Concrete driveway building in Imperial CA - a slab that stays put on clay ground

The price comes down to the driveway's size, whether an old slab has to be broken out and hauled away, how much ground work your soil needs and the finish you pick. Access for the trucks matters too, and so does any work where the driveway meets the street. I'll walk the job and give you the number in writing, so you're not comparing guesses.

Ask how they'll prepare the ground and how they'll check it, because ground prep guidance says the soil under a slab should be even and well packed, with its moisture and density checked before the pour. Uneven support is linked to cracking and uneven settling. We dig out, pack the base and check it before a truck is booked, and if someone tells you they'll just rake it level, that's your answer.

Clay that shrinks and swells is the usual cause, because expansive clay cracks as it dries and swells again when it gets wet, and uneven swelling under a slab is linked to cracking, lifting and tilting. Clay packed too dry soaks up water later and expands, so guidance recommends packing it a bit wetter than its optimum moisture, the level where it normally packs best. That's why the soil on your lot sets how much ground work we do.

Crews pour early or late to keep fresh concrete out of the worst heat. A hot weather concreting guide lists scheduling the pour for times of day or night when the weather is favorable, and keeping the time from truck to finished surface short. One concrete products maker's bulletin adds that cracks form more easily in hot weather and that adding water to cool the mix or make it easier to work shouldn't be allowed, because it can hurt strength and durability, so a crew hosing extra water into the mix at noon is a bad sign.

They can, because sulfates in soil or ground water can react with concrete and often cause it to break down. Where water carrying sulfates can reach the slab, industry guidance recommends precautions such as cement types known to resist sulfate attack. It's worth raising at the estimate, along with where the water on your lot runs.

California has a concrete contractor license class that covers pavement and flat concrete work, which the trade calls flatwork and which includes driveways. Someone unlicensed can only take a job under $1,000, and only when the work needs no permit and they employ nobody on it. So a crew with helpers that says it doesn't need a license is wrong.