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Carbonatation is a slow process that occurs in concrete where lime (CaO, or Ca(OH) 2 ) in the cement reacts with carbon dioxide (CO 2) from the air and forms calcium carbonate. The water in the pores of Portland cement concrete is normally alkaline with a pH in the range of 12.5 to 13.5.
Pure lime is soluble in water containing carbonic acid, a natural, weak acid which is a solution of carbon dioxide in water and acid rain so it will slowly wash away, but this characteristic also produces autogenous or self-healing process where the dissolved lime can flow into cracks in the material and be redeposited, automatically repairing ...
This contrasts with calcium hydroxide, also called slaked lime or air lime that is used to make lime mortar, the other common type of lime mortar, which sets by carbonation (re-absorbing carbon dioxide (CO 2) from the air). Hydraulic lime provides a faster initial set and higher compressive strength than air lime, and hydraulic lime will set in ...
Calcium hydroxide has many names including hydrated lime, caustic lime, builders' lime, slaked lime, cal, and pickling lime. Calcium hydroxide is used in many applications, including food preparation, where it has been identified as E number E526. Limewater, also called milk of lime, is the common name for a saturated solution of calcium hydroxide.
This reaction can take place at anywhere above 840 °C (1,540 °F), but is generally considered to occur at 900 °C (1,650 °F) (at which temperature the partial pressure of CO 2 is 1 atmosphere), but a temperature around 1,000 °C (1,830 °F) (at which temperature the partial pressure of CO 2 is 3.8 atmospheres [1]) is usually used to make the ...
Each mole of CO 2 (44 g) reacts with one mole of calcium hydroxide (74 g) and produces one mole of water (18 g). The reaction can be considered as a strong-base-catalysed, water-facilitated reaction. [5] The reaction mechanism of carbon dioxide with soda lime can be decomposed in three elementary steps:
Limestone is the raw material for production of lime, primarily known for treating soils, purifying water and smelting copper. Lime is an important ingredient used in chemical industries. [ 110 ] Limestone and (to a lesser extent) marble are reactive to acid solutions, making acid rain a significant problem to the preservation of artifacts made ...
The temperature at which limestone yields calcium oxide is usually given as 825 °C, but stating an absolute threshold is misleading. Calcium carbonate exists in equilibrium with calcium oxide and carbon dioxide at any temperature. At each temperature there is a partial pressure of carbon