The Process of Installing New Exterior Concrete: From Demolition to Sealing

New exterior concrete does more than improve curb appeal. A fresh driveway gives vehicles a level, durable surface, makes snow clearing faster, and adds usable parking and patio space. The same material produces driveways, walkways, patios, garage pads, steps, and retaining walls, with finishes from broom-finish gray to stamped patterns and exposed aggregate.

The installation process follows a fixed order: demolish the old surface, mark underground utilities, excavate and prepare the base, install forms and reinforcement, pour and finish, then seal. Each stage has a reason, and skipping one shows up later as cracks or settlement. In some cases the old slab can stay, and pouring new concrete over an old concrete surface is possible when the base is sound, though full replacement is the more common route.

Demolish and Remove the Old Concrete

Demolition is the loudest stage of the job. The contractor brings in heavy equipment, typically a skid steer with a breaker or a hydraulic hammer on an excavator, to break the old slab into manageable pieces. The crew loads the rubble into trucks and hauls it to a recycling facility, where it is crushed and reused as aggregate in road base and new concrete.

Recycling beats dumping twice: it keeps thousands of pounds of material out of landfills, and it avoids the tipping fees charged at disposal sites. In many regions, recycled concrete aggregate sells for less than virgin gravel, which keeps project costs down.

What demolition involves

• Disconnect or protect anything attached to the slab: downspouts, light fixtures, irrigation
• Cut the slab with a saw where a clean edge is needed
• Break the concrete with hydraulic equipment or jackhammers
• Load and haul the rubble, keeping the site clean
• Inspect the exposed subgrade for soft spots and buried debris

Replacement vs. overlay

Not every old slab needs to come out. If the existing concrete is level, uncracked, and well drained, an overlay can save the cost of demolition. The old surface must be clean and roughened so the new layer adheres, and the methods for bonding new concrete to hardened concrete determine whether the overlay lasts or delaminates within a few seasons.

Mark Utility Lines Before Any Digging

Every excavation starts with a locate. Underground gas, water, sewer, power, and communication lines run through most front yards, and hitting one is expensive and dangerous. In most regions, a one-call service coordinates the utility companies to mark their lines for free, and the crew waits until the marks are down before any machine moves dirt.

The marks come in standardized colors: red for power, yellow for gas, orange for communications, blue for water, green for sewer. The contractor also checks the depth of the new slab against the depth of the lines, because a base that sits above a shallow utility keeps future access simple.

The one-call process

1. Call the local one-call center a few business days before digging
2. The center notifies every member utility in the area
3. Technicians mark the ground with paint and flags
4. Confirm the marks before excavation starts
5. Re-mark if the marks fade before the crew digs

Mix design and site conditions

While the site is open, confirm the concrete mix. The specified strength, usually 3,000 to 4,000 psi for residential slabs, and the water-to-cement ratio control how the slab performs. The two are linked: concrete strength and porosity move in opposite directions, so a mix that is too wet to place easily can end up weaker and more absorbent, which matters in freeze-thaw climates.

Excavate and Prepare the Base

With the old slab gone and the utilities marked, the crew excavates to the design depth. A typical driveway section is 4 to 6 inches of concrete over 4 to 8 inches of compacted gravel, and the excavation goes below finished grade by the sum of both layers.

Base preparation steps

1. Excavate to the required depth, keeping the subgrade level
2. Remove soft or organic soil and replace it with compactable fill
3. Spread gravel in lifts and compact each layer with a plate compactor or roller
4. Check the grade with a laser or string line so water drains away from the house
5. Moisten the base before the pour so it does not pull water out of the fresh concrete

Machines vs. hand excavation

Skid steers and mini excavators move cubic yards of soil in minutes, which is why most contractors use them even for modest driveways. For tight spaces, side yards, and step locations, crews still dig by hand. Spray-painted lines on the subgrade mark where steps, landings, and different slab levels will go, and the base is shaped to match those levels before any concrete arrives.

