Asphalt Concrete | Asphalt Driveway Vs Concrete | Asphalt Concrete Driveway Installation
What is Asphalt concrete
Asphalt concrete is a composite material that is frequently used to pave highways, parking lots, airports, and embankment dam cores. Since the early twentieth century, asphalt mixtures have been employed in pavement building.
It is made up of layers of mineral aggregate bonded together with asphalt and compacted. Edward De Smedt, a Belgian-American inventor, refined and improved the method.
Asphalt (or asphaltic) concrete, bituminous asphalt concrete, and bituminous mixture are words that are normally reserved for engineering and construction documents that describe concrete as any composite material made of mineral aggregate attached to a binder.
The abbreviation AC is sometimes used to refer to asphalt concrete, although it can also refer to asphalt content or asphalt cement, referring to the composite material’s liquid asphalt component.
Different varieties of asphalt concrete exhibit varying levels of durability, tire wear, braking efficiency, and roadway noise. In general, determining optimal asphalt performance characteristics requires taking into account the volume of traffic in each vehicle category and the friction course’s performance criteria.
Asphalt Concrete Mix Design
Asphalt concrete is a mixture primarily made of mineral aggregates, asphalt binder, and additives that has been widely used in the construction of pavements.
Asphalt binder is believed to have the most significant effects and contributions to the overall performance of an asphalt pavement as an adhesive substance.
Because asphalt binder is temperature-sensitive, it is prone to become soft at hot temperatures and stiff at cold temperatures, resulting in rutting and cracking distresses on the pavement, respectively.
The black exterior of asphalt absorbs a significant amount of heat from sun radiation throughout the summer, which not only causes the high-temperature pavement distress discussed previously, but also aggressively accelerates the severity of asphalt’s thermal and photo oxidation aging.
Additionally, the high surface temperature of pavement exacerbates urban heat island effects, resulting in a slew of negative environmental consequences.
Characteristics of Asphalt Concrete
Asphalt concrete produces less noise on the roadway than Portland cement concrete and is often quieter than chip seal surfaces.
Because tire noise is formed when kinetic energy is converted to sound waves, it increases in volume as a vehicle’s speed increases.
In the early 1970s, the thought that highway design may incorporate acoustical engineering factors, including the type of surface paving, emerged.
In terms of structural performance, the asphalt behavior is determined by a range of elements, including the material, the load, and the surrounding environment. Additionally, pavement performance varies over time.
Asphalt Concrete’s Physical Properties
Asphalt is a water-repellent material with a compact structure that does not dissolve in water. It also has a high degree of flexibility, adhesive ability, and bond force with mineral materials, which contributes to the waterproofing of asphalt concrete.
The term “asphalt stability” refers to the material’s capacity to withstand deformation.
The concrete road will always crack and crumble as the temperature rises.
Unlike concrete, asphalt concrete has the physical properties of asphalt and can tolerate temperatures ranging from 64°C to -16°C.
That is why a driveway made of asphalt concrete is more durable.
Asphalt concrete’s plasticity increases as its composition, temperature, thickness, and stretching speed increase. The higher the elongation, the more plastic the structure.
The term “fatigue resistance” refers to the pavement’s ability to withstand repetitive bending under wheel loads (traffic). Air voids (related to binder content) and binder viscosity both have a considerable effect on fatigue resistance, according to research.
As the amount of air spaces in the pavement grows, either by design or due to lack of compaction, the pavement fatigue life decreases dramatically. Similarly, a pavement that has aged and hardened greatly reduces its resistance to fatigue.
The thickness and strength properties of the pavement, as well as the bearing capacity of the subgrade, all contribute significantly to pavement longevity and the prevention of load-related cracking.
Pavements that are thick and well-supported do not bend as much under weight as those that are thin or poorly supported do. As a result, their fatigue lives are prolonged.
Skid resistance refers to an asphalt surface’s capacity to prevent car tires from sliding or slipping, particularly when wet. Tire tread must be able to retain contact with the aggregate particles rather than riding on a film of water on the pavement surface to provide adequate skid resistance (hydroplaning).
Typically, skid resistance is determined in the field at a speed of 40 miles per hour using a regular tread tire and controlled wetness of the pavement surface. A uneven pavement surface with several small peaks and valleys resists skidding better than a flat surface.
The best skid resistance is achieved with coarse-textured aggregate in a moderately open-graded mixture with aggregates ranging in size from about 3/8 in. to 1/2 in. (10-13 mm).
