Sugar cane bagasse ash from a high-efficiency co-generation boiler as filler in concrete

• Published in: Construction & building materials Vol. 151; pp. 692 - 703
• Main Authors: Arif, Elisabeth, Clark, Malcolm W., Lake, Neal
• Format: Journal Article
• Language: English
• Published: Elsevier Ltd 01-10-2017
• Subjects: Chloride ingress; Co-generation boilers; Drying shrinkage; Filler; Sugar-cane bagasse ash; Co-generation boilers; Sugar-cane bagasse ash; Drying shrinkage; Filler; Chloride ingress
• ISSN: 0950-0618
• DOI: 10.1016/j.conbuildmat.2017.06.136

•Pozzolanic activity of these bagasse ashes is low and most beneficial as filler-materials.•As a filler material the concrete compressive is increased by ≈20% over controls.•Increases in sulphuric acid resistance as strength and reduced spalling are displayed.•Acid resistance is from either pore-filling and/or cement chemistry shifts from C3A, to C2S.•Rapid chloride permeability tests suggest increased permeability.
Bagasse ashes from high efficiency co-generation boilers have dominant filler effect in concrete from a greatly reduced pozzolanic activity because of quartz polymorph phase changes to α-quartz, rather than the often-reported α-cristobalite for bagasse derived silica. Sugar cane bagasse ash used as filler in concretes provided substantial improvements to compressive strengths at up to ≈20%. These combined filler effect and limited pozzolanic activity improved the acid resistance as measured by both mass loss and compressive strength tests. Improved acid resistance suggests pore filling and lowered permeability from the filler effects, whereas the limited pozolanic may be sufficient to shift cement chemistry to more acid resistant silicates mineral systems compared to aluminate minerals (e.g., C3A to C2S). Similarly, drying shrinkage improved. However, in contrast the rapid chloride permeability tests indicate increased chloride ingress, suggesting increased permeability, but these maybe possibly misleading results generated from the superplasticizer.