Sugar cane bagasse ash from a high efficiency co-generation boiler: Applications in cement and mortar production: Fid-Bau Portal

Sugar cane bagasse ash from a high efficiency co-generation boiler: Applications in cement and mortar production

Arif, Elisabeth / Clark, Malcolm W. / Lake, Neal

Highlights • Pozzolanic activity of these bagasse ashes is low and most beneficial as filler-materials. • Activity reduces from polymorph phase changes to α-quartz at high burn temperatures. • Increases in sulphuric acid resistance are displayed in compressive strength retention. • Acid resistance is reflected in significantly reduced mass loss from expansion, and spalling. • Acid resistance occurs from pore-filling and/or cement chemistry shifts from C3A, to C2S.

Abstract Sugarcane bagasse ash (SCBA) has been reported to be beneficial as cement replacement due to the pozzolanic and the filler effect. The SCBA from a high-efficiency (high temperature) co-generation boiler does not contain significant amorphous silica rather it contains α-quartz generated by phase transitions during combustion. The high combustion temperatures appear to deactivate the silica, and lime-SCBA pastes show little or no pozzolanic activity present, except at a 5% replacement. Compressive strength testing of the cement pastes also suggests that at 5% cement replacement level, the SCBA is potentially pozzolanic. However, up to 15% SCBA cement replacements achieve a pozzolanic index above 75%, which suggests increases in pozzolanic activity by the relative strength tests are more likely from a filler effect than true pozzolanic activity. Despite an apparent lack of pozzolanic activity all SCBA’s additions improved sulphuric acid resistance measured both through compressive strength testing and mass loss measurements.