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Calcium silicate, also known as slag, is produced when molten iron is made from iron ore, silicon dioxide and calcium carbonate in a blast furnace. When this material is processed into a highly refined, re-purposed calcium silicate aggregate, it is used in the remediation of acid mine drainage (AMD) on active and passive mine sites. [13]
Calcium ions then react with the soluble sodium silicate gel to convert it into solid calcium silicate hydrates (C-S-H). The C-S-H forms a continuous poorly permeable coating at the external surface of the aggregate. The penetrated alkaline solution (NaOH / KOH) converts the remaining siliceous minerals into bulky soluble alkali silicate gel.
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. Calcium silicate hydrate (also shown as C-S-H) is a result of the reaction between the silicate phases of Portland cement and water.
Ground granulated blast furnace slag is a latent hydraulic binder forming calcium silicate hydrates (C-S-H) after contact with water. It is a strength-enhancing compound improving the durability of concrete. It is a component of metallurgic cement (CEM III in the European norm EN 197).
Concrete creep is essentially the sagging of concrete over time. Creep and shrinkage of concrete are two physical properties of concrete.The creep of concrete, which originates from the calcium silicate hydrates (C-S-H) in the hardened Portland cement paste (which is the binder of mineral aggregates), is fundamentally different from the creep of metals and polymers.
Cement hydration and strength development mainly depend on two silicate phases: tricalcium silicate (C 3 S) , and dicalcium silicate (C 2 S) . [1] Upon hydration, the main reaction products are calcium silicate hydrates (C-S-H) and calcium hydroxide Ca(OH) 2, written as CH in the cement chemist notation. C-S-H is the phase playing the role of ...
Alkali–aggregate reaction is a term mainly referring to a reaction which occurs over time in concrete between the highly alkaline cement paste and non-crystalline silicon dioxide, which is found in many common aggregates. This reaction can cause the expansion of the altered aggregate, leading to spalling and loss of strength of concrete.
Alkali–aggregate reaction – Expansive chemical reaction damaging concrete (AAR) Alkali–silica reaction – Chemical reaction damaging concrete (ASR) Caesarea Maritima – Ancient Levantine city; its ancient artificial bay was built with pozzolan; Calcium silicate hydrate – Main product of the hydration of Portland cement (C-S-H)