CEE3104 Introduction to Environmental Oz Assignments

CEE3104 Introduction to Environmental Oz Assignments

CEE3104 Introduction to Environmental Oz Assignments

Introduction

The process of reducing air voids through mechanical energy is what is termed as soil compaction. The strength of soil is increased as a result of compaction and high load market structures for example roadways as well as dams depends on the stability of embankment. The measuring of soil compaction is carried out when it is dry and the addition of water to the soil to act as a softening agent. The dry weight of the soil after compaction upsurges with the content of moisture and the moisture content increases when there is a decrease in the dry weight. The Optimum moisture content is a point at which the maximum dry weight is attained and the Proctor Test is another name to mean compaction test.

The proctor compaction test was named in the honor of Ralph Proctor who showed that the density of the soil in the dry state for a given compactive effort relies on the amount of water contained when compacting the soil. It mostly known as standard proctor compaction test but later it was updated to modified Proctor compaction test.

The modified proctor compaction test is used in determining the compaction of different kinds of soil and the properties of soil with a change in the content of moisture and the connection involving moisture content and dry density.

Reducing the compressibility, permeability, future settlement and increasing the unit weight as well as shear strength is the main importance of having soil compaction. The compaction test is dived into two and that is the modified and standard compaction test but this particular report will tackle the modified compaction report.

Aim

This particular report aims at determining the optimum content of moisture as well as the dry density of a compacted soil sample so that it can be used in the field.

Materials

1. Soil molds
2. Manual soil drop hammer.
3. Balance
4. Microwave oven
5. Straight edge
6. Pans
7. Four sieves 

Modified Proctor Test Procedure

Measuring the mold mass (M1).

Approximately the soil to be taken should be 2.5kg and delivered via No. 4 sieve.

In this particular test, the compaction of soil in the mold in roughly five similar layers, and compacting every layer is done using 25 blows.

The trimming and weighing (M2) will be done when the mold is full of the soil sample.

The moisture content of the soil compacted to be determined. Weighing a plastic or glass can/dish after which a small amount of soil to be placed into the can/dish the weigh again. Record these in Datasheet 12.

The soil is microwaved for around 2 minutes until the complete dry out of the moisture. Another 2 minutes should be added again in case the moist still persist in the soil. Use the datasheet 12 to record the data obtained from weighing the can/dish as well as dry soil. The moisture content of the compacted soil to be computed.

Obtain the average results of at least two moisture contents readings.

Compute the bulk density of the compacted sample using 1000 cm3 as the volume of the mold.

Compute the compacted soil dry density using the moisture content in 7 and the results in 8.

Assuming the soil particles’ specific gravity is 2.65, complete the datasheet 11 results after calculating the density at zero and 5% air voids.

Steps 2 to 10 to be repeated up to 4 level of moisture content.

The dry density versus moisture content for the Modified as well as Standard Proctor tests to be plotted.

Discussion

In the construction process, the compaction of soil is an important aspect and it is used in structural entities for example constructing foundations, earth retaining structures and roadways. The soil to be compacted should have adequate strength, be relatively incompressible so that it can be stable against change in volume as the content of water vary. The process of densifying a soil mechanically is what it is known as a compaction. And densification of soil is achieved by pressing the particles of soil into a closed state of contact where the removal of air is done from the soil mass during the procedure. The stability of soil is normally achieved using mechanical compaction which is the most commonly used method and cost-effective in nature.

The knowledge behind the compaction of soil is mostly applied in the construction of foundations, airfields, embankments and also roads. And, proper soil compaction leads to the stability and durability of a structure. The data, we have acquired the dry density of soil for conforming moisture content[CITATION Fel07 \p 65 \l 1033 ].

From the information acquired, the plotting of a graph exhibiting dry density over moisture content has been done and the connection involving the content of the moisture and dry density is clearly shown. From the graph, 0.8 Mg/m3 which is the highest dry density and the conforming moisture content which is 11% and this is the moisture content at optimum. The greatest density attained for the soil compaction is at the moisture content of 11%.

There is the possibility of compacting normal soil since they have a larger portion of an air pocket. The process of compaction allows air to move out thus the density of the soil increases, and different sizes of soil particles make it difficult to fill the air void. This is the reason why the addition of moisture to the soil is carried out so as to fill the air void thus up surging the density. Addition of moisture should be done little by little until the maximum density is achieved, this is because the dry density of the soil can decrease when there is too much addition of moisture[CITATION Ric151 \p 49 \l 1033 ].

The optimum water content is the content of water that leads into the greatest density for a specific comp active effort. The level of compaction attained by the proctor test is sometimes like the compaction levels of building site under medium size rollers.

