Alkali-activated binders based on incinerator bottom ash combined with limestone-calcined clay or fly ash. (21st February 2022)

• Record Type: Journal Article
• Authors: Liu, Jun; Liang, Zhen; Jin, Hesong; Kastiukas, Gediminas; Tang, Luping; Xing, Feng; Ren, Jie
• Is Part Of: Construction & building materials. Volume 320(2022)
• Publication Date: 2022-02-21
• Subjects: Municipal incinerator bottom ash -- Limestone-calcined clay (LC2) -- Alkali-activated binders -- Mechanical properties -- Heavy-metal immobilization; Building materials -- Periodicals; 624.18
• DOI: 10.1016/j.conbuildmat.2021.126306
• Languages: English
• ISSNs: 0950-0618

Abstract

Highlights: LC2 was for the first time incorporated into AABA binders to improve properties. LC2 is better compared to FA when the N2 O dosage was higher. Higher compressive strength and heavy-metal immobilization capacity by replacing BA with LC2 or FA (no more than 30%). Increased N2 O dosage does not always lead to higher compressive strength. Abstract: This study investigates the feasibility of improving the properties of alkali-activated bottom ash (AABA) binders by incorporating limestone-calcined clay (LC2) or fly ash (FA) with the aim of treating and utilising bottom ash in a large-scale as a potential resource for construction materials. Experimental results revealed that increasing the substitution with LC2 or FA in the AABA binders increased both the compressive strength and the immobilization capacity of heavy metal when compared to the pure AABA binders. Given a Na2 O content of 5%, the compressive strength of the AABA binder with 30% bottom ash substituted by FA was almost 200% higher than that of the pure AABA binder. However, further increase in the Na2 O dosage did not necessarily lead to higher compressive strength, which was found to be controlled by the volume fraction of air voids and large pores. When greater Na2 O dosages were employed, i.e., 6 % and 7 %, LC2 was found to be more useful in improving the properties of AABA binders than FA. Furthermore, the substitution of bottom ash with FA resulted in the formation of N-A-S-H gels, whereas the substitution with LC2 led to the formation of more C-A-S-H gels. Finally, the immobilization capacity appeared to be influenced by many factors, such as hydration products, capillary pores and different types of heavy metals.