Grout
A fluid mixture of cement, sand, and water used to fill gaps, anchor bolts, or seal joints
Grout is a fluid mixture of cement, sand, and water used to fill gaps, anchor bolts, seal joints, or repair cracks. More fluid than concrete or mortar, grout flows into small spaces and voids, then hardens to provide structural support or create a seal.
Why It Matters
Grout fills spaces concrete can't reach. Anchoring bolts in holes, filling hollow masonry cells, sealing under base plates—grout flows into position, then hardens to transfer loads or prevent water infiltration. For concrete repair, grout fills thin cracks and small voids where normal concrete won't flow.
Different grout types suit different applications. Crack repair grout differs from structural grout differs from tile grout. Using the right grout type for each job ensures proper performance and durability.
Technical Details
Common grout types:
Cementitious grout:
- Sand-cement mixture for general purpose
- Fine grout (no sand) for cracks under 1/4 inch
- Coarse grout (with sand) for gaps over 1/4 inch
- Shrinkage compensated types for structural applications
Epoxy grout:
- Two-part adhesive system
- High strength, chemical resistant
- Used for machine bases, chemical exposure areas
- Higher cost, requires precise mixing
Resin-based grout:
- Polymer modified for improved properties
- Better adhesion and crack resistance than plain cement
- Common for tile and decorative applications
Grout strength varies from 2000 PSI (non-structural) to 10,000+ PSI (high-performance structural). For crack injection, viscosity matters more than strength—ultra-low viscosity grouts penetrate hairline cracks effectively.
Application tips: Remove loose material first, dampen surfaces, fill completely without voids, cure properly to prevent shrinkage cracks.
Related Terms
- Mortar - Similar material but stiffer consistency
- Cement - Primary binding ingredient in grout
- Filling - General process of filling voids
Learn More
- How to Repair Cracks - Using grout for crack repair
- Concrete Basics - Understanding cement-based materials
- Concrete Calculator - Calculate project volumes