Crushed stone or angular rock is a form of construction aggregate, typically produced by mining a suitable rock deposit and breaking the removed rock down to the desired size using crushers. It is distinct from naturally occurring gravel, which is produced by natural processes of weathering and erosion and typically has a more rounded shape.
Crushed stone is a major basic raw material used by construction, agriculture, and other industries. Despite the low value of its basic products, the crushed stone industry is a major contributor to and an indicator of the economic well-being of a nation. [5] The demand for crushed stone is determined mostly by the level of construction activity, and, therefore, the demand for construction materials. [6]
Stone resources of the world are very large. High-purity limestone and dolomite suitable for specialty uses are limited in many geographic areas. Crushed stone substitutes for roadbuilding include sand and gravel, and slag. Substitutes for crushed stone used as construction aggregates include sand and gravel, iron and steel slag, sintered or expanded clay or shale, and perlite or vermiculite. [7]
Crushed stone is a high-volume, low-value commodity. The industry is highly competitive and is characterized by many operations serving local or regional markets. Production costs are determined mainly by the cost of labor, equipment, energy, and water, in addition to the costs of compliance with environmental and safety regulations. These costs vary depending on geographic location, the nature of the deposit, and the number and type of products produced. Crushed stone has one of the lowest average by weight values of all mineral commodities. The average unit price increased from US$1.58 per metric ton, f.o.b. plant, in 1970 to US$4.39 in 1990. However, the unit price in constant 1982 dollars fluctuated between US$3.48 and US$3.91 per metric ton for the same period. Increased productivity achieved through increased use of automation and more efficient equipment was mainly responsible for maintaining the prices at this level. [6]
Transportation is a major factor in the delivered price of crushed stone. The cost of moving crushed stone from the plant to the market often equals or exceeds the sale price of the product at the plant. Because of the high cost of transportation and the large quantities of bulk material that have to be shipped, crushed stone is usually marketed locally. The high cost of transportation is responsible for the wide dispersion of quarries, usually located near highly populated areas. However, increasing land values combined with local environmental concerns are moving crushed stone quarries farther from the end-use locations, increasing the price of delivered material. Economies of scale, which might be realized if fewer, larger operations served larger marketing areas, would probably not offset the increased transportation costs. [6]
According to the United States Geological Survey, 1.72 billion tons of crushed stone worth $13.8 billion was sold or used in 2006, of which 1.44 billion tons was used as construction aggregate, 74.9 million tons used for cement manufacture, and 18.1 million tons used to make lime. Crushed marble sold or used totaled 11.8 million tons, the majority of which was ground very fine and used as calcium carbonate.
In 2006, 9.40 million tons of crushed stone (almost all limestone or dolomite) was used for soil treatment, primarily to reduce soil acidity. Soils tend to become acidic from heavy use of nitrogen-containing fertilizers, unless a soil conditioner is used. Using aglime or agricultural lime, a finely-ground limestone or dolomite, to change the soil from acidic to nearly neutral particularly benefits crops by maximizing availability of plant nutrients, and also by reducing aluminum or manganese toxicity, promoting soil microbe activity, and improving the soil structure.
In 2006, 5.29 million tons of crushed stone (mostly limestone or dolomite) was used as a flux in blast furnaces and in certain steel furnaces to react with gangue minerals (i.e. silica and silicate impurities) to produce liquid slag that floats and can be poured off from the much denser molten metal (i.e., iron). The slag cools to become a stone-like material that is commonly crushed and recycled as construction aggregate.
In addition, 4.53 million tons of crushed stone was used for fillers and extenders (including asphalt fillers or extenders), 2.71 million tons for sulfur oxide removal-mine dusting-acid water treatment, and 1.45 million tons sold or used for poultry grit or mineral food.
Crushed stone is recycled primarily as construction aggregate or concrete.
The term "high performance bedding" (HPB) is used to refer to 1/4" and 3/8" crushed rock.
Granular A, Granular B, and Granular C, all represent crushed rock mixed with sand in which Granular A has the least amount of sand, and Granular B has the most amount of sand. "Granular A" is also referred to as "angular crushed down to fines" or "minus" gravel. [8]
Limestone is a type of carbonate sedimentary rock which is the main source of the material lime. It is composed mostly of the minerals calcite and aragonite, which are different crystal forms of CaCO3. Limestone forms when these minerals precipitate out of water containing dissolved calcium. This can take place through both biological and nonbiological processes, though biological processes, such as the accumulation of corals and shells in the sea, have likely been more important for the last 540 million years. Limestone often contains fossils which provide scientists with information on ancient environments and on the evolution of life.
Marble is a metamorphic rock consisting of carbonate minerals (most commonly calcite (CaCO3) or dolomite (CaMg(CO3)2)) that have recrystallized under the influence of heat and pressure. It has a crystalline texture, and is typically not foliated (layered), although there are exceptions.
Gravel is a loose aggregation of rock fragments. Gravel occurs naturally on Earth as a result of sedimentary and erosive geological processes; it is also produced in large quantities commercially as crushed stone.
