OBJECT: To determine the Field Density by the Core Cutter Method.
OBJECTIVE AND SCOPE
This method covers the determination of the in-situ density of compacted soil by using a core cutter. The in-situ density of natural soil is needed for the determination of the bearing capacity of the soils, for the purpose of stability and slope analysis for the determination of pressures on underlying strata for the calculation of settlements and the design of underground structures. It is a very quality-controlled test, where compaction is required in cases like embankments and pavement construction.
STANDARDS
AASHTO T191-86
ASTM D1556-82
BIS1377:part 4
APPARATUS
Rammer, Cutter, Sensitive balance, Containers, Oven, Plate.
THEORY
The in-situ density is defined as the bulk density of the soil measured at its actual depth. By conducting this test, it is possible to determine the field density of the soil. The moisture content is likely to vary from time to time and hence the field density also varies, so the test result is reported in terms of dry density.
PROCEDURE
1.Measure the inside dimension of the cutter and calculate its volume. If not already known.
2.Weigh the cutter without the dolly.
3.Clean and level the site. Place the dolly over the cutter and ram it gently into the soil until about 1 cm of the dolly remains unfilled.
4.Dig out the cutter containing the soil from the ground. Remove the dolly and trim off soil extruding from the ends.5. Weigh the cutter full of soil.
6.Take a sample of the excavated soil in the weighed moisture container and place it in the oven for water content determination.
OBSERVATION AND CALCULATIONS
Internal diameter of ore cutter,(d) | |
|---|---|
Depth of core cutter, (h). | |
| |
Weight of core cutter. | |
Weight of core cutter + wet soil. | |
Weight of excavated soil, (w). | |
Bulk density of soil = (γ=w/v). | |
Container No. | |
Weight of container. | |
Weight of container + wet soil. | |
Weight of container + dry soil. | |
Weight of Water. | |
Weight of dry soil. | |
Water Content, (m.c). | |
Dry Density, (γd) |
RESULTS
The field Dry Density of the soil is____________
Review Questions
- What are the precautionary measures in this Test?
- What is the range of thickness of the fill layer in the preparation of the embankment?
- Which method is more accurate between core cutter and water displacement, to determine field density of soil and why?