Apart from having a rough surface, aggregates must be resistant to polishing (smoothing) by traffic.
Compared to siliceous aggregates, calcareous aggregates polish more easily. Unstable combinations that rut or bleed (flush the asphalt to the top) provide significant skid resistance issues.
Asphalt Concrete Density
Density is one of the most important parameters in construction of asphalt mixtures.Asphalt Concrete weighs 2.243 gram per cubic centimeter or 2,243 kilogram per cubic meter, i.e. density of concrete, Asphalt is equal to 2 243 kg/m³.
In Imperial or US customary measurement system, the density is equal to 140.0259 pound per cubic foot [lb/ft³], or 1.2965 ounce per cubic inch [oz/inch³] .
Asphalt Concrete Uses
Asphalt is used mostly in road building, accounting for 70% of its utilization, where it is employed as a glue or binder in conjunction with aggregate particles to form asphalt concrete.
It is also used extensively in bituminous waterproofing goods, including the manufacture of roofing felt and the sealing of flat roofs.
Contractors apply cut-back asphalt for tack coats, fog seals, slurry coats, and as a stability element in mixes, whereas mastic asphalt is used for roof construction and waterproofing of rooftops and underground storage.
Most architects include asphalt into the design of dams, reservoirs, playgrounds, and parks. Asphalt is used by farmers to line the bottoms of retention ponds used for fish farming and cattle containment pens.
Additionally, asphalt is an excellent option for flood management and soil erosion. Automobile manufacturers rely on asphalt to protect the fenders and hoods of their vehicles from rust and road noise.
How Is an Asphalt Concrete Driveway Installed?
Proper installation of the asphalt driveway can be the difference between a driveway that lasts a few years and one that can last up to twenty or even thirty years.
Proper subgrade preparation is critical for a long-lasting driveway. The better prepared the subgrade, the better the driveway.
Drainage design is the most critical component of the grading process. Excavation should be done at a fine grade to ensure proper water drainage.
Here, you should ensure that two things are accomplished:
- Ensure that water drains away from the asphalt.
- Prevent water from pooling and lying on the asphalt’s surface to prevent pavement failures and early deterioration
Prior to grading and paving a driveway, debris such as pebbles or gravel should be removed. Now, remove any soft or unstable material from the driveway, such as clay, sand, or topsoil.
Prior to placing the new hot asphalt, a strong base material such as road base, recycled concrete, or limestone should be installed. This will assist stabilize the subgrade and make the driveway stronger and more lasting.
Construct The Driveway Without a Crown.
Contrary to popular perception, lengthy driveways should not be graded with a crown. Long driveways should be graded flat with a modest pitch on each side to allow water to drain away from the asphalt’s surface.
There is no benefit to building a driveway with a crown. Indeed, crowning can result in premature deterioration and pavement failure.
Crowning a lengthy driveway is also a frequent method for asphalt contractors to defraud homeowners, so avoid crowns at all costs.
Once the subgrade has been graded, it should be compacted using rollers prior to putting the asphalt concrete. Following that, an herbicide should be applied to inhibit vegetation development.
Weeds that grow up through the asphalt can cause irreversible damage and eventually pavement failure, which is why a high-quality herbicide should be applied before to putting the asphalt.
Distribute The Asphalt Concrete
The following step is to lay the asphalt concrete. Asphalt should not be laid by hand but rather with an asphalt paving equipment. This will provide a uniform average depth of asphalt along the driveway, as well as a considerably smoother finish.
Certain regions that are too small for the equipment to access require manual installation, which adds a modest cost to the overall cost.
Asphalt rakers with experience are also a critical component of a properly polished surface.
When asphalt concrete is laid out of the paving machine, it is not yet compacted and hence requires compacting. Compact the asphalt immediately after it is laid out of the paving machine, while it is still hot.
If the asphalt cools too much before being rolled, it will not be compacted sufficiently.
- Inadequate compaction allows water to infiltrate the asphalt, causing it to deteriorate more faster and drastically reduces its life expectancy.
- Inadequate compaction when the asphalt is still hot can cause the asphalt to strain and crack, resulting in premature pavement failure.
Compaction strengthens and protects the edges, making them less prone to cracking and deterioration.
During the grading procedure, some of the subgrade material should be left along the edges so that it may be dragged up to the edge of the asphalt after the driveway is complete.
This creates the appearance of the driveway lying in the soil rather than being spread out on top or exposing exposed edges.
