February 24, 2023
In general terms, a quarry is a mining operation whose purpose is to extract raw material from the Earth for use or processing. Specific to Twisted Nail, an aggregate quarry is a quarry variation used to extract stones, rock, dirt, sand, and other aggregates that will be repurposed into building materials. Aggregate quarries belong to a subgroup of quarries called open pit mines. These mines are open to the earth’s surface and do not function below the ground, all activity is performed above ground. While there are many types of quarries that supply a wide range of products, aggregate quarries exist to dig up and process any stone-related materials that are used in construction. Texas has many quarries in general but has a significant number of aggregate quarries when compared to other states.
The most common quarry type in Texas is the aggregate quarry, which specializes in stone, gravel, sand, and fill dirt. While these quarries are similar to like-kind quarries in other states, Texas has a large number of quarries that make construction aggregates readily available in most regions of the state. To further categorize these aggregate quarries, we can break down the types of aggregate they produce into these main categories: sand, fill, rock, and stone.
Simply put, sand and gravel quarries are mines that are purposed for extracting sand and gravel from the Earth. While a quarry can be a mixture of sand, gravel, rock, and stone it is more common for a quarry to specialize. Sand and gravel quarries specialize in loose aggregates like various types of construction rock, sand, and fill dirt materials. In Central Texas, these quarries produce two main types of rock: river rock and limestone. Both river rock and limestone quarries will also produce select fill, common fill, washed sand, and various construction rocks ranging from crusher fines, 3/8”-1” rock, 2”-6” bull rock, and 6”-36” rip rap. Some materials are much more common, such as common fill, pea gravel, sand, and top soil; however, some materials, like silica sand and #57 rock, are exceedingly rare and often require import from other regions of the state. Application of these materials can be varied and the available use-cases are nearly endless. Most commercial projects will require a combination of select fill, state spec road base, ¾”-1” rock (#57 Rock), and rip rap with some projects requiring specialty materials depending on the projects requirements. For residential projects, the most commonly used materials include flexbase, pea gravel, 1” river rock, oversized river rock, common fill, and top soil.
Fill dirt is available in two main types: common fill and select fill. While both are made of a mixture of sand and clay, common fill is not bound by any testing metrics and can be delivered as any combination of the two materials. Select fill, however, implies that the material is tested and will conform to a standard composition of sand and clay. Common fill is an affordable option for many smaller residential projects, such as building an RV pad, but would not be a good material to use where long-term stability is a concern, such as a new home build. For long-term performance contractors and homeowners should defer to select fill, which will have an approved consistency and will perform better over time.
Topsoil is considered a category of fill dirt and is used in areas seeking to cultivate plant life, such as gardens or lawns. It is placed above all other fill dirt to help nourish the land, but can also be used on its own. Topsoil is a popular choice for landscaping projects.
Silica sand is exceedingly rare in Texas, so is much more expensive than other types of sand. However, while rare, it is still possible to source from within the state. Silica sand comes in a beautiful white color that is the result of quartz being broken down through erosion. Because of its price, it is most often used in specialty industrial projects as well as artificial beaches, golf courses, and for filtration.
Washed sand, also called concrete sand, is sand that has been processed through a series of screening and washing to remove impurities before being used for construction purposes. Washed sand is used in concrete applications as an additive to make concrete, for walkways, in golf courses, pool construction, patio builds, and other leveling projects. The material comes in an off-white color and is a key ingredient in concrete production, along with a coarse aggregate, cement, and water.
Most construction projects in Texas utilize limestone base in some capacity. Base is a mixture of rock and dirt (fines) that hardens after getting wet. The material composition can vary. Limestone flexbase is often used in residential projects such as country roads, driveways, or as pads for a shop or RV. Because flexbase does not require testing it can come in unpredictable compositions, with some batches delivered with more rock and others with more fines. State spec base, however, is regulated to a very specific combination and should always be delivered with a consistent composition. This composition is defined by the state and allows the material to be used in commercial applications. The material is widely available in Texas and is often found to be one of the cheaper material options available.
Crusher fines are a budget material that are a byproduct of the crushing process limestone must go through. Crusher fines are small in size, ranging from dust to 3/8” in diameter, and can function similar to road base depending on the materials composition. While not recommended for most commercial projects, crusher fines can be an excellent alternative to road base for non-foundation residential projects that are budget conscious. The material can be an excellent choice for country roads, pathways, driveways, RV pads or other casual projects requiring a little stability.
Crushed rock is a foundational aggregate in almost all construction projects. Crushed rock can come in untested and tested variations, with untested materials not conforming to any state specifications and tested versions conforming to very specific sieve tests to ensure uniformity in the material being delivered. This type of aggregate will range in size and can be anywhere from ¼” to 2” in size. Two common terms associated with crushed rock are screened and washed, referring to the material being processed through a screen (and therefore all non-conforming sizes filtered out) and washed referring to the material being cleaned of any sediment that is attached to the rocks after being mined. The popularity of crushed rock in construction uses can make this material very difficult to find and very expensive to purchase. ¾” Rock – 1” Rock, otherwise known as #57 rock, is an excellent example of this. This size rock, particularly in the washed variant, is used in almost all commercial earthwork projects and is a required additive for concrete production. The material is often easy to find in some capacity, but will frequently need to be imported if the project is not flexible on size or washed/unwashed requirements.
Bull Rock is limestone that is a step up in size from crushed rock, typically ranging from 2” in size to 6” in size. This rock is frequently used as a filter material or as a stabilizer on construction projects. The most commonly available bull rock is a 3”x5” rock, aka 3x5 or 3 by 5, and is used to create a stable entrance on construction projects. The material is incredibly durable and will allow heavy machinery to easily pass over.
