Case 3

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Remedial (see also Remedial)

Some of the measure to remove water ponding:

  1. Add Roof Drains. Roof drains can be added to remove water from impacted areas.
  2. Add Taper Systems. Rainwater on impacted areas can be diverted by adding tapered “crickets” (Figure 3.17).
  3. Redundant Membrane Layer. If it is not economical to re-work an impacted drainage area, the damages can be reduced by the application of redundant layer of membrane and flashing, in order to reduce the possibility of cutting or puncture.

Repairing

Begin patching the defect by first cutting across its face with a sharp utility knife. Once the affected area has been opened, check the inside to make sure that there is no water present. If water is present, make sure the area must be dried, either by leaving the blister open and letting the sun dry the area or by using a portable hair dryer.

When the area is completely dry, use a small putty knife to force roofing cement under both sides of the cut. Next, press the cut edges of the blister down into the roofing cement until they lie flat. Then apply a good coat of roofing cement over the top of the cut. Before this dries, cut a patch (from rolled roofing material) large enough to extend 50 mm beyond the orginal cut.

Press this patch down into the roofing cement and nail it into place, spacing the nail about 50 mm apart. The last step is to cover all of the exposed nailheads with a coat of roofing cement. Some professional roofers will also give the edges of the patch an additional coat of the cement.

The concrete where the crack occured is hack off. More thermal joints are added to accomodate the stresses bulit up in the concrete panels due to expansion and contraction forces.

  • It is important to determine if the cracks are live or not.
  • Live cracks must be treated as movement joints whereas dead cracks can be grouted or covered over [1].
  • If the cracks are only at the surface, cosmetic repair methods can be used, such as:
  • These repair techniques are limited to dormant cracks. The two most commonly used methods for non-structural cracks are epoxy injection and pressure grouting. The last two methods are used for active cracks. This means that these cracks will continue to grow and if arrested at its present location will propagate at another location.
  • Flexible sealing not only seals the crack but also allows continued movement at the location by allowing the crack to function as a movement joint. Stitching, on the other hand, does not close the crack but but prevents it from growing further.
  • For cracks that are less fine (less than 0.2mm wide) and hidden from public view, the process or autogenous healing should be allowed to take place. Autogenous healing relies on the inherent ability of the concrete to heal itself, it is applicable for closing dormant cracks in moist environment. Concrete repair by stitching is able to aid in autogenous healing of concrete.
  • Materials that can be used are as follows:
    • Cements – ordinary or rapid hardening Portland cement
    • Epoxide resins
    • Polyester resins
    • Rubber latex
    • Polyvinyl acetate
    • Surface Penetrating Sealants