Construction
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Rigid Pavement Placement

An overview of essential concepts in placement of ready mix concrete for rigid pavement construction. This includes placement, consolidation, finishing, curing, and jointing.

Figure 2. Side tie bar inserter.

Tie Bar Placement

Tie bars are typically placed after PCC placement either by hand or using a tie bar inserter attachment (slipform paving only). When one lane at a time is paved, tie bars are inserted at mid-slab depth and bent back until the adjacent lane is ready to be paved (see Figure 1). On slipform pavers, tie … Read more »

Figure 7. Joints sealed with hot-pour liquid sealant on a freeway on-ramp (normally, joints should coincide with lane divisions as they do near the horizon of this photograph).

PCC Joint Construction

Location Typical joint locations are covered in the article on Joints, and are not repeated here. However, it is important to note that joint locations should be indicated on the construction plans and planned in advance (Figure 1). Intersection joint locations can be quite complex and should be marked out on the base in advance … Read more »

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Other Joints

Expansion, isolation and construction joints are created by formwork before the PCC is placed. Since these joints are designed to completely separate adjacent masses of PCC, they are usually made by inserting a small non-PCC piece of material such as a strip of wood. Construction Joints Construction joints, sometimes called “headers” are usually made to … Read more »

Figure 7. Longitudinal and Transverse Construction Joints

Joints

Joints are purposefully placed discontinuities in a rigid pavement surface course. All types of joints are used in rigid pavement construction methods for all PCC pavement types. CRCP uses longitudinal reinforcing steel in order to limit the number of transverse contraction joints, but it still uses longitudinal joints and periodic transverse joints. Joints can be … Read more »

Figure 22. Curing seal applied by a hand-operated sprayer.

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 pieces of placing and finishing equipment. Fixed form paving is most appropriate for small jobs (see Figure 1), complicated geometry pavements … Read more »

Figure 6. Dowel baskets placed on a lean concrete base in advance of PCC placement.

Dowel Bar Placement

Dowel bars can be placed either before PCC placement by using dowel baskets, or after PCC placement by using an automatic dowel bar inserter. Their placement is crucial to proper joint load transfer. Skewed, shallow or excessively corroded dowels can fail causing faulting and/or cracking at the joint. Dowel Bar Preparation Dowel bars must be … Read more »

Figure 3. Placer/spreader receiving PCC from an end dump truck and placing it in front of the PCC paver.

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[1]): Uses low-slump … Read more »

Figure 4. Span saw.

Sawcutting

Sawcutting involves the formation of joints or breaks in a PCC mass (slab) by the use of mechanical cutting tools. Saw Blades Sawed joints are formed using hard-tipped rotary saws, which can use either diamond or other types of abrasive blades (Figure 1).   Diamond Blades Most joint sawing is done using industrial diamonds as … Read more »

Figure 2. Reinforcing bar in place (white items are support chairs).

Reinforcing Steel Placement

Proper reinforcing steel placement is crucial to CRCP performance. CRCP failures are usually associated with insufficient reinforcement bar lapping, unconsolidated PCC around the steel, improper position of the steel in the slab and extreme hot weather during construction. In general, CRCP seems to be less forgiving of construction errors than other types of rigid pavement … Read more »

Figure 1. Placement over dowel bars in an intersection.

PCC Placement

PCC can be placed directly in the desired location by truck or truck attachments (see Figures¬†1 and 2), or can be fed into a placement machine for more accurate and even placement.¬† PCC that is moved excessively once it has been unloaded from the transport truck will tend to segregate (become less homogeneous). During the … Read more »

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