STANDARD PRACTICE FOR CONCRETE PAVEMENTS
for airfield pavements. These ages are not adequate
1. Purpose. This manual provides information on the
for quality control in the field since a large amount
materials and construction procedures for concrete
of low-strength concrete could be placed before
pavements.
strength tests on samples revealed the problem.
Correlations can be established between a 14-day
strength and the 28- or 90day strength used in
2. Scope. This manual describes the constituents to
design, and this correlated 14-day strength can be
be used in concrete, the procedures to be used in
used as a strength check for a more timely concrete
manufacturing concrete, and the equipment and
mixture control in the field.
procedures to place, texture, and cure concrete for
pavements.
(l.) Materials and flexural strength. To select
suitable flexural strengths for the design of
pavements and for inclusion in contract specifica-
3. Responsibilities, strength, and air content.
tions, the contracting officer should have reliable
information regarding flexural strengths obtainable
a. Responsibility for mixture proportioning. The
with acceptable concrete materials which are available
responsibility for mixture proportioning must be
in the vicinity of the project. Typical design values
clearly assigned to either the contractor or the
for flexural strength of paving-quality concrete
contracting officer in the project specifications.
vary from 500 to 750 pounds per square inch (psi).
When the contracting officer is responsible for
mixture proportioning, he will approve all concrete
Numerous tests indicate considerable variation in
the flexural strength of concrete when different
materials as well as determine and adjust propor-
aggregates or different cements are used. There are
tions of all concrete mixtures as necessary to obtain
some indications that aggregate shape and modulus
the strength and quality of concrete required for the
of elasticity are relatively more important in
pavements. Cement will be a separate pay item in
concrete flexural strength than in compressive
the contract. When the contractor is responsible for
strength. Also, after optimum flexural strength is
mixture proportioning, he will control all proportions
reached, there usually is little increase in strength,
of the concrete mixture necessary to obtain the
even with a large increase in cement content. Mixture
strength and quality of the concrete required for the
proportioning studies will be made in accordance
pavements, and cement will not be a separate pay
with ACI 211.1 (see app A for referenced publications)
item in the contract. However, the contracting officer
to determine the flexural strengths to be used for
is responsible for approving the quality of all
the design of the project. The water-cement ratio-
materials the contractor uses in the concrete.
strength relations for mixture proportioning in ACI
211.1 are given in terms of compressive strength.
b. Approval responsibility. The contracting officer
Table 1 gives some approximate guidance for
is responsible for approval of all materials, mixture
relating the concrete modulus of rupture to the
proportions, plants, construction equipment, and
compressive strength-water cement ratio relation-
construction procedures proposed for use by the
ships given in ACI 211.1. All aggregates, cementitious
contractor. The contractor must submit proposed
materials, and admixtures used in the mixture
mixtures if he is responsible for mixture propor-
proportioning studies will be representative of
tioning; samples of all materials; and detailed
materials available for use in pavement construction.
descriptions of all plants, construction equipment,
In selecting a flexural strength for pavement design,
and proposed construction procedures prior to the
suitable allowance will be made for variations in
start of construction.
strength indicated by tests of different combina-
tions of aggregate and cement. Pavement design
c. Flexural strength. Structural designs are based
will be based on a realistic and economical strength
on flexural strengths that the concrete is expected
obtainable with available materials.
to obtain at 28 days for road pavements and 90 days
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