The ABCs of Concrete
To break it down further, let’s take a look at the “ABCs” of concrete in residential construction:
A: Aggregate and Ingredients
Concrete is composed of four main ingredients: cement, water, sand, and gravel (or crushed stone). These elements combine to form a strong, durable material when properly mixed and placed.
The water-to-cement ratio is critical: Too much water can weaken the mix, while too little can make it unworkable. Ready-mix concrete is commonly used on site for consistency and reliability to achieve an ideal compressive strength of 3,000-4,000 pounds per square inch (psi).
B: Base and Foundations
In most homes, the two most common foundation types are slab-on-grade and stem wall. A stable, compacted sub-base, usually 4-6 inches of granular fill, is essential to support the slab and reduce cracking.
Builders may also include a vapor barrier beneath the slab to prevent ground moisture intrusion. Reinforcing the concrete with steel rebar or welded wire mesh provides additional tensile strength and crack control.
C: Climate Considerations and Craftsmanship
Climate plays a critical role in how concrete performs, both during the pour and in the curing process. In cold regions, a concrete admixture of microscopic bubbles (also known as air-entrained) improves durability and workability and is often used to withstand freeze-thaw cycles and allow the concrete to dry (or cure) at an optimal pace.
In hot or dry climates, hydration—a chemical reaction that causes concrete to harden and gain strength—happens more quickly, which can lead to premature drying and unsightly cracking. In that case, your concrete trades must account for temperature, humidity, and wind when planning pours; timing and technique are critical to ensure a proper cure and long-term durability.