Conclusion

The results acquired from the test involving soil compaction were better and 11% optimum content was obtained. This means that 11% is the best moisture content needed to attain the maximum dry density strength. Obtaining the moisture content-dry density relationship of the soil was the main objective of this particular experiment and determination of optimum moisture content as well as the maximum dry density from the results obtained. The experiment was successful and this can be derived from the results obtained thus meaning the objective of the experiment was achieved. The results obtained were ultimately influenced by the errors which were identified in the discussion section.

Introduction

A hydrometer analysis or sedimentation test and sieve analysis are among the methods that are used to find out a particle size distribution of the coarse-grained soil (Soil 1). The classification of the tests from the results obtained based on the unified soil classification system. This particular test simply involves allowing the material to go through numerous sieves of increasingly smaller mesh size and measuring the weight of the amount of the material that is stopped by every sieve as a fraction of the whole mass.

When conducting a sieve analysis, it can be carried out on any type of organic or non-organic granular materials comprising soil, grains, rocks which are crushed, granites, clays and coal. For the test to be carried out smoothly, there is need of having sufficient sample of aggregate obtained from the source and the mixing of aggregate are done thoroughly to obtain an appropriate size required during testing. In the case of hydrometer analysis, hydrometer is used in measuring the relative density of liquids centered on the buoyancy concept. This particular instrument consists of a sealed hollow glass tube having a bottom which is wider for buoyancy.

Method

Looking at the size of the particle can help in determining the size of the particles and when the size of particles is larger compared to the coarse silt size then sieving can be used. Shaking a soil measuring 197.47g through a column of sieves gradually reduces the size of mesh, and then the remaining soil in every sieve is measured. Afterward, the hydrometer analysis or sedimentation method is applied in the case of particles which are tiny[CITATION Dan131 \p 77 \l 1033 ].

In this particular method, there is a need of using stroke law since it uses particles terminal velocity falling through a fluid with a recognizable velocity. In this particular procedure, it is assumed that the grain or soil particles are spherical though, in reality, it is not so.

Part 1: Sieve Analysis

Equipment

Weighing machine

Shaker

Procedure

Using the soil provided, weigh a sample amounting to 200gm

Collect runs of sieves starting with the biggest to the lowest; 4.75mm, 2.36mm, 1.18mm, 600um, and 75um.

Sieving the soil sample via a run of sieves and the mass of soil remaining on every sieve to be recorded.

To the fine materials in the pan, a sedimentation test will be carried out adhering to the procedures.

Data Sheet number 1- Sieve Analysis

Particle size analysis

Sieve analysis wet/dry

Original sample mass 19.47g

Datasheet number 2-Sieve Analysis plot

Discussion and Results

Is the soil sample dominated by many organic and leaves? No

Passing the No. 200 (75um) sieve is noted- P200

P200>50%

Is P200< 5%? No

Is P200>12%? No

Borderline Dual Symbols

The unstable readings, as well as the air in the lab, affected the digital marketing scale and this made the weights a bit hard and the tested sample of soil is Borderline Dual Symbol[CITATION Gly11 \p 321 \l 1033 ].

Sources of error

Failing to dry the soil for 24 hours before used to carry out test causing the presence of soil lumps.

Errors when reading the digital scale

Part 2 Sedimentation test

Procedure

Use distilled water to fill the cylinder until about ¾ full. Record the meniscus correction immediately after placing hydrometer in the cylinder not forgetting to mention the results water temperature[CITATION Jam102 \p 217 \l 1033 ].

The distilled water to be added to the milk shaker containing a fine-grained soil reserved in the pan until it is ¾ full. The shaking of the mixture to be done for around 2 minutes.

Pour the suspension into the 1000ml cylinder, wash all fines remaining in the container into the cylinder containing distilled water and distilled water to be added into the cylinder to make it 1000L.

Placing a stopper at the top of the cylinder and turning it upside down for about 25 times.

Start timing after placing the cylinder on the table and the readings from the hydrometer to be taken at the time interval of 30sec, 1 min, 2 min, and 4 min. After the fourth minute, the hydrometer is taken out, washed using distilled water then the last reading is taken at 8 min.

Datasheet Number 3-Particle Size Distribution-Hydrometer test

Description of the sample:

Mass in suspension Mo (g): 20g

Specific unit weight: 2.65

Dispersing agent correction Ca …...

Meniscus correction Cm :0.5

R’h= Rh + Cm where hydrometer reading is represented by R.

Factor F1 refers to the distance of falling particles.

Factor F2 refers to fluid viscosity, the density of the fluid as well as soil.

