Lime has been used as a primary ingredient in masonry mortars for centuries, and this important use continues to the present day in both historic and contemporary applications. Mortars made with lime and cement exhibit superior workability balanced with appropriate compressive strength, as well as low water permeability and superior bond strength. Lime is a major constituent in exterior and interior stuccos and plasters, enhancing the strength, durability, and workability of these finishes. All of these lime applications are supported by ASTM specifications and standards. Papers and articles on a variety of building lime applications are available at http://www.buildinglime.org/.

Performance in Historic Masonry Applications-Most masonry produced prior to the turn of the 20th century used lime-sand mortar. The elasticity of high lime content mortars allows for expansion and contraction of historic masonry walls without damaging the masonry units. These units can have low compressive strengths and can be damaged by modern masonry products with higher strengths.

Hydrated Lime for Plastering Purposes-Type S (Special) hydrated lime shows its versatility and beauty when used for interior and exterior plaster or render. ASTM C206 Standard Specification for Finishing Hydrated Lime requires that the finishing lime be free of any chemical or physical characteristics that would cause flaws in the plaster.

Other Uses of Lime in Building Construction:

Limewash- Limewash is a versatile, accommodating, and robust surface covering that is compatible with a variety of building surfaces. It is maintainable, beautiful, stable, and long lasting. A copy of a paper on limewash presented at the 2005 International Building Lime Symposium is available here.

Autoclaved Aerated Concrete (AAC) -Lime is also employed in the manufacture of innovative lightweight cellular concrete products, such as autoclaved aerated concrete (also called "aircrete"), which can be formed into block as well as large masonry units or insulation slabs. The 2005 International Building Lime Symposium included a paper on AAC.

Other Concrete Products-Hydrated lime can be added to the concrete mix in making block and other concrete products, in order to produce a denser, more water-resistant product. By adding greater plasticity to the mix, lime also produces concrete products with more precise edges and corners, improves reflectivity, and reduces loss through breakage.

Calcium Silicate Brick-Calcium silicate (sand-lime) brick is employed in standard masonry construction in the same manner as common clay brick. Sand is mixed with high calcium lime (quick or hydrated) in a wet state, and then molded into bricks and autoclaved. The lime reacts with silica to form complex hydro(di)calcium silicates that bind the brick and provide high dimensional stability. Lime is also used to make hollow sand-lime building block, tile, slabs, and pipe.

Insulation Materials-Some insulating materials, molded as units, contain lime and diatomaceous earth or lime and silica. In these products, lime serves as a binding agent, reacting chemically with the available silica present in the mix to form calcium silicates. The lime-silica reaction is also employed in making microporite insulation.


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