Bulk asphalt supplier South Wales

Asphalt is a mixture of aggregates, binders (bitumen) and fillers, and is commonly used for roads, pavements, bicycle lanes and sports areas. At GD Harries, the aggregates we use come from our own quarries and are a mixture of crushed stone, gravel and sand.

Bitumen is used as a binder to hold all the materials together. Bitumen is a sticky, black, highly viscous liquid or semi-solid form of petroleum.

Asphalt is primarily used for road construction, but it also has various other applications, including car parks, pavements, driveways, runways, and recreational surfaces like tennis courts and playgrounds, It’s incredibly versatile.

Asphalt is used in 96% of all roads in the UK. Different types of asphalt are used to construct a road and can be broken down as follows:

• The surface course, the uppermost layer, spans approximately 25-50mm in thickness. This layer serves as a seamless, skid-resistant, and water-resistant surface, ensuring safe and smooth travel.
• Next in line is the binder course, boasting a thickness of around 50-90mm. This sturdy layer bears the weight of traffic, effectively distributing it across the road’s surface and into the base course. Additionally, it functions as a levelling agent, ensuring the pavement’s uniformity.
• Finally, we have the base course, resting on top of a sub-base, offering essential load-bearing support for the road. As you go down through the layers from the surface to the base, the aggregate size typically increases while the bitumen content decreases, contributing to the road’s strength and stability.

While tarmac is often used as a colloquial term for asphalt, it is a different product. Tarmac (short for tarmacadum) was manufactured using tar and aggregates but hasn’t been used for roads for over 35 years as it subsequently considered a hazardous material.

Yes, asphalt is highly recyclable. Old asphalt pavement or other surfaces can be crushed and reused as aggregate in new asphalt mixtures, reducing the need for virgin materials and conserving resources. Recycling asphalt also helps reduce landfill waste and lowers construction costs. Asphalt recycling is a real success story of the construction industry.

Asphalt is typically produced through a process called hot mix asphalt (HMA) production. It involves heating aggregate materials, such as sand, gravel, and crushed stone, to high temperatures in a rotating drum. At the same time, liquid asphalt binder, derived from crude oil, is heated to a precise temperature and then mixed with the heated aggregates. This mixture is then transported to sites, where it is spread and compacted to form roads, car parks, or other hard surfaces.

Additionally, there are alternative methods such as warm mix asphalt (WMA) and cold mix asphalt (CMA), which involve different production techniques and temperatures to achieve similar results in asphalt production.

Hot Mix Asphalt (HMA) is the most common type of asphalt used for road construction and general paving. The production of HMA includes several stages. Firstly, our aggregates are carefully selected and prepared in order to meet specific requirements in terms of cleanliness and grade. This may involve crushing, screening and washing to ensure they meet our specification. The aggregates are then dried, either in a rotary dryer or a heated drum to remove any moisture content. Heating the aggregates also helps with the subsequent mixing process. An asphalt binder is heated separately to reduce its viscosity and make it easier to mix with the aggregates.

The heated aggregates and asphalt binder are thoroughly mixed together ensuring an even distribution of binder throughout the mixture. Additives can be introduced during the mixing process, which may include polymers, fibres or other materials that will enhance the performance, durability or workability of the asphalt. The subsequent output is known as hot mix asphalt (HMA), which is transported to the construction site while still hot to maintain its workability. The HMA is then spread and compacted using heavy machinery to form a smooth and durable asphalt surface.

Warm mix asphalt (WMA) is similar to hot mix asphalt but is produced at lower temperatures. It incorporates additives or foaming techniques to lower the viscosity of the asphalt binder, reducing the energy required for mixing and compaction. WMA offers environmental benefits by reducing energy consumption and greenhouse gas emissions during production.

Cold mix asphalt (CMA) is produced without the need for heating. It typically contains emulsified asphalt, which allows it to be mixed and compacted even in colder weather conditions. Cold mix asphalt is commonly used for temporary repairs, patching and pothole filling.

Permeable or porous asphalt surfaces can be used to manage stormwater effectively. It is made with larger particles of aggregate which allow water to infiltrate through the surface. This is good for use with pavements, allowing water to pass through the asphalt layer, reducing surface run-off.

Asphalt emulsion is a mixture of asphalt binder and water, stabilised with an emulsifying agent. It is commonly used in surface treatments and repairs, such as chip seals and slurry seals, to protect and rejuvenate existing asphalt surfaces. It is a cost-effective solution to preserve and maintain asphalt surfaces.

An asphalt concrete overlay is used to restore the condition of an asphalt road. It involves applying a new layer of asphalt over the existing surface to improve the condition and ride quality. The thickness of the asphalt overlay will depend on the condition of the road being treated.

Cymru Quarry Group supply a range of bituminous materials and we can also prepare a product to your exact specification.