REPAIR METHODOLOGY FOR MINOR CRACKS OBSERVED ON TOP / SOFFIT OF ROOF SLAB
1. Safety Precautions
a. For soffit repairs, proper scaffolding shall be ensured to be in place.
b. All workers undertaking the repair works shall wear adequate PPE.
c. The work area shall be isolated from construction materials (rebars etc…) and
live utility services.
2. Assessment and Preparation
a. The cracks shall firstly be inspected to determine the width, depth, and
possible cause.
b. The affected area shall be marked by outlining the crack with chalk / market
(extending 100mm beyond the visible damage).
c. The concerned surface shall be cleared by removing loose concrete using a wire
brush, or if more severe, using a chisel.
3. Crack Repair Preparation
a. The cracks (<3 mm) shall be widened into a V-groove (at 45-degree angle, about
10-20mm deep) using a grinder or chisel to improve mortar bonding.
b. For active cracks, stitching rods or epoxy injections (as per manufacturer’s
instructions) before mortar application.
c. The surface shall then be dampened to prevent rapid drying of the repair
mortar.
4. Application of Bonding Agent
a. A bonding agent, Epidermix 344, shall be applied to enhance adhesion.
5. Repair Mortar Application
a. A cementitious repair mortar, Sika Rep SA, shall be mixed as per the
manufacturer’s instructions.
b. The cracks shall be filled with the repair mortar using a spatula, trowel or putty
knife, while pressing firmly to eliminate voids.
c. The repair mortar shall be applied while the bonding agent (Epidermix 344) is
still wet. If the thickness to be applied exceeds 30mm, the repair mortar shall
be applied in layers in layers 10-15mm thick.
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d. As soon as the repair mortar has started to set, it shall be smoothed to match
the surrounding concrete using a wooden or synthetic float.
6. Curing
a. The repair mortar shall then be cured, after final setting, using light water
fogging / spraying for 48 hours.
7. Finishing & Protection
a. If a finer finish is required (as per the Architect’s requirements), SikaMonotop
625 Fine shall be applied over the cured repair mortar.
8. Post-Repair Inspection
a. Shrinkage cracks shall be checked visually after 24-48 hours (although this is
not expected when using Sika Rep since the latter compensates for shrinkage
losses).
9. Waterproofing
a. Following a conclusive flood test, a double-layer waterproofing membrane
shall then be applied on top of the roof slab.
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