Additionally, this increases the stiffness of both sides, minimizing cracks when the vehicle is driven off the driveway.
After the asphalt is installed, caution tape or cones should be placed at the end of the driveway to prevent people from driving on it until it has cooled completely.
Types of Asphalt Concrete
To meet the performance requirements of various sectors, a wide variety of asphalt mixtures can be used.
Due to the variety of requirements that a road must meet (heavy traffic, adverse weather conditions, etc.), the mix utilized must be sufficiently stiff and resistant to deformation to withstand the applied pressure from vehicle wheels.
On the other hand, they must possess sufficient flexural strength to withstand the cracking generated by the various forces applied to them.
Additionally, good workability during application is critical to ensuring that they are properly compacted for maximum longevity.
The various types include:
Hot Asphalt Mixture (HMA)
Hot mixes are prepared at temperatures ranging from 150 to 190 °C. Depending on the application, a different asphalt combination (Porous Asphalt, Stone Mastic Asphalt (SMA), Asphalt Concrete, Asphalt Concrete for very thin layers, or Double-layered Porous Asphalt) may be employed.
Warm Mixture Asphalt (WMA)
A typical WMA is manufactured at a temperature of between 20 and 40 degrees Celsius lower than an equivalent Hot Mix Asphalt.
Reduced energy consumption and a lower temperature in the mix during paving operations result in improved working conditions for the crew and an earlier road opening.
Asphalt – Cold Mix
Without heating the aggregate, cold mixes are created. This is only possible because of the use of a unique bitumen emulsion that ruptures during compaction or mixing.
After breaking, the emulsion coats the aggregate, increasing its strength over time. Cold mixes are especially recommended for roads with less traffic.
Mastic Asphalt Concrete, or Sheet Asphalt
This is obtained by heating hard grade blown bitumen (i.e., partially oxidized) in a green cooker (mixer) until a viscous liquid forms, at which point the aggregate mix is added.
After cooking (maturing) the bitumen aggregate mixture for approximately 6–8 hours, the mastic asphalt mixer is brought to the job site, where experienced layers empty the mixer and either machine or manually lay the mastic asphalt contents on the road.
Mastic asphalt concrete is typically laid at a thickness of 34–1 316 inches (20–30 mm) for footpath and road applications and at a thickness of 38 of an inch (10 mm) for flooring or roof applications.
Asphalt Concrete Mix Design
The proportions of an asphalt concrete pavement mixture that is suitably compacted are determined in the laboratory during mix design testing.
The laboratory routinely evaluates an asphalt paving mix’s capacity to withstand the potentially detrimental effects of the asphalt binder being stripped from the aggregate particles.
To work successfully in the field, a well-designed asphalt paving mixture must be correctly put and compacted.
Asphalt Vs Concrete
Both asphalt and concrete are made up of a combination of stone and several other materials, which gives them their respective levels of durability and attractiveness. While concrete is commonly used to construct sidewalks and patios, pavers use asphalt to construct roads and parking lots. Both materials, despite their variances, create great driveways.
Which Lasts Longer Concrete or Asphalt?
In general, if correctly placed in a suitable climate and maintained frequently, a concrete driveway should last between 30 and 40 years, and an asphalt driveway should last between 20 and 30 years.Concrete driveways typically outlast asphalt driveways.
Asphalt Driveway Cost Vs Concrete
Asphalt driveways cost between $2.00 and $4.00 per square foot, which is less than concrete driveways. Asphalt prices are subject to price swings in response to changes in the price of crude oil. In comparison, a conventional installation of a concrete driveway costs between $4.00 and $6.00 per square foot. Finishes, details, and stains can add up to $15.00 per square foot to the pricing.
Asphalt Driveway Characteristics Vs Cocrete
- Asphalt is more affordable than concrete.
- Asphalt is a softer substance, which means it deteriorates more quickly and easily than concrete.
- Costly repairs can be avoided with regular upkeep.
- While asphalt lacks the creative design potential of concrete, new innovations have enabled it to be colored or sealed with color tints.
- The material is designed to last 20 years or more.
- It requires resurfacing and resealing on an as-needed basis every three to five years.
- While asphalt requires more upkeep, it is easier to repair than concrete. For these reasons, asphalt driveways are not recommended for busy families with high traffic and heavy use. However, for those looking for a cost-effective option with a clean, sleek appearance, asphalt is the best option.
Concrete Driveway Characteristics Vs Asphalt
- Concrete is more resistant to deterioration than asphalt.
