The alkali-silica reaction, more commonly known as concrete cancer, is a detrimental swelling reaction that occurs over time in concrete between the highly alkaline cement paste and the reactive amorphous silica found in many common aggregates, with sufficient moisture. This reaction causes steel reinforcement within a concrete slab to rust, which in turn causes the surrounding concrete to become brittle and crack. This process is known as chipping, and it can trigger a vicious cycle by further exposing steel to the elements and accelerating the level of corrosion. Concrete cancer is a serious problem that, if left undiagnosed and untreated, can affect the structural integrity of the building.
Flat concrete roofs are particularly vulnerable to leaks and water-driven concrete cancer if they are not properly waterproofed. As the steel reinforcement oxidizes, it expands, causing the concrete around the steel to shift and chip. Chipping not only looks terrible, but it can also be dangerous as pieces of concrete may fall off and hit people underneath. It also weakens the strength of concrete. If you suspect that you have concrete cancer in any form, it's important to get treatment as soon as possible; otherwise, the problems will worsen.
Treatment should be performed by qualified professionals, since poor treatment will only hide and delay the problem. Plastering the concrete is not enough to hide the oxidized steel, as the oxidation process will continue underneath, causing a greater displacement of the concrete and even requiring total replacement of the reinforcing steel. The best way to prevent concrete cancer is to invest in good quality waterproofing membranes. When it comes to concrete repairs, be sure to seek the professional opinion of a reputable company like Freyssinet. Engineers work to prevent cancer from starting in concrete by designing concrete appropriately for the surrounding environment and their respective exposure conditions. If chloride pollution is the problem in buildings near the ocean, you may need specialized repair work to treat concrete cancer.
You should also have the concrete sealed regularly to protect it against water damage and wear. Steps must then be taken to properly waterproof the area before fresh concrete can be laid, especially in Brisbane, where high rainfall can be a problem. Common signs include cracking, crumbling, or flaking of concrete, rust spots or bubbles on concrete or cement plaster, and leaks in the ceiling and walls. Consider high-quality options such as Wolfin or Cosmofin waterproofing membranes to seal new horizontal concrete surfaces.
