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(3) Joint sealant and lubricant samples are sent to Waterways Experiment Station, Vicksburg,
MS. Contact CEWES for more information prior to sending.
(4) Mixing plant and paver. The Contractor should submit information on the mixing plant
and paver proposed for use as soon as possible, since this submittal often doesn't initially meet the
specification requirements. This is a critical submittal for it directly affects the quality of the
project. The paver requirements have been carefully prepared to avoid use of pavers that have
not performed adequately on previous similar work. Any paver submitted for use must be
carefully checked against the specification.
d. Concrete strength (para. x in xxxxx). These paragraphs spell out all of the flexural and
other strength requirements. Tests at 1 (accelerated splitting tensile test), 14, and 28 days are
required for early information. By comparing strengths at early ages with laboratory curves, the
contractor can get an indication of the strength potential at 90 days.
e. Slump (para. x in xxxxx). The slump limits in the specification are maximums, not
averages. The slump limit for slipform paving is especially critical for acceptable pavement
construction. Concrete which has a slump over these limits must be rejected.
f. Air entrainment. Air content is a critical parameter for frost areas. Air content below the
required limits will result in non-durable concrete. Air content above the required limits will
g. Materials (para. x in xxxxx).
(1) Aggregates must meet special grading requirements and special limits on deleterious
materials. Deleterious material limits are essential to avoid popouts and other durability problems
caused by weak aggregate particles. These have been a serious problem on a number of
pavements across the nation. Excessive wood chips can also be a problem with some local
aggregates, and must be removed.
(2) Cement and Class F or C Pozzolan. Pozzolan provides many benefits in concrete, but
must be carefully evaluated to avoid occasional problems. The source of pozzolan is an important
indicator of its performance. Contact the materials engineer for more information on sources.
(3) Admixtures. Note that retarding admixtures are not permitted for slipform paving, but are
allowed for fixed-form paving. Retarders are useful in hot weather to provide extra finishing
time, but cause excessive edge slump in slipform placements. Any admixture used in the concrete
construction must have been the same specific admixture used in the mixture proportioning