The microstructure and mechanical properties of blended cements hydrated at various temperatures

The development of microstructure and compressive strength of three blended cement pastes hydrated at temperatures ranging G-om 10 degreesC to 60 degreesC is described. The replacement materials were pulverised fuel ash (PFA), volcanic ash (VA), and ground, granulated blast furnace slag (GGBFS), and the blended cements had the same compositions as those reported in previous studies. The cement pastes were cured under water and tested for compressive strength at various time intervals over a period of 1 year. The only blended cement paste that had substantially improved strength compared with the neat cement paste was that containing blast furnace slag, especially at 60 degreesC. Selected samples were examined by backscattered electrons in scanning electron microscopy (SEM). Generally, the microstructures of the pastes cured at 60 degreesC showed greater apparent porosity than those cured at 10 degreesC. The mechanism of hydration of the various blended cements is discussed. (C) 2001 Elsevier Science Ltd. All rights reserved.