Development of controlled low strength material (CLSM) using self-cementitious flyash

This experimental investigation aims at developing controlled low strength materials (CLSM) using a self-cementitious fly ash and bottom ash (aggregate). The fly ash and bottom ash specimen used in this study were obtained from a circulating fluidized bed combustion boiler (CFBC). To find the optimum mixing condition satisfying flow consistency and unconfined compression strength (UCS), the CLSM specimens were prepared under various mixing conditions, including varying aggregate types and fractions. Additionally, the prepared specimens were evaluated through scanning electron microscope and X-ray diffraction (XRD). The results of this study demonstrate that the UCS ranges from 325 kPa to 1855 kPa, and the water content satisfying flow consistency ranges from 42 to 85%. The USC increases with increasing the fraction of aggregate in whole mixture. The flowability is improved with increasing the fraction of aggregate as well. SEM images and XRD patterns reveal that both geopolymerization and C-S-H reaction. With those results, CLSM based on CFBC fly ash could be used as an alternative material to apply various geotechnical problems.