Notable changes in modern portland cement properties

Q. What notable changes have taken place in the properties of portland cement as manufactured in the United States during the past years?

A. The most notable changes in the manufacture of portland cement were brought about by the demand for higher early concrete strengths. The cement industry accomplished this by increasing the calcium and hence, the

C₃S content and fineness, which had the effect of nearly equivalent increases in both 7- and 28-day strength. In general, these changes have produced a Type I cement with characteristics very similar to those of a traditional high-early-strength Type III. In some parts of the country, higher early concrete strengths with Type II and Type V cements have been obtained with increased fineness. A major change has also been the use of microscopy to control composition and microstructure of the clinker.

References: SP-1(02); E3-13

Topics in Concrete: Cementitious Material; Concrete Fundamentals