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RCC130H-CRACK SAW OPERATION AND PARTS MANUAL REV #1 (11/18/04) PAGE 29
ASSEMBLY INSTRUCTIONS/OPERATIONS
STOPPING THE RCC130H SERIES GASOLINE
POWERED CRACK SAWS.
1) Position the quick change height lever over center
to its rear most (up) position.
2) Stop the Crack Saw by moving the engine throttle
control lever to the idle speed position. Turn the
ignition switch located on the engine to the OFF
position. Consult the material supplied by the engine
manufacturer for specific information.
OPERATIONAL PARAMETERS AND
TECHNIQUES FOR THE RCC130H SERIES
CRACK SAW.
Basic definitions.
There are very few aspects of the pavement
maintenance industry that all members, including
contractors, engineers, researchers and government
agencies can agree on except the inevitability of
cracks forming in all types of pavements. To
properly address the crack repair procedures,
contractors must have a basic understanding of why
crack repair is beneficial, crack types to address and
the repair materials and methods available.
A basic understanding of the difference between
crack filling and crack sealing and the working
knowledge to understand which one is appropriate
for a specific job application is essential for any
pavement maintenance contractor.
An industry accepted definition of crack filling is the
placement of materials into cracks to reduce water
intrusion and reinforce the adjacent pavement.
Crack sealing is the placement of specialized
materials either above or into working cracks to
prevent the intrusion of water and incompressibles
such as sand, aggregate and dirt.
Why Do It at All?
Crack sealing is used as a first line of defense
against the deterioration of pavement because of its
inherent benefits:
a) It protects the base and sub-base. A good
pavement requires a base and sub-base of high
structural integrity. Effective crack sealing
procedures eliminate water from entering and
weakening these areas. The resulting weakness
can result in the loss of structural support, which can
then further result in the formation of additional
cracks and settling around the crack area.
b) It preserves the pavement adjacent to the
cracking. Cracks that are properly cleaned and
sealed contain filler materials that firmly adhere to
the crack sides during times of both expansion and
contraction. Without the addition of these filler
materials, the adjacent pavement would have
increased exposure to the elements, resulting in
increased oxidation of the binder, hardening and
secondary cracking along the main crack.
c) It eliminates the damaging effects of
incompressibles such as sand, aggregate and dirt.
When these materials get into a crack they can
restrict crack closure during periods of warm
weather. The resulting compressive stresses at the
faces can create spalling and loosening. In some
highly oxidized pavements these stresses can even
create pavement lipping, which is the upheaval of
pavements at their transverse cracks.
d) It extends pavement life. Sealing procedures
allow the contractor to effectively exert control over
the base and sub-base conditions, pavement
interference and crack growth, thereby extending
the pavement's service life.
Types of Cracks.
There are several basic types of cracks:
a) Reflective. This type of crack appears primarily in
resurfacing projects, although it can also occur in a
new pavement surface. Reflective cracks occur
when an existing crack or joint in the underlying
pavement structure reflects upward through the
surface.
b) Joint. A joint is the edge of the individual paving
pass made during construction. Such construction
joints usually have a lower density than the
remaining material. When the placed mats do not
bond properly (for any number of reasons), joint
cracks can appear.
c) Slippage. Slippage cracks are usually crescent
shaped and are created by heavy traffic that is either
stopping, turning or climbing a hill. Resultant
stresses can cause a bond failure between upper
and lower pavement layers. The open end of the U
shaped crack always points in the direction of the
applied force.
d) Thermal. All pavements expand and contract due
to temperature variations. This movement can
create cracks. To better allow for movement,
pavements need to be constructed with the correct
percentage of air voids, which provide for internal
stress relief. When the air void percentage is not
correct, thermal cracks appear.