Cracking on concrete is unavoidable. There are certain limits of crack width that a structure may have. But it is of serious concern if exceeds the limit. There are several types of cracks such as shrinkage crack, thermal expansion crack, hairline crack, crack due to outright loading, and many more. The root cause of cracking needs to be identified first before adopting any repair strategy.
But concrete cracks can also be avoided if you follow some important rules in the preparation for work on-site such as proper installation of reinforcement, the spacings of rebars must not have wide gaps and proper compaction of concrete. Actually, there are 5 methods to avoid concrete cracking.
Here we discuss the 7 Types of Concrete Crack Repairing.
Grouting is the technique in which white cement or hydraulic cement is filled in the crack. First, the crack is chiseled to identify the actual depth of the crack. Groove made by chiseling is cleaned from small broken particles, dirt, and paint. The grouting material is filled in the groove. When it is set, the surface is sealed with sealing material so that it may not deteriorate or get stain.
In this method of repairing, after cleaning the crack line, small nails are fixed in the cracked line at a regular distance. An injection cord is hung on each nail and the concrete filler is injected. When it hardens, the injection cord is cut. Filler can be injected with pressure. This is how to repair concrete crack with epoxy, it must be followed seriously because failure may occur when done the other way. The injection type is one of the most popular concrete crack repairing ever known.
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Stitching is similar to stapling paper. Two holes are made on each side of the crack and a staple is inserted. Similarly, more staple/fasteners are inserted throughout the length of the crack. This technique is also known as sewing.
4. Reinforcement Addition
If the crack is wide or critical, which may lead to a brittle failure, it is necessary to reinforce it properly. For this, the concrete cover is removed and the surface is cleaned from dust. If reinforcement is rusted, it needs to be cleaned and painted with corrosion-resistant emulsion. Additional reinforcement is drilled where required. Lastly, the surface is re-concreted and plastered. This type of concrete crack repairing is rarely used in construction but it can be also done when agreed by site parties such as consultants and quality managers.
5. Steel Plate and Bolts
Bridges and industrial buildings have severe impact loadings. They are more prone to environmental and hazardous chemicals. Cracks in such structures may lead to strength failure due to creep. Ordinary repairing techniques are not effective for these structures. Steel Plates are bolted or riveted at the locations of crack to strengthen the cracked area.
6. Wire Mesh and Plaster
This technique is useful in areas where there are large numbers of hair cracks. Wire mesh is wrapped or fixed with nails on the cracked surface after cleaning. The surface is plastered again. This is also used in combination with bolts and plates.
7. Fiber Reinforced Polymer (FRP) Strengthening
Fiber Reinforced polymer is the composition of fibers that are reinforced with a polymer matrix. Fiber Reinforced is an excellent retrofitting material that can be used as strips, plates, rods, and spray. FRP is a high strength, durable, light density, and flexible material. FRP wrapping around cracked structure not only prevent cracking but it improves the overall structural strength.
FRP can be used at beam soffits, slabs, and around openings. It is applicable in the areas where other retrofitting techniques are not applicable due to the complexity of the structure. Fiber Reinforced Polymer improves building performance for both gravity and lateral loadings (wind and seismic).
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In order to avoid repairing concrete cracks, you must ensure that the ongoing construction of structural elements on site must be aligned in the approved plans and specifications which I already mentioned in the upper paragraph.