What is Mastic Asphalt?

Mastic asphalt is a building material that is used for paving, roofing and flooring. It is similar to traditional concrete asphalt in that it forms a very dense solid-surface material under average temperature conditions. When exposed to extremely high temperatures, mastic asphalt forms a thick, liquid substance that can be poured or spread over a surface.

The primary difference between mastic asphalt and asphalt concrete lies in each material's level of permeability. Asphalt concrete is fairly permeable under most conditions, allowing some water to seep through. Mastic versions are virtually waterproof, and can be used in applications where moisture-resistance is a primary concern.

The impervious quality of mastic asphalt can be attributed to its high concentration of bitumen. Bitumen is a by-product of petroleum refinement, and is used as a binding agent in asphalt-based products. The bitumen content in mastic mixtures is typically double that found in concrete asphalt, which helps to bind the particles more closely together to keep water out.

In addition to bitumen, mastic asphalt is also made up of aggregate. This aggregate may include sand, gravel, or many other different types of stone products. Polymer compounds and pigments are often added to give the material color or enhance strength and durability. European producers often add a material known as lake asphalt to mastic mixtures. Lake asphalt is a naturally occurring mineral that is similar to bitumen and helps to further bind the aggregate particles together.

Mastic asphalt is used for paving roadways, sidewalks, driveways and parking lots. It is often applied to residential and commercial roofing structures because of its superior waterproofing capabilities. This material may be used to coat floors in factories and other industrial facilities, particularly those subject to frequent spills or high amounts of chemical use. Mastic asphalt is also used to line holding tanks in order to prevent leaks over time.

This material offers many benefits to builders and homeowners. It is impervious to water and most chemicals, and is resistant to damage from pests and insects. It is also very strong and durable, and can be expected to last for decades in many common applications. Like other asphalt products, mastic mixtures are virtually fireproof, and can be easily recycled to avoid negative environmental impacts.

One of the primary disadvantages of this material is that is contains petroleum-based products in the form of bitumen. Bitumen not only has a noxious odor in many cases, but may also produce hazardous fumes long after it is installed. Finally, like all asphalt products, mastic can be difficult to work with due to the high temperatures that must be maintained when spreading this material.