Ground granulated blast furnace slag (GGBS or GGBFS) is obtained by quenching molten iron Iron is the most common element in the earth as a whole, and the fourth most common in the Earth's crust. It is produced as a result of stellar fusion in high-mass stars, and it is the heaviest stable element produced by stellar fusion because the fusion of iron is the last nuclear fusion reaction that is exothermic. Iron is the most widely used slag Slag is a partially vitreous by-product of smelting ore to separate the metal fraction from the unwanted fraction. It can usually be considered to be a mixture of metal oxides and silicon dioxide. However, slags can contain metal sulfides and metal atoms in the elemental form. While slags are generally used as a waste removal mechanism in metal (a by-product of iron and steel Steel is an alloy that consists mostly of iron and has a carbon content between 0.2% and 2.1% by weight, depending on the grade. Carbon is the most common alloying material for iron, but various other alloying elements are used, such as manganese, chromium, vanadium, and tungsten. Carbon and other elements act as a hardening agent, preventing making) from a blast furnace A blast furnace is a type of metallurgical furnace used for smelting to produce industrial metals, generally iron in water or steam, to produce a glassy Glass is an amorphous solid material. Glasses are typically brittle, and often optically transparent. Glass is commonly used for windows, bottles, and eyewear; examples of glassy materials include soda-lime glass, borosilicate glass, acrylic glass, sugar glass, Muscovy-glass, and aluminium oxynitride. The term glass developed in the late Roman, granular product that is then dried and ground into a fine powder.
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Applications
GGBS is used to make durable concrete Concrete is a construction material composed of cement and other cementitious materials such as fly ash and slag cement, aggregate (generally a coarse aggregate made of gravels or crushed rocks such as limestone, or granite, plus a fine aggregate such as sand), water, and chemical admixtures structures in combination with ordinary portland cement Portland cement is the most common type of cement in general use around the world because it is a basic ingredient of concrete, mortar, stucco and most non-specialty grout. It is a fine powder produced by grinding Portland cement clinker (more than 90%), a limited amount of calcium sulfate (which controls the set time) and up to 5% minor and/or other pozzolanic A pozzolan is a material which, when combined with calcium hydroxide, exhibits cementitious properties. Pozzolans are commonly used as an addition to Portland cement concrete mixtures to increase the long-term strength and other material properties of Portland cement concrete, and in some cases reduce the material cost of concrete. Pozzolans are materials. GGBS has been widely used in Europe Europe is one of the world's seven continents. Comprising the westernmost peninsula of Eurasia, Europe is generally divided from Asia to its east by the water divide of the Ural Mountains, the Ural River, the Caspian Sea, the Caucasus region (Specification of borders) and the Black Sea to the southeast. Europe is bordered by the Arctic Ocean and, and increasingly in the United States ^ b. English is the de facto language of American government and the sole language spoken at home by 80% of Americans age five and older. Spanish is the second most commonly spoken language and in Asia Asia is the world's largest and most populous continent, located primarily in the eastern and northern hemispheres. It covers 8.6% of the Earth's total surface area and with approximately 4 billion people, it hosts 60% of the world's current human population. During the 20th century Asia's population nearly quadrupled (particularly in Japan Japan is an island country in East Asia. Located in the Pacific Ocean, it lies to the east of the Sea of Japan, China, North Korea, South Korea and Russia, stretching from the Sea of Okhotsk in the north to the East China Sea and Taiwan in the south. The characters that make up Japan's name mean "sun-origin", which is why Japan is and Singapore Singapore, officially the Republic of Singapore, is an island country off the southern tip of the Malay Peninsula, 137 kilometres north of the equator, in the Southeast Asian region of the Asian continent. It is separated from Malaysia by the Straits of Johor to its north, and from Indonesia's Riau Islands by the Singapore Strait to its south. A) for its superiority in concrete durability, extending the lifespan of buildings from fifty years to a hundred years.[citation needed]
Two major uses of GGBS are in the production of quality-improved slag cement In the most general sense of the word, a cement is a binder, a substance which sets and hardens independently, and can bind other materials together. The word "cement" traces to the Romans, who used the term "opus caementicium" to describe masonry which resembled concrete and was made from crushed rock with burnt lime as binder, namely Portland Blastfurnace cement (PBFC) and High Slag Blastfurnace cement (HSBFC), with GGBS content ranging typically from 30 to 70%; and in the production of ready-mixed or site-batched durable concrete.
