Text Box: Table 4 Comparison of aspects of durability for concrete containing FA of differing fineness (Thomas, 1991) Durability property Design Strength (N/mm2) Fly ash fineness 3.5% 35.0% (i) chloride diffusion (cm2/s x 10-9) 35 9.4 10.2 50 4.9 4.3 60 1.2 1.5 (ii) carbonation depth (mm) 25 31.0 32.0 35 17.0 17.5 (iii) sulfate resistance, 25 41 45 expansion (% x 10-3) 35 28 28 50 0 0 (iv) Freeze-thaw durability factor (%) 35 51 48 50 72 65 35 † 98 97 (v) abrasion (mm) ‡ 35 1.10 0.92 50 0.79 0.80 FA content = 30% by mass of PC +FA (i) two compartment cell, (ii) 4.0% enriched CO2, 20°C, 55% RH (30 weeks), (iii) 6.0g/l MgSO4 (184 days exposure), (iv) ASTM C666, Procedure A, (v) Modified BCA method. † air entrained concrete, ‡ cured for seven days wrapped in polythene and then air at 20°C, 55% RH to 28 days