Title: A tribute to "The Influence of Gypsum on the Hydration and Properties of Portland Cement Pastes"

Author(s): W. Lerch

Publication: Symposium Paper

Volume: 249

Issue:

Appears on pages(s): 93-140

Keywords:

DOI: 10.14359/20127

Date: 3/1/2008

Abstract:

Due to copyright issues, this paper is only available by purchasing the SP-249.

The manner in which the added gypsum controls the setting of cement has been the subject of many investigations and of some controversy. It is generally agreed, however, thtat its effect is to stop the rapid reaction normally shown by the calcium alumniates. In the absence of precise information relative to the function of gypsum in regulating the initial hydration and in order to provide ample protection against the abnormal expansion that might result from the use of excess amounts of gypsum it has been the custom from the beginning to place a limit on the SO3 content of portland cement in standard specifications. In the A.S.T.M. specification for cement this limit has not been changed since 1917 except to permit a higher value for high early strength cement. In the belief that the quantity of gypsum required to regulate properly the hydration and hardening would vary with cement composition and fineness, the studies described in this paper were undertaken.