Comparative study of methods to measure the density of Cementious powders.
The accurate measurement of the density of hydraulic cement has an essential role in the determination of concrete mixture proportions. As more supplementary cementitious materials (SCM), such as fly ash, and slag, or cement replacements materials such as limestone and calcium carbonate are used in blended cements, knowledge of the density of each powder or of the blended cement would allow a more accurate calculation of the proportions of a concrete mixture by volume instead of by mass. The current ASTM standard for measuring cement density is the "Test Method for Density of Hydraulic Cements" (ASTM C188-14), which utilizes a liquid displacement method to measure the volume of the cement. This paper will examine advantageous modifications of the current ASTM test, by alcohol substitutions for kerosene. In addition, a gas (helium) pycnometry method is evaluated as a possible alternative to the current standard. The described techniques will be compared to determine the most precise and reproducible method for measuring the density of hydraulic cements and other powders.
National Institute of Standard and Technology, MS 8615, 100 Bureau dr., Gaithersburg MD 20899.
Michelle A
MA
Helsel
National Institute of Standard and Technology, MS 8615, 100 Bureau dr., Gaithersburg MD 20899, clarissa@nist.gov , 301-975 6711.
Chiara F
CF
Ferraris
National Institute of Standard and Technology, MS 8615, 100 Bureau dr., Gaithersburg MD 20899, Dale.Bentz@nist.gov , 301-975 5865.
Dale
D
Bentz
density; hydraulic cement; liquid displacement; pycnometer; volume