Take this lesson to heart with any concrete repair, and you'll be off to a good start. First, find out what caused the damage, make the necessary preparations to remove unusable concrete and contamination, and then install a repair designed to solve the problem.
The worst thing you can do is make a repair that won't last. Someone once told me that more than 50 per cent of concrete repairs fail again within two years.
Concrete deterioration can be due to corrosion, structural damage, water infiltration, seismic activity, or many other reasons. That is not a track record that inspires confidence. Years of research and practical experience have enabled Sika to develop a complete solution for restoring and rehabilitating concrete structures. Sika's advice and customer support are second to none, from concept to successful completion on site.
All this is based on more than 100 years of experience in large and small projects worldwide. Zugerstrasse 50 CH-6341 Baar (ZG) Switzerland. With a standard repair procedure, you can consistently assess concrete repairs in every case. It can be used for both major and minor defects.
Concrete repair manual
An up-to-date concrete repair manual is also highly recommended. Traditional concrete repair materials, which use components similar to the original ones, should have a service life equal to the structure to be repaired (many decades for high-quality concrete).
These products are ideal for repairing holes, spalls and cracks in concrete in both internal and external situations where heavy vehicle traffic is expected. The best concrete repair method depends on the type of damage and whether it is a slab, driveway, pool deck, interior floor or another surface.
The significance of excess water on concrete
Excess water increases porosity, reduces strength, increases shrinkage (except for autogenous shrinkage of low water-cement concrete, which is controlled by entirely different mechanisms, such as chemical shrinkage and self-drying, both of which are outside the scope of this chapter), increases creep and reduces the abrasion resistance of the concrete.
Sika concrete repair mortars
For more significant repairs, the plugs need more substantial fixings to support the weight of the repair concrete. Companies like Slabtec who specialise in the repair of concrete are suitable for restoration work and repair of spalling and damaged concrete in all types of structures, including buildings, bridges, infrastructure and superstructures.
Previous evaluations of "clean" concrete have shown that it returns to its "darkened" colour in less than four years.
Typically, 10-15 test flags should be carried out for the same type of concrete using different combinations of cement (WPC and OPC), different sands and different types and sizes of aggregates to match those of the original concrete, bearing in mind that for more delicate repairs it may be necessary to reduce the size of the aggregates.
The specified concrete mix should be selected from the slab library to match the particular area's colour and texture to be repaired. In the case of slab-marked concrete, horizontal lines should run along the edges of the slab markings.
The bond strength depends on the characteristics of the repair material and the surface roughness of the concrete substrate.
FRP reinforcement resists expansion forces caused by corrosion, thus reducing crack growth and maintaining the bonding interaction between the reinforcing steel and the concrete.
Alternatively, the forms can be supported outside the repair patch by fixing the central concrete; however, additional holes in the main concrete require subsequent filling.
In conclusion, the authors hope that the use of concrete repairs that conform to the original structure, that continue to weather similarly, and that improve the longevity of buildings and enhance their unique character will become more widespread.