Steel slag may be processed into coarse or fine aggregate for use in dense and open-graded hot mix asphalt concrete pavements (1,2,3), as well as cold mix or surface treatment applications. The density of the product depends on the amount of air voids present in the material. Cold mix asphalt products are used primarily as surfacing materials such as roofing granules, while hot mix asphalt products are used as binders for road construction and maintenance.
Slag can be used instead of gravel in driveway and parking lot applications. It's also used as a filler in low-profile roads and cross-country courses. When used as a filler, it's usually mixed with sand or stone to increase its weight so that less is required of each truckload delivered. Slag has many other uses as well; for more information, see our slag page.
Yes, if you want an asphalt pavement that will last longer, look better, and require less maintenance, then using slag instead of gravel in your asphalt pavement projects should be considered.
However, keep in mind that slag is made up of silicon and oxygen, while asphalt is made up of carbon, hydrogen, and nitrogen.
Steel slag is not just useful for roadways; it is also utilized as a landscaping stone in back yards surrounding pool areas or patios by homeowners. Steel slag is a tough and long-lasting aggregate that is ideal for covering parking lots. The steel inside the slag has been used over time to create decorative effects on roadways, while the exterior is still capable of withstanding heavy vehicle traffic.
In addition to being useful for building materials, steel slag can be employed as an industrial waste product. This resource recycling method reduces the amount of material ending up in landfills while at the same time providing an alternative use for an otherwise undesirable substance.
Slag may contain metals such as calcium, magnesium, potassium, and silicon. These elements are important for plant growth, so using steel slag as a garden additive is an effective way to add these nutrients to your yard. Slag has a gray color which comes from the inclusion of aluminum oxide and iron oxide within the steel structure when it was produced. However, over time this mixture will break down under sunlight and weather conditions into its original components: silicon, calcium, magnesium, and oxygen. These elements are then available for plant uptake.
The quality of steel slag varies depending on how it is produced. For example, steel slag generated from blast furnace processes contains more calcium and less iron than that derived from an electric arc furnace.
Most people are unaware of the existence of slag as a driveway material. Steel slag is a result of steel mill smelting and is made up of byproducts of the process such as silicon dioxide, elemental metals, metal oxides, and metal sulfides. Slag can only be used as a driveway material in limited areas due to its color (black) and composition (steel). However, it is available at most asphalt yards for use as an additive.
People often ask me why I choose not to use blacktop or other traditional driveway materials. The answer is simple: durability. Blacktop wears out over time due to traffic loads and weather conditions. By using slag instead, my driveway will last longer and require less maintenance.
Slag is also environmentally friendly because it does not go away anytime soon like many other materials do. At the end of its life, slag can be recycled just like steel shavings or rock. Recycling slag helps save landfill space and reduces our dependence on foreign oil.
Finally, slag is inexpensive. You can buy bags of it at most asphalt yards for $15-$45 per ton. That's less than half the price of blacktop!
Not only is slag more durable, it's also eco-friendly and affordable.
Slag cement is the most often used cementitious component in concrete, either as a standalone cementitious component or as part of a blended cement. It works in tandem with Portland cement to improve strength, minimize permeability, resist chemical assault, and prevent rebar corrosion. Slag has higher alumina content than Portland cement, which results in a concrete that is more resistant to acid attack.
Slag can be used instead of Portland cement if acceptable results are needed for other properties of the concrete. For example, if adequate compressive strength is not required or if low heat release is desired, then using slag would be a suitable alternative. However, due to its high aluminum content, slag requires greater amounts of cement to produce an equal volume of concrete. This means that less-dense materials such as soil should be used as aggregate when making concrete with slag so that it has enough weight to be useful.
Slag also increases the abrasion resistance of the concrete. This is beneficial because most roads are subjected to some form of abrasive wear. The aluminum oxide in slag creates a protective layer on the surface of the concrete that reduces its sensitivity to cutting fluids and acids used by drivers on car tires during maintenance procedures. The aluminum also adds mass to the concrete, which improves its resistance to impact damage.
Finally, slag lowers the pH of the concrete environment.
Asphalt concrete pavement mixtures are generally made up of 5% asphalt cement and 95% aggregates (stone, sand, and gravel). Asphalt cement, due to its high viscosity, must be heated before it can be combined with aggregates at the asphalt mixing plant. Heating asphalt cement lowers its fluid content so that it can be mixed with aggregate.
Asphalt cement becomes a liquid at temperatures between 120° and 140°F. The heating process also breaks down some of the larger molecules in the cement, allowing them to combine with other molecules. This produces more uniform particles that are less likely to cause dust problems when they are mixed with other materials.
Asphalt mixes may also include crumbly bits of hardened asphalt called macadam. These stones are harder than granite and come from different sources than the base course. They are used to create a rough surface that helps vehicles gain traction when driving on hot days or when it has rained recently. The macadam is usually about 1 inch (2.5 cm) in diameter and comes in white, gray, or black.
Roads are typically built using an array of small pieces of asphalt known as bitumen chips. These chips are placed on the ground and then rolled out by a vehicle called a roller. The roller smoothes out the bitumen and packs it into the cracks between the stone chunks.