Earthworks Design: ECEDE4A - Soil Classification and Compaction

Vocabulary flashcards covering key terms, rock weathering processes, soil classification categories, Atterberg limits, and soil compaction equipment from the lecture notes.

Soil

Unconsolidated material composed of solid particles produced by mechanical and chemical disintegration of rocks.

Igneous Rocks

Primary rocks formed by the cooling of molten magma.

Mechanical Weathering

The process by which rocks are broken into smaller pieces with no associated chemical changes by physical forces including running water, wind, ocean waves, glacier ice, frost, and heat.

Chemical Weathering

The weathering process in which the original material or rock is changed into something new through reactions such as oxidation, carbonation, hydration, hydrolysis, and leaching.

Oxidation

A chemical weathering process involving the union of oxygen with minerals in rocks to form another mineral.

Hydration

A chemical weathering process in which water enters the crystalline structure of minerals to form another group of minerals.

Hydrolysis

A chemical weathering reaction involving the release of hydrogen from water, which then combines with rock minerals.

Carbonation

A chemical weathering reaction occurring when carbon dioxide available in the air in the presence of water reacts with minerals, resulting in the formation of carbonates.

Leaching

The process in chemical weathering in which percolating water washes out water-soluble salts from the soil.

Weinert N Value

An index value used in soil classification where $N < 5$ indicates a moisture surplus with dominant decomposition, and $N > 5$ indicates a moisture deficit with dominant disintegration.

Residual Soils

Soils formed by the weathering of rocks and deposited near the place of their formation, with depth varying between $5\,m$ and $20\,m$.

Transported Soils

Soils formed by the weathering of rocks and transported away from their place of formation by agents such as air, water, ice, and snow.

Alluvial Soils

Transported soils carried and deposited by flowing water.

Lacustrine Deposits

Soil deposits made specifically in lakes.

Marine Deposits

Soil deposits formed when flowing water carries soil to the ocean.

Aeolian Soil

A type of soil consisting primarily of sand or silt-sized particles transported from one place to another by the wind.

Liquid Limit ($LL$)

The moisture content at which soil begins to behave as a liquid material and begins to flow, corresponding to a shear strength of approximately $2.5\,kN/m^2$ for fine-grained soil.

Plastic Limit ($PL$)

The moisture content at which soil begins to behave as a plastic material.

Plasticity Index ($PI$)

The difference between the numerical values of Liquid Limit and Plastic Limit ($PI = LL - PL$), giving the range of moisture content for which soil behaves like a plastic material.

Shrinkage Limit ($SL$)

The moisture content at which no further soil volume change occurs with further reduction in moisture content.

Soil Compaction

The process of bringing soil particles closer to a dense state by mechanical means, reducing voids through the expulsion of air to increase unit weight.

Standard Proctor Test

A laboratory compaction test introduced by Ralph R. Proctor in $1933$ using a $2.5\,kg$ ($5.5\,lb$) hammer dropped $12\,in$ on $3$ layers with $25$ blows per layer in a $0.001\,m^3$ ($0.03\,ft^3$) mold with a compactive effort of $16778\,Nm$ ($12375\,ft\text{-}lbs$).

Smooth-wheel Rollers

Compaction equipment weighing from $5\,tonnes$ to $15\,tonnes$, suitable for compacting sand, gravel, and broken stones for highway base courses.

Sheep Foot Rollers

Rollers with metal pieces shaped like sheep feet fixed to the outer surface of a cylinder, weighing between $1.5\,tonnes$ and $10\,tonnes$, suitable for cohesive soil.

Pneumatic Rollers

Compaction machines consisting of a number of rubber tires, suitable for compacting fine-grained soil and well-graded sands, but not recommended for Stone Mastic Asphalt layers.

Grid Rollers

Rollers featuring a cylindrical heavy steel surface with a network of steel bars forming a grid with square holes, whose weight can be increased by ballasting with concrete blocks.

Tamping Rollers

Rollers similar to sheep foot rollers but with lugs of larger area, having static weights from $15\,tonnes$ to $40\,tonnes$, best suited for compacting cohesive soils.

Vibrating Plate Rollers

Compaction equipment used for small areas, weighing from $100\,kg$ to $2\,tonnes$ with plate areas between $0.16\,m^2$ and $1.6\,m^2$.

Rammers

Compaction equipment providing impact load to soil in small areas, hand or machine operated, with base sizes such as $15\,cm \times 15\,cm$ or $20\,cm \times 20\,cm$.