chapter 3 rigid pavement - DOT On-Line Publications - Department ...

FHWA TECHNICAL ADVISORY T 5080.17
July 14, 1994
maximum aggregate size should be limited to
'20 percent of the narrowest dimension of a
concrete member, 75 percent of the clear spacing
between reinforcing steel, or 33 percent of the
depth of a slab for unreinforced concrete.
b. The minimum cement content refers to all
cementitious and pozzolanic material in the
concrete, including cement and any mineral
admixtures that are being added to or substituted
for cement. Replacement rates should be based on
those contained in paragraph 3d(3).
(I) The PCA,recommends a minimum cement content
of 335 kg/m' for concrete placed in severe
exposure conditions and AC1 316R recommends a
minimum cement content of 335 kg/m3 for
concrete pavements in all locations unless
local experience indicates satisfactory
performance with lower cement contents. Even
if strength requirements can be met with a
lower cement content, a minimum cement
content of 335 kg/m3 should be used unless it
can be demonstrated,that the concrete will be
durable,
(2) In cases where local experience allows a
reduction in cement content below 335 kg/m3
the cement content should not be reduced
below the following minimum cement contents
recommended by AC1 302.1R Table 5.2.4 for
concrete slab and floor construction. The
minimum cement contents listed below are
based on the nominal maximum size of the
aggregate.' The cement content decreases as
the nominal maximum aggregate size increases
due to the decrease in aggregate surface
area.
Nominal maximum size Cement content
aggregate, mm kg/m'
37.5mm 280kg/m'
25mm 310kg/m3
19mm 320kg/m3 /
12.5mm 350kg/m3
9.5mm 365kg/m'
3.10.12