Masonry Mortars, Stuccos, and Plasters
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
www.buildinglime.org. Type S (Special) hydrated lime is a fine, white, high purity product specially hydrated for convenient, trouble-free use in mortar applications. It is a uniquely American product, with much more stringent requirements for masonry performance than those imposed by any other country. Type SA (Special Air-Entrained) hydrated lime is similar, except that it includes an air entraining agent which produces minute voids in the mixed mortar. Either type will provide a superior quality mortar. Both are subject to the
ASTM C207 Standard Specification for Hydrated Lime for Masonry Purposes.
Modern Masonry Applications
Studies have compared the performance of cement-lime mortars to that of masonry cement mortars (which use limestone and other additives in lieu of hydrated lime) and mortar cements. Cement-lime mortars have shown higher bond and shear strength and lower water leakage. For a more information on the use of hydrated lime for masonry purposes,
click here. For a fact sheet on the use of lime-based mortars to create watertight walls,
click here.
Historic Masonry Applications
Most masonry produced before the turn of the 20th century used lime-sand mortar. The elasticity of high lime content mortars allows for expansion and contraction of such 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.
Plastering Uses
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 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 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.
Site Preparation
Lime can be used to dry wet sites. Lime can also react with clays in soil to provide a more stabile base for building construction. For more information on these uses,
click 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 concrete mix used to make 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 pipes.
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. For more information see:
Building Lime Producers Complete List of Building Publications.
Building Construction (see also, buildinglime.org)
| Title | Year | Description |
|---|
| 2005 International Building Lime Symposium Proceedings (ISBN 0-9767621-0-2) , See Abstracts | 2005 | State-of-the-art papers on lime in contemporary and historic building applications, including mortar, plaster, stucco, and limewashes. CD includes 39 papers by authors from 10 countries (To order Proceedings CD, click here. Cost $30.00 plus shipping and handling). Also included are several important historical documents related to building lime. Also, see Abstracts (42 pp) |
| Lime-Based Mortars Create Water Tight Walls | 2000 | Technical summary on lime mortar's effectiveness in resisting moisture damage. |
| Fact Sheet on Hydrated Lime for Masonry Purposes | 1999 | Includes uses for mortar, stucco, masonry, and masonry cement. |
| Efflorescence of Mortars | 1990 | Discusses causes of efflorescence including construction/design practices, masonry units, and mortar materials. Includes research information. (Reprinted 1990 (1966), 7 pp) |
| Durability of Mortar & Masonry | 1989 | Reviews the use of lime in mortar for watertight walls and durable masonry structures. Also, autogenous healing, efflorescence, air content, and permeability. (Reprinted 1989 (1964), 5 pp) |
| Strength Considerations of Mortar & Masonry | 1989 | Describes attributes of well-balanced lime-cement mortars for strength, improved workability, and water retentivity for maximum adhesion and bond. (Reprinted 1989 (1964), 8 pp) |
| Bond of Mortar to Masonry Units | 1985 | Discusses factors influencing strength, extent, and durability of bond, and the ability of lime to make mortar highly plastic and workable. (Reprinted 1985 (1964), 10 pp) |
