STP40

    The Hydration of Magnesian Lime and the Autoclave Test

    Published: Jan 1940


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    Abstract

    Magnesian limes are used in the construction industry in the form of hydrated limes or putties made from quicklimes of various sizes. The magnesium oxide may be wholly, partially, or negligibly hydrated when the lime is used. In general magnesian hydrated limes have from a small percentage to 25 or 30 per cent of the magnesia in the form of hydroxide. In recent years an autoclave test has been suggested for the testing of lime. It, likewise, has been suggested for the testing of mortars to determine expansion. The autoclave test consists essentially of testing the sample in an autoclave under 120 lb. or more steam pressure over various periods of time. It has been claimed that the autoclave test may well be indicative of the performance of a material. In 1918 Charles and Irving Warner patented a process for hydrating magnesian limes in a closed vessel with steam pressure. In 1924, before the National Lime Association, Irving Warner stated that the magnesia in hydrated lime was not hydrated in some limes and that in others from, 5 to 7 per cent of the total weight was hydrated. He stated further that the magnesia hydrated in time and that the hydration of the magnesia was dependent to a great extent on the burning temperature and time of burning.


    Author Information:

    Welch, F. C.
    Chemist, The Western Lime and Cement Co., Milwaukee, Wis.


    Paper ID: STP47162S

    Committee/Subcommittee: C07.05

    DOI: 10.1520/STP47162S


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