Abstract
Coal gangue-slag geopolymer is a kind of environment-friendly material with excellent engineering performance and is formed from coal gangue and slag after excitation by an alkaline activator. In this study, three kinds of coal gangue-slag geopolymer were activated by different activators, and the compressive and flexural strengths of water and sulphate solutions in the wetting-drying (W-D) cycles were compared. The microscopic mechanism was analyzed by the XRD, the FTIR and the SEM. The following conclusions are drawn: The influence of W-D cycles on flexural strength was greater than compressive strength. The water migration and the recombination of geopolymers lead to the change of colour, as well as the reduction of flexural strength and compressive strength of geopolymers. The SH geopolymer had excellent anti-erosion ability in terms of flexural strength, and the reason for this was the recombination and polymerization reaction of geopolymer being weaker than the SS and the SSG. The corrosion resistance of the SS was reflected in the compressive strength, because its geopolymerization reaction was fierce, which produced more Na-rich C–N–A–S–H, N–A–S–H and C–A–S–H gels. Therefore, the compressive strength could still reach more than 39 MPa after 150 cycles. Sulfate solution could effectively control the reduction of compressive strength of the SH and the SS geopolymers during W-D cycles. The SSG had the worst corrosion resistance.
Highlights
Published: 28 November 2021A geopolymer is a three-dimensional inorganic polymer with high strength mechanical properties, physical properties, durability, and low carbon dioxide release [1,2,3,4]
High-temperature calcination, and grinding, coal gangue will be transformed into high-purity kaolin, and it can be transformed into metakaolin when the calcination temperature is controlled in the low-temperature calcination zone, 500–900 ◦ C [11]
Whether coal gangue-based geopolymers pressive strength, and corrosion resistance coefficient (Kf), and the microscopic mechacan adapt to extreme weather conditions has become a problem that must be considered nism was analyzed for byitsX-ray diffractometry (XRD), fourierthetransform radiation wide promotion in engineering
Summary
A geopolymer is a three-dimensional inorganic polymer with high strength mechanical properties, physical properties, durability, and low carbon dioxide release [1,2,3,4]. Geopolymers prepared only with coal gangue as raw materials have a long hardening time and low strength after alkali activation, which limits their wide application in engineering. Geopolymers will shrink strength performance of gangue-slag geopolymer under ordry and transformation wet environments cracks coal or decrease strength due to water evaporation material in high temperature or humid weather were [20]. Whether coal gangue-based geopolymers pressive strength, and corrosion resistance coefficient (Kf), and the microscopic mechacan adapt to extreme weather conditions has become a problem that must be considered nism was analyzed for byitsX-ray diffractometry (XRD), fourierthetransform radiation wide promotion in engineering. The total time of each W-D cycle was (24 ± 2) h with following segments: The test piece was soaked in the solution for (15 ± 0.5) h, air-dried for 30 min, China) together with the coal gangue and slag powder mixture. The SEM (Zeiss Sigma 500, Zeiss, Oberkochen, Germany), and the FTIR ( Nicolet iS5, Thermo Fischer Scientific Inc., Waltham, MA, USA) methods were used to analyze the microscopic mechanism
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