Asphalt, also known as bitumen, is a petroleum liquid or semi-solid material that is sticky, black, and highly viscous. Asphalt is primarily used in road building as a glue or binder mixed with aggregate particles like stone and sand gravel to form asphalt concrete.
When cured, asphalt concrete is considered flexible, as opposed to cement concrete, which is rigid and hard. Since it’s a highly recyclable material, it is considered to be extremely cost-efficient and environmentally sustainable.
What are the different types of Asphalt used in construction?
There are several types of asphalt pavements based on the variants of asphalt used in pavement design. The following are the five most frequent types of asphalt pavements used in construction:
- Hot mix Asphalt (HMA)
- Warm Mix Asphalt (WMA)
- Cold Mix Asphalt
- Cut Back Asphalt
- Mastic Asphalt
Hot Mix Asphalt (HMA)
This is made by combining a heated asphalt binder with dried aggregates. Before mixing, the asphalt is heated to reduce its viscosity, and the aggregates are dried to remove moisture. For virgin asphalt, mixing is usually done with the aggregate at around 150–170 °C. The ratio is usually 5% asphalt added to 95% aggregate particles.
This is the most commonly used variant all over the world for road paving, runway construction, racetracks, etc., due to its resilience to weather, flexibility, and impermeability.
Warm Mix Asphalt (WMA)
When additives like water, zeolites, or waxes are added to asphalt before the heating process, it results in lower temperatures. This translates to lower mixing and layering temperatures, thereby resulting in lesser use of fossil fuels.
A warm mix helps in quicker curing times and frees up the road to resume activities faster. This is used in commercial area paving, driveways, and other residential-type works.
Cold Mix Asphalt
This is made by emulsifying asphalt in water with an emulsifying agent before combining it with aggregate. The asphalt is less dense and easier to deal with and compact when emulsified. After enough water evaporates, the emulsion will break, and the cold mix will ideally have the qualities of an HMA pavement.
They’re generally used in places with freezing temperatures where HMA is not practical. Additionally, they’re also used as temporary patchwork materials for roads until permanent repairs can be made.
Cutback Asphalt
This is a kind of cold mix asphalt made by dissolving the binder in kerosene or another lighter petroleum component before mixing it with the aggregate. The asphalt is less viscous, easier to deal with, and more compact when dissolved. The lighter component evaporates when the mix is poured down.
Because of worries about pollution from the volatile organic chemicals in the lighter fraction, asphalt emulsion has mostly replaced cut-back asphalt.
Mastic Asphalt
This is made by heating hard-grade blown bitumen (partially oxidised) in a green cooker (mixer) until it becomes a viscous liquid, then adding the aggregate mix.
They’re generally used for thicker roads, footpaths, flooring, or roofing applications.
How to choose asphalt?
Different varieties of asphalt concrete perform differently in terms of surface durability, tyre wear, braking efficiency and traffic noise.
In general, the volume of traffic in each vehicle category, as well as the performance needs of the friction course, must be considered when determining optimal asphalt performance characteristics. Asphalt concrete produces less road noise than Portland cement concrete.
Other elements that can influence the spread rate achieved on-site and the overall tonnage required are as follows:
- Variation in level
- The thickness of the project
- Ground conditions
- Compaction and the rollers used.
- Weather conditions and material temperature
See also: Cement calculator: How to calculate the right amount of cement every time?
Asphalt calculator: How to calculate the amount of asphalt required?
When you want to build a road, you’ll need to know the amount of asphalt required for the project. This is achieved using the asphalt calculator.
These are the numbers that are ideal to be taken into consideration
Volume of project
Lightly used driveways and residential roads can be 2 inch, whereas heavily used ones will be 3 inch. For a light vehicle parking space, 4 inch is recommended, whereas, for heavy vehicle parking, 7-8 inch are necessary. In addition to this, the length and width of the project are also required.
Density of asphalt used
The standard density of asphalt is 2322 kg/m3, which will vary according to the type of asphalt used in the specific project.
Once we have the volume and weight, we have all we require.
The formula for calculating the amount of asphalt required is,
Total quantity=Total volume × density of asphalt
Make sure to use the inputs in the same units, i.e., feet with inch and pounds with meter.
FAQs
Is the asphalt calculator accurate?
No. Depending on the difference in materials, conditions, and other factors the value could vary based on different use cases.
What is porous asphalt?
Porous asphalt pavements are primarily used in parking lots, allowing water to flow through the pavement surface into a stone recharge bed and penetrate the soils beneath the pavement. It allows water to drain through it, naturally returning water to the water table and assisting in managing stormwater runoff and drainage issues.
What is the formula for getting asphalt?
Get cubic feet by multiplying length, height and width. Multiply cubic feet by 145 to get the pound of asphalt needed.
What is the density of asphalt?
Density of asphalt can be determined by mix design, density of source rock and geology of the stone used
How is hot mix asphalt tonnage calculated?
Hot mix asphalt tonnage depends on the depth and measurements of the space you want to fill.
What are bitumen?
These are hydrocarbons that are found in oil sands and pitch lakes.
What is asphalt used for?
Asphalt is used for construction of roads, runways, tracks etc.
What are the aggregates that can be used for asphalt mixture?
Crushed rock, gravel etc. are aggregates that can be used for asphalt.
| Got any questions or point of view on our article? We would love to hear from you. Write to our Editor-in-Chief Jhumur Ghosh at jhumur.ghosh1@housing.com |
With 16+ years of experience in various sectors, of which more than ten years in real estate, Anuradha Ramamirtham excels in tracking property trends and simplifying housing-related topics such as Rera, housing lottery, etc. Her diverse background includes roles at Times Property, Tech Target India, Indiantelevision.com and ITNation. Anuradha holds a PG Diploma degree in Journalism from KC College and has done BSc (IT) from SIES. In her leisure time, she enjoys singing and travelling.
Email: anuradha.ramamirtham@housing.com
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