TY - JOUR A1 - Carabba, L. A1 - Pirskawetz, Stephan A1 - Krüger, Simone A1 - Gluth, Gregor A1 - Bignozzi, M.C. T1 - Acoustic emission study of heat-induced cracking in fly ash-based alkali-activated pastes and lightweight mortars T2 - Cement and Concrete Composites N2 - Alkali-activated fly ashes have been proposed for various applications where resistance against high temperatures is required, yet several details regarding the response of these materials to heat-exposure need to be clarified. In the present study, heat-induced cracking in fly ash-based alkali-activated pastes and lightweight mortars was analyzed by in-situ acoustic emission (AE) detection during complete heating-cooling cycles (up to ∼1100 °C), augmented by thermogravimetry and ex-situ SEM and XRD analyses. The applicability of the lightweight mortars as passive fire protection coatings was assessed by recording temperature-time curves of mortar-coated steel plates. Cracking during heating was limited and associated exclusively with the dehydration of the materials in the temperature range ∼90–360 °C. However, samples heated to temperatures above ∼600 °C exhibited intense cracking on cooling. This was attributed to differential deformations caused by local sintering and partial melting at the glass transition temperature, and subsequent quenching on cooling. PB - Elsevier KW - Alkali-activated materials KW - Acoustic emission KW - Fire proofing KW - Heat resistance KW - Cracking PY - 2019 UR - https://opus4.kobv.de/opus4-bam/frontdoor/index/index/docId/47904 AN - OPUS4-47904 SN - 0958-9465 SN - 1873-393X VL - 102 SP - 145 EP - 156 AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany