PAVEMENT Hardcore TEGARTurapan is Layered Structure Consisting of a Slab Surface Layer and the Base or Subbase Konkritbertetulang Built on the Subgrade

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rigid pavement is a layered structure consisting of a layer of reinforced concrete slab surface and the

base or sub-base built on the subgrade.

Lebuhraya Air Keruh

–Pagoh.

•Lebuhraya Kuala Lumpur

–Tanjung Malim.

•Lebuhraya Gurun

Bukit Kayu Hitam.

Mass concrete

Mass concrete brings with it many challenges, among them the generation of high heat and problems that

can stem from it. While creating these projects can be difficult, careful design of mass concrete can

minimize or eliminate issues, and new research points to approaches that will allow us to create bigger

projects than ever before.

Jointed Reinforced Concrete Pavement

Jointed reinforced concrete pavement (JRCP, see Figure 1) uses contraction joints and reinforcing

steel to control cracking. Transverse joint spacing is longer than that for JPCP and typically ranges

from about 7.6 m (25 ft.) to 15.2 m (50 ft.). Temperature and moisture stresses are expected to



cause cracking between joints, hence reinforcing steel or a steel mesh is used to hold these cracks

tightly together. Dowel bars are typically used at transverse joints to assist in load transfer while the

reinforcing steel/wire mesh assists in load transfer across cracks.

Continuous reinforce concrete pavement

Continuously reinforced pavement is pavement in which the continuity of the longitudinal reinforcing steel

is interrupted only at structures or at the ends of the projects. There are no transverse joints other than

construction joints and expansion joints at structures. The whole idea of continuously reinforced

pavement is based essentially on the "so let is crack" philosophy rather than the fussy concept of avoiding

cracks at any price. The important difference, however, is that a continuously reinforced pavement is

designed to keep the cracks tightly closed so that the slab will retain its structural integrity. In an

unreinforced slab cracks which occur will normally widen and get progressively worse under the effects of

traffic and climatic conditions. Fortunately, the amount of reinforcement needed to control the cracking is

relatively low if the length of the slab is short. But as the length of the slab increases the amount of steel

needed also increases. This is the main reason why the length of conventional slabs has always stayed

within 40 to 100 feet. It has simply proved more economical from a first cost standpoint. However, the

steel is not directly proportional to the slab length as is usually assumed in the design of conventional

jointed reinforced pavement. As a matter of fact, the relationship is a parabolic function with the steel

increasing at a progressively decreasing rate as the slab length increases and reaching a maximum at

slab length of 600 to 800 feet. It has also been found that as the amount of steel in the slab is increased,

the number of cracks also increases. Theoretically, this is highly desirable because it means that stresses

due to any cause will be distributed more evenly among the cracks and no single crack will then show a

tendency to open excessively. An excessive number of cracks has no real influence on the structural

efficiency of the slab. The design, therefore, should include only the optimum amount of steel that will (1)

cause sufficient cracks to occur and (2) ensure that they will remain tightly closed under service.

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6_body.htm

Prestressed Pavement

The PCP concept incorporates prestressing in both the transverse and longitudinal direction in

the form of pretensioning and/or post-tensioning. As discussed in the previous chapter,

prestressing provides numerous benefits for long-term pavement performance. Prestressing

induces a compressive stress in the slab, helping to reduce or even eliminating the occurrence of

cracking, while also reducing the required slab thickness.

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In general, the precast panels are pretensioned along the long axis of the panel (transverse

pavement direction) during fabrication, and post-tensioned together along the short axis

(longitudinal pavement direction) after installation, as will be described below. Transverse

pretensioning not only provides the necessary permanent prestress in the pavement slab, but also

permits longer and thinner precast panels to be used as it helps counteract lifting and handling

stresses. Likewise, the longitudinal post-tensioning not only provides the necessary permanent

prestress, but also provides load transfer between the panels.

The post-tensioning system used for the longitudinal tendons is a bonded post-tensioning system.

After the longitudinal post-tensioning tendons are tensioned, grout is pumped into the ducts to

bond the strands to the precast panels. A bonded post-tensioning system provides continuity

between the prestressing strand and concrete, reducing the amount of non-prestressed steel

required in the panels. This continuity also permits individual panels to be sawcut and removed

from the pavement, if necessary, without compromising the integrity of the entire longitudinal

post-tensioning system. Grouting also provides an additional layer of corrosion protection for the

post-tensioning tendons, which is critical in colder climates where deicing salts are used

http://www.fhwa.dot.gov/pavement/concrete/pubs/hif08009/hif08009.pdf

FIXED FORM PAVING

In fixed form paving, side forms are used to hold fresh PCC in place at the proper grade and

alignment until it sets and hardens. These forms may also serve as tracks for various


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pieces of placing and finishing equipment. Fixed form paving is most appropriate for small

jobs (see Figure 7.110), complicated geometry pavements or variable width pavements,

however it can be used for large jobs as well (see Figure 7.111). Particular advantages of

fixed form paving are (ACPA, 1995):

Tight tolerances and side clearances. Existing curbs or other features can beused as forms.

Custom geometry . Forms can be placed in just about any pavement geometry,

which allows for multiple changes in pavement width, smooth curves, blockouts

and other abnormalities.

