Lime Characteristics and Their Effect on Construction

Classifications of Lime: Limes may basically be classified on their variances in: (a) chemical composition, and (b) commercial state for use. The Society's specifications provide the following classifications for lime composition: High-calcium limes result from the burning of calcite (CaCO3), and dolomitic or magnesian limes result from the burning of magnesian limestone (x CaCO3 · y MgCO3). In the presence of silica (SiO2), alumina (Al2O3), and the oxide of iron (Fe2O3), variations in temperature produce some variations in behavior. High-magnesian limes should not be subjected to temperatures above 1600 F., while high-calcium limes should be burned at temperatures below 2100 F. Excessive temperatures tend toward “dead-burning” which seriously affects the structural properties of the product. It may be said that variations in composition and temperature of burning do exist and that these may affect the properties of the product. Limes which meet the above A.S.T.M. specifications, however, will in general produce a uniform, desirable product. The commercial state of the lime may be as a quicklime or as a hydrate. Quicklimes are furnished as lump lime, pebble lime, and powder.