Pre-treatment and cleaning of reinforcement
In most cases, corrosion of reinforcement is manifested by damage to the concrete covering of reinforcement. The main purpose of pre-treating and cleaning steel reinforcement is to remove corroded or otherwise damaged areas of it.
In the course of corrosion, thicker layers of corrosion products accumulate on the steel reinforcement, causing the concrete cover to separate and peel off. Removal of accumulated oxides is a necessary prerequisite for achieving the long-term success of the repair.
The degree of cleansing of the reinforcement depends on the materials that will be applied to the reinforcement for its protection (EN 1504-10 standard). The most commonly used levels of cleansing are Sa 2 and Sa 2½ following the EN ISO 8501-1 standard.
Cleansing the reinforcement can be done in several ways, as follows:
• Needle rust removal
• Cleaning using high-pressure water jet technology
• Compressed air cleaning with abrasive (e.g. Sandblasting)
• Brushing with a mechanical wire brush
Needle rust removal
Needle rust removers are pneumatic tools that use thin steel rods operated by an internal piston. Steel rods strike the cleaned surface and remove surface materials. The use of needle cleaners is effective both for removing thick layers of hydroxides that are forming rust on the reinforcement and for cleaning smaller parts of concrete surfaces.
Cleaning with high-pressure water jet technology
In the previous section, there is a description of this method and its advantages applied to the pre-treatment of concrete. For the pre-treatment and cleaning of the reinforcement, the methodology to be followed when using this procedure is essentially the same.
There is also the option of adding abrasive materials to the water, in this case, the technique is referred to as blasting, which utilizes both the abrasive effect of the water jet itself and the abrasive effect of the released material or the added abrasive.
Cleaning with compressed air with abrasives
The use of abrasives mixed with compressed air and applied with a nozzle is a very appropriate method to clean reinforcement and concrete. Although, it must be noted that airborne debris (dust) is environmentally problematic. However, water can be injected into the nozzle to reduce dust during this process.
Brushing with a mechanical wire brush
Mechanical wire brushes are effective tools for removing unwanted oxides from steel surfaces. Nevertheless, it must be noted that using a wire brush when cleaning reinforcement on an inaccessible (rear) surface is very time-consuming and inefficient.