Riprap (Rip Rap) refers to limestone that is a further step-up in size, typically ranging from 6” to 36” in diameter. These rocks are very large in size and are typically used in erosion control and for stability purposes. Riprap can also be used around culverts, bridges, drains, and other banked slopes that run the risk of washing away in heavy rain or when exposed to heavy waters.
Pea gravel is made of smaller rocks (<3/8” diameter). The coloring of the material depends on the root source material: limestone is available in varying shades of tan and white while river rock is available in a mixture of tan, red, brown, and other natural colors. Pea gravel is a popular choice for landscaping, playgrounds, walking paths, driveways, patios, gardens, and other areas that are more focused on appearance rather than utility.
Screened River Rock refers to a river rock that has been filtered with a series of sieves so that the final product is a consistent size range. These rocks can be various sizes, depending on the quarry, and typically range from 3/8” to 2” in size. Screened river rock can also come washed or unwashed, depending on the quarry capabilities, which refers to if the rock has been cleaned of any natural sediment attached to the rocks when mined. Screened rock, particularly the 1” #57 rock variety, is very popular in construction projects and is a popular additive to concrete. The material is excellent for landscaping purposes, but is not always a great fit for a driveway, walkway, or otherwise project requiring stability. The material’s round edges prevents any type of lock-in and allows the material to wiggle out of the way as pressure is applied.
Oversize River Rock refers to a river rock that is larger than 2” in diameter. Oversize river rock should be produced at any quarry that is capable of mining river rock, but will not always be available in a washed variety. Because of the rocks’ large size, it can be rather tough on washing and screening equipment, meaning that a quarry with specialty equipment capable of handling the rocks larger size. This rock is almost exclusively used for landscaping purposes.
We at Twisted Nail Sand & Gravel provide an easy, efficient way for our customers to have their aggregates sourced and delivered. As experts in both the trucking and aggregate sides of your project, we can provide trucking for the materials that you have sourced or can provide fully landed quotes by sourcing the materials that you need. When it comes to quarries and to material delivery, we offer a combination of pit-to-plant, pit-to-jobsite, and pit-to-consumer hauling; this means that no matter where you need aggregate, Twisted Nail and our team of expert owner operators can deliver. We operate in and around Waco, Austin, and Bryan, Texas. We look forward to hearing back from you and are confident that we are the aggregate solution to ensure your job is on time and on budget!
An end dumps carry weight depends heavily on the specific road regulations, the power unit weight, and the composition of the trailer. A steel trailer, typically referred to as a Round Bottom, will be heavier and will have a payload of approximately 21 to 23 tons. By contrast, an aluminum end dump is much lighter and can carry anywhere from 23-28 tons, with some set-ups being able to approach 30-ton payloads.
End dumps are typically loaded by heavy machinery, such as a front-end loader or excavator, or by a series of conveyor belts. End dumps are top load trailers. An owner-operator with an end dump trailer will uncover the trailer via an electric tarp switch in the cab. With the trailer uncovered, the heavy machinery is free to load from the top of the trailer, being careful to evenly distribute the material. Once loaded, the owner-operator flips the tarp switch, covers the load, and continues their run.
There are several different types of hydraulic lifts that are usually part of dump trailers. These include telescopic, dual-piston, and scissor lifts, among others. Most dump trailers use hydraulics to automatically lift the dump box and unload the materials in a quick, seamless action.
An end dump is an excellent investment for owner operators or construction companies that transport bulk aggregate on a frequent basis. Depending on your needs, a steel or aluminum end dump will ensure that you are able to reliable keep your customers jobsites and stockpiles full.
Depending on market timing, a typical aluminum end dump will range between $15,000 to $70,000+, with steel round bottoms priced around $10,000-$50,000+. These trailers are also offered for rent or lease, with trailers available for around $850-$2,000 per month. When renting or leasing, it is typical for all repairs to be the responsibility of the renting owner operator.
Flex base can be an excellent choice for a driveway but is not often used as a primary input in TXDOT construction. Flex base is best suited for farm roads, driveways, RV pads, and for other foundations that will not receive heavy traffic. Flex base is cheaper than most alternative options, such as asphalt or base that meets TXDOT specifications. Additionally, once set and compacted, a flex base road or driveway is cheaper and easier to maintain.
Yes, road base and flex base are the same material family. That said, the differentiating factor is typically the testing results of each material. When shopping for material, it is important to identify exactly what type of material you are buying. Retailers will categorize Base as a broad category and can leave identification to consumers, which is challenging and confusing. In general, if a retailer is selling a Road Base it can be assumed that the material is of higher construction quality than flex base, meaning it will have a wider range of approved uses. However, some vendors will sell Flex Base as a Road Base; this makes it important to understand if the material you are purchasing is a true Flex Base, is ‘Spec 247’, or is TXDOT approved. With each increase in quality comes an increase in cost, so it is important to identify which material will best suit the needs of your project.
Flex Base is a mixture of loose aggregate and coarse aggregate, can be a wide range of color based on source location, and is composed of materials ranging from dirt to rock that are 1”-3” in size. Most Flex Base, particularly around Central Texas, will range from tan to brown, will consist of a dirt material and rocks that range from 1” to 2” in diameter. There are specialty materials that will include rocks up to 3” in size, but these are typically reserved for heavy construction projects.
Any driveway’s depth should be at least 5” to ensure structural integrity and better load capacity. For road base in particular, experts recommend a thickness of 6-8”.
Twisted Nail is here to help. If you need something hauled in central Texas, we can get your job done, safely, timely, and reliably.