Abstract
Creep is the time dependant increase in strain of a solid body under sustained stress. In concrete, the negative effects of creep are often responsible for excessive defl ection at service loads which can result in cracking, creep buckling of long columns and loss of prestressing force. While it is conceptually easy to appreciate that the stiffness of the aggregate in concrete will infl uence the magnitude of creep, the extent of this effect across the range of commonly used aggregates in South Africa has not been assessed. This paper discusses the results of an investigation that was aimed at quantifying the infl uence of aggregate stiffness on the measured creep behaviour of plain concrete. The experimental programme included measurements of total creep on concrete specimens of two different strength grades for each of three different but commonly used South African aggregate types (quartzite, granite and andesite). In addition, elastic modulus tests were conducted on cores of the aggregate types assessed. The test results revealed that no clear correlation exists between the creep of concrete and the stiffness...