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ASTM C 185 08: Test for Air Content in Hydraulic Cement Mortar

  • Flow determination

1. Place flow mold in centre of flow table

2. Using spoon, place 25 mm thickness of mortar in mold, tamp 20 times

3. Overfill mold with ~20 mm, then tamp again 20 times

4. Cut off the mortar in a plane surface using straightedge

5. Lift mold away after 1 minute

6. Immediately drop table 10 times


  • Mass per 400 mL of mortar
whole process must be done within 1.5 minutes

1. When water needed for 87.5% flow has been determined, immediately determine mass of 400 mL of mortar remaining in mixing bowl (CANNOT reuse the one used for flow)

2. Using spoon, place mortar in 400 mL measure in 3 equal layers, tamp each layer 20 times in a complete revolution

3. Overfill final layer by ~20 mm

4. After filling and tamping, tamp the sides of the measure 5 times in different locations using stick of tamper

5. Cut off mortar using straightedge using two strikes, perpendicular to each other

6. Determine the mass of the mortar in grams


  • Calculation

Air content, volume% = 100 – W[(182.7 + P) / (2000 + 4P)]

W = mass of 400 mL of mortar, g P = percentage of mixing water, based on mass of cement used