All You Need To Know About Portland Cement

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Portland cement is not a brand name, but the generic term for the type of cement used in virtually all concrete, just as stainless is a type of steel and sterling a type of silver. Cement comprises from 10 to 15 percent of the concrete mix, by volume. Through a process called hydration, the cement and water harden and bind the aggregates into a rocklike mass. This hardening process continues for years, which is why concrete gets stronger as it gets older.

In the United States, portland cement is produced at more than 100 plants in 37 states, according to USGS figures. Most of these plants are located near limestone deposits. The 10 leading producing states, in descending order, are: Texas, Missouri, California, Florida, Michigan, Alabama, Pennsylvania, Georgia, Ohio and Indiana.

The originators of portland cement were Joseph Aspdin in England and Eugene Vicat in France. Aspdin’s first patent was issued in 1824 for a material he called “portland cement” because the concrete made from it looked like Portland stone, the famous building stone from the Isle of Portland off the British coast. Vicat first produced his artificial cement in 1817; it was patented in France in 1818 and later used to

The active component in slag cement is ground granulated blast furnace slag (GGBFS). When a small amount is added to portland cement, the product is called blended cement. When a larger amount of GGBFS is added, the product is called slag cement or ground granulated blast furnace slag (GGBS).

Slag cement is manufactured by adding water to GGBFS and grinding it into a fine powder. The resulting material is then stored, shipped and used as a replacement for portland cement in concrete. Because of its high glass content, slag cement generates less heat as it hardens than portland cement and produces stronger, more durable concrete than ordinary portland cement.

The manufacture of Portland cement is a complex process and done in the following steps:

grinding the raw materials, mixing them in certain proportions depending upon their purity and composition, and burning them to sintering in a kiln at a temperature of about 1305 to 1425 degree centigrade. The material thus produced is called clinker.

Slag cement is a hydraulic cement formed when granulated blast furnace slag (GGBFS) is ground to suitable fineness and is used to replace a portion of portland cement. It is a recovered industrial by-product of an iron blast furnace. Molten slag diverted from the iron blast furnace is rapidly chilled, producing glassy granules that yield desired reactive cementitious characteristics when ground into a fine powder.

The slag is first cooled as rapidly as possible in order to produce crystalline material, then crushed and ground into a fine powder. Slag cement is generally available in the form of ground, granulated blast furnace slag (GGBS). Some manufacturers also produce it in the form of condensed or pelletized slag or as dried granulated slag.

Class C (i.e., high early strength) portland-slag cements are manufactured by intergrinding portland cement clinker with granulated blast furnace slag or by blending portland cement with ground GBFS. A typical specification for Type IS portland-slag cement requires it to consist essentially of portland cement clinker and up to 40 % GBFS. ASTM C595 allows for intergrinding 20-70 % GGBS with clinker

Slag cement is a hydraulic cement while Portland cement is non-hydraulic. It is made of a mixture of calcium silicates and aluminate-ferrite. The main chemical ingredient is limestone, which when mixed with clay and heated creates a product called clinker. Slag cement is obtained by crushing the oxides present in blast furnace slag, which is a waste material produced during the production of iron in a blast furnace. It undergoes grinding to form granulated blast furnace slag (GBFS), which is like slag cement.

Slag cement has superior durability and strength, produces concrete with better workability, and contributes to sustainability through reduced energy consumption during production. This type of cement is used where resistance to sulfate attack, high compressive strength, low heat of hydration, low alkali-silica reactivity and permeability are required.

In general, the use of slag cement improves the long term properties of concrete such as durability through reduction in permeability due to its low alkali content, resistance to attacks by sulfates, chlorides and acids due to its higher content of aluminate, ferrite and sulfide phases resulting from the presence of tricalcium aluminate (C3A) and dicalcium sil

Blast furnace slag cement is the mixture of ordinary Portland cement and fine granulated blast furnace slag obtained as a by product in the manufacture of steel with percent under 70% to that of cement. Ground granulated blast furnace slag (GGBS) cement is a fine glassy granules which contain cementatious properties. In this article we discuss about composition, properties, advantages and disadvantages of GGBS cement.

Ground Granulated Blast Furnace Slag (GGBS)

The granulated slag after drying and ground in a rotary drum ball mill up to a very fine powder is GGBS. This powder is then mixed with ordinary Portland cement clinker, gypsum and other additives, if required in required proportion. The resulting product is cement that possess strength and workability similar to ordinary portland cement.

Composition Of GGBS Cement

The chemical reaction that takes place between Ordinary Portland Cement clinker and water to form hydration products is known as hydration of OPC. The chemical reaction between OPC clinker, water and granulated blast furnace slag to form hydration products are called the hydration of blended cement. The main chemical compositions of OPC clinker are calcium oxide (CaO), silicon oxide

The term “slag” refers to the glassy residue left over after a desired metal has been separated (i.e., smelted) from its raw ore. Slag is usually a mixture of metal oxides and silicon dioxide. However, slags can contain metal sulfides and elemental metals. While slags are generally used to remove waste in metal smelting, they can also serve other purposes, such as assisting in the temperature control of the smelting, and minimizing any re-oxidation of the final liquid metal product before the molten metal is removed from the furnace and used to make solid metal.

The properties of the slag are highly dependent upon the chemistry of the raw materials used. In general, the alkali content, calcium oxide concentration and modulus (CaO/SiO2 ratio) of slag increase with increasing amounts of Portland cement clinker in Portland blast furnace slag cement mixtures (PBFS). The addition of Portland cement clinker to a slag also reduces the melting point and fluidity of the slag allowing it be used at lower temperatures in PBFS blends.

Blending granulated blast furnace slag with Portland cement clinker or with hydrated lime produces more durable concrete structures than using

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