Concrete strength for fire safety design

Abstract

Idealised data have been derived for the compressive strength of a number of concretes for fire safety design. The data are derived from the author's own research including test series not published before and from more than 400 other test series comprising approximately 3000 specimens known from literature and personal contact. The data cover a variety of concretes with aggregates such as siliceous materials, limestone, granite, sea gravel, pumice, and expanded clay to fire-resistant concrete based on chamotte or Danish mo-clay. Processes are briefly described that are responsible for the deterioration of the materials when they are heated and when they are cooled down after a fire. In addition, it is explained how variations of the concrete composition influences the deterioration. Necessary characteristics of design methods are derived for variable fire courses based on analyses of consequences of material deterioration. The paper serves as a basis for a number of papers presenting calculation methods developed by the author for load-bearing capacity of any structure of any concrete at any time of any fire exposure. Some of these methods and related materials data are adopted in the CEN: ENV 1992-1-2 code and national codes such as the Danish DS411. The present paper serves as a part of the documentation for the methods and it is therefore also a supporting document for these standards.