Is a branch of engineering that studies the behavior of soil as a construction material. It focuses on

understanding how soil responds to stresses and loads, particularly in relation to supporting structures and

infrastructure.

The foundation of all civil engineering projects, ensuring that structures are safe, stable,

and sustainable by understanding and managing the behavior of soil and rock beneath the ground.

Is the loose, weathered material on Earth's

surface that supports plant life and is a complex

mixture of minerals, organic matter, water, and air.

• - A natural aggregate of mineralogical composition that is bounded by strong and cohesive force.

• - Are formed when the modern magma gets cools down after reaching the earth’s surface.

• - Are hard and impermeable

• - The breakdown of rocks into smaller particles, which eventually become soil.

• - The process of breaking down rocks by mechanical and chemical

  processes into smaller pieces.

• - Also called as “Physical Weathering”

• - Breakdown of rocks without changing their chemical composition.

• Caused by: Temperature changes (freeze-thaw cycles) and Abrasion by wind, water, or ice

• - Breakdown of rocks due to chemical reactions with water, air, or acids.

• - Alters the mineral composition of rocks.

• Common processes: Oxidation, Hydrolysis, and Carbonation

Caused by living organisms such as bacteria, fungi, and plant roots.

• - Formed from the cooling and solidification of molten magma or lava.

• - Usually strong and durable; good for foundations and aggregates.

• - Formed from the compaction and cementation of sediments.

• - The deposits of gravel, sand, silt, and clay formed by weathering may become

  compacted by overburden pressure and cemented by agents like iron oxide, calcite, dolomite,

  and quartz.

• - Formed when existing rocks are changed by heat, pressure, or chemical processes, without melting.

• - Generally hard and strong; used in construction and decorative stone.

For soil to form from rocks, it takes an average of * years or more. The soil is usually formed when

rocks break up into their constituent parts.

• - Consists of small particles of weathered rock.

• - One of the poorest types of soil for growing plants because it has very low nutrients and poor water holding capacity.

• - This type of soil is very good for the drainage system.

• - Known to have much smaller particles compared to sandy soil and is made up of rock and other

mineral particles, which are smaller than sand and larger than clay.

• - Smooth and fine quality of the soil that holds water better than sand.

• - Is easily transported by moving currents and it is mainly found near the river, lake and other water

  bodies.

• - The smallest particle amongst the other two types of soil. The particles in this soil are

tightly packed together with each other with very little or no airspace.

• - Has very good water storage qualities and makes it hard for moisture and air to penetrate

  into it.

• - Very sticky to the touch when wet, but smooth when dried.

• - A combination of sand, silt and clay. It has the ability to retain moisture and nutrients; hence, it is more suitable for farming.

• - This soil is also referred to as agricultural and it also happens to have humus.

• - It also has higher calcium and pH levels because of its inorganic origins.

These are the mineral grains and organic matter that make up the soil skeleton.

Derived from weathered rocks (sand, silt, clay).

Decomposed plant and animal material that enriches the soil and affects its

properties (especially in topsoil).

Occupies some of the voids between soil particles.

Drains freely due to gravity.

Held between particles.

Thin film tightly bound to particle surfaces.

• - Fills the remaining pore spaces not occupied by water

• - Essential for plant roots and microorganisms in topsoil.

• - In saturated soils, air is minimal or absent.

Are characteristics that describe the physical, chemical, and biological components of soil and how these

components interact.

Defined as the ratio of the unit weight of a given material to the unit

weight of water.

Specific gravity of common soils usually falls within the range of

Soils generally are called *,

depending on the predominant size of particles

within the soil.

Mechanical analysis is the determination of the size range of

particles present in a soil, expressed as a percentage of the

for particle sizes larger than 0.075 mm in diameter, and

for particle sizes smaller than 0.075 mm in diameter.

Also called as (grain size analysis) consists of shaking the

soil sample through a set of sieves that have

progressively smaller openings.

Is based on the principle of sedimentation of

soil grains in water.

It is assumed that all the soil particles are spheres and

that the velocity of soil particles can be expressed by

Are formed mostly by mechanical weathering of rock and minerals. Geologists use

such terms as angular, subangular, subrounded,

and rounded

Have very low sphericity usually 0.01 or less. These particles are

predominantly clay minerals.

Are much less common, Examples are some coral deposits and

attapulgite clays.