What Causes Cracks & Dips in Driveway Asphalt?

Weak Foundation

• Dips in an asphalt driveway can eventually lead to entire sections sinking and cracking. One of the common causes for this is a weak foundation. If the aggregate base beneath the surface isn't deep enough or properly compacted, underground moisture will eventually wear the rocks down, leaving an open expanse beneath the surface. Without a firm aggregate base to support its heavy weight, asphalt begins to dip.

Frost Heaves

• Frost-heave damage occurs when temperatures drop below freezing, forcing the ground to shift and expand. Asphalt driveways crack when the ground shifts, because the asphalt has no control joints that enable it to expand and contract as necessary. Frost-heave damage is typically minor, but should be patched as soon as possible to keep cracks from spreading. During installation, dig the foundation below the frost line and compact the rocks as much as possible to limit the chances of frost-heave damage occurring.

Stains

• Grease and oil stains leak from vehicles on occasion, but if they're not scrubbed off, these stains eat away at the sealant and asphalt. By weakening the surface, stains make it easier for moisture to penetrate the surface and cause cracks. Use a power washer and asphalt stain remover to wash away stains without damaging the asphalt.

Narrow Foundation

• Unlike with concrete, brick and other types of paved driveways, the gravel foundation of an asphalt driveway should be about 6 inches wider than the surface on each side. This provides a barrier against moist soil, reducing the possibility of cracks forming along the sides. Conceal the additional gravel with edging, sod, mulch or decorative pebbles.