Heavy construction equipment makes it possible to manage an astonishing variety of construction jobs. Getting the right equipment for the job – especially heavy-duty machinery used to move and manage tons of aggregate materials used in the building, development and landscaping processes is mandatory for efficiency and safety. A basic knowledge of what’s involved can prove invaluable when planning and budgeting for any construction project.
Material processing equipment used to move and process tons of aggregate materials for building, development and landscaping processes are critical pieces in many projects. Did you know that the construction of a new home uses an average of 400 tons of aggregate products? Wallboard, for example, requires aggregate as one of its major components.
Often overlooked, aggregate compounds play an important role in most construction projects. Aggregates include gravel, rocks, minerals and other materials that are used for surfaces, parking, commercial construction, civil engineering, landscaping, and environmental management.
The construction aggregate industry generates many billions of dollars each year in every sector of construction. The industry employs more than 81,500 men and women in more than 10,000 operations that serve hundreds of thousands of customers. Construction processes that depend on aggregate use the following equipment to manage tons of materials used in construction:
Rock Crushers
It’s important to reduce aggregate to an optimal size for various construction applications. The best example is gravel, which includes pea gravel, crushed stone and quarry process gravel composed of stone dust and crushed stone.
There are many types of crushers, but the process usually involves primary, secondary, tertiary and quaternary crushing. Primary crushing is usually done on-site where the aggregate is obtained. The process further reduces the stone after the initial blast. Crushers should be chosen based on the type of stone and logistical details – such as blast patterns and the size of loading equipment. The most popular primary crushers include gyratory, jaw and impact crushers.
Gyratory crushers employ a mantle within a concave bowl. The mantle makes contact with the bowl during gyration, which fractures the rock. Jaw crushers use compression between the two parts of the “jaw” to crush rock into smaller pieces. Impact crushers use a shaft that turns blow bars or hammers to impact stone and break it down.
Many primary crushers are fitted onto flatbeds to make them mobile. They can be moved between quarries and construction sites. Secondary, tertiary and quaternary crushers are used to further reduce the size of aggregate stone as needed. Secondary crushers are usually cone crushers or impact crushers using horizontal shafts. Tertiary and quaternary crushers consist of cone crushers and vertical-shaft impact crushers.
Cone crushers can crush aggregate as small as a 6:1 ratio. These crushers work like gyratory crushers, but the bowl chamber isn’t as steep. Cone crushers can be used in secondary, tertiary and quaternary crushing applications. Vertical-shaft impact crushers use a rotating shaft attached to wear-resistant shoes that throw rock chunks against an anvil. The twin impacts against shoes and anvil break up rock along natural fault lines.
Screeners
Screeners are machines that separate aggregate into different sized products. Typically, a vibrating screen box with different-sized templates allows material to fall through at increasing sizes as the screen is changed. Screeners can be track or wheel-mounted, and conveyors usually carry the appropriately sized aggregate to a collection area where it can be used for various construction needs.
Screeners are machines that separate aggregate into different sized products. Typically, a vibrating screen box with different-sized templates allows material to fall through at increasing sizes as the screen is changed. Screeners can be track or wheel-mounted, and conveyors usually carry the appropriately sized aggregate to a collection area where it can be used for various construction needs.
Screens can be customized to suit a builder’s or contractor’s needs, and they can be inclined and wet or dry. Water often increases throughput efficiency by making it easier for stones to fall through the holes. Materials for screens include:
- Rubber: Rubber offers the best combination of efficiency and maximum throughput.
- Hybrid: These screens offer benefits such as noise reduction and longer wear. One example of a hybrid screen is one made of Urethane-encapsulated wire.
- Piano Wire: Piano wire or harp screen wire form efficient longitudinal wires that are locked into place by various methods to prevent wear.
- Woven Wire: Woven wire cloth screens are durable, inexpensive and accurate. Screens made in this way are the longest and widest on the market to deliver maximum throughput for medium screening applications.
- Finger Deck Screen: This type of specialty screen works best on difficult-to-screen materials. These include wet, clumped aggregate and material subject to binding, clogging, pegging, and matting.
- Punch Plate Screens: These custom-engineered screens have a longer life expectancy than other screens and deliver greater screening efficiency.
From small, compact units to screeners for high-output, heavy-duty productivity, screeners are available in all shapes, sizes, and configurations to suit any builder’s needs.
Conveyors
Conveyor systems save money and speed construction processes by automating the transport of aggregate to where the product is needed. Conveyors can be used to load trucks and bins and to build stockpiles of aggregate for multiple uses. Customized conveyor systems can be used anywhere to streamline loading, transfer materials between locations, minimize the use of trucks and loaders and reduce the logistical cost per ton of using aggregate in construction projects. Studies show that the average cost of transporting aggregate runs about 2.25 times higher than the cost of the material, so reducing the costs of transport automation is a critical concern.
