What are the causes of soil compaction?

Effects of compaction on pore space. Soil compaction occurs when soil particles are pressed together, reducing pore space between them (Figure 1). Heavily compacted soils contain few large pores and have a reduced rate of both water infiltration and drainage from the compacted layer.

What is the compaction test?

The Proctor compaction test is a laboratory method of experimentally determining the optimal moisture content at which a given soil type will become most dense and achieve its maximum dry density. This process is then repeated for various moisture contents and the dry densities are determined for each.

Why compaction test is done?

Standard Proctor Compaction Test: Standard Proctor Compaction Testing can be performed in a lab. The testing first determines the maximum density achievable for the soil and uses it as a reference for field testing. It also is effective for testing the effects of moisture on the soil’s density.

How can soil compaction be avoided?

To prevent soil compaction, avoid wheel traffic and tillage of wet soils; use wider tires, dual tires, or tracks; minimize tractor weight; maintain the minimum tire inflation pressure needed for an acceptable tire life; avoid using oversized equipment; try to combine field operations to make fewer passes over the field

What is the compaction of soil?

Soil compaction can be a serious and unnecessary form of soil degradation that can result in increased soil erosion and decreased crop production. Compaction of soil is the compression of soil particles into a smaller volume, which reduces the size of pore space available for air and water.

What is compaction of soil?

In geotechnical engineering, soil compaction is the process in which a stress applied to a soil causes densification as air is displaced from the pores between the soil grains. Normally, compaction is the result of heavy machinery compressing the soil, but it can also occur due to the passage of (e.g.) animal feet.

What is the compaction test?

The Proctor compaction test is a laboratory method of experimentally determining the optimal moisture content at which a given soil type will become most dense and achieve its maximum dry density. This process is then repeated for various moisture contents and the dry densities are determined for each.

How does compaction affect the soil?

Soil compaction increases soil density, reduces porosity (especially macroporosity), and leads to increased penetration resistance and a degradation of soil structure. This degradation is enforced when tillage is used to break up compacted soils. Soil biota suffers from compaction.

How construction can lead to soil erosion?

Construction of roads and buildings, logging, mining, and agricultural production have resulted in large amounts of soil erosion in the U.S. and around the world. Leaving the soil surface with little or no vegetation provides a prime opportunity for soil to be eroded by wind or water moving across the soil surface.

Is volcanic soil fertile?

Volcanoes soil are also know as andisols. Andisols are formed from volcanic ash. Volcanic materials break down and weather to form some of the most fertile soils on Earth. Volcanic ash often contain minerals that are beneficial to plants, and if it is very fine ash it will break down quickly and get mixed into soil.

How can soil compaction be measured?

To find out how well a soil has been compacted we must measure the dry unit weight or dry density in pounds per cubic foot. Dry density is a measure of the weight of solid material present in a cubic foot of soil. There is also a method for determining the in-place density of soils by nuclear methods (ASTM D 2922).

What does 95% compaction mean?

Usually we do proctor compaction test to find out the maximum dry density(MDD) and optimum moisture content (OMC) of a soil. It means a compaction in the field equal to 95 % of that obtained by a reference laboratory test, usually standard Proctor or modified Proctor compaction tests.

What causes salinity in soil?

Soil salinity is the salt content in the soil; the process of increasing the salt content is known as salinization. Salts occur naturally within soils and water. Salination can be caused by natural processes such as mineral weathering or by the gradual withdrawal of an ocean.

What is the meaning of soil aeration?

Aeration involves perforating the soil with small holes to allow air, water and nutrients to penetrate the grass roots. This helps the roots grow deeply and produce a stronger, more vigorous lawn. The main reason for aerating is to alleviate soil compaction.

What is a soil crust?

Soil crusting is a thin layer of dense and tough material. Soil crusting is considerably more compacted and packed than the underlying material. A soil crust tends to look smooth and even when compared to freshly exposed soil. Rain impact on exposed soil is the main cause of soil crusting.

How does soil compaction happen?

Effects of compaction on pore space. Soil compaction occurs when soil particles are pressed together, reducing pore space between them (Figure 1). Heavily compacted soils contain few large pores and have a reduced rate of both water infiltration and drainage from the compacted layer.

What is the soil acidification?

Soil acidification is the buildup of hydrogen cations, also called protons, reducing the soil pH. Chemically, this happens when a proton donor gets added to the soil. The donor can be an acid, such as nitric acid and sulfuric acid (these acids are common components of acid rain).

How is a hardpan formed?

Hardpan. There are different types of hardpan, all sharing the general characteristic of being a distinct soil layer that is largely impervious to water. Some hardpans are formed by deposits in the soil that fuse and bind the soil particles.

What is consolidation of soil?

Consolidation is a process by which soils decrease in volume. According to the “father of soil mechanics”, Karl von Terzaghi, consolidation is “any process which involves a decrease in water content of saturated soil without replacement of water by air”. This can be used to predict the amount of consolidation.

What is the difference between compaction and consolidation?

In both processes soil is compressed but consequences of both are different. Compaction is process when a impact load is applied to soil which expells air from voids. Consolidation is a process where gradual load is applied for a very long period of time which leads to expulsion of water from voids.

What is consolidation test of soil?

In a saturated soil mass having its void filled with incompressible water, decrease in volume or compression can take place when water is expelled out of the voids. Such a compression resulting from a long time static load and the consequent escape of pore water is termed as consolidation.

What is the shear strength of soil?

Shear strength is a term used in soil mechanics to describe the magnitude of the shear stress that a soil can sustain. The shear resistance of soil is a result of friction and interlocking of particles, and possibly cementation or bonding at particle contacts.

What is Preconsolidated soil?

Preconsolidation pressure is the maximum effective vertical overburden stress that a particular soil sample has sustained in the past. This quantity is important in geotechnical engineering, particularly for finding the expected settlement of foundations and embankments.