Fire Performance of Alkali Activated Slag and Geopolymers

Download or read book Fire Performance of Alkali Activated Slag and Geopolymers written by Maurice Guerrieri and published by . This book was released on 2008 with total page 358 pages. Available in PDF, EPUB and Kindle. Book excerpt: The most significant finding of this thesis is the total strength loss of AAS paste specimens at 50°C under air flow for up to 24 hours. A detailed investigation of this instability attributed this strength loss to the loss of chemically bound water from the breakdown of the C-S-H in the AAS paste. This also explains the reasoning behind the high thermal shrinkage of the AAS paste which caused differential thermal shrinkage causing damage at higher temperatures. The slag/fly ash systems were investigated in the next step, since they have been shown to be more stable than AAS systems. The influence of the initial compressive strength, the silicate modulus (SiO2/Na2O) and the concentration of activator used (%Na) of slag/fly ash geopolymer systems were investigated with sixty mixes. The residual strength performance of the slag/fly ash geopolymer pastes after exposure to a temperature of 800°C was linked to the ductility/brittleness of the material. The inability of the materials with low ductility to accommodate thermal-incompatibilities arising from uneven temperatures during heating is concluded to have been the major factor contributing to strength losses of the geopolymer pastes investigated. This phenomenon is in fact a recurring theme with all the different systems investigated in this thesis, and should be a major consideration in the pursuit of the development of fire resistant concretes.