Better construction staging. Forms can be placed such that staged construction

can be used to maintain traffic flow or intersection use (see Figure 7.112).

Less expensive equipment and mobilization. Forms and equipment are less

expensive than slipform paving equipment. If paving operations are small

enough, this cost savings can more than offset the higher production rates of

slipform paving.




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Figure 7.110 (top left):

Small Fixed Form Job

Figure 7.111 (top right):

Large Fixed Form Job

Figure 7.112 (right):

Construction Staging Using Fixed Form Paving

This section presents PCC forms, placement, consolidation, finishing and curing as they are

typically done in fixed form paving. Often more than one of these steps can be performed

by the same piece of equipment, such as a vibrating screed, which serves to strike off andconsolidate the fresh PCC, or a traveling carriage paver which can perform all three steps.


SLIPFORM PAVING

Slipform paving is defined as a process used to consolidate, form into geometric shape and

surface finish a PCC mass by pulling the forms continuously through and surrounding the

plastic concrete mass.

Slipform paving is most appropriate for larger jobs that require high production rates.

Particular advantages of slipform paving are (ACPA, 1995):






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Uses low-slump PCC . Low-slump PCC (on the order of 0 - 75 mm (0 - 3 inches))

is necessary so that the fresh PCC is able to hold its shape once the slipform

paver has passed. Low slump PCC can be made with less water and usually has

higher compression and flexural strengths than comparable high slump mixes.

High productivity . Large jobs generally require high production rates in order to

be profitable. Slipform paving production rates are typically in the range of 65 -

100 m3 /hr (85 - 131 yd3 /hr) for mainline paving. That translates into between 70

- 90 m/hr (230 - 300 ft./hr) of 3.66 m (12 ft.) wide, 250 mm (10 inch) thick PCC

surface course.

Smooth riding surface. Automation and computer control allow slipform pavers

to produce very smooth riding surfaces (IRI on the order of 0.90 m/km or less).

This section presents PCC placement, consolidation, finishing and curing as it is typically

done in slipform paving. Most often, these steps are accomplished by three pieces of

equipment: theplacer/spreader (used for rough placement), the concrete paver (used for

final placement, consolidation and initial finishing), and the texturing and curing machine.

These machines usually travel together in series down the length of the project.

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.

Longitudinal Joints

The first signs of distress in a hot mix asphalt pavement occur at the weakest point in the

pavement, usually the longitudinal joint. Construction of durable longitudinal joints is critical to a

pavement‟s service life.

The optional methods for constructing longitudinal joints are butt joints and tapered wedge joints.

When using either method, the standard specification states that placement of the surface course

should be carefully planned to ensure that the longitudinal joints in the surface course will

correspond with the edges of the proposed traffic lanes. Refer to Standard Specifications §402-

3.09B for details of construction of butt and tapered joints.

The designer must include a special note in the project proposal that indicates if the longitudinal

pavement joint can be left exposed to traffic overnight. This requirement will help the Contractor

bid the contract accordingly. (Note: Refer to §619-3.01G3 for the case when the longitudinal joint

is the lane/shoulder joint. The Contractor shall provide traffic protection in accordance with the

provisions of Table 619-1 for drop-offs within three meters of the travel lanes, except bridge dropoffs or

other drop-offs in excess of 1.8 m deep). If the designer anticipates the longitudinal

pavement joint in excess of 30 meters can be left exposed to traffic overnight they should include

maintenance and protection of traffic requirements to alert drivers of the uneven edge. As a

minimum, W8-39, „UNEVEN LANES‟ signs should be posted on both sides of the roadway at a

maximum 300 meter spacing. Consideration should be given to include R4-10, „STAY IN LANE‟

signs. The Regional Traffic and Safety Unit should be consulted. An exposed longitudinal

pavement joint should not be allowed if it is expected that traffic will frequently change lanes. Under

no circumstances can traffic be allowed to travel over a longitudinal pavement joint constructed as

a butt joint. Minimizing damage to the shape of the joint (urban vs. rural projects) and the safety

of the motoring public must be considered in the decision to allow an exposed longitudinal

pavement joint. The following are examples of special notes for the designer to use:

• “During paving operations on this contract a longitudinal pavement joint length in excess of

30 meters at the end of the working day is prohibited.”



• “Prior to paving operations on this contract, the contractor may request approval, in writing,

to leave exposed a longitudinal pavement joint in excess of 30 meters at the end of the work

day. Approval is contingent upon the use of Option B - Tapered Wedge Joint of Section 402-

3.09 Joints, of the Standard Specifications. Maintenance and protection of traffic

requirements to provide adequate, advanced warning to motorists must be provided as

detailed in these contract documents. As a minimum W8-39, „UNEVEN LANES‟ signs must

https://www.dot.ny.gov/divisions/engineering/design/dqab/cpdm/repository/chapter8.pdf

Cross Section of a Rigid Pavement

Figure shows a typical cross-section of

a rigid pavement

The pavement can be placed directly on

prepared subgrade or on a singular

layer of granular or stabilized material

The only layer of material under concrete

and above subgrade is called base

course or subbase

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PAVEMENT Hardcore TEGARTurapan is Layered Structure Consisting of a Slab Surface Layer and the Base or Subbase Konkritbertetulang Built on the Subgrade