Learning Center · Basics
Concrete Basics
What concrete actually is, how it gains strength, and the vocabulary you'll hear on a quote.
Almost every bad concrete experience starts with a misunderstanding rather than a mistake. Someone assumes concrete dries like paint, or that a crack means the job failed, or that a higher number on a quote means a better slab. None of those are true, and all of them are fixable with twenty minutes of reading.
This category covers the fundamentals: what concrete is made of, what actually happens in the twenty-eight days after a pour, what PSI and slump and aggregate mean, and how to read the specification on an estimate so you can tell one quote from another.
You don't need any of this to hire a contractor. But knowing it is the difference between accepting a number and understanding what you're buying.
Every guide in Basics
Most readWhat is concrete?
What concrete is actually made of, why it isn't cement, and what happens chemically between the pour and thirty years later.
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Most readHow long does concrete take to cure?
When you can walk on it, drive on it, park heavy loads on it, and seal it — with the reasoning behind each number.
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What does PSI mean?
What the strength number on your estimate actually measures, which PSI each application needs, and why higher isn't automatically better.
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Pouring in winter
What cold and rain actually do to a pour, when it's fine to go ahead, and when waiting is the right call.
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Concrete slab cost
Installed concrete prices by project type, what's inside the number, and why a contractor's price per square foot isn't the price of concrete.
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Rebar vs wire mesh
What reinforcement actually does in a slab, when rebar beats wire mesh, and why placement matters more than which one you choose.
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Control joints
Why concrete has lines cut into it, how far apart they should be, how deep, and what happens when they're cut too late.
Read the guide3000 vs 4000 PSI
What 3000, 4000, and 5000 PSI concrete mean, where each is used, and why the right strength depends on the job — not 'stronger is better.'
Read the guideConcrete Basics: What Every Property Owner Should Know
Concrete is a mix of cement, water, sand, and crushed stone. Cement and water react in a process called hydration, forming a paste that binds the sand and stone into a solid mass. It doesn't harden by drying out — it gains strength chemically, which is why new concrete is kept moist while it cures and why it reaches its specified strength at 28 days.
Strength is measured in PSI, pounds per square inch of compressive load. Residential patios and walks typically use 3,000 PSI, driveways 4,000 PSI, and commercial work 4,000–4,500 PSI or more. But strength is only one part of a durable slab. Base preparation, slab thickness, reinforcement placed in the middle of the slab, control joints cut on time, and proper curing decide whether concrete lasts 30–50 years or cracks and settles early.
The guides in this section explain those fundamentals in plain English — what's actually in the mix, how long curing takes, what PSI numbers mean, how reinforcement and joints work, and what a slab really costs. They're the background you need to read a quote critically and ask the right questions before any work starts.
Concrete Basics: Common Questions
More guides beyond Concrete Basics
All topicsPlanning a concrete project?
Free written estimates across San Jose & the greater Bay Area — with the specification stated, not just a price.