Estimation of the degree of hydration of blended cement pastes by a scanning electron microscope point-counting procedure

• Published in: Cement and concrete research Vol. 34; no. 10; pp. 1787 - 1793
• Main Authors: Feng, X., Garboczi, E.J., Bentz, D.P., Stutzman, P.E., Mason, T.O.
• Format: Journal Article
• Language: English
• Published: New York, NY Elsevier Ltd 01-10-2004; Elsevier Science
• Subjects: Applied sciences; Blended cement; Buildings. Public works; Cement concrete constituents; Cements; Exact sciences and technology; Fly ash; Granulated blast-furnace slag; Hydration; Materials; Point counting; Properties of anhydrous and hydrated cement, test methods; Fly ash; Granulated blast-furnace slag; Point counting; Hydration; Blended cement; Scanning electron microscopy; Regression analysis; Experimental study; Portland cement; Particle size distribution; Cement paste; Adjuvant; Chemical composition
• ISSN: 0008-8846; 1873-3948
• DOI: 10.1016/j.cemconres.2004.01.014

A scanning electron microscope (SEM) point-counting technique was employed to study the hydration of plain portland and blended cement pastes containing fly ash or slag. For plain portland cement pastes, the results for the degree of cement hydration obtained by the SEM point-counting technique were consistent with the results from the traditional loss-on-ignition (LOI) of nonevaporable water-content measurements; agreement was within ±10%. The standard deviation in the determination of the degree of cement hydration via point counting ranged from ±1.5% to ±1.8% (one operator, one sample). For the blended cement pastes, it is the first time that the degree of hydration of cement in blended systems has been studied directly. The standard deviation for the degree of hydration of cement in the blended cement pastes ranged from ±1.4% to ±2.2%. Additionally, the degrees of reaction of the mineral admixtures (MAs) were also measured. The standard deviation for the degree of fly ash reaction was ±4.6% to ±5.0% and ±3.6% to ±4.3% for slag. All of the analyses suggest that the SEM point-counting technique can be a reliable and effective analysis tool for use in studies of the hydration of blended cement pastes.