Mortar Penetration Resistance Apparatus (H-4137)
Page 4 of 6
Instruction Manual Rev.0; August 14, 2003
Copyright 2003 Humboldt Mfg. Co., Norridge, IL. 60706, U.S.A.
All rights reserved. Printed in U.S.A.
6.3 Insert a needle of appropriate size in the apparatus and bring the bearing surface
of the needle into contact with the mortar surface. Gradually and uniformly apply
a vertical force downward on the apparatus until the needle penetrates the mortar
to a depth of 1 inch (25mm) as indicated by the scribe mark read at top of slide.
The time required to penetrate to the scribe mark shall be approximately 10
seconds. Record the force required and time of application, measured as elapsed
time after initial contact. In subsequent penetration tests, avoid areas where
mortar has been disturbed by previous tests. Distance between impressions
should be at least two (2) diameters of the needle used, but not less than ½ ”
(13mm) and at least 1” (25mm) from the side of the container being used.
6.4 Make penetration tests at hourly intervals for normal mixtures and normal
temperatures. The initial test being made after an elapsed time of 3 to 4 hours. In
some instances, the initial elapsed test times maybe increased or decreased.
6.5 Not less than six (6) penetration determinations should be made in each rate of
hardening test. The time intervals between penetrations resistance determinations
shall be such as to give a satisfactory rate of hardening curve. Continue test until
one penetration resistance of at least 4,000 psi (27.6 mpa) is reached.
7. Calculation
Calculate the penetration resistance, in pounds per square inch, or mega Pascal, as the
force required to cause a 1" (25mm) depth of penetration of the needle divided by the
area of the bearing face of the needle.
8. Replacement Needles
Needle Size
Model No. Square Inch Square MM
H-4143.1 1 645
H-4143.50 ½ 323
H-4143.25 ¼ 161
H-4143.10 1/10 65
H-4143.05 1/20 32
H-4143.025 1/40 16
