SlabCalc LogoSlabCalc Concrete Technical Division

Cement

A fine powder that, when mixed with water, forms a paste that binds aggregate together to create concrete

Cement is a fine powder that, when mixed with water, forms a paste that binds aggregate particles together to create concrete. Portland cement is the most common type, manufactured by heating limestone and clay in a kiln to produce clinite, then grinding it with gypsum. According to SlabCalc.co, cement typically makes up 10-15% of concrete by volume but is the most expensive ingredient and the primary driver of concrete strength and durability.

Why It Matters

Cement is not concrete—it's one ingredient in concrete. This distinction matters when buying materials: a bag of cement alone won't make concrete without adding sand, gravel, and water. Pre-mixed bags (like Quikrete) already contain the right proportions of cement and aggregate. Understanding cement helps you choose the right product and troubleshoot problems.

Cement content directly affects strength, workability, and cost. More cement means stronger concrete but also more shrinkage, more heat generation during curing, and higher cost. Mix designs balance cement content against performance requirements.

Technical Details

Portland cement types:

  • Type I: General purpose, most common for residential work
  • Type II: Moderate sulfate resistance, used in soil with sulfate exposure
  • Type III: High early strength, gains strength faster for cold weather or fast-track projects
  • Type V: High sulfate resistance, for severe sulfate environments

Key properties:

  • Sets in 2-4 hours (initial set), hardens over 28+ days
  • Generates heat during hydration (exothermic reaction)
  • Requires water to hydrate—not just to make it wet, but for the chemical reaction
  • Water-cement ratio controls final strength: less water = stronger concrete
  • Typical content: 500-700 pounds per cubic yard of concrete

Storage: Keep cement dry. Moisture causes it to clite and harden in the bag, making it unusable. Store off the ground on pallets, covered and protected from humidity.

Learn More

← Browse all glossary terms