Laboratory+report+1-4 PDF

Preview

Summary

Download Laboratory+report+1-4 PDF

Description

Laboratory Session 1: Soil Compaction 1. Introduction The purpose of soil compaction is to remove the air voids within the solid particles. Soil is made up by three main components which are solid particles, air voids and water voids. There are two processes to remove the voids in soil. Compaction is one of the processes where compaction is used to remove the air void. Another process to remove the water voids called as consolidation. The density of the soil increasing as we compact the soil which meant improves the overall strength of the soil and its stiffness. Different soil types will require different number of compaction because they have variety of characteristic and amount of water contain. There are four primary methods of compacting soil which are: 1.Static force; 2.Manipulation; 3.Impact force; 4.Vibratory. Generally, engineers do not like the void inside the soil because without voids the soil provides higher strength. However, the fact it is hard to happen because of cost consideration.

2. Aim / Objective The aim of this laboratory is to determine the relationship between the moisture content and the dry density of a soil for a specified compactive effort based on AS 1289 standard.

3. Method/Procedure Each group will be given about 3 kg of soil. The moisture content of the soil will be advised. Determine the mass of compaction mould plus base-plate to the nearest 5g. Determine the volume of the mould by measurement to nearest 10 ml. Assemble the mould, collar and base-plate 4. Take the soil as provided, mix it thoroughly and compact it into the mould in 3 layers not varying in compacted thickness by more than 5 mm. Compact each layer by 25 uniformly distributed blows of the compaction hammer falling freely from a height of 300 mm. The drops should be applied at a uniform rate not exceeding around 1.5 seconds per drop. Use only sufficient soil to slightly overfill the mould, leaving not more than 5 mm to be struck off after removing the collar. Free the material from around the inside the collar and then carefully remove the collar. Trim and determine the mass of the mould, soil and base-plate to the nearest 5 g. Remove the soil specimen from the mould and obtain a representative sample from the full height of the specimen for moisture content determination. For this purpose remove 10 to 30 grams of soil with a spatula. Use a moisture can and weigh the can as well as the can together soil sample to the nearest 0.1 g. Return the remainder of the soil taken out from the compaction mould to the soil sample, remix the soil and add sufficient water to increase the moisture content by 2% approximately. Mix thoroughly, and repeat steps (4) to (7) until a total of four different moisture contents have been tested. Return the next day to weigh the moisture content sample. (in this case, it was weighted by the laboratory mentor and the data provided on excel format)

4. Result

5. Discussion As shown in the figure, the maximum dry density is 1.929 g/cm^3 and optimum moisture content is 28.70%. This percentage of water permits higher strength to be applied to compact the soil and allows less voids to be present in the soil. The zero air void line is a limit where there is no air voids within the soil which meant the soil is fully saturated (no air contained then the degree of saturation is equal to 1). The soil sample have to be well compacted to achieved a soil with zero air void. The 90% saturated line is the line that having degree of saturation of 0.9, meant there is air voids in the sample which is 10%. The zero air void line and 90% saturated line are perfectly parallel as we can see from the figure, the difference is zero air void having degree of saturation of 1 and 0.9 for 90% saturated soil. The specific gravity value has been assumed as 2.65 for this practical.

Conclusion To conclude the report, the purpose of soil compaction is performed to get the maximum dry unit weight, lower compressibility, higher tensile strength and reduce the permeability of the soil. From the experiment, the maximum dry density and optimum moisture content has been observed after 8 groups is compacting the same type of soil. Zero air void line and 90% saturated line are parallel which degree of saturation of 1 and 0.9 respectively. The practical has been performed by following the AS 1289 standard.

Laboratory Session 2: Soil Classification 1. Introduction The soil classification can be determine visually, the size of the aggregate is the main characteristic to determine the classification of the soil. Sieve analysis is being performing to determine the size of the soil aggregates either course (gravel and sand) or fine (clay and silt). As an engineers, the soil can be classify by touch, see and smell the soil sample.

2. Aim This session is aim to find the classification of various types of soils by visual means and testing them under certain conditions. Plasticity and grading are the main factors to consider to classify the soil. Plasticity is measured by Atterberg limit (Liquid and Plastic limits) where the grading is determined using sieving analysis and then the soil samples can be classify based on UCSC classification.

3. Method/Procedure 3.1.Dry Sieve Analysis 1. A dry soil sample is poured onto the top sieve and the top is covered. Dry Sieve Analysis 2. The sieve is then switched on and vibrates mechanically to shake the sample through the sieve layers. This is done until each particle has dropped to a sieve with opening too small to pass, and the particles are retained. 3. The cumulative weight of all material larger then each sieve size is determined and divided by the total sample weight to obtain the percent retained for that sieve size, and this value is subtracted from 100% to obtain the percent passing that sieve size. 4. Results are recorded for further analysis and calculation. 5. Plot the result into a size distribution curve on a normal-log scale. The % passing is plotted on the normal axis while the sieve size is plotted on the log-scale axis. 6. Classify the soil example according to USCS classification. 3.2.Visual Inspection 1. Begin examination of one sample by determining if the soil is coarse grained or fine grained by visually inspecting the sample. Visual Inspection 2. Determine the Dilatancy, (an increase in volume in reaction t shearing) 3. Determine its dry strength and toughness. 4. Record these findings in the result and calculation section. 5. Repeat step 1 to 4 for other samples. 6. Carry out a sieve analysis on soil and record in the result and calculation section, recording the sieve size and the mass of the soil retained on the sieve.

4. Result 4.1 Dry sieve analysis

Gravel (> 2.360mm) = 100 – 17.58 = 82.42% Sand (0.075< Sand...