ETL 1110-3-488
1 Mar 98
(6) Ready mix concrete sources. For smaller jobs, the use of readymix concrete may be
considered, to avoid mobilization of relatively expensive central mix plants typically used on
medium to large size projects. When applicable, this section provides information on the sources
and distances from local readymix plants to the project.
(7) Aggregate test results. Small bagged samples of potential aggregate should be taken
during field inspections, for preliminary petrographic examination. If preliminary examinations
and information indicate an aggregate source should be considered for use, then bulk samples are
obtained and transported to the test laboratory. The results of aggregate physical quality,
chemical, petrographic and deleterious material testing are evaluated together to determine the
suitability of each aggregate for the purpose and environmental conditions the concrete will be
subjected to. EM 1110-2-2000, "Standard Practice for Concrete," provides guidance on
aggregate testing. TM 5-822-7, "Standard Practice for Concrete Pavements," provides additional
guidance on aggregate testing, including guidance for deleterious materials testing. The results
from concrete aggregate testing should be recorded in Technical Memorandum 6-370, "Test Data
- Concrete Aggregates and Stone Riprap in Continental United States and Alaska.
(8) Mixture proportioning test results. Sufficient time is seldom available to complete
aggregate testing prior to the initiation of mixture proportioning studies. Both aggregate testing
and mixture proportioning studies, conducted by the Government and directed by the materials
engineer, are generally pursued concurrently during the design stage. Mixture proportioning
studies are essential for concrete pavements to determine the potential concrete properties for
design, to evaluate the cost efficiency and suitability of each aggregate source, to establish which
aggregates can be used (and possibly listed in the specifications), and to assist in the development
of cost estimates for the project. Poor aggregate quality may limit the strength of the concrete to
moderate or even low values. Mixture proportioning studies are also used to examine the range
of strength obtainable with a particular aggregate. Typically three water-cement ratios are
selected for mixture proportioning that will bracket the water-cement ratio expected to provide
the strength level desired. These water-cement ratios should be widely spaced so that a full range
of strength performance is provided. The same water-cement ratios should be used for all the
aggregates investigated to allow for direct comparison of the strength performance of the
aggregates. The "efficiency" of each aggregate source can be evaluated by comparing similar
mixes using the different aggregates. This can be done by comparing the "cement efficiency" of
each mixture, that is, the strength divided by the cementitious material content of the mixture.
(9) Service record studies. Study of the performance of aggregates in existing concrete
pavements in the region of the project must be conducted to provide information on the long-term
durability and performance of those aggregates. These pavements could include older pavements
at the installation, local state highways, county or city roads, or pavements at local airports.
Records of aggregates and other materials used in these older pavements are generally difficult to
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