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Natural hydraulic lime (NHL) is produced by heating (calcining) limestone that naturally contains clay and other impurities: no materials may be added to create the hydraulicity. In the United States NHL may be called 'hydrated hydraulic lime' (HHL) per ASTM C-141 Standard Specification for Hydrated Hydraulic Lime for Structural Purposes. [1]
For natural hydraulic lime (NHL) mortars, the lime is obtained from limestone naturally containing a sufficient percentage of silica and/or alumina. Artificial hydraulic lime is produced by introducing specific types and quantities of additives to the source of lime during the burning process, or adding a pozzolan to non-hydraulic lime.
Artificial hydraulic lime is made by adding forms of silica or alumina such as clay to the limestone during firing, or by adding a pozzolana to pure lime. [13] Hydraulic limes are classified by their strength: feebly, moderately and eminently hydraulic lime. Feebly hydraulic lime contains 5-10% clay, slakes in minutes, and sets in about three ...
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 water (see hydraulic and non-hydraulic lime plaster). Hydraulic cements (e.g., Portland cement) set and become adhesive through a ...
The curing time of lime plaster can be shortened by using (natural) hydraulic lime or adding pozzolan additives, transforming it into artificially hydraulic lime. In ancient times, Roman lime plaster incorporated pozzolanic volcanic ash; in modern times, fly ash is preferred. Non-hydraulic lime plaster can also be made to set faster by adding ...
Calcined gypsum is an alternative material in industrial plasters and mortars. Cement, cement kiln dust, fly ash, and lime kiln dust are potential substitutes for some construction uses of lime. Magnesium hydroxide is a substitute for lime in pH control, and magnesium oxide is a substitute for dolomitic lime as a flux in steelmaking. [28]
Hempcrete is made of the inner woody core of the hemp plant (hemp shives), a lime-based binder, and water. [6] The binder consists of either hydrated lime or natural hydraulic lime. [7] Hydrated lime is made from pure limestone and sets through the absorption of CO 2 during the carbonation process. [7]
Earthen plaster is made of clay, sand and often mixed with plant fibers. The material is often used as an aesthetically pleasing finish coat and also has several functional benefits. This natural plaster layer is known for its breathability, moisture-regulating ability and ability to promote a healthy indoor environment.