Effect of pretreated biomass fly ash on the mechanical properties and durability of cement mortar

Abstract

As the reduction of CO2 emissions is set as an international goal, the use of biomass is increasing. However, the large amount of ash generated after using biomass is an important issue to deal with. The chemical composition of some biomass fly ash is similar to that of C-class fly ash, so it is suitable for use as supplementary cementitious materials, and many analyses have been performed in existing studies. However, due to its high porosity and unburned particles, it is insufficient as a complete alternative material for cement. Therefore, this paper conducted a study on the mechanical properties and durability of mortar including BFA by improving the irregular particle structure of BFA and removing unburned particles by applying two processes. Specimens were manufactured by mass substitution 10%, 20%, and 30% of BFA for cement, and a water reducer was added for improving the workability. As a result, mortar containing pretreated BFA (PBFA) had significantly improved strength and chloride penetration resistance compared to mortar containing untreated BFA (UBFA). The average pore size of the specimen including PBFA was greatly reduced, and the untreated ash showed an irregular average pore size depending on the replacement rate. Thus, this study showed that pretreatment on BFA could have a positive effect on mechanical properties and durability.

Keywords

• Biomass fly ash
• Pretreatment
• Mechanical properties
• Chloride diffusivity