Where is crushed stone mined? Extraction and production
Crushed stone is one of the most widely used non-metallic construction materials. It is used for foundations, road construction, concrete production, site drainage systems and landscape design.
This article is useful for anyone who wants to understand where crushed stone comes from and what stages the material passes through before delivery to a site.
Crushed Stone Extraction
So where is crushed stone mined, how does it reach construction sites and how is it produced? The main source is stone quarries, where dense rocks are developed: granite, limestone, gravel rock, dolomite, basalt and other materials suitable for crushing. Quarries are usually located as close as possible to major consumers, because transporting a heavy bulk material noticeably affects the final cost.
The mining process starts with opening and preparing a rock section. Then drilling is carried out and, if the rock is strong enough, controlled blasting loosens the rock mass. During blasting, work in the hazardous area is stopped and personnel are removed from the work zone. Such operations are performed according to a technological plan and industrial safety rules.
Drilling and blasting, loading and crushing at a quarry are carried out by trained specialists using specialized equipment.
After blasting, large pieces of rock are obtained. Oversized fragments are additionally broken with a hydraulic hammer if necessary, then the rock is loaded into dump trucks or onto conveyors and delivered to the crushing and screening line.
Crushed Stone Production
Next, the stone is unloaded into a receiving hopper and fed to crushers. This is where crushed stone of different fractions is produced. A fraction is the size range of crushed stone grains. There are main and associated fractions; one of the most demanded is 5-20 mm. It is used in concrete, road bases and other construction mixtures. Crushers can be jaw, cone, impact, hammer and roll types; they differ by the way they break rock and by their area of use.
To obtain the finished product, sorting is required. It is carried out on screens: vibrating sieves with one or several decks that separate material by grain size. This produces individual crushed stone fractions and screenings.
Sorting is performed in several stages. First, large pieces are separated from smaller ones. Material that does not meet the required size is sent for repeated crushing. Then screenings are separated from crushed stone. Screenings are the fine fraction of crushing, most often up to 5 mm, visually similar to coarse sand. They cost less than crushed stone but are also widely used: in paving slab production, road works, bedding layers, anti-icing applications and some construction mixtures.
The field of application depends on the characteristics of the crushed stone. These include strength, frost resistance, flakiness, water absorption, content of dust and clay particles, grading and radiation safety indicators. These properties are determined by laboratory methods according to applicable standards. By radiation safety, crushed stone is divided into classes: first-class material is usually allowed for residential and public construction, second-class material for road works and some non-residential facilities, and third-class material for road construction outside populated areas and other limited uses.
Granite crushed stone description
Frequently Asked Questions
Where is crushed stone usually mined?
Crushed stone is produced at rock quarries that extract granite, limestone, dolomite, basalt, gravel deposits and other rocks suitable for crushing. Quarries are often located close to large consumers because transport has a major effect on the final price.
How is rock turned into crushed stone of a required fraction?
The rock is first extracted from the deposit, then crushed and screened. Oversized material is returned for secondary crushing, while the finished product is separated into fractions by particle size.
Which crushed stone properties should be checked before use?
Important properties include strength, frost resistance, flakiness, gradation, dust and clay content, water absorption and radiation safety where applicable. For critical construction work, it is better to use material with a quality certificate.