ASTM and Fall Cone Test

ASTM And Fall Cone Test Objective

The objective of this test is to add specific water quantities to a dry clay sample in accord with ASTM Designation Designation and Fall Cone test procedure. The purpose will be to determine the water contents at which the soil undergoes behavioural changes and to determine the Plasticity Index. The limits that we aim to find are those pertinent to engineering applications such as the Plasticity Limit (PI) and Liquid Limit L imit (LI).

Results

The liquid and plastic limit we obtained were 66.18% and 17% respectively. The PI found was 49%. Using the Soil Classification Chart provided in the text the classification given to this soil sample is ³fat clay´ or highly plastic (1). In terms of error our soil samples slightly larger penetrations with respect to TA results and other groups. This could be due subsequent loss of material when filling/cleaning containers and/or human error associated associated with adding to more than required amounts of water. These errors would essentially lead to higher water contents and higher penetrations.

Applications

The results of the ASTM and Fall Cone tests aid in the classification of fine-grained soils  by means of a Plastic Index and Liquidity Index. The Plasticity Index as shown on the first page is a difference of the liquid and plastic limits. The Plasticity Index is an indication of the range of  water contents for which a soil remains plastic. The liquid and plastic limits coupled with the natural water content of the soil are used to find the Liquidity Index which is gives indication of  a soils consistency. The values discussed ultimately help us to evaluate soils to be used in various construction applications such as structural fill for dams, embankments and land fills (1).

References

 Essentials of Soil Mechanics and Foundations: B asic Geotechnics 7 th by David F. McCarthy, Pearson Prentice Hall.