Humboldt H-4134 Concrete Pocket Penetrometer - Manual (Page 2)

General Information
Lightweight, spring-reaction type concrete penetrometer for field and lab
evaluation of the initial set of concrete mortar, based on ASTM C403.
Penetration plunger has a 1/20 sq. in. tip area. Plunger is steadily pushed
into the mortar to a 1 in. depth, as indicated on the shaft, at periodic
time intervals. Penetrometer’s calibrated range is 0-700psi. Resistance in
psi is indicated on the scale. The term “initial set” is the semi-hardened,
partially hydrated condition of the concrete beyond which it can no longer
be worked. The point of initial set is reached when the penetration value
is 500psi. Meets ASTM C780.
The H-4134 Concrete Mortar Penetrometer is used for field and laboratory
evaluations of the initial set of concrete mortars. The Penetrometer can also be
used on light-weight concrete, special roof mixes and concrete additives.
“initial set” of concrete is reached when the penetration resistance is 500 psi
(3,448 kPa). “Initial set” is the semi-hardened, partially hydrated condition of the
concrete beyond which it can no longer be worked or consolidated by vibration.
The test involves forcing the Penetrometer's shaft into the mortar to a depth of
I" (25.4 mm) at constant rate and time intervals. The resistance in psi is shown on
the Penetrometer's direct-reading scale.
The 38-2695 (CT-421A) Concrete Mortar Penetrometer incorporates the following
features:
• Direct-reading scale from 0 to 700 psi
• Indicator sleeve which holds reading until released
• Lightweight, pocket-size design
• Convenient belt-loop style, canvas carrying case
Test Procedure
A. Holding the sleeve of the penetrometer, slide the indicator ring towards
the sleeve until the ring touches the sleeve.
B. Positioning the shaft at right angles to the concrete mortar surface, force the
shaft into the mortar to the 1" (25.4 mm) depth mark, scribed on the shaft.
C. Pull out the penetrometer and take the reading on the scale at the low-reading
edge of the indicator ring.
D. Before doing another test, slide the indicator ring to the sleeve edge.
E. Take several readings and calculate the average value in psi or kPa if desired.
NOTE: Immediately after each penetration test, clean the shaft by wiping off the
wet mortar with a piece of cloth.