- Atterberg Limits (Liquid Limit Test and Plastic Limit Test
- Compaction test using a Standard Proctor test
- Identification of rocks by their key characteristics
Characterisation of granular soils
Granular materials can be characterised based on particle size using a sieve analysis. Below are the results obtained from the experiment.
- Table 1 shows the sieve analysis for sand
- Table 2 shows the sieve analysis for gravel
Sieve Analysis Results
Table 1 – Sand Sieve Analysis Results
Table 2 – Gravel Sieve Analysis Results
Grading Chart for Gravel Graph shows that the gravel soil sample holds a lot of particles which are between 5mm and 6.3mm in size as there is a greater percentage of these particles passing through the sieves at this size.
Classification of Cohesive Soils
Liquid Limit Test Results
Table 3 – Cone Penetrometer Results
Table 4 – Liquid Limit Moisture Content Results
Table 3 shows the Cone Penetrometer results for the Liquid Limit Test and Table 4 shows the moisture content of the soil samples for the Liquid Limit Test. From the results a graph was plotted for moisture content against penetration of the soil to determine the liquid limit of the soil (see Liquid Limits Test – Moisture Content Vs Penetration of Soil Graph). The liquid limit is the estimated moisture content corresponding to a penetration of 20mm. From the graph shown, the Liquid Limit (LL) of the soil tested is 42.8%.
It should be noted that only one set of penetration measurements had less than 0.5mm difference between them, the A1/A2 set. The other 3 set of penetration measurements had differences greater than 0.5mm (see last column in Table 3). The test measurements can only be considered valid if the difference in penetration between the two soil samples of the same moisture content is less than 0.5mm. However, we could not plot a graph with only one set of co-ordinates and we had no time to repeat the tests to obtain valid data, so we had to use all the results and draw a best line of fit through the co-ordinates to obtain the liquid limit. The graph does show that the co-ordinates obtained from the results does not stray too widely from the line of best fit, so although the liquid limit determined will not be very accurate, our results will give us a reasonable estimate.
Plastic Limit Test Results
Table 5 – Plastic Limit Moisture Content Results
Table 5 shows the moisture content of the soil samples for the Plastic Limit test. The Plastic Limit is taken to be the % moisture content when the average water content from the two 10g samples is within 0.5% of one another. From the table only the B1/B2 samples fit this criteria, therefore the Plastic Limit (PL) is 12.44% for the soil tested.
The Plasticity Index (PI) is the range of water content over which a soil behaves plastically, and is calculated using the formula:
PI = LL - PL
For the soil sample tested, the Plasticity Index is
PI = 42.8% - 12.44% = 30.36% = 30.36/100 = 0.3036
Compaction test
Soil Compaction Test Results
Table 6 – Standard Proctor Soil Test Results
Table 6 shows the results obtained for the soil compaction Standard Proctor test. The results have been plotted in the graph - Standard Proctor Test – Water Content Vs Dry Density of Soil Graph. From the graph plotted we can determine the Maximum Dry Density and the Optimum Moisture Content from where the water content soil in the mould passes its maximum value and begins to decrease. The soil’s Maximum Dry Density is 2.01g/cm3 and its Optimum Moisture Content is 14.2%.