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Frequently Asked Soil-Cement Questions
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FAQs > Testing of In-place Cores or Beams
Should the acceptance criteria of completed soil-cement
be based on compressive or flexural strength test results of in-place
cores or beams?
 The
Portland Cement Association (PCA) does not recommend the use of
strength test results from in-place cores or beams as acceptance
criteria for completed soil-cement including cement treated base
(CTB) and full-depth reclamation (FDR). In addition, acceptance
criteria for unconfined compressive or flexural strength test results
based on molded specimens in the field are also not recommended.
The problem is the difficulty in obtaining representative samples
of the in-place material as well as the time delay in addressing
a possible problem that may exist. It is extremely rare for state
or local transportation agencies to base their acceptance criteria
on the in-place unconfined compressive strength of completed soil-cement
bases due to the many difficulties involved and questionable results.
Occasionally cores, beams, or field molded cylinders are obtained
and tested, but these results are used for record purposes, and
not used as acceptance criteria.
As an alternative to taking cores or beams, PCA promotes the adherence
to quality control during design and construction. The normal steps
to ensure that a quality project meeting the required specifications
is met are as follows:
- In the laboratory, determine the proper cement content that
will be necessary to adequately stabilize the project materials
as well as the optimum moisture content and maximum dry density
for these materials.
- In the field, apply the amounts of cement and water determined
in the laboratory to the in-place materials.
- In the field, thoroughly mix the in-place materials, cement,
and water until a homogenous blend is obtained.
- In the field, thoroughly compact and then shape the soil-cement
material to project requirements.
- In the field, properly cure the completed soil-cement until a
final pavement surfacing is applied.
 The
purpose of field inspection and control of soil-cement during construction—
cement content, moisture content, mixing, compaction, and curing—is
to ensure that the results set out in the plans and specifications
are obtained and if problems do arise they can be handled immediately.
Further information on the proper construction and quality control
of cement-stabilized pavement materials are available in PCA publications
Soil-Cement Construction
Handbook,
EB003 and Soil-Cement
Inspector’s Manual,
PA050.
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