A quarry is a type of open-pit mine in which dimension stone, rock, construction aggregate, riprap, sand, gravel, or slate is excavated from the ground. The operation of quarries is regulated in some jurisdictions to manage their safety risks and reduce their environmental impact.
A gravel pit is an open-pit mine for the extraction of gravel.
Aggregate or aggregates may refer to:
Industrial resources (minerals) are geological materials that are mined for their commercial value, which are not fuel and are not sources of metals but are used in the industries based on their physical and/or chemical properties. They are used in their natural state or after beneficiation either as raw materials or as additives in a wide range of applications.
Concrete recycling is the use of rubble from demolished concrete structures. Recycling is cheaper and more ecological than trucking rubble to a landfill. Crushed rubble can be used for road gravel, revetments, retaining walls, landscaping gravel, or raw material for new concrete. Large pieces can be used as bricks or slabs, or incorporated with new concrete into structures, a material called urbanite.
Chat is fragments of siliceous rock, limestone, and dolomite waste rejected in the lead-zinc milling operations that accompanied lead-zinc mining in the first half of the 20th century. Historic lead and zinc mining in the Midwestern United States was centered in two major areas: the tri-state area covering more than 2,500 square miles (6,500 km2) in southwestern Missouri, southeastern Kansas, and northeastern Oklahoma and the Old Lead Belt covering about 110 square miles (280 km2) in southeastern Missouri. The first recorded mining occurred in the Old Lead Belt in about 1742. The production increased significantly in both the tri-state area and the Old Lead Belt during the mid-19th century and lasted up to 1970.
Construction aggregate, or simply aggregate, is a broad category of coarse- to medium-grained particulate material used in construction, including sand, gravel, crushed stone, slag, recycled concrete and geosynthetic aggregates. Aggregates are the most mined materials in the world. Aggregates are a component of composite materials such as concrete and asphalt; 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 roadside edge drains. Aggregates are also used as base material under foundations, roads, and railroads. In other words, aggregates are used as a stable foundation or road/rail base with predictable, uniform properties, or as a low-cost extender that binds with more expensive cement or asphalt to form concrete. Although most kinds of aggregate require a form of binding agent, there are types of self-binding aggregate which require no form of binding agent.
Graniterock is an American corporation, founded in 1900 as "Granite Rock", and based in Watsonville, California. It operates in the construction industry providing crushed gravel, sand, concrete, asphalt and paving services.
Hydrocarbons are the leading sector in Algeria's mineral industry, which includes diverse but modest production of metals and industrial minerals. In 2006, helium production in Algeria accounted for about 13% of total world output. Hydrocarbons produced in Algeria accounted for about 2.9% of total world natural gas output and about 2.2% of total world crude oil output in 2006. Algeria held about 21% of total world identified resources of helium, 2.5% of total world natural gas reserves, and about 1% of total world crude oil reserves.
The Michigan Limestone and Chemical Company operated the world's largest limestone quarry, which is located near Rogers City in Presque Isle County, Michigan. It was formed and organized in 1910; however, production did not begin until 1912. Ownership of the quarry has changed a number of times, but it is still one of the largest producers of limestone in the United States. The quarry was inextricably interlinked with lake shipping and railroad transportation.
In 2006, Cambodia's mineral resources remained, to a large extent, unexplored. Between 2003 and 2006, however, foreign investors from Australia, China, South Korea, Thailand, and the United States began to express their interest in Cambodia's potential for offshore oil and gas as well as such land-based metallic minerals as bauxite, copper, gold, and iron ore, and such industrial minerals as gemstones and limestone.
The following outline is provided as an overview of and topical guide to mining:
Sand is a granular material composed of finely divided mineral particles. Sand has various compositions but is defined by its grain size. Sand grains are smaller than gravel and coarser than silt. Sand can also refer to a textural class of soil or soil type; i.e., a soil containing more than 85 percent sand-sized particles by mass.
The cement industry in the United States produced 82.8 million tonnes of cement in 2015, worth US$9.8 billion, and was used to manufacture concrete worth about US$50 billion. The US was the world's third-largest producer of cement, after China and India. The US cement industry includes 99 cement mills in 34 states, plus two plants in Puerto Rico. The industry directly employed 10,000 workers in 2015. Ten percent of the cement used in the United States in 2015 was imported.
In the Earth sciences, aggregate has three possible meanings.
In 2017, the aggregate industry in the United States mined and sold 2.12 billion metric tons of crushed rock, sand and gravel valued at US$20.9 billion. There are thousands of aggregate-producing companies in the US, operating in each of the 50 states, and employing 105,000 people. Most aggregate is used by the construction industry, where it is an essential raw material and the main ingredient in concrete and asphalt concrete.
The strength and stiffness of the course of compacted angular stone came from the mechanical interlock which developed between individual pieces of stone. The principle is still used in modem road construction and since 1820 McAdam's name has been remembered by the term macadam used to describe the courses of unbound angular stone which he introduced.
Crushed stone can be used without binder for a variety of construction or industrial applications, or it may be mixed with a matrix binding material, such as bituminous or portland cement.
