Concrete around Ocala holds up when the sand beneath it is ready

Sand on top, limestone below

A concrete slab behaves like a stiff board laid flat on the ground. It can carry a lot of weight as long as the ground beneath pushes back evenly. Take support away from one area and the board has to span the gap, and concrete is weak when it bends. A crack forms along the line where support changed, which is why so many local driveways have a single crack running across them a few feet out from the garage.

Around Ocala, that ground is usually sand. In many places it is fine and pale and runs deep; in others it is mixed with pockets of clay or darker organic soil, especially in low spots and on old pasture. Sand has real advantages. Rain soaks through it quickly instead of sitting under the slab, and it does not swell and shrink the way heavy clay soils do in other parts of the country. Its weakness is that loose sand compresses. Fill that was pushed around during home construction, or a trench that was backfilled without packing, keeps settling for years under the weight of a slab and the cars on it.

Below the sand lies limestone, the same rock that feeds Silver Springs and the clear rivers to the west. Water slowly dissolves that rock, and sinkholes are a known feature of the region. The vast majority of driveways and patios are never affected. Even so, a dip in the yard that keeps deepening or a spot where rain vanishes unusually fast is worth mentioning before anyone lays out a new slab over it, and a geotechnical professional, not a concrete contractor, is the right person to judge what is going on.

Heat, humidity and the daily summer storm

Central Florida concrete never deals with freeze-thaw cycles or winter road salt, which removes one of the biggest causes of surface damage seen in colder states. The pressures here are different. The first is heat. On a summer morning, the top skin of a new slab can dry out well ahead of the concrete under it, which leaves a weak, dusty top layer and fine surface cracks. That is why warm-season pours often begin at first light and why curing, using a sprayed compound, wet coverings or both, matters so much.

The second is water. From late spring through early fall, afternoon thunderstorms drop a lot of rain in a short time. On a flat lot with no planned slope, that water sits on the slab or runs back toward the house. On a sloped lot, it follows the edge of the concrete and carries sand away with it. A slab that sheds water in a controlled direction, onto grass or toward a swale, lives far longer than one that lets runoff choose its own path.

Humidity adds a third concern: mildew, algae and staining. Shaded patios, north-facing walks and pool decks can turn green or black in a single wet season. Good drainage, a suitable sealer and occasional cleaning keep that under control. Hurricane season rounds things out, mostly by moving dates on the calendar rather than by harming slabs that are already in place.

What happens before the pour decides how long it lasts

Two driveways can look identical the week they are finished and very different a decade later. The difference usually comes from work that disappears under the concrete, which is exactly why it should be spelled out in a quote before anything is poured.

Clearing and compaction

Roots, sod, organic soil and soft pockets should come out. The base, whether crushed stone or clean fill, should be moistened to the right degree and compacted in layers with a plate compactor or roller. On sand, this single step does more to prevent settlement than almost anything else on the list.

Thickness matched to the load

Patios and car driveways are commonly about four inches thick. Pads for RVs, boats on trailers, horse trailers, farm equipment or heavy work trucks are often thicker, and the strips where wheels climb onto the slab often get added depth. A quote should say what thickness is planned and where it changes.

Joints on a plan

Concrete shrinks as it cures, so some cracking is expected. Control joints give that cracking a straight, tidy place to happen. Panel size is usually tied to slab thickness, and joints must be cut deep enough and soon enough to work. Ask to see the joint layout on a sketch.

Reinforcement held at the right height

Wire mesh, rebar and fibers keep any cracks that do form closed and flush, yet no reinforcement makes a slab crack-proof. Steel lying on the ground under the slab does very little, so ask how it will be supported during the pour. Near the Gulf coast, the depth of concrete covering the steel deserves extra attention.

Curing, slope and edges

The slab should keep its moisture for the first days of hardening. The finished surface should fall away from the house. And the sand along the edges should be covered with sod, mulch or a graded shoulder soon after the forms come off, so the next storm does not wash the support out from under the edge.

Request an estimate visit

Send the property address and a short note about the project: a new slab, a replacement, or concrete that has cracked or sunk. A reply will follow to arrange a visit.

Six kinds of residential concrete work

Most homeowner projects fall into a handful of categories, and many combine more than one. A new driveway often comes with a front walk. A patio may connect to a lanai or step down from a sliding door. Stamped patterns, stains and textured coatings can dress up most of them, though every decorative surface brings some maintenance along. Fixing or replacing old concrete is its own category, since the opening question is whether the slab you already have can be rescued.

What to have ready before the estimate visit

A few details shared up front make the first call shorter and the site visit more useful. None of this is required, and rough answers are fine.

• The address, and whether a homeowners association or community review board approves exterior changes.
• What you want built or replaced, and roughly how large. Pacing it off is close enough for now.
• What the slab will carry: cars, a golf cart, a work truck, an RV, a boat, a horse trailer, a hot tub or patio furniture.
• What is there now, such as grass, shell rock, gravel, pavers, an old slab or asphalt, and whether it needs removing.
• Where storm water runs and puddles today, including gutters and downspouts that empty nearby.
• Big trees close to the work area, especially live oaks, whose roots spread a long way from the trunk.
• How a mixer truck would reach the spot, since gates, septic drain fields, wells and soft lawn all affect access.

If the work touches the road, such as a new driveway connection, a culvert or a change to the roadside swale, find out from the city or county what sign-off is needed, and ask your association what it expects as well. The answers vary by address, and getting them early prevents a delay later.

How a project usually moves from request to finished slab

After you send a request, a site visit is arranged, and that walk around the property is where the real scope gets settled. Standing on the lot shows the soil, the slope, the trees, where water runs after a storm, why an old slab failed and how equipment can get in. Plenty of projects that seem straightforward in a picture end up calling for more base, a drain or a revised layout after an in-person look.

The contractor then writes up an estimate. A useful one lists the area, thickness, base material and compaction method, reinforcement, joint layout, finish, any demolition and hauling, and which way water will leave the slab. Compare estimates line by line. When two numbers for the same yard are far apart, they are usually describing different work, and the written scope shows where.

Once you decide to go ahead, the pour date is picked around the weather. In summer that often means an early start to beat the heat and the storms; during an active stretch of hurricane season it can mean waiting a few extra days. After the pour, people can usually walk on the slab within days, while vehicles wait longer, and the contractor gives exact timing for that particular slab.

Where requests come from around Ocala

Most requests come from Marion County and its two neighbors to the south and west. Horse farms, retirement communities, older in-town streets and coastal lots all sit within a short drive of each other, and soil, drainage and community rules can differ from one street to the next.

Ocala concrete questions, answered plainly