Assessment of Sieving as a Mean to Increase Utilization Rate of Biomass Fly Ash in Cement-Based Composites

Abstract

Biomass fly ash is a growing challenge for combustion by-product (CBP) management. This research was conducted to investigate the influence of activation by sieving through a 63 µm sieve and a 125 µm sieve on fresh and hardened cement mortar properties. Sieving increased the CaO content by 9.3 percentage points (p.p.) in the oxide composition of the fly ash. The 28-day Strength Activity Indices increased by 24.9 p.p. A 25% replacement rate of cement with fly ash sieved with a 63 µm sieve increased the 2-day compressive strength of mortars by 24% when compared with untreated fly ash. The 90-day compressive strength results of cement mortars with a 15% replacement rate of cement with fly ash sieved with a 63 µm sieve were similar to the control specimen results. The utilization rate of biomass fly ash can be increased to 15% of binder mass without the detrimental effect of the mechanical properties of cement mortar. SEM and TG analyses showed that activated biomass fly ash promoted the growth of the C-S-H phase and ettringite.

Keywords

• fly ash
• cement mortars
• activation
• sieving
• biomass