BT1: MATERIALS OF REINFORCED CONCRETE 1

Concrete

the most widely used construction material globally. It is strong in compression but weak in tension, which is why we add reinforcement (usually steel).

Reinforced Concrete

Concrete in which steel reinforcement is embedded in such a manner that the two materials act together in resisting forces.

Types of Concrete

Plain, Reinforced, Ferrocement, and Cast-in-Place Concrete

Materials of Reinforced Concrete

Cement, Fine Aggregates, Coarse Aggregates, Water, Steel Reinforcement, Standard Tie Wire, and Admixtures

Cement

A fine powder (usually Portland cement) that reacts chemically with water to form a paste that binds aggregates together.

Type 1: Ordinary Portland Cement (Normal)

for general use when special properties are not required, such as resistance to sulfate attack.

Type II: Modified Portland Cement (Moderate)

Generates less heat and at a slower rate during the hydration process. hydration: The formation of a compound by combining water with some other substance; the chemical reaction between cement and water.

Type III: High Early Strength Cement (Extra Rapid Hardening Cement)

For use where high strength is desired at early periods. usually within a week or less.

Type IV: Low Heat Cement

For use where low heat of hydration is desired; develops strength at a much lower rate than Type l.

Type V: Sulfate Resistant Cement

Used when high resistance to sulfate action is desired. Sulfate action: An expansive reaction occurring when the cement matrix of concrete or mortar comes in contact with sulfates dissolved in groundwater or in soil.

Type IS: Portland Blast Furnace Slag Cement

An interground mixture of Portland cement clinker and granulated blast furnace slag.

Type IP: Portland Pozzolan Cement

An interground mixture of Portland cement clinker and pozzolan

White Portland Cement

Uses selected raw material so that the finished product will be white rather than gray.

Masonry Cement

A mixture of Portland cement, air-entraining additives, plasticizers, etc.

Pozzolan Modified Portland Cement

A siliceous material, such as fly ash, that reacts chemically with slaked lime in the presence of moisture to form a slow-hardening cement, named after Pozzuoli, an ancient Roman town near Vesuvius

Block Cement

Similar to Type II cement, except that close control of uniform color is provided.

Expansive Cement

Increases in volume during setting and retains a portion of such in volume after hardening.

Gun Plastic Cement

Similar to plastic cement, except that it was developed for application by compressed air, guns ,or pumps.

Oil Well Cement

A slow-setting cement resistant to high temperatures and pressure, used for sealing oil wells.

Pipe Cement

Specifically designed for centrifugally spun pipes.

Plastic Cement

A mixture of Types I or II Portland cement and plasticizing agents; used for making mortar, cement plaster, and stucco.

Regulated Set Cement

An early- and fast-acting cement, effective from a few hours to one hour.

Waterproofed Cement

Standard or white cement incorporating water-repellant additives.

Pipe Cement

Specifically designed for centrifugally spun pipes.

Plastic Cement

A mixture of Types I or II Portland cement and plasticizing agents; used for making mortar, cement plaster, and stucco.

Regulated Set Cement

An early- and fast-acting cement, effective from a few hours to one hour.

Waterproofed Cement

Standard or white cement incorporating water-repellant additives.

Hydration

The chemical reaction that takes place when Portland cement and water are mixed together.

Setting

When cement is mixed with water to form a fluid paste, the mixture will eventually become stiff and then hard.

False Set (Portland Cement)

The abnormal premature stiffening of cement occurs within a few minutes of mixing with water. A false set of Portland cement is a phenomenon that is tested to assess the cement's behavior and quality, often using methods like ASTM C 359.

Heat of Hydration

Refers to the heat generated when water and cement chemically react. The test of hydration is used to evaluate the quality and performance of materials, such as cement. This exothermic reaction measures the heat released when a material, such as cement, reacts with water.

Aggregates

Any of various hard, inert materials, such as sand and gravel, added to cement to make concrete or mortar.

Aggregates

As defined in the field of construction, are granular materials of mineral composition, used either in combination with a binding medium to form concrete, mortar, and plaster. It is also used for various infrastructure projects and even as a material for decorative pieces

Two Categories of Aggregates

Fine and Coarse Aggregates

Fine Aggregates

product of natural disintegration of silica-bearing or calcium-bearing rock.

Coarse Aggregates

consisting of crushed stones, gravel, or blast furnace slag having a particle size larger than 1/4 inch (6.4 mm)

Boulders

Rock fragments with an average dimension of 12 inches or more. Used for massive backfill, filter beds, soil stabilization, massive foundations, dams, dikes, embankments, etc.

Cobblers

Aggregates with average dimension from3-12 inches. Used for embankments, backfills, foundations, dikes, soil stabilization of smaller magnitudes, backfill, ripraps, canal linings, decorative units, etc.

Gravel

Sizes from 3 inches down to that retained in a no. 4 (4.75 mm) sieve. Used as ingredients for concrete and asphalt, pre-cast concrete, base and sub-base courses for roads, granular bedding, filler, railroad ballast, ornaments, etc.

Fine Aggregates or Sand

Particles that pass the no. 4 (4.75 mm) sieve and are retained on a no. 200 (75 micron) sieve. Used as a vital ingredient for concrete and asphalt mixes, pavement seal coat, sand bedding, fairways sand cap, masonry, etc. Commercially known as S-1, S-3, Manufactured Sand, Natural Sand, or White Sand.

Manufactured Aggregates

Aggregates from substantial deposits (such as mountains), which are extracted through quarrying and processed to be of commercial value.

G1 Aggregates

20mm to 40mm in size. Usually used for premium subbase and base course material for roadworks and foundations, as well as in concrete mixed with coarser specifications

3/4 Aggregates

3-inch aggregates; most common. Widely used in construction for its ideal size and shape.

3/8 Aggregates

10 mm. Commonly used in flooring, driveways, walkways, and other thin sections, especially in areas with tight reinforcement spacing or limited cover.

Natural Aggregates

Those which need to be removed from their natural deposits as unconsolidated sediments (gravel, sand, stone from the river).

Round Aggregates

naturally occurring, smooth-edged.

Types of Steel Reinforcements

Reinforcing and Deformed Bar

Reinforcing Bar

For reinforcing concrete, usually specified by the number equivalent to its diameter in eighths of an inch, also called rebar.

Deformed Bar

A reinforced bar, hot rolled with surface deformations to develop a greater bond with concrete.

Reinforcement

Absorbs tensile, shear, and sometimes compressive stresses.

Deformed Bar

Hot-rolled steel with ridges for better bond with concrete.

Tension Reinforcement

Carries tension stresses.

Compression Reinforcement

Resists compressive stresses in columns and beams.