LEADING CAUSE OF DEFECT ISSUES IN CONCRETE

Remedial waterproofing and concrete repairs are a fact of life for any organisation whose assets include sizeable concrete structures. Car parks in both residential and commercial buildings often require maintenance and repair. Undercover or underground/basement car parks are especially prone to water seepage and concrete deterioration.

A moisture-borne contamination is often the cause of steel-enforced concrete deterioration. In other words, the penetration of water or water-borne compounds (chlorides, sulphates, carbonates, etc.).

Unprotected concrete structures may deteriorate faster in coastal climates with high humidity, salts in the soil, rain, and airborne salts. Concrete structures degrade and corrode when their alkalinity is reduced by carbonation or by chlorides (salts).

When corrosion builds up, it creates tensile stresses as it thickens. Concrete forms cracks near the steel due to the pressure, which will with time lead to more extensive cracks as the rust builds up until the concrete begins to separate from the reinforcing steel bars (fracturing of concrete) and expose corroded reinforcing steel rods.

Corrosion of reinforcement steel causes a reduction in the resistance of the steel bars, which depending on the severity can adversely affect the load-bearing capacity and service life of the concrete.

WHAT ARE THE RISK FACTORS THAT CAN CONTRIBUTE TO CONCRETE CANCER AND SPALLING?

Several factors predetermine the risk of concrete cancer, including proximity to the coastline and a built-up environment; the degree of concrete cover to steel reinforcing; the presence of differential metals; the quality and density of coating systems; inadequate waterproofing; building defects cracking; joint and penetration detailing and the level of preventative maintenance.

One of the most common locations one can find corrosion of reinforcement steel are in columns and beams with the primary cause being lack of concrete cover to protect the steel and/or poor-quality concrete. Other common areas of water-driven concrete cancer are basements, underground car parks, flat concrete rooftops and balconies.

Corrosion of the reinforcing steel or other embedded metals is by far the leading cause of premature ageing, deterioration and durability issues in concrete. Concrete cancer can happen in many areas of a concrete structure, so it is a good idea to regularly look out for tell-tale signs so that it can be remedied before it gets severe and becomes a serious problem and starts affecting the strength and structural integrity of the building.

To help prevent spalling from occurring, cracks and holes should be adequately sealed as soon as possible. Cracks can be repaired using a technique called crack injection where suitable epoxy or polyurethane resins are injected. A protective coating, a penetrative concrete sealer or a waterproof membrane will provide a barrier against moisture, salts and chemical attacks.

SIGNS TO LOOK OUT FOR IN CONCRETE AND CEMENT RENDER:

• Flaking, crumbling, spalling, expanding concrete
• Rust Stains leaking out of the concrete
• Bubbling, blistering, plating of concrete render
• Leaks in overhead concrete surfaces
• Rusting and exposed reinforcement pushing concrete so that it cracks and becomes loose

Unfortunately, the problem is likely to be much more extensive than symptoms on the concrete surface suggest. As steel rusts, it can expand up to eight times its original size, causing the surrounding concrete to break away. Once established, the rusting will spread along the reinforcing in each direction. It is impossible to know the full extent of the damage until the concrete is chiselled away.

HOW TO FIX CONCRETE CANCER

Singapore Waterproofing is an industry leader in concrete repair and protection of concrete structures.

Our extensive experience on major civil projects has afforded Singapore Waterproofing opportunities to design with industry-leading engineers and tackle some of the most complex concrete repair challenges imaginable in the built environment. Using this knowledge, we can provide you with a range of options to best meet your project criteria.

With extensive training both locally and internationally our team stays up to date with the latest local and international standards to ensure our repair work is of the highest quality available. Singapore Waterproofing also works closely with external specialist remedial engineers as required to ensure the best outcome for our clients.

Having earnt our reputation based on countless repair projects, Singapore Waterproofing adds value to our clients’ assets and ensures their durability for the years to come.