Construction aggregateFrom Wikipedia, the free encyclopedia

Limestonequarry.

10 mm graded crushedbasaltrock or aggregate, for use in concrete, called "blue metal" in Australia.

20 mm graded aggregate.

A gravel and sand extraction facility inMeimurje County,CroatiaConstruction aggregate, or simply "aggregate", is a broad category of coarse particulate material used inconstruction, includingsand,gravel,crushed stone,slag, recycled concrete and geosynthetic aggregates. Aggregates are the most mined materials in the world. Aggregates are a component ofcomposite materialssuch asconcreteandasphalt concrete; the aggregate serves as reinforcement to add strength to the overall composite material. Due to the relatively high hydraulic conductivity value as compared to most soils, aggregates are widely used in drainage applications such as foundation and French drains, septic drain fields, retaining wall drains, and road side edge drains. Aggregates are also used as base material under foundations, roads, andrailroads. In other words, aggregates are used as a stable foundation or road/rail base with predictable, uniform properties (e.g. to help prevent differential settling under the road or building), or as a low-cost extender that binds with more expensive cement or asphalt to form concrete.Preferred bitumenous aggregate sizes for road construction are given in EN 13043 as d/D tonnes valued at $2.59 billion from 378 quarries, traprock was 148 million tonnes valued at $1.04 billion from 355 quarries, and the balance other kinds of stone from 729 quarries. Limestone and granite are also produced in large amounts asdimension stone. The great majority of the crushed stone moved by heavy truck from the quarry/plant to the first point of sale or use. According to theUSGS, 2006 U.S. sand and gravel production was 1.32 billion tonnes valued at $8.54 billion (compared to 1.27 billion tonnes valued at $7.46 billion in 2005), of which 264 million tonnes valued at $1.92 billion was used as concrete aggregates. The great majority of this was again moved by truck, instead of byelectric train.Currently, total U.S. aggregate demand by final market sector was 30%35% for non-residential building (offices, hotels, stores, manufacturing plants, government and institutional buildings, and others), 25% for highways, and 25% for housing.[2]Top 10 Aggregates Companies[edit]Vulcan Materials Company (VMC)is the largest producer of construction aggregates in the United States by sales, with $3.3 billion of revenues in 2007. VMC is divided into three segments; Aggregates, Cement, and Asphalt and Concrete.Martin Marietta Materials (MLM)is the second largest construction aggregates company in the United States by sales, with $2.2 billion of revenues in 2007. MLM is divided into five segments; Aggregates, Asphalt, Concrete, Road Paving, and Specialty Products.Oldcastle Materials, Inc.is a subsidiary of Ireland's CRH plc. Oldcastle is divided into two units; Products and Distribution and Materials, the latter of which produces aggregates, asphalt, and ready-mix concrete.Hanson Building Materialsis the American subsidiary of Britain's Hanson plc. Hanson Building Materials is divided into two units Hanson Aggregates, which sells aggregates, ready-mixed and precast concrete, and asphalt, and Hanson Pipe & Products which produces buildings products ranging from concrete pipes to clay bricks.Rinker Materials Corp.is a subsidiary of Australia's Rinker Group, which is in turn majority-owned by Cemex S.A.B. de C.V. (CX). Rinker Materials produces concrete, aggregates, and heavy building products.Lafarge North Americais a subsidiary of France's Lafarge, an industrial company specializing in four major products: cement, construction aggregates, concrete and gypsum wallboard.Cemex S.A.B. de C.V. (CX)is a Mexican aggregates company. It is the world's largest building materials supplier and third largest cement producer by sales, with $21.6 billion of net sales (worldwide) in FY2007.Holcim Aggregatesis a subsidiary of Switzerland's Holcim, which sells aggregates, cement, and concrete worldwide.MDUproduces and sells aggregates, ready-mixed concrete, cement, and asphalt primarily in the central and western United States.Florida Rock Industries (FRK)was acquired by Vulcan Materials Company (VMC) in November, 2007.[3]Recycled materials for aggregates[edit]The largest-volume of recycled material used as construction aggregate isblast furnaceand steel furnaceslag. Blast furnace slag is either air-cooled (slow cooling in the open) or granulated (formed by quenching molten slag in water to form sand-sized glass-like particles). If the granulated blast furnace slag accesses free lime during hydration, it develops strong hydraulic cementitious properties and can partly substitute forportland cementin concrete. Steel furnace slag is also air-cooled. In 2006, according to theUSGS, air-cooled blast furnace slag sold or used in the U.S. was 7.3 million tonnes valued at $49 million, granulated blast furnace slag sold or used in the U.S. was 4.2 million tonnes valued at $318 million, and steel furnace slag sold or used in the U.S. was 8.7 million tonnes valued