Factor F3 refers to time.

D= F1 x F2 x F3

K= mass of the remaining oil in the pan/ the overall soil applied during sieving analysis x density.

Conclusion

The experimentation was carried out by a group of students together with the help of an expert in soil mechanics. Approximately 2 hours was used in conducting this particular experiment and every student was assigned a particular task during the experiment.

Shear Box Test Report

Introduction

Every year, there are numerous lives that are lost and also thousands of structures destroyed as a result of soil shearing. Understanding the collapsing of soil profiles under shear as well as through the appropriate use of building codes centered on shear analysis can help in preventing the collapse of the soil profile. This particular test it to investigate how the density of a certain soil sample can be affected by the strength.

The horizontal division of the box into two halves is one of the features of the shear box apparatus, and the upper box is movable while the lower box is fixed. The metal plates or stone plates are placed below or above the specimen while the soil requiring testing is placed in the two half box. The shearing of soil prism along the dividing plane of the box begins by the application of horizontal force to the upper half of the box. This will assist in measuring the horizontal load needed to shear a soil corresponding to any vertical normal compressive load.

The direct shear test is carried out on a three or four specimen from a comparatively uninterrupted soil sample whereby the placing of the specimen is done at the shear box which comprise of two stacked rings for holding the sample. The shear strength parameters are achieved by testing numerous specimens. And conducting the direct shear tests can be done under numerous conditions, before the test, the sample is normally saturated before conducting the test but can be run at the in-situ moisture content. The advantages of the direct shear test over other shear tests are the simplicity of set up and the equipment used.

Aim

This experiment aims at using the direct shear test to determine the strength of shear of a sample of soil and further investigating the impact of soil density on the strength of soil.

Materials

1. Load
2. Pan scale/balance
3. Digital gauge.
4. Shear box apparatus with ADU.

Procedure for loose sand

A number of text amounting to six to be carried out by every group. The three tests are to be carried out on the loose specimen at ordinary masses of 5,25 and 50 kg.

Measuring the mass as well as the measurements of the unfilled shear box internally.

The placing of sand at the shear box for every initial dense specimen plus the compaction using 25 blows of the provided hammer. In the box, the depth of the sand is measured and the capacity of the sand is computed, and the cap is placed on the uppermost of the specimen after which the density of the sand which was compacted is obtained after weighing the sand and the box together.

The pouring of sand is done gently and evenly to every initial loose specimen and the depth of sand is measured after leveling the sand surface. To avoid compaction of the loose sand, there is a need for avoiding vibration.

The normal loads are applied after the transfer the shear box to the loading frame.

The shearing of the specimens starts after engaging every box clutch.

The reading of the shear force and vertical dial gauge for each 0.25mm displacing horizontally. The continuation of the test ought to proceed till an entire movement of 6mm is attained.

Discussion

A critical void is attained as the loose sample becomes denser in the shearing period. The plotted graph for the stress ratio and horizontal displacement shows that the tests initially rise to a steep and eventually becomes stable and continue at the same value as the horizontal alignments get larger. The adjusted weight was used by the machine since the proper force value needed was not contained in the masses. It was shown that the angle was 23 degrees and cohesion of 2000 as a result of the slope of the sheer strength on the shear stress vs normal stress graph[CITATION Ian16 \p 128 \l 1033 ].

There were certain errors in this particular test for example; trimming caused disturbance in the soil sample and trimming should be carried in a humid room to reduce the disturbance of the natural content or structure of the soil. Another error was, there was not constancy in the region affected by the vertical and shear loads during the test. Some errors arise while fitting the sample of soil into the shear box. And their exact fitness is important to ensure complete lateral confinement. The error resulting from the equipment should also be considered.

Conclusion

Based on the observation, it can be clearly being noticed that the flow of stress ratio vs horizontal displacement graph. Smaller ratios are depicted as the tests get larger. The determination of the sand shear strength parameter using a shear box test was the main objective of this psychology experiment and the determination of the angle of the trend and shear stresses strength were obtained.

Bibliography

1. Duncan, I., 2016. Deformation characteristics of geomaterials. s.l.: Wiley.
2. Hatchell, G., 2011. Soil compaction and loosening treatments. s.l.:Informa.
3. Hillel, D., 2013. Introduction to environmental soil physics. s.l. Scholastic.
4. Johnson, R., 2015. Managing soil compaction. s.l. Adventure Works Press.
5. Kolymbas, F., 2007. Compaction of soils, granulates and powders. s.l. Media Participations.
6. Syvitski, J., 2010. Principles, methods, and applications of particle size analysis. s.l. OLMA Media Group.