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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.
ASTM C1293: "Test Method for Concrete Aggregates by Determination of Length Change of Concrete Due to Alkali-Silica Reaction". It is a long-term confirmation test (1 or 2 years) at 38 °C in a water-saturated moist atmosphere (inside a thermostated oven) with concrete prisms containing the aggregates to be characterised mixed with a high-alkali ...
Primary efflorescence is named such, as it typically occurs during the initial cure of a cementitious product. It often occurs on masonry construction, particularly brick, as well as some firestop mortars, when water moving through a wall or other structure, or water being driven out as a result of the heat of hydration as cement stone is being formed, brings salts to the surface that are not ...
A fairly well-defined reaction front can often be observed in thin sections; ahead of the front the concrete is normal, or near normal. Behind the reaction front, the composition and the microstructure of concrete are modified. These changes may vary in type or severity but commonly include: Extensive cracking; Expansion
GGBS cement also produces a smoother, more defect-free surface, due to the fineness of the GGBS particles. Dirt does not adhere to GGBS concrete as easily as concrete made with Portland cement, reducing maintenance costs. GGBS cement prevents the occurrence of efflorescence, the staining of concrete surfaces by calcium carbonate deposits.
South Korea's transport ministry said on Wednesday that it would remove the concrete embankment installed at Muan International Airport following last month's Jeju Air crash, its deadliest ...
Concrete waste that is rich in alkaline calcium compounds can be used to remove and recover various elements from an aqueous solution. Waste concrete has been used as a sorbent to remove phosphorus from wastewater after the removal of excess sludge in sewage treatment plants. [27] Concrete waste may also be used as an inexpensive gas treatment ...
Degrading concrete has been the focus of many studies and the most obvious sign is calcium-rich leachate seeping from a concrete structure. [5] [6] [7]Calthemite stalactites can form on concrete structures and "artificial caves" lined with concrete (e.g. mines and tunnels) significantly faster than those in limestone, marble or dolomite caves.