WHY BUILDINGS CRACK (PART 2)

WHY BUILDINGS CRACK(PART 2)

Remedies to the Cracks on your building

The remedies to cracks in buildings are of two categories; one is the preventive measures and another the corrective measures.

a.   Preventive measures: As per the saying “Prevention is better than cure", taking the following measures will definitely lead to you owning a building "Free of cracks".

•    Ensure you engage the services of a qualified and experienced Architect and Structural Engineer at the design stage despite their service charge.
•       There should be a preliminary site investigation by the design team at the design stage. This will help them determine the appropriate type of foundation to be recommended and relevant knowledge of the soil condition of the proposed project site.
•      The design/drawings and specifications so produced must be properly detailed.
•     All material must be of good quality, purchased/procured from certified distributors. On no account should cheap/inferior material be used.
•    Engage a qualified and experienced Engineer/Builder/Contractor during the construction of your building. This will ensure proper interpretation of drawings and specifications and effective supervision at all the stages of the construction.
•      Building owners must desist from making indiscriminate alteration and changing of designs during construction (changing a bungalow design to multiple stories). All alterations must get the necessary approvals from the Architect and structural Engineer respectively.

b.   Corrective measures: when cracks could not be prevented by following the above listed measures, sooner or later various types of cracks will appear on the building.

To correct the cracks, engage an expert Engineer/Builder/Contractor who would:

·        Study the cause of the crack.

·        Observe the characteristics of the cracks.

·        Analyze and categorize the crack.

·        Recommend the most effective solution to the crack.

 Proven methods of curing cracks

                     i.        Epoxy injection:

If cracks are as narrow as 0.002 in. (0.05 mm), it can be bonded by the injection of epoxy. The method generally entails establishing entry and venting ports at close intervals along the cracks, sealing the crack on exposed surfaces, and injecting the epoxy under pressure.

                   ii.        Routing and sealing

This method can be used in conditions requiring remedial repair and where structural repair is not necessary. It involves enlarging the crack along its exposed face and filling and sealing it with a suitable joint sealant. This is a common technique for crack treatment and is relatively simple in comparison to the procedures and the training required for epoxy injection. The procedure is most appropriate to approximately flat horizontal surfaces such as floors and pavements.

                 iii.        Stitching

This method is achieved by drilling holes on both sides of the crack and grouting in U-shaped metal units with short legs (staples or stitching dogs) that span the crack. Stitching may be used when tensile strength must be reestablished across major cracks. Afterdrilling holes on both sides of the crack, the holes are cleaned, legs of the staples are anchored in the holes, with either a non-shrink grout or an epoxy resin-based bonding system.

                 iv.        Gravity Filling

In this method, low viscosity monomers and resins can be used to seal cracks with surface widths of 0.001 to 0.08 in. (0.03 to 2 mm) by gravity filling.  The lower the viscosity, the finer the cracks that can be filled. The typical procedure is to clean the surface by air blasting and/or water blasting. Wet surfaces should be permitted to dry several days to obtain the best crack filling.

                   v.        Drilling and plugging

This method consists of drilling down the length of the crack and grouting it to form a key. This technique is only appropriate when cracks run in reasonable straight lines and are only accessible at one end. This method is most often used to repair vertical cracks in retaining walls.

                 vi.        Overlay and surface treatments

Fine surface cracks in structural slabs and pavements may be cured either by using a bonded overlay or surface treatment. This method is appropriate if there will not be further significant movement across the cracks. Unbounded overlays may be used to cover, but not necessarily repair a slab. Overlays and surface treatments can be appropriate for cracks caused by one-time occurrences and which do not completely penetrate the slab.