Writing Procedure for soil compaction - Lab Report Example

Soil Compaction Experiment Procedure Fang argues that soil compaction is one of the most crucial components in construction of airfields, roads and building foundations (250). Architectures and engineers argue that the stability and durability of a structure are directly related to the achievement of proper soil compaction. As such, structural failures of airfields and roads, as well as damage resulting from settlement of foundation are due to failure to achieve the desired soil compaction. But what is soil compaction?

Soil compaction refers to the mechanical process of densifying a soil. This is achieved by pressing the soil particles together into a close state of contact so as to expel air from the soil mass. This helps in reducing void ratio. The main purpose of soil compaction is to reduce settlement under working loads, increase the soil shear strength, and prevent accumulation of large water pressures that may result in soil liquefaction during earth tremors.EquipmentThe following equipment will be necessary in order to achieve a proper soil compaction: 5 small tin containers; compact mould; metallic mixing pan and a plastic water bottle; weighing balance of up to 10kg for determining the weight of soil mass; a sieve; straight edged steel to smoothen soil sample ends; and a compaction hammer of about 5.

5 lbs (Fang 262).Procedure for soil compactionThe whole process begins by preparing the soil sample to be used during compaction. To begin with, a soil mass is taken and passed through a sieve so as to ensure that the right quantity and type of soil is obtained. The soil sample is passed through the sieve until 3-4 lbs of the sample is obtained. The sample soil is then wetted with the right quantity of water and missed thoroughly. Once this has been done, the wetted soil sample is carefully put into a plastic bag and left overnight (Fang 268).

This is done to ensure that water in the soil sample is thoroughly absorbed so as to obtain homogeneous water content as shown in figure 1.However, before beginning compaction, it is important to set up equipments properly. As such, the compaction mold with the base plate is measured is weighed using the weighing balance and the measurement recorded (Fang 268). It is worth noting that the compact mold should be greased to prevent soil sample from sticking in the mold.After preparing the sample, the next procedure involves testing the compaction.

The first step is to lock the mold, base and the collar plate together. The soil is added to the mold and filled until over half the mold is filled with loose soil. Then, using the compaction hammer, the first layer known as a lift, is formed by releasing the hammer at a height of 12 inches above the soil and allowing it to transfer all of it’s energy into the soil, resulting in the compaction of the soil. The reason behind allowing the hammer to fall in a circular manner is to ensure that the lift is evenly compacted.

And, once the lift is complete, the surface of the lift is scratched and more soil added to fill the mould to the brim. A second lift is created using similar method. The third lift is also created with the loose soil climbing into the collar. Once compacted, the collar is removed. The compacted soil is then smoothened using straight edge steel. Once this has been done, the mold together with plate and the soil is weighed on a balance and weight recorded. As this is done, the empty containers are also weighed and recorded (Fang 269).

Once this has been done, more water is added to the soil and thoroughly mixed so as to spread water making water content uniform. The test is repeated preparing the 3 lifts in a similar manner and collection the sample soil in the tin cup. Once the second test is complete, three more tests are performed then the sample allowed to dry up for a period of 24 hours by placing it in an oven. This ensures that all water contents are removed from the soil. Finally, the sample is re-weighed to obtain the dry weight of the soil mass.

This gives a figure by which the water content can be calculated from each of the soil samples (Fang 269).Once the water content has been calculated and figure recorded the next data to be calculated is the soil mass in the mold. The density of the soil mass is then calculated in g/cm3. It is noted that the value of wet soil sample can be calculated using the formula γwet = ρ x 9.807. Finally the dry weight is calculated using the formula γdry = γwet / [1+ (ω%/100)]. From these values the soil compaction can be obtained (Fang 269).

Figure 1 – Wetted soil sample. Work CitedFang, Hsai-Yang. Foundation Engineering Handbook. Norwell, MA Springer, 1991 Print.