Effects of elevated temperatures on the properties of nanomodified rapid hardening concretes

Abstract

Effects of elevated temperature exposure and hardening age on mechanical properties of nanomodified concrete are presented. The mass loss, compressive strength and shrinkage of the exposed to the elevated temperatures and cooled specimens were determined. Nanomodification by ultrafine mineral additives and polycarboxylate eter superplasticizer provides direct early structure formation, higher strength at early and later ages, and improved thermal resistance in a range of 200-350 °C of cement-base materials. High specific surface area of ultrafine mineral additive particles and their "excess surface energy" determine interaction degree with powder part components of concrete and allow realizing dense packing, filler, high water-reducing, early pozzolanic reaction, high early strength effects to increasing the rigidity of the cement matrix to resist deformation at impact of elevated temperature.