Grout is a fluid, free-flowing mortar of cement, water and usually a fine aggregate or admixtures, used to completely fill or inject voids, joints and gaps. Because grout is thin enough to flow everywhere and shrinks little as it sets, it creates a fully filled, load-bearing connection.
Properties
Good grout is characterised by:
- High flowability — fills even narrow and hard-to-reach voids
- Low shrinkage or slightly expansive — avoids voids and ensures full contact
- High final strength — transfers the load once set
- Adjustable setting time — matched to the application
Applications
Grout is widely used in building and structural work, including for:
- Bedding steelwork — filling the gap between a steel column base plate and the foundation, so the load is transferred evenly
- Bedding precast elements — filling the joint beneath precast walls and beams
- Anchors and dowels — fixing bars or bolts into drilled holes
- Injection into ground and masonry — filling cracks, voids or pores to strengthen or seal
- Tile joints — although for tiling the word “tile grout” is more common
For structural work a factory-blended, non-shrink grout is often used, with guaranteed strength and flowability. The correct water-cement ratio is decisive: too much water lowers the strength.
Related terms
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