Relationship between moisture content and density of soil

relationship between moisture content and density of soil

density of soils either in the laboratory or in place is often encountered. In connection with the study of moisture movement in soils, or density changes of soils. The effect of bulk density on moisture content at 50 mb tension in four soils of different textures was studied. The volumetric water content increased linearly with. tively (in relation to soil initial state from. to 29%). At moisture content 16%, the wheel passages caused the strongest soil compaction. Mean dry soil density .

These forces do not go skin deep and work only for the upper surface of the soil mass. Vibratory forces, on the other hand, work for the whole soil mass and are not limited to the upper surface only. Along with the dead-weight of machine, compactors and vibrators are connected that not only exert pressure on the soil mass, but also shuffle the entire soil mass so that the overall soil mass is compacted uniformly.

Both the top and deeper layers get blows from the vibrator and compactor resulting in denser and tightly packed soil. For mechanical soil compaction, four main compaction techniques are mentioned here.

Kneading Compaction Vibration Compaction Impact Compaction Compaction equipment is selected based on the type of soil. For clayey soils, kneading techniques and equipment have to be used because clay soils exist in the form of clods and kneading is the best way to break the clods and densify clay soils.

On the other hand, for granular soils, a vibratory or shaking motion of the compacting device is required so that uniform compaction is achieved.

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Popular compaction equipment types are mentioned below. Smooth Wheel Rollers — Single axle, equipped with a steel cylinder, sand or water are used to increase its self-weight.

How to calculate Maximum Dry Density and Optimum Moisture content of Soil, Solved Example.

Pushes the soil in the direction of movement and results in soil compaction. Sheep Foot Roller — Different style of sheep rollers, can be used for different types of soil, best suited for cohesive soils.

Soil Mechanics: Moisture-Density Relationship and Soil Compaction

Covers less surface area but pressure per unit area is very high resulting in healthy compaction. Vibratory Drum Roller — Suitable for compaction of sand, gravel, asphalt, and other heavy aggregates.

relationship between moisture content and density of soil

Very powerful compaction devices, provide uniformly dense soil because of vibrator attached to them. Vibratory Padfoot Compactors — Compactors work mainly in landfill regions and padfoot compactors have pads attached to their drums making them work fast and deliver efficient results in confined and tight areas.

relationship between moisture content and density of soil

Tamping Foot Rollers — Basically, these devices are compactors but are popularly known as tamping foot rollers. Kneading, impact compaction and pressure compaction happen simultaneously with these devices. Different classification systems divide soils according to their characteristic properties and accordingly compaction method is selected. Virbratory Dynapac Agricultural Aspects of Compaction Soil compaction is equally important for agricultural works.

However, soil compaction has certain disadvantages associated with it for agricultural activities. If the natural soil structure is disturbed by compaction, by natural or artificial methods, the soil's ability to produce a good yield decreases considerably.

Compaction, as we have seen in case of engineering works, affects soil porosity, natural air and water flow through the soil, and curbs root penetration of soil, which acts in an otherwise manner for crops. The resulting plot usually has a distinct peak as shown. Dry density can be related to water content and degree of saturation S as Thus, it can be visualized that an increase of dry density means a decrease of voids ratio and a more compact soil.

Similarly, dry density can be related to percentage air voids na as The relation between moisture content and dry unit weight for a saturated soil is the zero air-voids line. It is not feasible to expel air completely by compaction, no matter how much compactive effort is used and in whatever manner.

Soil Mechanics: Moisture-Density Relationship and Soil Compaction

Effect of Increasing Water Content As water is added to a soil at low moisture contents, it becomes easier for the particles to move past one another during the application of compacting force. The particles come closer, the voids are reduced and this causes the dry density to increase. As the water content increases, the soil particles develop larger water films around them.

relationship between moisture content and density of soil

This increase in dry density continues till a stage is reached where water starts occupying the space that could have been occupied by the soil grains. Thus the water at this stage hinders the closer packing of grains and reduces the dry unit weight. Effect of Increasing Compactive Effort The effect of increasing compactive effort is shown.