Concrete made with GGBS cement sets more slowly than concrete made with ordinary Portland cement, depending on the amount of GGBS in the cementitious material, but also continues to gain strength over a longer period in production conditions. This results in lower heat of hydration Mineral hydration is an inorganic chemical reaction where water adds to the crystal structure of a mineral, usually creating a new mineral, usually called a hydrate and lower temperature Historically, two equivalent concepts of temperature have developed, the thermodynamic description and a microscopic explanation based on statistical physics. Since thermodynamics deals entirely with macroscopic measurements, the thermodynamic definition of temperature, first stated by Lord Kelvin, is stated entirely in empirical, measurable rises, and makes avoiding cold joints easier, but may also affect construction schedules where quick setting is required.
Use of GGBS significantly reduces the risk of damages caused by alkali-silica reaction The ASR reaction is the same as the Pozzolanic reaction which is a simple acid-base reaction between calcium hydroxide, also known as Portlandite, or (Ca2), and silicic acid (H4SiO4, or Si(OH)4). For the sake of simplicity, this reaction can be schematically represented as following: (ASR), provides higher resistance to chloride The chloride ion is formed when the element chlorine picks up one electron to form an anion Cl−. The salts of hydrochloric acid HCl contain chloride ions and can also be called chlorides ingress — reducing the risk of reinforcement corrosion — and provides higher resistance to attacks by sulfate In inorganic chemistry, a sulfate is a salt of sulfuric acid and other chemicals.
How GGBS cement is used
GGBS cement is added to concrete in the concrete manufacturer's batching plant, along with Portland cement, aggregates and water. The normal ratios of aggregates and water to cementitious material in the mix remain unchanged. GGBS is used as a direct replacement for Portland cement, on a one-to-one basis by weight. Replacement levels for GGBS vary from 30% to up to 85%. Typically 40 to 50% is used in most instances.
The use of GGBS cement in concrete in Ireland Ireland (pronounced [ˈaɾlənd],; Irish: Éire, pronounced [ˈeːɾʲə] ( listen); Ulster Scots: Airlann) is the third largest island in Europe and the twentieth largest island in the world. It lies to the northwest of continental Europe and is surrounded by hundreds of islands and islets. To the east of Ireland is Great Britain, separated from is covered in the new Irish concrete standard IS EN 206-1:2002. This standard establishes two categories of additions to concrete along with ordinary Portland cement: nearly inert additions (Type I) and pozzolanic or latent hydraulic additions (Type II). GGBS cement falls in to the latter category. As GGBS cement is slightly less expensive than Portland cement, concrete made with GGBS cement will be similarly priced to that made with ordinary Portland cement.
Architectural and engineering benefits
Durability
GGBS cement is routinely specified in concrete to provide protection against both sulphate attack and chloride attack. GGBS has now effectively replaced Sulfate Resisting Portland cement (SRPC) on the market for sulfate resistance because of its superior performance and greatly reduced cost compared to SRPC. Most projects in Dublin's Docklands, including Spencer Dock, are using GGBS in subsurface concrete for sulfate resistance.
To protect against chloride attack, GGBS is used at a replacement level of 50% in concrete. Instances of chloride attack occur in reinforced concrete in marine environments and in road bridges where the concrete is exposed to splashing from road de-icing salts. In most NRA The National Roads Authority (Irish: An tÚdarás urn Bóithre Náisiúnta) is a state body in the Republic of Ireland, responsible for the national road network. The NRA was established as part of the Roads Act 1993, and commenced operations on 23 December 1993 in accordance with S.I. 407 of 1993 projects in Ireland GGBS is now specified in structural concrete for bridge piers and abutments Abutment is also a term used by civil engineers in dam construction; moving water from a large reservoir to a channel such as a spillway, there are smooth transition walls at both sides named abutments which minimize the water's energy loss for protection against chloride attack. The use of GGBS in such instances will increase the life of the structure by up to 50% had only Portland cement been used, and precludes the need for more expensive stainless steel In metallurgy stainless steel, also known as inox steel or inox from French "inoxydable", is defined as a steel alloy with a minimum of 10.5 or 11% chromium content by mass. Stainless steel does not stain, corrode, or rust as easily as ordinary steel, but it is not stain-proof. It is also called corrosion-resistant steel or CRES when the reinforcing.
