Standard Test Average Test Average ASTM C 97 Absorption (3) 0.89 % Bulk Specific Gravity (3) 2 628 ASTM C 99 Modulus of Rupture Day (3) 1 900 psi ASTM C 170 Compressive Strength Day (5) 19 800 psi ASTM C 241 Abrasion Resistance Day (3) 38.8 Ha ASTM C 880 Flexural Strength Day (5) 1 900 psi