Abstract
This paper presents the effects of alkali-activated blast furnace slag and fly ash (AASF) paste added with waste ceramic powder (WCP) on mechanical properties, weight loss, mesoscopic cracks, reaction products, and microstructure when exposed to 300, 600, and 900 °C. Using waste ceramic powder to replace blast furnace slag and fly ash, the replacement rate was 0–20%. The samples cured at 45 °C for 28 days were heated to 300, 600, and 900 °C to determine the residual compressive strength and weight loss at the relevant temperature. We evaluated the deterioration of the paste at each temperature through mesoscopic images, ultrasonic pulse velocity (UPV), thermogravimetric analysis (TG), Fourier transform infrared (FTIR) spectroscopy, X-ray diffraction (XRD), and with a scanning electron microscope (SEM). Relevant experimental results show that: (1) with the increase in waste ceramic powder content, the compressive strength of samples at various temperatures increased, and at 300 °C, the compressive strength of all the samples reached the highest value; (2) the residual weight increased with the increase in the content of the waste ceramic powder; (3) with a further increase in temperature, all the samples produced more mesoscopic cracks; (4) at each temperature, with the rise in waste ceramic powder content, the value of the ultrasonic pulse velocity increased; (5) the TG results showed that, as the content of waste ceramic powder increased, the formation of C-A-S-H gel and hydrotalcite decreased; (6) XRD and FTIR spectra showed that, at 900 °C, the use of waste ceramic powder reduced the formation of harmful crystalline phases; (7) the SEM image showed that, at 900 °C, as the content of waste ceramic powder increased, the compactness of the sample was improved. In summary, the addition of waste ceramic powder can improve the mechanical properties of the alkali-activated paste at high temperatures, reduce the occurrence of cracks, and make the microstructure denser.
Highlights
It undergoes a series of dissociation, precipitation, and polymerization reactions to form a solid-phase calcium aluminosilicate hydrate (C-A-S-H) gel that can affect its mechanical properties and thermal durability [8,12,13]
When the samples were processed at 300 ◦ C, the compressive strength of all samples increased, especially waste ceramic powder (WCP)-0, which had the highest increase in rate of compressive strength
The compressive strength decreased with increasing temperature
Summary
The raw materials of alkali-activated materials are usually industrial byproducts such as blast furnace slag (BFS) and fly ash (FA). Their use significantly reduces CO2 emissions and reduces environmental pollution. Xie [10] studied the performance of alkali-activated BFS and FA geopolymer recycled concrete. They believe that the combination of geopolymer binder and recycled concrete can exhibit excellent compression resistance. Xie [11] studied the sulfate resistance of recycled aggregate concrete containing BFS and FA geopolymers. It undergoes a series of dissociation, precipitation, and polymerization reactions to form a solid-phase calcium aluminosilicate hydrate (C-A-S-H) gel that can affect its mechanical properties and thermal durability [8,12,13]
Sign-in/Register to view highlights & summary Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
