample was collected. 2) 3kg of dry soil passing through sieve opening was prepared. 3) Empty mold, collar and base plate was weighed. The empty containers were also weighed. 4) The sample was mixed thoroughly with a small amount of water. 5) The soil sample was divided into three sections. 6) The first section was placed in the mold, compacted and distributed 25 blows uniformly over the surface to ensure that rammer always fell freely and was not obstructed by soil in the guide tube. 7) The second section and the third section were placed into the mold and compacted followed by the last section of soil sample. 8) The attached collar was removed when the compaction had been completed. 9) The compacted soil was trimmed using the straightedge. 10) A Small amount of soil from the upper mould and bottom mould was taken and placed into a container. 11) The experiment was repeated with six varying water contents. 12) Containers with the soil samples were weighed. 13) Containers were placed into an oven to determine its moisture contain. 15) The compacted soil sample unit’s weight was determined by dividing the weight of the compacted soil in the mould with the soil sample volume (volume of the mould). 16) The dry density was computed by using the compacted soil’s wet (bulk) density and the moisture content was known. 17) The soil’s dry density versus moisture content graph was plotted.

RESULTS AND CALCULATIONS

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DISCUSSION

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CONCLUSION

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REFERENCES