Effect of grinding method and particle size distribution on the properties of Portland-pozzolan cement

• In PPC, the presence of Trass improved the particle size distribution.
• Durability properties of cements were not affected by fineness significantly.
• The use of cements with high fineness seems not economically beneficial.

This paper describes the influence of the producing method (Inter-grinding or separate grinding) and particle size distribution (PSD) on properties of Portland-pozzolan cements (PPC). Experiments were carried out on cement paste including normal consistency, time of setting, Ca(OH)2 content, and heat of hydration, on cement mortar including potential alkali-silica reaction, and on concrete including compressive strength, sorptivity, electrical resistivity, and rapid chloride permeability. In this study, 10 types of cements including two types of Portland cement (PC), and eight types of Portland-pozzolan cement (PPC) were used. The results show that PPC provided better mechanical and durability properties compared to PC properties. This was evident especially in PPC containing 25% Trass. Also, the durability properties of cements were not affected by increase of fineness significantly. Particle size distribution (PSD) of PPC varied for each method of production, which was largely due to the amount of Trass in the PPC. Finally, it was concluded that physical properties of cements obtained by Inter-grinding were slightly better than that of separate grinding; however, durability properties were not affected by grinding method. Also, for achieving the same percentage of 45-μm residue, Inter-grinding is less energy-demanding than separate grinding (shorter grinding time is required). In addition, the use of cements with high fineness seems not economically beneficial due to its low effect on long term properties.