Underground Construction - June 2017 - 16

Job-Site Geo
ble. The ASTM test procedure uses a Kelly Ball to measure when the flowable fill has set up enough to place backfill over it. As described in ASTM
D 6024, the test involves dropping a steel ball five times on the surface
of the hardened material and measuring the diameter of the impression.
If the diameter is 3 inches or less, the material is able to have backfill or
pavement placed over it.
The test apparatus is the same equipment as that used in ASTM C 360
for concrete, but the procedure is slightly different. In C 360, the ball is
suspended at the surface of fresh concrete, released, and the depth of
penetration measured. The average depth penetration of three determinations is correlated with the standard slump test.
Some agencies have required the use of a Proctor penetrometer, ASTM
D 1558, to judge set time. The 1-inch tip for the Proctor penetrometer
should be used, particularly for native flowable fill containing soil clods.
The penetrometer is much more convenient to use than a Kelly ball. The
suggested procedure is to perform companion tests of the Kelly ball and
the Proctor penetrometer early in the project and establish a correlation
so that only the penetrometer need be used. This correlation should be
repeated if there are significant changes in the mixture. Alternatively, the
pocket penetrometer used for soils has also been used.

is filled with the slurry, the top struck off
level, and the container weighed.
For stiffer mixes of flowable fill,
ASTM C 138 may be more appropriate
to use, since it prescribes rodding or vibrating the mixture to remove air pockets that do not exist when the material is
in slurry form.
REFERENCES

Unit weight, yield, air content

Howard, Amster (2015) Pipeline Installation
2.0, Relativity Publishing
ASTM C 39, Test Method for Compressive
Strength of Cylindrical Concrete Specimens
ASTM C 138, Standard Test Method for Unit Weight, Yield, and Air Content
(Gravimetric) of Concrete
ASTM C 143, Standard Test Method for Slump of Hydraulic-Cement Concrete
ASTM C 172, Standard Method of Sampling Freshly Mixed Concrete
ASTM C 360, Standard Test Method for Ball Penetration in Fresh Portland Cement
Concrete
ASTM D 1558, Standard Test Method for Moisture Content Penetration Resistance
Relationships of Fine-Grained Soils

ASTM D 6023 has been developed to measure the unit weight of the
fresh material. The procedure also gives formulas for calculating the yield,
cement content, and the air content of the soil-cement slurry. The procedure is similar to ASTM C 138 for concrete. A container of known volume
(capacity depends on the maximum particle size present in the mixture)

ABOUT THE AUTHOR: Amster Howard is a civil engineering consultant from
Lakewood, CO, and a recognized expert on soil interaction. This article is based
on an excerpt from his book Pipeline Installation 2.0. For more information, go
to Pipeline-Installation.com.

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NEW Why "self-compacting" soils are not.
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NEW How to increase sustainability using flowable fill.
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This is an excellent book. My family was in the metal
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This is the most complete book I've seen on this topic.
David Dow
Trench Safety and Supply, Inc.
Memphis TN

PIPELINE-INSTALLATION.COM/BOOK
16

ucononline.com

Underground Construction June 2017

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