Characterization, pretreatment, and valorization of wood biomass fly ash in a binary cement-free binder
Xuhui Liang (TU Delft - Civil Engineering & Geosciences)
Hua Dong (TU Delft - Civil Engineering & Geosciences)
Zhenming Li (Harbin Institute of Technology)
Chen Liu (TU Delft - Civil Engineering & Geosciences)
Shizhe Zhang (Renewi Mineralz & Water, TU Delft - Civil Engineering & Geosciences)
Guang Ye (TU Delft - Civil Engineering & Geosciences, Universiteit Gent)
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Abstract
This research investigated the use of wood biomass fly ash (WBFA) as a key component in developing low-carbon cementitious materials. WBFA was first subjected to water pretreatment and grinding to remove metallic aluminum and free lime, reducing expansion and cracking risks. Characterization of WBFA showed its high calcium and alkali-bearing phases but limited aluminosilicates. Dissolution test showed WBFA had strong alkalinity, suggesting its role as an activator for aluminosilicate-bearing minerals. A novel cement- and chemical-free binary binder was developed using 50 % treated WBFA and 50 % blast furnace slag (BFS). Paste with a water-to-binder ratio of 0.4 achieved 40 MPa compressive strength at 60 days. The use of superplasticizer significantly improved flowability, allowing the water-to-binder ratio to be reduced to 0.25, which resulted in compressive strength up to 58 MPa at 60 days. Calcium aluminate silicate hydrates (C-A-S-H) gels and ettringite were identified as the main reaction products in the pastes.
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