Cement vs Concrete: What Is the Difference?

What is cement?

Cement is a fine gray powder, and the kind used in concrete is portland cement. Per the American Cement Association, it starts as limestone, clay and sand pulled from a quarry, which get ground, blended and run through a kiln where a flame takes the material to about 2,700 degrees Fahrenheit. What comes out is called clinker. A ball mill grinds the clinker with gypsum into the finished powder, about 150 billion grains per pound by their count.

Mixed with water it turns into a paste, and the paste is what sets.

Why people say cement driveway

Mostly habit, and nobody on a job site is going to correct you. When you collect quotes you're pricing concrete either way, and what separates one quote from another is usually the base under the slab and how it's reinforced. For what it's worth, our crews are all in-house.

How does concrete harden?

Concrete hardens because the cement reacts with the water, a chemical reaction, and not because the water evaporates. The ACA's wording is that as the cement reacts with the water it binds the aggregates into a rock-like mass. The same source says concrete keeps gaining strength over time, with most of it developing in the first few weeks after placement.

A slab that looks hard the next morning is still gaining strength for weeks, so the crew will tell you when it's ready to walk on and when it can take a car. Pour-day weather matters for the same reason, and we wrote about why fall is a good window to pour in the Upstate. If you're still choosing a surface, our guide to concrete vs asphalt driveways is the next read.

How strong does concrete need to be around a house?

Cement content and water are what set concrete's strength, and building codes put numbers on how strong is strong enough. Table R402.2 of the 2021 International Residential Code sets minimum 28-day compressive strengths by how exposed a pour is to weather. Foundations and interior slabs that never see weather need at least 2,500 psi at every weathering level. Exposed walls and other above-grade work step up to 2,500, 3,000 or 3,000 psi depending on the weathering category where the job sits. Porches, carport slabs, steps and garage floor slabs need 2,500, 3,000 or 3,500 psi. A note on that same table lets a steel-troweled garage floor drop its air content to as little as 3 percent if the mix is raised to at least 4,000 psi instead. Which weathering column applies on a given lot is set by the jurisdiction's own local Table R301.2.

None of this is a target to aim for, it's the code floor, the least concrete is allowed to be, and South Carolina cities are already enforcing that 2021 edition. Spartanburg's own Building Inspections department says publicly that the city began enforcing the 2021 International Codes, along with the 2020 National Electrical Code, on January 1, 2023, which is the same code edition Table R402.2 above comes from. The American Concrete Institute's residential concrete standard, ACI CODE-332-20, covers this same territory in more depth: it sets requirements for cast-in-place concrete on one- and two-family homes and townhouses, including footings, foundation walls and slabs-on-ground specifically, rather than commercial paving. The full standard and its own strength tables sit behind ACI's paywall, so for the actual numbers a homeowner or contractor works from, Table R402.2 above is the citable source.

Who is actually allowed to pour concrete in South Carolina?

South Carolina licenses two different kinds of residential concrete contractor, and the line between them is dollars, not the type of work. Under the state's residential builder law, anyone who constructs, repairs or improves a residential building or structure, which can include driveway, patio or slab work, needs a residential builder license once a job's cost passes $5,000. Below $5,000 but above $500, the same law treats that work as residential specialty contracting, a category built for trades like masonry and carpentry that the state's separate commercial rules don't reach; the statute does not list concrete as a trade of its own.

Getting a residential builder license takes more than passing a test. State law requires the Residential Builders Commission to issue that license only once the applicant either posts a surety bond of at least $15,000 or gives the Commission proof of financial responsibility it accepts, and the Commission's own registration instructions set a $5,000 bond for a residential specialty contractor once a single job for one property owner tops $5,000 in materials and labor. Workers' compensation coverage is one factor the Commission may weigh when it licenses a residential builder, but state law does not make it a flat condition of the license. Separately, South Carolina's Workers' Compensation Act itself only applies to a business once it regularly employs four or more people in the state, or paid more than $3,000 in total payroll the year before, so a smaller outfit sits outside that law altogether, whatever kind of concrete work it does.

On the commercial side, a different board, the Contractor's Licensing Board, groups driveways, parking lots and sidewalks over $100,000 under a subclassification the state defines as Concrete Paving, which it spells out as covering "the construction, rehabilitation and repair of concrete streets, roads, highways, driveways, parking lots, airport runways and aprons, and concrete work incidental thereto including, but not limited to, sidewalks, curbs, medians, and barrier walls." That subclassification requires the bidding contractor to pass a financial test tied to job size: a Group One general contractor, bidding jobs up to $100,000, needs $20,000 in net worth or $10,000 in working capital on file with the state. None of this tells a homeowner what a fair concrete price looks like, but it's worth asking whoever quotes a driveway or patio which license covers the job, and what it's bonded for.