Basic Soil Test on Sub Grade Soil Materials and Flexible Pavement Design on Road Linking
CHAPTER ONE
OBJECTIVES
The objectives of the laboratory testing program were
- To obtain a general information regarding the nature of the soil and their variation with depth throughout the length of the road under consideration.
- To obtain information regarding the strength characteristics of the soil.
- To obtain information which will enable engineers to group soils according to their appearances of the purposes of complying different soils.
CHAPTER TWO
MECHANICAL ANALYSIS
(Sieve Analysis)
AIM: To get the particle size distribution of the soil sample. This is universally used in engineering soil classification.
Apparatus:
- Weighting Balance
- Iron Brush
- Oven
- Set of Bs Sieves
13.2mm, 6.3mm, 5.9mm, 4.75, 2.4mm (No 7)
1.2mm, 600
MICRONS, 420m (No 36) .300m, .210m, .120m and .75m (No 200).
PROCEDURE
100kg of the material is weighted out and put into a bowl for washing using the .75m sieve to decant. The essence of the decanting is to remove clay, dust and silt. Several buckets of water are used for the water until the sample become less turbid. The residue after the dry sample is then removed from the oven and put into the arranged set off sieves and retainer. The set of sieves are then taken to the sieve shaker for 10 minutes.
The percentage weight passing through each sieve is plotted against the sieve size.
CHAPTER THREE
COMPACTION TEST
AIM: To determine the optimum moisture content (OMC) and maximum dry density (MDD) of the soil sample.
APPARATUS:
Mould, moisture content cans 2.5kg, rammer, a straight edge, weighing balance, pan, electric oven, oil for out letting the mould, mixing pan and standard proctor compaction mould with collar.
PROCEDURE:
3000gm of the sample is measured out using the weighing balance.
The weighted sample is put into the large mixing pan where 8% water of the soil mass is added
8% water = 240cc
The mixed sample is divided into three portions and each portion is put into the mould in three layers each with a compaction of 25 blows with the 2.5kg rammer falling through a height of 300mm.before the last layer, the collar is fitting and after the compaction the collar is removed with the straight edge used to trim off the excess soil to flush with the mould.
CHAPTER FOUR
ATTERBERG LIMIT TEST
This test comprises of two test viz;
- Liquid limit test
- Plastic limit test
AIM: The aim of the atterberg limit test is for the classification and identification of granular materials according to their liquidity and plasticity characteristics.
APPARATUS:
The apparatus for both test are: Liquid limit device, grooving tool, moisture content can, soil mixing equipment (porcelain and spatulas) desiccators sieve no 420m with pan and lid.
CHAPTER FIVE
CALIFORNIA BEARING RATIO
AIM:
To determine the shear strength of soil sample.
APPARATUS
– Cylindrical mould – Diameter = 15cm, depth = 12.5cm.
– 4.5kg Rammer and 450mm free fall
– Weighing balance
– Measuring cylinder, strength edge
– Oil for oiling / lubricating
– Large mixing pan
– CBR machine
CHAPTER SIX
ANALYSIS
From the analysis of test results on the sample, it was found that sample A and B are generally made up of fine grains with a greater percentage of it passing sieve No 200, while sample C is excellent and very good for pavement design.
Sample A was collected some metres into the pathway then sample was collected about half way into the pathway (CH A – B = 124.7m), but than sample C was collected at the end of the pathway very close to the express linking Ugwuaji (CH B – C = 331m).
CONCLUSION AND RECOMMENDATION
From the results of the tests, it was found that the samples A and B are generally composed of sility day, which does not allow easy drainage of water. It rather retained a lot of water, which result in the swelling of the soil with consequent collapse under load. Sample C was found to be excellent.
Further study shows that when the soils are stabilized by the mechanical stabilization method, their plasticity indices reduced this rendering the soil more stable with variations in its moisture contents.
BIBLIOGRAPHY
- Berry, Peter L and Reild, David (1986)
- An introduction to soil mechanics.
- McGraw Hill Book Company
- (UK) Limited Berkshare
- Craig K.R. (1994) Soil mechanics fourth Edition Van Nostrand
- Keinhold (UK) Co Ltd. Molly Millers Lone, Wokingham, Berkshire, England.
