ASTM C140:21 pdf free download – Standard Test Methods for Sampling and Testing Concrete Masonry Units and Related Units.
7.4.3 Speed of Testing-Apply the load (up to one half of the expected maximum load)at any convenient rate,after which
adjust the controls of the machine as required to give a uniform rate of travel of the moving head such that the remaining load is applied in not less than I nor more than 2 min.The results of the first specimen shall not be discarded so long as the actual loading time for the second half of the actual load is greater than 30 s.
Note 11-The allowance for a loading rate outside of I to 2 min for the first specimen acknowledges that the expected load may be different than the actual maximum load.The load rate for the remaining two specimens should be adjusted based on the first specimen results.
7.4.4 Maximum Load-Record the maximum compressive load in pounds [newtons]as P
8.Absorption
8.1 Apparatus-Unless specified otherwise in the appropriate annex,the following equipment shall be used:
8.1.1 Balance-A balance readable and accurate to 0.1 of the weight of the smallest specimen tested.Balances shall be
calibrated in accordance with Practice C1093.
8.1.2 Oven-A ventilated oven of appropriate size capable of maintaining a uniform temperature of 2309F
[110+5C].Ovens shall be verified in accordance with Practice C1093
8.1.3 Timer-A timer readable and accurate to 1 second. Timers shall be verified in accordance with Practice C1093.
(See Note 12.)
Note 12-Recommended procedures for verifying timers can be found in NIST Special Publication 960-12 (2009):NIST Recommended Practice Guide-Stopwatch and Timer Calibrations.
8.2 Test Specimens:
8.2.1 Unless specified otherwise in the applicable annex, test three specimens in absorption.
8.2.2 Unless specified otherwise in the applicable annex, tests shall be performed on full-sized units or specimens
saw-cut from full-sized units.Calculated values for absorption and density of reduced-size absorption specimens shall be considered as representative of the whole unit.
8.2.2.1 When test specimens are saw-cut from full-sized units,the test specimen shall have an initial weight after cutting of no less than 20%of the initial received weight of the full-sized unit.
Note 13-When performing absorption tests on reduced-sized specimens,it is preferable to have a test specimen that is as large as practically possible and can be accommodated by laboratory equipment.
This helps to reduce any location-specific variability from the absorption results.
8.3 Procedure:
8.3.1 Immerse the test specimens in water at a temperature of 60 to 80F [15 to 27C]for 24 to 28 h such that the top
surfaces of the specimens are at least 6 in.[150 mm]below the surface of the water.Specimens shall be separated from each other and from the bottom of the immersion tank by at least 0.125 in.[3 mm],using wire mesh,grating,or other spacers.
The spacer shall not cover more than 10 of the area of the face that is in direct contact with the spacer (see Note 14).