January/February 2021 - 96

Testing Updates
The revised standard requires that a
load cell or equivalent device must be
placed in series with the hydraulic jack.
The standard does not specifically
discuss which reading to use when
readings diverge. Section 1.4 states, " A
qualified geotechnical engineer should
interpret the test results ... . " If the
engineer interpreting the results does
not monitor the actual test, how do they
know which data to trust? Does this
mean that it is left to someone's judgment? Many contractors and engineers
have found that load cells tend to be
more precise when unaffected by
environmental and loading conditions.
However, load cells tend to be more
sensitive to field conditions and can be
in greater error when affected by field
conditions. Interestingly, some
contractors and engineers have found
that, on long overnight holds, the load
cell reading is often more stable than
the hydraulic jack reading. Everyone
needs to remember that the calibrations
were performed in a laboratory
environment. The laboratory will
remind you of this when you question
the calibration.
Section 10 (Procedure) includes the
statement, " Failure as used in this
section may be understood to mean
such rapid displacement of the element
that further loading is not possible. "
This statement is not meant to replace a
proper review and determination of
geotechnical capacity after the testing
is complete.
In section 10, procedures are provided for three types of load tests that
have undergone some modifications:
quick test, maintained test and constant
rate of penetration test. Meanwhile, four
other procedures have been removed:
loading in excess of maintained test,
constant time interval, and constant
time and cyclic loading.
The primary change to the quick test
method is that the selected load
increment can be between 5% and 10%
of the expected failure load. As before,
96 * DEEP FOUNDATIONS * JAN/FEB 2021

all load increments are the same and all
hold times are the same, except that the
engineer may consider a longer time
interval for the failure load as a way to
assess creep, or for the final zero load to
assess rebound behavior.
The primary change to the constant
rate of penetration test focuses on what
directions are given on how to maintain
a constant rate. The directions now
recommend to " Control the rate of
penetration by checking the incremental penetration rate every 15
seconds and then adjusting the jacking
accordingly to maintain the selected
penetration rate. "

directly by a load cell. There was strong
disagreement about specifying one
approach over the other among
committee members, reflecting the
overall sentiment throughout the deep
foundation industry. The DFI Codes and
St a n d a r d s Co m m i t t e e h a s t h u s
recommended that the institute's
Testing and Evaluation Committee
investigate this issue. Simpson also
serves as the vice chairman of that
committee, and is working to gather
volunteers for a working group to
address this unresolved matter. The
group would produce a peer-reviewed
white paper for possible publication.

Remaining Considerations

Standard Renewal Steps

The most significant issue that remains
unresolved with the revised ASTM
D1143 is that the standard does not
specifically discuss which load reading

Regardless of headway by that DFI
working group, all ASTM Standards
must be reapproved every 7 years or
they are removed from the ASTM
library of standards. A removed
standard would not be available for
purchase or included in larger
collections or volumes.
The process of renewing a standard
can be simple in concept. At any time in
the 7 years of its lifespan, an ASTM
member can request a work item and be
named a technical contact. That
member then becomes the person in
charge of balloting the standard for
renewal, with or without making
proposed changes to the standard.
Changes can be as simple as a small
editorial correction, or adding a required
caveat or definition - or changes can
include major revisions. All ASTM
subcommittee members then vote on
the renewal request.
For a revised standard to be
approved, all subcommittee members
must vote affirmative or abstain, with or
without comments. This total agreement
almost never happens, with a single
negative vote stopping the whole
process. The technical contact must then
address the negative voter's comments
and make changes that will not trigger
new negatives. The power of the single
voter is somewhat unique. But the single

High capacity D1143 load test in Georgia

to u s e w h e n r e a d i n g s d i v e r g e .
Regarding the Section 1.4 wording
shared earlier that a qualified engineer
should interpret results, how does that
engineer know which data to trust if
they do not monitor the specific test?
The specific issue is that engineers both
use, and are comfortable with, load data
derived from pressure data with a
calibrated jack, and also the data given
January/February 2021

Table of Contents for the Digital Edition of January/February 2021
