Soil preparation is among the most important elements of a successful concrete project.
Under ideal circumstances, the soil would be properly leveled and compacted to provide the best possible substrate for a concrete pour.
However, life isn’t always ideal. If the ground can’t be made level and compact, will a concrete pour fail? Not if it’s done right. Here are some elements to consider:
Soil disturbances. The more you disturb the soil, the more likely it is that you’ll experience settling and compacting, which could result in cracked and failing concrete. If you’re on a slope, do your best not to disturb the ground underneath your concrete pour without properly compacting it.
Speaking of soil disturbances, you’ll also want to be careful to ensure that water runoff does not undercut your concrete or otherwise erode the soil under or around your pour.
Dig deeper: How to perform a concrete slump test.
Concrete thickness. Concrete is not a terribly liquid material, but you’ll nonetheless want concrete with a low slump factor — likely 3 or lower — to maximize your success on a slope. A concrete’s “slump” factor is essentially a measurement of its runniness, which is dependent on its water content. If your project involves a path over a sloping hill, you’ll want low-slump concrete to ensure that it doesn’t just run to the bottom of the path.
Here at Custom Concrete Contracting, we do a fair amount of work on uneven surfaces, including on sloped driveways and paths. Whatcom and Skagit counties are, after all, quite hilly places. This sloped concrete driveway in Bellingham featured a mix of stamped traditional concrete and pervious concrete.
Rebar use. The use of reinforcing steel, or rebar, can help mitigate the hazards posed by sloping subgrades. One this Whatcom County step pour, for example, Custom Concrete’s crews made good use of rebar to help hold the entire structure together.
Also, when pouring stairs on a slope, it’s critical to remember that the concrete must be sufficiently strong even at its weakest point. On this pour, we ensured that no area of concrete was thinner than 6 inches.
Another Bellingham step installation project included a water runoff trough alongside the concrete stairs.
Dig deeper: All about rebar.
Expansion joints. If your concrete project includes several different grades — perhaps a flat portion of the driveway that connects with a sloped area, for example — it’s important that expansion joints be placed at the junction. This hilly driveway project in Whatcom County is a great example.
Cracking is natural in concrete, so it’s important to place joints in the areas where you want or expect the cracks to occur.
If your project is on a sloped or hilly site and you want to ensure that it is done right — the first time — please give Custom Concrete Contracting a call.