Base quality controls the slab’s future. A well-compacted base spreads the load evenly, while a soft spot lets one corner settle and crack. This is also why old concrete often surpasses new concrete in strength when the old slab was poured on a properly prepared base and the new one was not, so do not let a contractor rush the base work.

Install Bracing, Rebar, and Utility Conduits

Before the truck arrives, the crew sets the forms: wood or metal edges that define the shape and thickness of the slab. Stakes and bracing hold the forms at the correct elevation, and the top of the form becomes the screed guide for the pour. Forms must be straight, level, and rigid enough to hold wet concrete without bulging.

Reinforcement

Rebar and welded wire mesh give the slab tensile strength where concrete is weakest. A typical driveway uses 3/8 or 1/2 inch rebar on a grid, placed on chairs so it sits in the middle third of the slab and lapped at the joints. Fiber reinforcement can supplement the steel and helps control shrinkage cracking.

Conduits and protection

If power, low-voltage lighting, or irrigation will run under the slab, the conduit goes in before the pour and is stubbed up where it exits. The crew also protects the house: poly sheeting along the walls and garage doors keeps wet concrete off the siding, and the forms keep the pour inside the planned footprint.

Tools that make the difference

Finishing concrete is equipment-heavy. Power trowels, laser levels, and power screeds speed the work, and the new concrete and masonry tools released each year refine the same tasks. A contractor who invests in current equipment finishes flatter slabs with fewer crews.

Pour, Finish, and Seal the Concrete

Pour day starts with the truck. The concrete is discharged into the forms, spread with rakes, and leveled with a screed pulled across the forms. From this point the clock runs: the crew has a limited window before the concrete sets, and the finishing steps happen in a precise order.

Finishing steps in order

1. Screed the concrete level with the forms
2. Bull-float the surface to close it and bring cream to the top
3. Wait for bleed water to evaporate, then edge and joint
4. Trowel or broom the surface to the specified texture
5. Cure the slab with moisture, curing compound, or wet coverings

Choosing a finish

• Broom finish: brushed texture, the standard for driveways and walkways
• Stamped concrete: patterns pressed in to imitate stone or tile
• Exposed aggregate: top layer washed away to reveal the stone
• Stained or colored finishes: pigments added to the mix or applied after
• Smooth troweled finish: used where a sleek interior-style look is wanted

Curing and sealing

Curing keeps the concrete moist while it gains strength, and the first seven days set the pace for long-term durability. Concrete reaches most of its design strength in 28 days, though foot traffic is fine within a day or two and vehicles can usually park after a week. Sealing happens after the slab dries, and the sealer protects against stains, deicing salts, and freeze-thaw damage.

Curing methods

The three common approaches are keeping the surface wet with soakers or misters, applying a liquid curing compound that seals in moisture, or covering the slab with wet burlap or plastic. All three work; the choice depends on the weather and the crew’s schedule.

Sealer types

Penetrating sealers soak into the surface and protect against salt and water without changing the look. Film-forming sealers add gloss and deepen color, which suits stamped and decorative work. Reapply penetrating sealers every few years and film-forming types when the film wears thin.

Coordinate the Project Around the New Slab

Exterior concrete rarely happens in isolation. A new driveway leads into a garage, a patio sits beside a deck, and a walkway runs to a front door. Plan the concrete early: forms need access, and nothing else on the site should drive over fresh concrete.

Inside the house, the slab becomes the reference for the next trade. If the new pad connects to a living space or a garage that will be finished, the interior work starts from the same level surface, and tasks like installing wooden flooring over a concrete slab depend on the concrete being dry and level first.

On the outside, the same sequencing applies. A new garage pad pairs with garage construction, and installing composition roofing on a new garage often falls in the same project window, so group the exterior trades into one permit where you can. When the concrete is placed, finished, and sealed on schedule, the rest of the project has a stable surface to build from.

Project sequencing checklist

• Order concrete early, since ready-mix plants book delivery windows
• Schedule the locate call before the excavation date
• Protect fresh concrete from construction traffic for at least seven days
• Book the sealer application after the slab cures
• Coordinate with roofers, siding crews, and landscapers on site access