Mechanical and durability properties of alkali-activated mortar based on sugarcane bagasse ash and blast furnace slag

Abstract

A. Pereira; Akasaki, JL.; J.L.P.Melges; Mitsuuchi Tashima, M.; Soriano Martinez, L.; Borrachero Rosado, MV.; Monzó Balbuena, JM.... (2015). Effect of sugarcane bagasse ash (SBA) added to alkali-activated blast furnace salg (BFS) AbstractSugarcane bagasse is an agricultural waste which can be transformed, for cementing purposes, into an interesting material by combustion. Specifically, the ash (SBA) obtained by autocombustion was used for preparing alkali-activated cements by blending blast furnace slag (BFS). SBA had a large amount of quartz; however, it reacted in high alkaline medium. Mixtures of BFS/SBA have been used for preparing alkali-activated mortars, by using NaOH (8M solution), sodium silicate (8M solution in Na + and SiO 2 /Na 2 O molar ratio of 0.5) and KOH (8M solution) as activating reagents. Replacements of 25, 33 and 50% of BFS by SBA were carried out and compressive strengths in the range 16-51 MPa were obtained after 90 curing days. Microstructural studies demonstrated that the hydration products formed in the activation of BFS are not significantly affected by the presence of SBA in the mixture. The durability of alkaliactivated mortars was compared to ordinary Portland cement (OPC) mortar in the following media: hydrochloric acid, acetic acid, ammonium chloride, sodium sulphate and magnesium sulphate. The behaviour of alkali-activated mortars with BFS and BFS/SBA was better than that found for plain OPC mortars, especially in ammonium chloride, acetic acid and sodium sulphate media. After 200 days of testing in ammonium chloride solution, the compressive strength loss for Portland cement mortar was about 83.3%. For the same test conditions, alkali-activated mortars presented a maximum reduction of 48.4%. The presence of SBA in alkali-activated BFS mortars did not produce any serious problems in durability. As a general conclusion, sugarcane bagasse ash (SBA) obtained by autocombustion showed good cementing properties as a mineral precursor blended with blast furnace slag (BFS) in alkali-activated systems.

Increasing the sustainability of alkali-activated binders: The use of sugar cane straw ash (SCSA)

“…In this particular study, it will be assessed as a component in an AA binder system with blast furnace slag. The huge amount of this waste generated and previous studies on agroindustry residues in AA binders support this study [20,21]. SCSA from this study was obtained from an auto-combustion process of the straw.…”

“…First, regarding the raw materials, the main vibration bands of BFS and SCSA were 964 and 1028 cm À1 (Si(Al)-O-Si vibration), respectively. The pastes showed peaks in the range of 940-980 cm À1 (SiAOAT vibration, T = Si or Al) [20]. With an increase in the amount of SCSA in the mixture, the main vibration band shifted to higher wavenumber values.…”

Management and valorisation of wastes through use in producing alkali‐activated cement materials

“…More recently Pereira et al also produced blended activated cements based on blast furnace slag and SCBA, and evaluated the durability of these binders when exposed to hydrochloric acid, acetic acid, ammonium chloride, sodium sulfate and magnesium sulfate. These cements performed much better than Portland cements when exposed to ammonium chloride, acetic acid and sodium sulfate; however, little advantage was observed when the specimens were exposed to hydrochloric acid or magnesium sulfate.…”

An Approach to a New Supplementary Cementing Material: Arundo donax Straw Ash

“…Other ashes have been studied to assess their properties in terms of their reactivity in cementing systems. These include sugarcane bagasse ash (SCBA), studied in ordinary Portland cement (OPC) mixes [8,9], and sugarcane straw ash (SCSA), studied in geopolymeric systems based on blast furnace slag [10]. Rice straw ash (RSA) has been characterized and used to replace 10% and 25% OPC [11].…”