7.2 Special Classes:
7.2.1 If permitted by the owner, the manufacturer may
request approval by the owner of a special class of pipe having
D
Ult
and D
design
values that differ from those shown in Table 1.
7.2.2 Such special classes of pipe shall be based on the same
design/testing requirements as required for those classes found
in Table 1.
7.3 The manufacturer shall formulate for their own produc-
tion practices and records the following for each pipe product
and size.
7.3.1 Pipe Strengths—(D
design
) and (D
Ult
).
7.3.2 Material Strengths:
(a) Minimum Compressive Strength of the Concrete - (f
c
),
(b) Minimum Reinforcement Yield Strength and Ultimate
Strength - (f
y
) and (f
u
),
(c) Minimum Elastic Modulus of Reinforcement – (E
s
).
7.3.3 Quantities of Materials:
(a) The concrete mix design, including all materials and
admixtures within the concrete matrix,
(b) Area of continuous reinforcement in units of in.
2
/ft
[cm
2
/ m],
(c) Volume of noncontinuous reinforcement in units of
lb/yd
3
[kg/m
3
] or percent of volume of concrete.
7.3.4 Physical Characteristics—Diameter, wall thickness,
laying length, and joint details.
8. Reinforcement
8.1 Where one line of circular reinforcement is used, the
protective cover of the concrete over the circumferential
reinforcement in the wall of the pipe shall be
3
⁄
4
in. [19 mm].
8.2 In pipe having two lines of circular reinforcement, each
line shall be so placed that the protective covering of concrete
over the circumferential reinforcement in the wall of the pipe
shall be 1 in. [25 mm].
8.3 In pipe having elliptical reinforcement with wall thick-
nesses 2
1
⁄
2
in. [63 mm] or greater, the reinforcement in the wall
of the pipe shall be so placed that the protective covering of
concrete over the circumferential reinforcement shall be 1 in.
[25 mm] from the inner surface of the pipe at the vertical
diameter and 1 in. [25 mm] from the outer surface of the pipe
at the horizontal diameter. In pipe having elliptical reinforce-
ment with wall thicknesses less than 2
1
⁄
2
in. [63 mm], the
protective covering of the concrete shall be
3
⁄
4
in. [19 mm] at
the vertical and horizontal diameters.
9. Joints
9.1 The joints shall be of such design and the ends of the
concrete pipe sections so formed that the pipe can be laid
together to make a continuous line of pipe compatible with the
permissible variations given in Section 13.
9.2 Joints shall conform to the requirements of Specifica-
tions C443,C990/C990M,C1628, or other established joint
types approved by the owner, including, but not limited to,
mortar, sealant or externally-wrapped joints.
10. Manufacture
10.1 Mixture—The aggregates shall be sized, graded,
proportioned, and mixed with such proportions of cementitious
materials, water, and admixtures, if any, to produce a thor-
oughly mixed concrete of such quality that the pipe will
conform to the test and design requirements of this specifica-
tion. Cementitious materials shall be as specified in 6.2 and
shall be added to the mix in a proportion not less than 470
lb/yd
3
[280kg/m
3
] unless mix designs with a lower cementi-
tious materials content demonstrate that the quality and per-
formance of the pipe meet the requirements of this specifica-
tion.
10.2 Curing—Pipe shall be subjected to any one of the
methods of curing described in 10.2.1 to 10.2.4 or to any other
method or combination of methods approved by the owner, that
will give satisfactory results. The pipe shall be cured for a
sufficient length of time so that the specified D-load is obtained
when acceptance is based on 5.1 or so that the concrete will
develop the specified compressive strength at 28 days or less
when acceptance is based on 5.2.
10.2.1 Steam Curing—Pipe shall be placed in a curing
chamber, free of outside drafts, and cured in a moist atmo-
sphere maintained by the injection of live steam for such time
and such temperature as needed to enable the pipe to meet the
strength requirements. At no time shall the ambient tempera-
ture exceed 160°F [71°C]. The curing chamber shall be so
constructed as to allow full circulation around the inside and
outside of the pipe.
10.2.2 Water Curing—Concrete pipe may be water-cured by
covering with water saturated material or by a system of
perforated pipes, mechanical sprinklers, porous hose, or by any
other approved method that will keep the pipe moist during the
specified curing period.
10.2.3 A sealing membrane conforming to the requirements
of Specification C309 may be applied and should be left intact
until the required strength requirements are met. The concrete
at the time of application shall be within 10°F [6°C] of the
atmospheric temperature. All surfaces shall be kept moist prior
to the application of the compounds and shall be damp when
the compound is applied.
10.2.4 The manufacturer may, at his option, combine the
methods described in 10.2.1 to 10.2.3 provided the required
concrete compressive strength is attained.
11. Pipe Proof of Design Testing
11.1 Load Bearing Test:
11.1.1 Basis of Acceptance of Design—Three representative
specimens or special class test pipe in accordance with 7.2
shall be tested to the D
design
load and D
ult
strength load in
accordance with the requirements of Test Methods C497 with
any laps or splices placed in the critical zone, and the results
recorded and witnessed. All specimens shall meet or exceed the
required limits to qualify the design of the pipe.
NOTE 3—The critical zone in 11.1.1 is at 12/6 o’clock for inner or single
cages, and at 3/9 o’clock for an outer cage.
11.1.2 The pipe shall be deemed acceptable for the desig-
nated class if the D
design
strength and ultimate strength of the
tested pipe are equal to or greater than the required D
design
and
D
Ult
for that class.
11.2 Sample Testing of Pipe Strength—If any part of the
material or manufacture of the pipe in accordance with Section
C1846/C1846M − 19 (2024)
3