On29.8.2024, Professor Fang worked with the research team from University College London (UCL) together to publish a research paper entitled "Micromechanical analysis of alkali-activated fly ash-slag paste subjected to elevated temperatures" in Cement and Concrete Composites (Q1, IF: 10.8). This paper presents a systematic experimental study on microstructural characteristics and micromechanical properties of alkali-activated fly ash-slag paste (AAFS) after exposure to 20-800 ºC. Professor Fang from Shenzhen University and Professor Zhang from UCL are co-corresponding authors.
Alkali-activated materials have been considered as a promising alternative to ordinary Portland cement because of their superior mechanical performance, significant reduction in CO2emissions, alkali-activated fly ash-slag (AAFS) is an attractive type of AAM in blend precursor system, which combines the advantages of alkali-activated fly ashandalkali-activated slag to achieve excellent engineering properties and durability at ambient temperature curing. High-temperature exposure can be one of the most crucial factors that determines the suitability of AAFS as fire-resistant and thermal energy storage materials. Thus, it is vital to carry out a thorough investigation into the high-temperature performance of AAFS.However, existing studies still lacka comprehensive understanding of the evolution of micromorphology and gel compositions, as well as the relationships between microstructure and mechanical performance in AAFS at elevated temperatures, andno work has attempted to explore the micromechanical properties of AAFS paste after exposure to high temperatures and link them with microstructural characteristics.To address this issue,this paper presents a systematic experimental study on microstructural characteristics and micromechanical properties of AAFS after exposure to 20-800 ºC. The microstructural evolution in terms of morphology, phase assemblage and gel compositions wereexamined using backscattered scanning electron microscope-energy dispersive spectrometry (BSEM-EDS), while atomic force microscopy (AFM) and nanoindentation tests were conducted to evaluate the micromechanical properties at elevated temperatures. Results indicate that the volume fraction of unreacted particles drops from 29.7% to 4.0%, whereas porosity in AAFS paste goes up from 4.1% to 15.4% at up to 800 ºC. The average hardness and elastic modulus are in the ranges of 0.6-14.5 GPa and 27.0-104.2 GPa,respectively. Based on the obtained experimental results, the microstructure-micromechanical property relations and inherent damage mechanisms were then discussed in depth from a multiscale viewpoint.
This study was supported by the National Natural Science Foundation of China and the Shenzhen Municipal Science and Innovation Commission.
The original article can be found at:https://doi.org/10.1016/j.cemconcomp.2024.105735
Fig.1 Schematic illustration of microstructure-micromechanical property relationships in AAFS paste at elevated temperatures
