What is the condition of your road?

A careful analysis of the condition of an existing road structure is required to define the optimum maintenance measures. Visual inspection alone will not provide sufficient information for an adequate rehabilitation program.

However, the general condition of a pavement, as well as the location and type of cracks or larger deformations, can be estimated. Identifying the source of damage in the pavement structure is crucial for the successful application of an asphalt interlayer system. In many cases, additional measures, such as drill cores, ground radar, road surface scans, or falling weight deflectometer tests, are used to analyze the road's condition. The images below show typical examples of failures where MIRAGRID^® PGM can be successfully applied. Keep in mind that the images only describe the surface of the road and that in certain cases, an asphalt interlayer might not resolve deeper problems with cracked road surfaces.

What are the expected traffic loads?

Traffic loads can be defined by the number of vehicle passes. Usually, truck loads have the strongest impact on the lifetime of a road. This modeling approach implies many simplifications, such as a standard axle load, typically set at 100 kN, and assumes moderate climatic conditions. It must also be considered that the estimated number of passes is always linked to a certain road structure lifetime and that traffic volumes typically increase during the design lifetime of a road. For simplicity, traffic loads have been categorized by the estimated number of trucks per day for one lane, with an assumed lifetime of 4 to 8 years, as could be the case for a high-volume road. The number of trucks per day is indicative and will vary depending on the road category (e.g., residential street or high-volume road).

What is the thickness of the new asphalt layer like?

Hot mix asphalt can be laid over MIRAGRID PGM and MIRAGRID PGL-G in the normal way immediately after unrolling it. This layer can be a surface course or a binder course. The thicker this layer above the interlayer, the better the stress distribution and load-bearing behavior will be of the whole structure. A thicker asphalt overlay will also contribute more to the crack-retarding effect than a thin layer. However, the layer thickness will depend on economic and geometric constraints. Layer thicknesses of less than 40 mm thickness will require special consideration and care during asphalt installation.

What are the desired functions of the interlayer?

The European Standard EN 15381 defines three functions for asphalt interlayers: stress relief, sealing, and reinforcement.

For MIRAGRID PGM-G products, the functions of stress relief and sealing are fulfilled by a non-woven impregnated with a bituminous tack coat. The purpose of the bitumen-saturated non-woven is merely to "decouple" the upper and the lower (cracked) asphalt concrete. This reduction of tensile stresses helps to increase the lifetime of the newly applied road surface. The function of reinforcement is fulfilled by a grid structure of glass-fiber yarns. If only the reinforcement function is needed, grid structures alone or grid structures with a lightweight non-woven (MIRAGRID PGL-G) are used.