Strain rate effects in fracture of polymer modified cements

Abstract

Because of the role of the polymer in governing the fracture behaviour of polymer modified (ICI ‘NIMS’) cements, it is of considerable importance to investigate the effects of strain rate. Creep rates in polymers are generally higher than those associated with cement or concrete; this is particularly the case when a polymer is plasticised. One of the most effective plasticisers for a water soluble polymer is obviously water. It is known that polymer modified cements suffer a relatively rapid loss of strength on immersion in water. However, this loss will be exacerbated by creep effects, especially in the presence of stress concentrations, resulting in fracture through stress corrosion processes. This paper presents recent data obtained on these problems for both Portland and calcium aluminate cements.

MST/717