What Is Concrete? Composition, Mixing Process, and Curing Explained

Concrete is one of the most widely used construction materials in the world. It is made from a combination of coarse aggregates—such as sand, gravel, crushed stone, or slag—bonded together with cement and water. Cement acts as a binding agent that adheres to the aggregates and hardens over time, forming a strong, durable material.

Among the many types of cement available, Portland cement is the most commonly used and serves as a key ingredient in concrete, mortar, and plaster.

Forms of Concrete and How It Is Supplied

Concrete can be purchased in several forms, depending on the scale of the project:

• 60- or 80-pound bags for small construction or DIY projects

• Ready-mix concrete, delivered by specialized concrete mixer trucks for large-scale applications

Proper concrete mixing is essential to ensure strength, durability, and uniformity. The mixing process involves carefully combining cement, aggregates, water, and any required additives or admixtures.

Concrete Mixing and Placement

Concrete production is time-sensitive. Once mixed, concrete exists as a viscous fluid and must be placed, poured, and shaped before it begins to harden. Failure to do so can weaken the final structure.

Some concrete mixes are engineered to set rapidly, making them ideal for projects that require fast turnaround times. In contrast, industrial and factory settings often use drier concrete mixtures to produce precast concrete products, such as concrete walls, beams, and panels.

Concrete Curing Process

After placement, concrete undergoes a process known as curing, which is critical to achieving its full strength and durability. Curing is a gradual process:

• Concrete typically reaches over 90% of its final strength in about four weeks

• Strength development can continue for up to three years

Maintaining adequate moisture during early curing stages significantly improves concrete strength. Common curing methods include:

• Spraying curing compounds that form a moisture-retaining film on the surface

• Ponding, where concrete is submerged in water and covered with plastic sheeting to reduce moisture loss

Understanding what concrete is, how it is mixed, and how it cures is essential for producing high-quality, long-lasting structures. Proper material selection, mixing techniques, and curing practices play a vital role in maximizing concrete performance in both residential and commercial construction.