at $40 million. Air-cooled blast furnace slag sales in 2006 were for use in road bases and surfaces (41%), asphaltic concrete (13%), ready-mixed concrete (16%), and the balance for other uses. Granulated blast furnace slag sales in 2006 were for use in cementitious materials (94%), and the balance for other uses. Steel furnace slag sales in 2006 were for use in road bases and surfaces (51%), asphaltic concrete (12%), forfill(18%), and the balance for other uses.Glass aggregate, a mix of colors crushed to a small size, is substituted for many construction and utility projects in place of pea gravel or crushed rock, often saving municipalities like the City ofTumwater, WashingtonPublic Works, thousands of dollars (depending on the size of the project). Glass aggregate is not sharp to handle. In many cases, the state Department of Transportation has specifications for use, size and percentage of quantity for use. Common applications are as pipe beddingplaced around sewer, storm water or drinking water pipes to transfer weight from the surface and protect the pipe. Another common use would be as fill to bring the level of a concrete floor even with a foundation. Use of glass aggregate helps close the loop inglass recyclingin many places where glass cannot be smelted into new glass.[4]Aggregates themselves can be recycled as aggregates. Unlike deposits of sand and gravel or stone suitable for crushing into aggregate, which can be anywhere and may require overburden removal and/or blasting, "deposits" of recyclable aggregate tend to be concentrated near urban areas, and production from them cannot be raised or lowered to meet demand for aggregates. Supply of recycled aggregate depends on physical decay of structures and their demolition. The recycling plant can be fixed or mobile; the smaller capacity mobile plant works best for asphalt-aggregate recycling. The material being recycled is usually highly variable in quality and properties.Many aggregate products of various types are often recycled for other industrial purposes. InBay City, Michigan, for example, a recycle program exists for contractors and their own unused products. These piles are composed of unused mixed concrete, block, brick, gravel, pea stone, and other used materials. Composed of several alternating piles that grow to hundreds of feet in height and diameter. These piles are then crushed to provide gravel for roads and driveways, among other purposes. This program has huge economic and environmental benefits to the local and surrounding area. Contractors save on disposal costs and less aggregate is buried or piled and abandoned.[citation needed]According to theUSGSin 2006, 2.9 million tonnes of Portland cement concrete (including aggregate) worth $21.9 million was recycled, and 1.6 million tonnes of asphalt concrete (including aggregate) worth $11.8 million was recycled, both by crushed stone operations. Much more of both materials are recycled by construction and demolition firms not in the USGS survey. For sand and gravel, the USGS survey for 2006 showed that 4.7 million tonnes of cement concrete valued at $32.0 million was recycled, and 6.17 million tonnes of asphalt concrete valued at $45.1 million was recycled. Again, more of both materials are recycled by construction and demolition firms not in this USGS survey. The Construction Materials Recycling Association indicates that there are 325 million tonnes of recoverable construction and demolition materials produced annually.Many geosynthetic aggregates are also made from recycled materials. Being polymer based, recyclable plastics can be reused in the production of these new age of aggregates. For example, Ring Industrial Group's EZflow[5]product lines are produced with geosynthetic aggregate pieces that are more than 99.9% recycled polystyrene. This polystyrene, that would have otherwise been destined for a landfill, is instead gathered, melted, mixed, reformulated and expanded to create low density aggregates that maintain high strength properties while under compressive loads. Such geosynthetic aggregates replace conventional gravel while simultaneously increasing porosity, increasing hydraulic conductivity and eliminating the fine dust "fines" inherent to gravel aggregates which otherwise serve to clog and disrupt the operation of many drainage applications.Recycled aggregate production in the UK[edit]Recycled aggregate in the UK is defined as aggregate resulting from the processing of inorganic material previously used inconstruction. To ensure the aggregate isinert, it is manufactured from material tested and characterised underEuropean Waste Codes.[6]In 2008, 210 million tonnes of aggregate were produced in the UK of which 67 million tonnes was recycled product, according to the Quarry Products Association (QPA).[7]The Waste and Resource Action Programme (WRAP)[8]has produced a Quality Protocol for the regulated production of recycled aggregates.[9]The recycled aggregate is delivered with documentation that states it has been produced using a quality assured system for the manufacturing process to ensure an aggregate that conforms to the relevant European standards.[10]