The Main Concrete Problems in Need of Repair
It is not uncommon for commercial buildings to be developed with canopies. These can act as an architectural marker to reveal a main entrance, for example, or simply as a way to offer some type of protection against adverse weather conditions for people to shelter under. Some buildings are actually built with a metal canopy that has a different purpose altogether, designed to catch concrete that has flaked off a building and thereby ensure the safety of anyone in the vicinity. Concrete canopies need to be tested for structural safety, and where issues are identified, repairs need to be undertaken with due diligence by professionals.
Office canopy repair in Hong Kong is common, with so many high-rises and office buildings, many of which were first built a few decades ago. Because of this, canopy repair has become a specialist service area with a range of tests from visual inspections to more intrusive investigations. In most cases, concrete repair involves dealing with steel reinforcement corrosion, with specific tests such as a half-cell survey mapping this particular issue. Before repairs can be carried out properly, it is necessary to really get to grips with what the underlying issue is that is causing the damage.
When corrosion takes place, the main risk to a canopy is as a result of oxide, which can cause the concrete to crack and also to spall, which literally means to fall off. The dangers of this happening overhead are obvious. Cracking can also occur due to fire damage as well as frost-thaw damage.
One problem that can cause concrete issues that lead to canopy repairs is carbonation, particularly with older structures where less concrete has been used and the structure is more porous. Because canopies are exposed to the sun and the rain, this can speed-up the carbonation process. The implications of this in Hong Kong, which boasts a tropical climate, are clear, meaning that potential carbonation of canopies has to be identified.
Salt-water can batter concrete structures with chlorides, which have an impact on the reinforcing steel in concrete, too. The result is an acceleration of corrosive activities. What essentially is happening in cases of corrosion is that a layer of oxide is created around the reinforced steel. In turn, this oxide has a negative effect on the surrounding concrete. An office canopy is at particular risk because of its position.