Standard Test Method for Determination of Pack-Set Index of Portland Cement
This method is intended to help manufacturers determine the relative pack-set tendency of their cement(s). The test establishes a pack-set index which, when properly correlated with field performance, is useful in predicting or preventing field unloading difficulties.
The test is an aid to routine control during cement production and is not suitable for specification purposes.
In general, field performance of cement flowability is satisfactory when the pack-set index as determined on freshly ground cement averages 0 to 15 and is unsatisfactory when the index exceeds 25. Any prediction of field performance of cement flowability measuring 16 to 25 is tenable. These are general ranges and the field performance of individual cements may not necessarily fall within these ranges. Additional conditions, after the cement has left the control of the manufacturing facility, can affect the apparent pack set index as well.
Any attempt to apply the critical range of pack-set index numbers based on freshly ground cement to job cement without special treatment of the sample would be problematic. The test is a “GO-NO GO” type of test and should not be used for specification purposes.
The pack-set index of field cement can be evaluated in terms of the pack-set index ranges of that cement as determined when freshly-ground. This comparison can aid the manufacturer in producing cement that offers the best field performance for pack-set properties.
Silo storage of cement may result in a greater amount of consolidation than this method is designed to induce, and the resulting forces required to overcome that consolidation are not measured by this test method.
Pack set is not to be confused with “warehouse set” which results from surface hydration of the cement from adsorbed moisture.
1.1 This test method covers the determination of the pack-set index, which provides an indication of the mechanical force needed to overcome the consolidation of portland cement.
1.2 The pack-set index number provides a numerical value useful for manufacturers who desire to measure and control the effect that vibration-induced consolidation has upon the manufactured cement.
1.3 The values stated in SI units are to be regarded as the standard. Values stated in Inch-Pound units are for informational purposes only and are enclosed in parentheses. Values stated in SI units shall be obtained by measurement in SI units or by appropriate conversion, using the rules of Conversion and rounding given in Standard IEEE/ASTM SI 10, of measurements made in other units.
1.4 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use. (WARNING—Fresh hydraulic cementitious mixtures are caustic and may cause chemical burns to skin and ittuse upon prolonged exposure).
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