Experimental Investigation of Mortar Compressive Strength Using 5.08 cm. Cubes and 7.62 cm. × 15.24 cm. Cylinders

ASTM C270 “Mortar For Unit Masonry” lists compressive strength requirements under the property specification based on 5.08 cm. cubes. ASTM C780 “Preconstruction and Construction Evaluation of Mortars For Plain and Reinforced Unit Masonry” allows the use of 5.08 cm. × 10.16 cm. cylinders, 7.62 cm. × 15.24 cm. cylinders or 5.08 cm. cubes in determination of mortar compressive strength. The cylinder compressive strength may be considered to be equal to 85% of the cube compressive strength. An experimental investigation of the compressive strength relationship between 5.08 cm. cubes and 7.62 cm. × 15.24 cm. cylinders for (1) laboratory mortars cured in a moist room, (2) job site mortars cured in laboratory air, and (3) job site mortars cured outside has been conducted. The data includes portland cement lime mortar, masonry cemment mortar, and ready mix mortar.