Effect of heat treatment and cooling rate on the microscopic structure of portland cement clinker

Abstract

Ten commercial portland cement clinkers with their slowly and quickly cooled counterparts were examined microscopically. Methods are given for the conduction of the microscopical examination.The appearance of the clinker phases after the different heat treatments is described and the structure of the clinkers discussed.In general, for all clinkers, the phase compositions as calculated with consideration of glass agreed better with the microscopically determined phases than did those based upon the calculations in which complete equilibrium crystallization was assumed. The microscopically determined 3CaO.Si02 was nearly always greater and the 2CaO.Si02 lower than that calculated by either of the other methods. The 3CaO.AhOa was always less than that calculated from chemical analyses. Generally the 4CaO.AI20a.Fe20a found microscopically exceeded that calculated by either of the other methods. The glass determined microscopically and the values obtained from the heat of solution method agreed better for slowl y and plant cooled than for quickly cooled clinkers. CONTENTS Page

Further phase-equilibrium studies involving the potash compounds of portland cement

“…63 percent of Na,O. [9], in his comparisons between the calculated and microscopically observed phases of commercial clinker, reports that the agreement between the values for free MgO as determined microscopically and as calculated was usually good. This indicates that the stability of MgO is not affected by the existence of the potash compounds in clinker.…”

Building research at the National Bureau of Standards

“…Significant improvements in petrographic analysis through resin impregnation and etching of clinker sections were made by Insley and Ward [247][248], while Hansen and Harrington [249][250], were perhaps the first to apply x-ray diffraction to identification of crystalline and glassy constituents. Sophisticated quenching furnaces were developed, along with differential thermal analyses furnaces, a thermogravimetric apparatus, and a small rotary laboratory kiln [251][252][253].…”

Cement and Cement Products

“…The studies of Tavasci (11), Insley (6, 7), Ward (12), and others have indicated how useful the metallographic method of polished sections is for determining the microstructure and phase relations in Portland cement clinker. In general, the method of preparation follows that for metals except that care must be used to prevent hydration of the clinker during preparation.…”

“…Among those who have made contributions to the techniques and the results of microscopic observation may be mentioned Brown (4), Brownmiller (5), Insley (6,7), Bates and Klein (8), Parker (9), Radczewski (10),Tavasci (11), and Ward (12). Among those who have made contributions to the techniques and the results of microscopic observation may be mentioned Brown (4), Brownmiller (5), Insley (6,7), Bates and Klein (8), Parker (9), Radczewski (10),Tavasci (11), and Ward (12).…”