Only enough water shall be added to make concrete workable for
its intended use. The engineer will determine the slump ranges within
which the contractor must work. Ready-mix or transit mix concrete
may be used if obtained from sources approved by the engineer. Equipment
used to proportion and mix concrete on the job is subject to the approval
of the engineer.
Reinforcements shall be accurately cut, bent and placed in accordance
with the plans. It shall be free of excessive scale or any foreign
material that would tend to reduce bond. It shall be securely supported,
tied and fastened to prevent movement while concrete is being placed.
Subgrades, excavations, and soil bases for foundations and slabs
shall be properly finished to the prescribed lines, grades and dimensions,
and shall be approved by the engineer before concrete is placed. All
areas to receive concrete shall be free of frost, foreign matter and
excessive water; provided, however, that forms and soil surfaces shall
be uniformly damp when the concrete is placed.
Concrete shall be handled and placed so as to avoid any segregation.
Concrete which has begun to set or which has been contaminated with
foreign materials or to which too much water has been added shall
not be used. Pouring of concrete shall generally be a continuous operation
until the placing of an individual section has been completed. Concrete
shall be thoroughly compacted with vibrators or by other suitable
means.
Expansion joints, dummy joints, construction joints and other
appurtenances shall be provided as shown on the standard details.
Expansion joints shall have joint filler of the thickness indicated
which shall extend the full depth of the concrete.
After removal of forms, all permanently exposed surfaces shall
be cleaned of stains and dirt, and all surface defects which do not
impair structural strength shall be repaired by cutting and patching.
Concrete shall not be poured when the atmospheric temperature
is below 40° F. or when there is any precipitation, unless precautions
satisfactory to the engineer have been taken to prevent any damage
to the work. Precautions necessary to avoid freezing of the concrete
shall be in accordance with the current recommendations of the American
Concrete Institute.