Using conveyors for more efficient material handling delivers these three key benefits:
- Lower Operational Costs: Conveyors and automated loading systems reduce the cost of manual labor, minimize expensive accidents and ensure continuous delivery throughout the entire work period without worries about work breaks and delays for shift changes.
- Better Quality of Product: It might seem that aggregate, made of rock and minerals, is immune to damage, but contamination and accidents can greatly reduce the yield and quality of the aggregate – especially in circumstances where the shape of the rocks is important. Conveyor systems prevent contamination and compression of the aggregate materials to deliver consistent quality.
- Conveyor Transport is Relatively Immune to Budget-busting inflation that results from rising energy and fuel costs. Electricity costs remain fairly stable even when fuel prices are rising, and the aggregate materials can always be moved during off-peak periods when electricity prices are lower.
Conveyor systems include mobile systems, short-distance conveyors and overland conveyors, product stacking conveyors that move materials directly from the mining source to a central warehouse or construction site.
Washing Equipment
Getting clean aggregate is essential for many construction processes including mixing concrete, laying road bases, removing clay and salt, eliminating grease, and reducing contaminants like twigs, roots, and trash. No cleaning method is perfect but reducing impurities within certain percentages is critical for safety and durability.
Aggregate washers include equipment that uses hydraulic, sand, and chemical processes to remove impurities to prevent cracking in structural projects and improve drainage when needed. As mining operations increasingly tap into reserves, greater amounts of contaminants become common in aggregate. That’s why it’s important to test the aggregate source against the purity requirements of the application to use the aggregate to maximum efficiency.
Crushing, screening, washing, and blending help to produce the right mix for various construction applications. Washers include those designed for coarser materials and screened aggregate sizes. Sandscrew washers work well for fine materials, and log washers work well for washing under harsh conditions.
Settling ponds are another method of cleaning aggregate, but this method often causes a loss of water to evaporation and percolation and is contraindicated when the cleaning water is needed in the plant or construction project. This method requires lots of empty space, and the time spent on cleaning the ponds and treating contaminated water could render the method impractical for many applications.
Sand classifying tanks work on dry materials and slurry. These washers use fine screens and separation based on settling rates. Attrition scrubbers are designed to remove deleterious materials. Some washers use various screens to remove impurities during the dewatering, degritting, rinsing, desliming, scrubbing, and washing processes.
Shredders
Shredders provide great benefits for large construction projects. The benefits include size reduction of construction and recycling materials, security shredding, material preconditioning, and many specialty applications. The types of shredders include:
- High Volume Shredders
These can provide 24/7 operation with continuous material feeds.
- Rotary Grinders
Single-shaft grinders can be fitted with various screens to process many types and sizes of materials.
- Security Shredders
These machines can be preset to shred in certain patterns – such as strips, crosscut shredding, and particle-size pieces.
- Hammer Mills
These machines destroy existing materials such as paper, wood pallets, waste products, rocks, and other solid wastes.
- Granulators
These machines reduce plastics to flakes before the remelting process in recycling.
Classifiers
Classifiers use various methods to classify aggregate into lightweight and heavyweight categories. Lightweight categories include paper, lightweight concrete, pumice, glass, brick rubble, and synthetics. Heavyweight aggregates include steel, limonite, barite, magnetite, steel, and other heavy rocks and minerals.
Classifiers can separate aggregate based on grain size, density, shape, and geographical origin. Grain size classifications include two major categories: coarse and fine. Density classification subcategories include lightweight, standard, and high density. Shape classification affects the performance of concrete. Different aggregate shapes include rounded, which is desirable for greater workability in concrete applications, irregular, angular, flaky, elongated and flaky, and elongated. Geographical classification primarily includes separating materials into natural and manufactured aggregate.
Quarry Spreader
Quarry spreaders are machines that can pick up aggregate, deliver it to a construction site and spread it where needed as-is, which eliminates many steps. Contractors, landscapers, sewer and drainage companies, homeowners, and quarry operators can all benefit by using quarry spreaders for simple transport operations.
Spreaders throw aggregate an average of 100 to 130 feet, and standard mixes of natural aggregate include hard and soft rocks, rocks formed under pressure, rocks consolidated from glaciers, volcanic rock and ash, and rocks from seabeds with fossilized skeletal remains
Aggregate and Waste Management
Almost any construction project involves the use of aggregates and the need to manage waste products. Builders have a choice for dealing with aggregate and waste issues – buy or rent the necessary equipment or hire a contractor, subcontractor, or developers with the right tools to manage structural aggregate and construction waste products.
Bringing it all together
Each construction project requires large quantities of materials to scale. Foundations, parking lots, roads, and landscaping features require aggregate as the fundamental building blocks. Construction aggregate includes sand, gravel, slag, granite, limestone, crushed stone, and geosynthetic materials.
When planning any building project, aggregate needs should be considered and fit into the budget, whether as part of a third-party service or renting or buying the necessary equipment.
For more information on material processing equipment, please contact Murrysville Machinery Company at 1-800-662-1626.