GGBS is also routinely used to limit the temperature rise in large concrete pours. The more gradual hydration of GGBS cement generates both lower peak and less total overall heat than Portland cement. This reduces thermal gradients in the concrete, which prevents the occurrence of microcracking which can weaken the concrete and reduce its durability, and was used for this purpose in the construction of the Jack Lynch Tunnel in Cork Cork is the second largest city in the Republic of Ireland and the island of Ireland's third most populous city. It is the principal city and administrative centre of County Cork and the largest city in the province of Munster. Cork has a population of 119,418, while the addition of the suburban areas contained in the county brings the total to 190.
Appearance
In contrast to the stony grey of concrete made with Portland cement, the near-white color of GGBS cement permits architects to achieve a lighter colour for exposed fair-faced concrete finishes, at no extra cost. To achieve a lighter colour finish, GGBS is usually specified at between 50% to 70% replacement levels, although levels as high as 85% can be used. GGBS cement also produces a smoother, more defect free surface, due to the fineness of the GGBS particles. Dirt does not adhere to GGBS concrete as easily as concrete made with Portland cement, reducing maintenance costs. GGBS cement prevents the occurrence of efflorescence Efflorescence, in chemistry, is the loss of water of crystallization from a hydrated or solvated salt to the atmosphere on exposure to air, the staining of concrete surfaces by calcium carbonate Calcium carbonate is a chemical compound with the chemical formula Ca deposits. Due to its much lower lime Lime is a general term for calcium-containing inorganic materials, in which carbonates, oxides and hydroxides predominate. Strictly speaking, lime is calcium oxide or calcium hydroxide. It is also the name for a single mineral of the CaO composition, occurring very rarely.[citation needed] The word 'lime' originates with its earliest use as content and lower permeability, GGBS is effective in preventing efflorescence when used at replacement levels of 50% to 60%.
Strength
Concrete containing GGBS cement has a higher ultimate strength than concrete made with Portland cement. It has a higher proportion of the strength-enhancing calcium silicate hydrates (CSH) than concrete made with Portland cement only, and a reduced content of free lime, which does not contribute to concrete strength. Concrete made with GGBS continues to gain strength over time, and has been shown to double its 28 day strength over periods of 10 to 12 years.[citation needed]
References
- U.S. Federal Highway Administration The Federal Highway Administration is a division of the United States Department of Transportation that specializes in highway transportation. The agency's major activities are grouped into two "programs," the Federal-aid Highway Program and the Federal Lands Highway Program. "Ground Granulated Blast-Furnace Slag". http://www.fhwa.dot.gov/infrastructure/materialsgrp/ggbfs.htm. Retrieved 2007-01-24.
- Civil and Marine Company. "Frequently Asked Questions". http://www.civilandmarine.com/pages.en/products/ggbs/ggbsfaqs.html. Retrieved 2007-01-24.
- EnGro Corporation Ltd.. "Ground Granulated Blastfurnace Slag (GGBS)". http://www.engro-global.com/productrange.html#GGBS. Retrieved 2007-01-24.
- Construct Ireland. "Ground Granulated Blastfurnace Slag (GGBS)". http://constructireland.ie/Vol-2-Issue-12/Articles/Sustainable-Building-Technology/-The-Eco-Friendly-Durable-Low-Energy-Alternative-to-OPC.html. Retrieved 2008-02-21.
Categories: Amorphous solids Categories: Amorphous matter | Solids | Glass physics | Glass compositions | Cement | Concrete Categories: Heterogeneous chemical mixtures | Structural engineering | Materials | Building materials | Pavements | Crystalline solids | Materials In the industrial sense, materials are inputs to production or manufacturing. They are often raw–that is, unprocessed–but are sometimes processed before being used in more advanced production processes
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It reduces the amount of cement used in concrete by replacing about half of it with blast furnace slag fly ash the residue left when coal is burned to ...
Q. If our "state of the art", cement mix of (cement/ fly ash/ slag/ stainless rebar/ silica/ water/ chemical agents/ compaction) is supposedly the product of the most advanced civilization of the world, how come certain Roman constructions are still used still after a little less than 2000yrs. The Pantheon-aquaducts-tunnel s cement have been investigated but never understood. Geopolymers have been investigated, but waiting another 2000yrs to see if their works are proof, is very unlikely.
Asked by andy f - Wed Jul 5 08:10:49 2006 - - 3 Answers - 0 Comments
A. Our "state of the art" technology is not so much concrete but the combination of steel and concrete, and that's where the corrosion problems lie. Given modern analysis methods, I would be very surprised if nobody had done a detailed mineralogical and chemical analysis of Roman concrete. Electron Microprobes and transmission electron microscopes ought to be able to identify the concrete mixture.
Answered by jorganos - Wed Jul 5 08:22:37 2006
