Dr E. Ramanathan PhD
Terrace grouting before applying a crack sealer is essential when dealing with deep, structural cracks or voids beneath the surface. Here’s how and why it’s done:
🔹 Purpose of Grouting Before Crack Sealer
- Fill internal voids, honeycombing, and deep cracks.
- Strengthen the concrete substrate.
- Prevent hidden water pathways below the surface layer.
- Provide a solid base for surface crack sealing and coating.
🔹 Step-by-Step Process
1. Inspection and Identification
- Mark all visible cracks, especially ones >1 mm wide.
- Tap surface to detect hollow-sounding areas (indicating voids).
2. Chasing the Cracks
- Cut open the cracks in V or U shape to expose internal gaps.
- Clean dust, debris using air or water jet.
3. Grouting Application
- Material:
- Cementitious grout (for general terrace use).
- Polymer-modified grout (for better bonding and flexibility).
- Epoxy grout (if structural cracks or high strength is needed).
- Method:
- Mix and inject into cracks using low-pressure gun or manual hand pump.
- Let it fill and settle into voids.
- Cure as per material specification.
4. Surface Sealing
- After grouting is fully cured (24–48 hours typically), apply crack sealer (elastomeric or acrylic) on the surface cracks.
- Ensure a smooth, continuous finish.
5. Proceed with Primer + Waterproof Coating System
🔹 Why Not Skip Grouting?
- Crack sealers only bridge the surface – without grouting, water may still seep under through micro-voids or capillaries.
- Grouting strengthens substrate and prolongs the life of the waterproofing.
