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  2. Alkali–silica reaction - Wikipedia

    en.wikipedia.org/wiki/Alkali–silica_reaction

    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.

  3. Concrete degradation - Wikipedia

    en.wikipedia.org/wiki/Concrete_degradation

    In very old concrete where the calcium hydroxide has been leached from the leachate seepage path, the chemistry may revert to that similar to "speleothem" chemistry in limestone cave. [ 12 ] [ 13 ] This is where carbon dioxide enriched rain or seepage water forms a weak carbonic acid , which leaches calcium carbonate (CaCO 3 ) from within the ...

  4. Sulfate attack in concrete and mortar - Wikipedia

    en.wikipedia.org/wiki/Sulfate_attack_in_concrete...

    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

  5. Geopolymer - Wikipedia

    en.wikipedia.org/wiki/Geopolymer

    There is often confusion between the meanings of the terms 'geopolymer cement' and 'geopolymer concrete'. A cement is a binder, whereas concrete is the composite material resulting from the mixing and hardening of cement with water (or an alkaline solution in the case of geopolymer cement), and stone aggregates.

  6. Alkalinity - Wikipedia

    en.wikipedia.org/wiki/Alkalinity

    Conversely, the addition of acid converts weak acid anions to CO 2 and continuous addition of strong acids can cause the alkalinity to become less than zero. [12] For example, the following reactions take place during the addition of acid to a typical seawater solution: B(OH) − 4 + H + → B(OH) 3 + H 2 O OH − + H + → H 2 O PO 3− 4 + 2 ...

  7. Calcium silicate hydrate - Wikipedia

    en.wikipedia.org/wiki/Calcium_silicate_hydrate

    When water is added to cement, each of the compounds undergoes hydration and contributes to the final state of the concrete. [2] Only calcium silicates contribute to the strength. Tricalcium silicate is responsible for most of the early strength (first 7 days). [3] Dicalcium silicate, which reacts more slowly, only contributes to late strength.

  8. Cement - Wikipedia

    en.wikipedia.org/wiki/Cement

    Concrete is the most widely used material in existence and is behind only water as the planet's most-consumed resource. [ 2 ] Cements used in construction are usually inorganic , often lime - or calcium silicate -based, and are either hydraulic or less commonly non-hydraulic , depending on the ability of the cement to set in the presence of ...

  9. Properties of concrete - Wikipedia

    en.wikipedia.org/wiki/Properties_of_concrete

    Concrete has a very low coefficient of thermal expansion, and as it matures concrete shrinks. All concrete structures will crack to some extent, due to shrinkage and tension. Concrete which is subjected to long-duration forces is prone to creep. The density of concrete varies, but is around 2,400 kilograms per cubic metre (150 lb/cu ft). [1]