Asphalt Driveway Know How

Asphalt Driveway Know How

The most important factor in having a long-lasting driveway is the underlying granular base. It is necessary for this base to have the correct thickness and composition. Base materials can vary in different areas of the country but they are typically compose of crushed stone or recycled concrete and asphalt. Crushed coarse materials like these have jagged surfaces so they compact and lock together tightly. Coarse materials also drain water from under the driveway so ice won't form and crack the asphalt surface.

Once the old driveway has been torn out, examine the existing base and possibly remove or add material. Digging into the exposed base will also tell you its type and thickness. Recommended thicknesses are 8 in. of base over clay soils or 4 in. over well-drained sandy soils. If your base is inadequate, it must be upgraded.

Mechanical compaction of the base, sub-base and asphalt is crucial for a long-lasting driveway. It's recommended that the new base sit for about a week so that natural settling can occur. When compacting sub-bases, a heavy drum roller, plate compactor or similar machine will be used. But when rolling out asphalt, heavy compacting equipment is definitely needed. A contractor typically would use a 1- to 3-ton roller (rental item shown) for compacting the asphalt itself. The edges are raked and formed to 45-degree angles, then packed with a hand tamper. Also make sure that the driveway will have a slope to run water off and away from the surface. Otherwise, pooling water can seep underneath to weaken the soil or cause problems in winter.

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