Operations manager, Southwestern Portland Cement Co., Los Angeles, CA
A current proposal in ASTM Committee C-1 on Cement would allow up to 5% limestone to be interground with clinker into portland cement under the provisions of ASTM Specification for Portland Cement (C 150), the basic standard covering portland cement. This important and far-reaching proposal would change the definition of portland cement and has resulted in considerable controversy within the Committee. There are strong arguments on both sides of the question. The proponents claim a significant savings of energy during production without a degradation in quality and even cite improvements in some cement and concrete characteristics. The opponents charge that limestone acts merely as an adulterant, that strengths are reduced, and that the proposal should be abandoned on ethical grounds.
A very interesting adjunct to the carbonate additions proposal—the name used in committee work—has been the sense of history that this proposal has inspired. Regardless of individual viewpoints, many Committee C-1 members have turned to the past in an effort to gain insight into the ramifications of this proposal. This paper is a historical review of portland cement and cement specifications.
Paper ID: CCA10024J