- Due to the material’s reduced flexibility, it cracks in freezing temperatures, prompting many individuals to employ concrete mending materials.
- Concrete is a durable material that can be used for over 30 years.
- All that is necessary in terms of maintenance is the periodic degreasing.
- Resurfacing a concrete driveway provides more design options. It can be imprinted with patterns, colored with various colors, given various finishes, or engraved with designs.
- While concrete is more durable in general, when damage does occur, concrete restoration is more difficult and expensive than asphalt repair.
How are Asphalt and Asphalt Concrete Different?
Asphalt concrete is a type of composite material made up of mineral aggregate and asphalt. After being spread in layers and compacted, it is extensively utilized as driveway pavement.
Asphalt concrete is typically composed of four components: sand, stone chips, 5-10 mm stone, and 10-15 mm stone.
Asphalt is a thick, sticky liquid that ranges in color from dark brown to black. It is derived from petroleum distillation byproduct. Asphalt is a refined product derived from the heavy component of crude oil, not from tar.
Although it is utilized in dam proofing, coatings, paints, and waterproofing, it is primarily employed on roads.
Both materials – asphalt concrete, and asphalt – are commonly employed in road surface.
The asphalt binder, also known as asphalt cement binder or asphalt cement, is a critical component in asphalt concrete; it is the cement that holds the aggregate together.
Asphalt binder is a byproduct of the petroleum refining process, which generates gasoline, diesel fuel, lubricating oil, and a variety of other petroleum products.
Asphalt binder is made from the thick, heavy residue (residuum) left over after petroleum has been distilled to remove its fuels and lubricants.
Although the asphalt binder component normally accounts for around 5% to 6% of the mass of an asphalt paving mixture, it is critical to select the appropriate grade of asphalt (asphalt cement or emulsion) for the traffic and climatic circumstances to which the paving mixture will be exposed.
Several of the more significant features of asphalt cement that are used to differentiate between different types of cement and to determine their quality are as follows:
- Incompatibility — the degree to which the components of polymer-modified asphalt binders phase separate during storage and usage. This separation is undesirable because it results in considerable differences in the binder’s properties and those of the asphalt in which it is utilized.
- Viscosity – a property of asphalt cement that indicates its reluctance to flow at a certain temperature.
- Penetration – a property of an asphalt cement (or emulsion) that indicates its relative softness or hardness at a certain temperature.
- Ductility — a property of asphalt cement that indicates its ability to elongate under tensile stress at a certain temperature.
Concrete Roads vs. Asphalt Roads
Concrete is composed of aggregate (such as crushed rock and sand), cement, and water. In concrete, the cement functions as a binder, binding the material together.
When the mixture dries, it hardens into a stiff, unforgiving solid that is prone to cracking and breaking, even more so if the surface beneath it is not completely smooth.
Asphalt, like concrete, is composed of aggregate. Bitumen, a black, sticky material generated from crude oil, serves as its binder.
When asphalt is used to construct roads, parking lots, and driveways, hot asphalt (bitumen mixed with fine aggregate) is poured onto a bed of heavier aggregate and then crushed into place with a steamroller.
Once the asphalt has cooled to the temperature of the surrounding air, it becomes robust enough to resist automotive traffic. While asphalt is highly hard and resilient, it also has the ability to accommodate flaws in underlying surfaces, something concrete sadly lacks.
In comparison to asphalt roads, concrete roads are extremely durable and environmentally beneficial. Asphalt paving, on the other hand, is far less expensive than concrete paving.
Additionally, an asphalt road gives a slight increase in vehicle safety against snow and skidding.
Asphalt is less expensive than concrete, and it takes less time to construct an asphalt road.
Additionally, asphalt, like concrete, is recyclable, as it can be melted down and repurposed. This is advantageous for individuals who are curious about the expense of asphalt.
Additionally, asphalt is suitable for rural road building and maintenance since certain types of thick asphalt structures are durable and require only surface care.
Numerous advancements in asphalt overlay technology have streamlined and reduced the cost of these solutions for city and rural roads.
While asphalt is more prevalent than concrete, this does not mean it is always the best option. Asphalt roads in areas prone to heavy rains and cold, icy winters suffer deterioration as a result of extreme weather conditions and normal wear and tear.
On asphalt roads, potholes are prevalent. Due of the material’s proclivity for degrading in cycles of freezing and thawing, maintenance teams frequently return the same potholes throughout the season. This might result in greater inefficiencies and expenses over time.