Concrete – Driveways, Sidewalks & Patios
Residential concrete driveways are usually designed to be at least four inches thick, as thinner driveways are more apt to crack. They must also manage water properly; water should never puddle on the surface or run along the sides of the driveway because this can erode the driveway’s base and damage the structure.
The first step in replacing a concrete driveway is to break up and remove the old driveway. Then, the contractor may put down additional gravel or fill to create a stronger base. With temporary forms in place, the concrete is poured and smoothed, and control joints, shallow grooves made in the newly poured slab, are made. The forms are removed once the concrete hardens. Control joints are key. As concrete sets, it has a tendency to shrink, which results in cracks. Control joints allow the concrete to contract while minimizing fissures in the surface. Due to variability in materials, terrain, and weather conditions, companies cannot guarantee their concrete projects against superficial cracking.
Patios and Walkways
There are a few common methods for incorporating brick, stone, or pavers into a patio or walkway. The first involves pouring a concrete foundation, allowing it to set, and then attaching bricks or stone to the concrete with mortar. The second method involves preparing a sand bed and placing bricks or interlocking pavers directly onto it with no mortar application. Some contractors attempt a third method: placing the bricks or stone on a sand bed and then mortaring between them. This method is not recommended because materials sitting on sand move slightly with normal use, which could break up mortar joints. If you want mortar joints in your patio, insist on a concrete foundation.
Pavers are brick-like pieces of high-density concrete that can be molded by the manufacturer to create many different looks, including cobblestone, brick, and slate. They come in many shapes, sizes, and colors and can be used to either pave an area or simply accent one. Pavers are usually more expensive than standard concrete but less expensive than brick or natural stone.
How Climate Influences Installation
Concrete installation varies slightly based on the different soil types found around the country. For example, in areas of the country with expansive soil—soil that shrinks and expands significantly with changing moisture levels—contractors will need to add anywhere from two to eight inches of crushed gravel to create a solid, even base for new concrete. Contractors working in parts of the country with very dry soil will need to dampen the soil before pouring any concrete. This prevents the soil from leaching water from the wet concrete, which can make the finished concrete structure brittle and prone to cracking.