TM 5-822-5/AFM 88-7, Chap. 1
CHAPTER 17
ROLLER-COMPACTED CONCRETE PAVEMENTS
transfer at the joints, i.e. assuming all joints/cracks
17-1. Introduction.
to be a free edge condition.
Roller-compacted concrete pavement (RCCP) is a
zero-slump portland cement concrete mixture that
17-3. Thickness Design.
is placed with an asphalt concrete paving machine
and compacted with vibratory and rubber-tired
The thickness design curves shown in figure 12-1
rollers. Mixture proportions and most engineering
will be used to determine thickness requirements for
properties of RCCP are similar to those of conven-
RCCP. These curves are the same as used for plain
tional plain concrete pavements. The mixture pro-
concrete roads and streets.
portions of RCCP are not appreciably different than
those used in conventional concrete; flexural
17-4. Multilift Pavements.
strengths of beams taken from RCCP facilities and
The maximum lift thickness that can be placed at an
test sections routinely exceed 650 psi at 28 days.
acceptable grade and smoothness and compacted to
Limited tests have shown that the fatigue charac-
a uniform density is about 10 inches. Therefore, if
teristics of RCCP mixtures are similar to those of
the RCCP design thickness is greater than 10
conventional concrete pavement mixtures. In
inches, two or more lifts will be necessary to
Canada under moderately severe environmental and
achieve the design thickness. If possible, the upper
heavy loading conditions, RCCP hardstands have
lift should be of minimal thickness, preferably one-
performed well for over 10 years alongside
third of the total pavement thickness (but no less
conventional concrete hardstands. Therefore, it may
than 4 inches), to aid in creating a smoother surface
he assumed that the same rationale applied to the
finish. The type of bond achieved between the lifts
thickness design for plain nonreinforced concrete
is a function of the construction sequence and
pavement thickness may also be applied to the
timing and will govern the method of thickness
design of RCCP.
design used for multilift RCCP. The three types of
bonding conditions to be considered in RCCP thick-
17-2. Load Transfer.
ness design are full bond, partial bond, and no bond.
a. Full bond. Full bond may be assumed between
A major difference exists in the assumptions of load
transfer at joints made for plain concrete pavements
adjacent lifts if they are placed and compacted
and RCCP, which directly effects the design stress
within 1 hour of each other, or if a thin grout is
and therefore the thickness of the pavement. RCCP
placed between the upper and lower lifts. The
has typically been allowed to crack naturally, and
surface of the lower lift must be kept clean and
spacings between these cracks are usually irregular,
moist until the upper lift is placed and should not he
ranging from 40 to 70 feet apart (although spacings
rolled with the rubber-tired roller. If the full bond
much greater and much lower than these have been
condition is achieved, the thickness should be
reported). Consequently, the width of the crack
determined as if a monolithic slab were used, with
opening will he greater and the load transfer
no consideration for the joint between lifts in the
developed from aggregate interlock at the cracks
thickness design calculations.
b. Partial bond. Partial bond should be assumed
will be highly variable, if not totally lost. Limited
tests at Fort Hood, TX, and Fort Steward, GA,
between subsequent lifts if they are placed and
have revealed average load transfer at transverse
compacted more than 1 hour apart. The surface of
contraction cracks of 18.6 percent (standard
the lower lift must he kept clean and moist until the
deviation of 6.7 percent) and longitudinal cracks
upper lift is placed. The thickness should be
16.7 percent (standard deviation of 5.9 percent),
designed as a rigid overlay of a rigid base pavement
respectively. Tests on longitudinal and transverse
with partial bonding according to the guidance in
cold (construction) joints revealed even less load
chapter 14.
c. No bond. No bond may be assumed between
transfer. Therefore, the assumption of 25 percent
load transfer at joints in open storage areas
adjacent lifts if some type of bond breaker is used
constructed of plain concrete would not be valid for
between the lifts, such as a curing compound or
RCCP thickness design. The approach then would
asphalt emulsion sprayed on the surface of the
be to base the thickness design of RCCP on no load
lower lift. The thickness should be designed as a
17-1
Previous Page
