Measurement of Particle Size Distribution in Portland Cement Powder: Analysis of ASTM Round Robin Studies

Abstract

A distribution of particle sizes or particle size distribution (PSD) is a fundamental characteristic of cement powder. Accurate PSDs are required in computational efforts to model the hydration process and it is an important practical issue for the cement industry. Presently, the only available standard method for measuring the PSD of cement, namely ASTM C115, is limited in scope, with a lower size detection limit of 7.5 µm. Since there are no standard procedures that adequately cover the broad particle size range associated with portland cement powder, the implementation of different measurement techniques varies widely within the industry. Two ASTM-sponsored round robin tests were performed to (1) ascertain the techniques and methods currently used in the cement industry and (2) develop and refine a standard method or methods. The results have been incorporated into a best practice method based on the technique of laser diffraction. The aim of the current paper is to summarize the findings based on the data generated during the round robins and to summarize the various approaches available to measure the PSD of cement. A summary of the statistical analysis of the test results is described.

Physical characterization methods for supplementary cementitious materials

“…diffracted light) is considered to calculate the projected area of a sample. It is important to note that diffraction is independent of the composition of the particles [36], unlike the reflection and refraction that are not considered in this model.…”

Studies of light backscattering at concrete during its hydration

“…The refractive index of cement materials is complex ( χ i n m + = ), with its real and imaginary parts diverging in different works as much as n = 1.5-1.7 and χ = 0.003-1 [1][2][3][4][5]. Finally, the average particle radius has been taken as 2.4-14 µm.…”

“…Formation of concrete passes through a process of hydration, interaction of cement and water. According to existing models, concrete induration occurs due to enlargement and accretion of powder cement particles [1][2][3][4][5]. The beginning and the end of induration of concrete solution is usually determined [6,7] using Vicat apparatus.…”

“…Cement particle size distribution may differ not only for various kinds of cement, but for different consignments, too. Measurements of the particle size distribution are performed with different methods, such as Electrical Zone Sensing, Sedimentation and Scanning Electron Microscopy [1][2][3][4][5]. A standard procedure is to measure remains weight on a sieve while screening consecutively from the biggest mesh aperture to the smallest.…”

“…A standard procedure is to measure remains weight on a sieve while screening consecutively from the biggest mesh aperture to the smallest. Laser diffraction method [5] is used for studying real-time distribution of cement particle sizes.…”