Two frequently asked questions I get from owners:
- My input sounds hollow… is that bad?
- The sand runs out at the end of my path after it rains… is that bad?
If you have significant voids or gaps between the concrete and the subgrade or if your driveway is on a steep slope, this can certainly be “bad.” Does your drive make a thud when you drive it? Maybe it sways when you walk over it. Can you see between the joints? Are there visible cracks? Does your concrete driveway seem to be slipping? Perhaps the unit has even sagged causing tripping hazards. These are all signs or symptoms that you may be missing some subgrade below the concrete, which is very important to the integrity of your unit.
Four to six inches of sand are placed and compacted, providing base and support for the concrete when it is poured. Sand subgrade can settle if repeatedly exposed to water, creating a small space or void between the bottom of the slab and the sand. Other causes can be incorrect compaction, organic soils or lack of sand. Driveways that are sloping are more susceptible to water erosion and settling because water runs downhill through joints and cracks. Those of you who have this problem know exactly what I mean.
How can I fix this problem on my input?
- Drill and fill voids under the concrete (commonly known as mud lift).
- Seal all joints and cracks with a good quality concrete mastic.
- Redirect downspouts and water that could wash underneath.
How can I prevent this from happening to my drive?
- Seal all cracks and joints with a good quality concrete mastic; this keeps water running over the top from getting under.
- Make sure the water drains away from your unit, preventing it from running under the tile.
- Direct downspouts away from your concrete.
- If you are installing a new unit, make sure the contractor properly compacts the correct amount of sand for your foundation.
Whether it’s a hollow-sounding driveway or a washed-up gritty mess, a reputable concrete repair company can fix it. If you have cracks in your sidewalk, patio, or pool deck, concrete repair contractors can repair them. Typically, a good concrete lifting contractor will have the ability to deal with any of your concrete problems, whether they’re lifting, repairing, or replacing it.