FAQs

Terminology & Specifications

Q: What is lime? What are the differences between quicklime and hydrated lime, high calcium lime and dolomitic lime?

A: Lime is a generic term, but by strict definition it embraces only the manufactured forms of lime—quicklime and hydrated lime. It does not include limestone, which is the feedstock for lime manufacturing (click here for a short description on how lime is produced).

Quicklime, the product of calcination of limestone, consists of the oxides of calcium and magnesium, and in the United States it is available in three forms:

Hydrated lime is a dry powder manufactured by treating quicklime with sufficient water to satisfy its chemical affinity for water, thereby converting the oxides to hydroxides. Depending upon the type of quicklime used and the hydrating conditions employed, the amount of water in chemical combination varies, as follows:

Q: What about physical specifications for lime?

A: Hydrated lime is available only as a fine powder or a slurry. Normal grades of hydrated lime suitable for most chemical purposes will have 85 percent or more passing a 200-mesh sieve, while for special applications hydrated lime may be obtained as fine as 99.5 percent passing a 325-mesh sieve.

Quicklime, however, is commercially available in a number of sizes (the following definitions are derived from ASTM Standard C51):

Q: What are the differences between Type N, NA, S, & SA hydrated lime used for mortar and other building applications?

A: A short fact sheet on hydrated lime for masonry purposes is available.

Hydrated limes used in building applications are divided into four types, as described in ASTM Standard Specification C 207 (Hydrated Lime for Masonry Purposes):

Types S and SA are differentiated from Types N and NA principally by the unhydrated oxide content and their water retention value. Type S must meet a water retention value of 85%, while Type N hydrate lime must have a water retention value of 75%. No distinction is made based on the nature and source of limestone.

The maximum air content of cement-lime mortar made with Types NA and SA is 14%; with Types N or S lime, 7%.

Q: Is aglime the same as lime?

A: The term agricultural lime, or "aglime," usually refers to crushed limestone. Limestone (calcium carbonate) is not the same as hydrated lime (calcium hydroxide).

Q: Do you have a listing of the specifications for lime in various industrial uses?

A: A complete list of standards is available at Lime Standards

Q: What procedures should I use to test lime?

A: ASTM has Standard Methods for testing chemical (C25) and physical (C110) properties. These standards can be purchased directly from ASTM at www.astm.org.

Handling & Transport

Q: Do you have technical advice on how to design lime storage and conveyance systems? What type of lime handling equipment should I buy?

A: NLA’s "Lime Handling, Application & Storage" publication includes information on the handling and storage of lime, equipment for application of lime, lime slaking and slurry handling, and factors affecting the selection of lime.

Contact your lime supplier for more specific technical assistance and advice on equipment vendors.

Q: Are there any handling or safety precautions that workers should follow?

A: Please see "Fact Sheet: Lime Safety Precautions."

Q: What regulations apply to transporting lime?

A: Lime is generally not regulated as a hazardous chemical when transported. The one exception is airborne shipments of quicklime. A fact sheet on shipment of quicklime by air is available.

Soil-Related & Agricultural Applications

Q: How much lime should I use to stabilize soils?

A: A fact sheet on soil stabilization is available under Technical Information. NLA offers several free downloads on soil stabilization with lime.

Q: Can’t lime be used to dry up mud—for short-term soil modification to expedite construction?

A: Yes, a fact sheet on using lime to dry up mud called “Lime Dries Up Mud” is available.

Q: How much lime should I use on my garden?

A: Hydrated lime can be used to raise the pH of acidic soils. This is also referred to as soil "sweetening." Hydrated lime is available from garden centers and should be applied in the amounts and using the procedures recommended on the packaging.

Lime Suppliers

Q: Where can I obtain lime?

A: A list of U.S. and Canadian lime suppliers by state/province is available under Find a Lime Plant.

Q: Where can I obtain food grade lime?

A: We are aware of one company that makes food grade lime: Mississippi Lime (www.mississippilime.com).

Q: Where can I obtain lime for masonry and other building applications?

A: Building lime can be obtained from Carmeuse, Graymont, Lhoist North America, and Mississippi Lime.

Other Topics

Q: How do I use lime to make whitewash?

A: NLA has no current publications that address whitewash. Other references include:

If you have a question concerning lime, please e-mail us or contact us at (703) 243-5463 ext. 226.