1. CONCRETE REPAIR PROCEDURE
1.1. GENERAL
Repairs to concrete shall be carried out within 24 hours after the removal of forms of
formed surface or placement of concrete for unformed surfaces.
All repaired concrete shall be cured and protected as per specification for Structural
Concrete and Reinforcing ( 0000-15-SPE-0003 )
1.2. INSPECTION AND APPROVAL PROCESS
All defects will require inspections and approvals.
Option 1 will have GCR to use method of repair outlined in this procedure.
Option 2 will require COMPANY engineering to approve corrective action.
1. If the defect is less than 100 cm2 in surface area, GCR engineers are to inspect
at each stage outlined below.

Prior to starting surface preparation

After surface preparation but ptior to repair

Completion of repair

Inspections and repairs shall be documented using ITP form (Structural
Concrete and Reinforcing)
2. If the defect is greater than 40 mm deep and/or larger than 100 cm2 in surface
area, joint GCR and COMPANY engineering inspections will be required.

Prior to starting surface preparation. GCR to advise corrective action and
COMPANY to approve.

After surface preparation but prior to repair

Completion of repair

Request for inspection be COMPANY shall be made using form
(Structural Concrete and Reinforcing)
1.3. APPLICATION FOR STRUCTURAL REPAIRS
Unless otherwise specified or permitted by the Engineer, tie holes, honeycombs, and
other concrete surface defects shall be repaired as outlined below. This shall be done
as soon as practical after form removal, and at such times and in such a manner as not
to delay, interfere with, or impair the proper curing of the fresh concrete.
Patching mortar shall be a free-flowing polymer-modified cementitious coating,
Engineer-approved, equivalent to SIKA MONOTOP 412 NFG or SIKA MONOTOP 612
by Sika
Other pre-packaged grouts, patching compounds and high-strength epoxy may be used
after receiving Company’s approval, Grout application shall be in accordance with
manufacturers recommendations with mphasise on temperature limits.
As an afternative, a patching mortar similar to the concrete mix minus the coarse
aggregate can be used. Do not use more than 1-part cement to 2½ parts sand by damp,
loose volume. Match the colour of the surrounding area.
1.4. GENERAL REPAIR PROCEDURE
1.4.1 FOR CRACKS
Acceptance Criteria:

Crack Width ≤ 0.2 mm:
Acceptable without repair

Cracks Width > 0.2 mm:
Needs to be repaired following below
procedure
In case where there is more than a single crack on a surface, the crack pattern
and the extent of the cracks shall be evaluated in each individual case before a
repair is agreed upon.
Procedure:

Using grinder, run a cut throught the line of the cracks with a depth of 10 mm
minimum.

Clean the line of cracks using steel brush/ paint brush.

Saturate the crack for a period not less than 3 hours.

Mix an amount of Sika Monotop 412 NFG or Sika Monotop 612 with water until
producing a cementitious paste with viscosity enough to seal the cracks. Only full
bags of product shall be mixed i.e no splitting of bags.

Fill the cracks with Patching mix and press using spatula to make sure that
cracks line will be sealed.

Cure using approved curing compound.

After drying clean, the excess by grinding or sandpaper.
1.4.2 FOR HONEYCOMBS
Acceptance Criteria:
All honeycombs are to be repaired.
Procedure:

Identify the portion needed to be repaired and cut the edge of the area using
abrasive disc to a minimum of 10 mm.

Remove the loose concrete and the required level of roughness.

Clean the concrete surface using paint brush.

Saturate the repair area by water for a period not less than 3 hours.

Combine appropriate amount of SikanMonotop 412 NFG or Sika Monotop 612 with
water just enough to provide consistency for plastering. Only full bags shall be
used.

Apply the mix on the affected area giving an even finish. If necessary, formwork
shall be used to maintain profile and add support to repair.

Cure using approved curing compound.

After drying clean, the excess by grinding or sandpaper.
1.4.3 FOR BLOWHOLES/BLISTERING
Acceptance Criteria:

Blowholes larger than 50 mm in diameter or deeper than 15 mm shall be repaired.

All blowholes less than 10 mm in diameter and less than 5 mm in depth shall be
neglected.

Procedure:

Blowholes shall be repaired using the same procedure for honeycombs.
1.4.4 FOR BROKEN-OFF CORNERS
Acceptance Criteria:
All broken-off corners are to be repaired.
Procedure:

Identify the portion needed to be repaired.

Remove all loose concrete on the surface of affected portion.

Cut perimeter to a minimum of 10 mm depth and prepare required roughness to
surface.

Clean the surface to be repaired using paint brush.

Fix the required appropriate formwork.

Saturate the affected portion with water for a period not less than 3 hours.

Combined appropriate amount of Sika Monotop 412 NFG or Sika Monotop 612
with water enough to provide consistency. Use only full bags.

Apply the mixture on the affected portion.

Apply approved curing compound immediately.

Remove the formwork after a minimum of 24 hours after application.

Apply surface grinding or sanding if required.

Block shall not be removed for at least 24 hours after application.