The impact of variation in chemical and physical properties of PFA and BPD semi-dry cement paste on strength properties

• The addition of BPD in PFA–OPC blends results in strength loss.
• PFA and BPD give variability in both physical and chemical properties.
• At 14 days, the fineness of PFA has greater impact on strength.
• At 28 days, the SiO2 content of PFA has greater impact on strength.
• Particle size variability of BPD plays a major role in the strength development.

The effect of Pulverised Fuel Ash (PFA) and By-Pass-Dust (BPD) in ternary semi-dry cement pastes was reported. As well as this, the variability over 6 months in chemical composition and particle distribution was reviewed to determine impact on strength. The addition of BPD in ternary pastes resulted in a reduced strength when combined with PFA. PFA and BPD samples obtained over a 6 month period showed variability in both chemical composition and particle distribution. For PFA, it was reported that at 14 days the particle size distribution had greatest impact on strength and at 28 days the SiO2 content had greatest impact. The high variability in BPD particle size distribution resulted in finer particles achieving the greatest strength.