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The alkali–silica reaction (ASR), also commonly known as concrete cancer, [3] is a deleterious internal swelling reaction that occurs over time in concrete between the highly alkaline cement paste and the reactive amorphous (i.e., non-crystalline) silica found in many common aggregates, given sufficient moisture.
Example of flat piece of concrete having dislodged with corroded rebar underneath, Welland River bridge across Queen Elizabeth Way in Niagara Falls, Ontario. The expansion of the corrosion products (iron oxides) of carbon steel reinforcement structures may induce internal mechanical stress (tensile stress) that cause the formation of cracks and disrupt the concrete structure.
Research from major concrete authorities, including the American Concrete Institute, Portland Cement Association, and the National Ready Mixed Concrete Association confirm that most concrete damage is attributable to surface moisture intrusion. [citation needed] The most pervasive form of concrete damage is surface scaling from freeze/thaw.
CPP and CPR methods, developed over the last 40 years, are used in lieu of asphalt overlays and bituminous patches to repair roads when longer lasting solutions are desired. When installing pavers over top of an existing asphalt of concrete pad, there are three installation options: sand set, bituminous set, and mortar set. [ 1 ]
Smaller pieces of concrete are used as gravel for new construction projects. Aggregate base gravel is laid down as the lowest layer in a road, with fresh concrete or asphalt placed over it. Crushed recycled concrete can sometimes be used as the dry aggregate for brand new concrete if it is free of contaminants, though the use of recycled ...
Robotic Hydrodemolition in Ystad, Sweden. Hydrodemolition of concrete exposing the rebar.. Hydrodemolition (also known as hydro demolition, hydroblasting, hydro blasting, hydromilling, waterblasting, and waterjetting) is a concrete removal technique which utilizes high-pressure water, often containing an abrasive material, to remove deteriorated and sound concrete as well as asphalt and grout.
An owner may also contract with a construction project management company as an adviser, creating a third contract relationship in the project. The construction manager's role is to provide construction advice to the designer, design advice to the constructor on the owner's behalf and other advice as necessary. The construction project manager ...
Shotcrete, gunite (/ ˈ ɡ ʌ n aɪ t /), or sprayed concrete is concrete or mortar conveyed through a hose and pneumatically projected at high velocity onto a surface. This construction technique was invented by Carl Akeley and first used in 1907. [1]: 7 The concrete is typically reinforced by conventional steel rods, steel mesh, or fibers.