The most common in-place structures in con- crete paving are light cans. The following guid- ance is a summary taken directly from IPRF’s Report IPRF-01-G-002-03-1, “Constructing In- Pavement Lighting, Portland Cement Concrete Pavement.”Readers should consult the full re- port for design and construction details.
Locating a light base too close to a pave- ment joint, setting it at the wrong height or setting it at an angle with respect to plumb will usually result in a deficient installation.
The solution is removal and replacement.
Chapter 8 – Concrete Placement, Finishing, Texturing and Curing
Light cans may be installed using one of the fol- lowing techniques:
1. Blockouts–not a preferred method for installing light cans.When there is con- flict between a pavement joint and a light base, the use of a boxout to expedite project design should be avoided. Using a boxout in a new runway pavement for centerline and/or touchdown zone lights should be rare because the tolerance for the starting locations of configuration is forgiving. It is expected that there will be a conflict at pavement intersections be- cause of the close light spacing, curved alignment and changes in jointing pat- terns. Design disciplines should closely coordinate their effort and resolve conflict within FAA tolerance. If the tolerance is not sufficient to resolve a conflict, a modi- fication of the FAA standard should be considered before using a boxout. The result will benefit the owner because there is a higher probability that there will be better construction and reduction in long term maintenance and repair needs.
When no other option exists, consult the IPRF report for design and construction details of boxouts.
2. Split cans and coring– Use of this tech- nique allows the pavement to be slip- formed with pre-placed light cans that are anchored in place and then later adjusted for final elevation
3. Cookie cutter– similar to the coring method, light cans are anchored in place and paving is placed over them.
Figure 8.12 illustrates the pre-placement of light cans for both the coring and cookie cutter meth- ods.
Figure 8.13 depicts slipform paving placement around a light base.
The coring method is completed as follows:
• The concrete is allowed to harden.
• Coring equipment is used to remove con- crete and expose the protective mud plate on top of the light base. The core is typi- cally 13.5 to 14 in. diameter for a 12 in. di- ameter light base.
When using the core method, the quality of the pavement surface is not dependent upon hand finishing. However, coring is usually more ex- pensive and coring operations could damage the light base when there is uncertainty with respect to the light base location.
The cookie cutter method is completed as fol- lows (Figure 8.14):
• After the paving machine passes over a light base, a “cookie cutter” is pressed into the plastic concrete by a workman sitting on a bridge suspended over the pavement.
• After the concrete sets (sufficiently rigid for the reservoir to retain its shape but plastic enough to allow surface finishing) the cookie cutter is removed, the concrete in- side the impression is removed and dis- carded, and the surrounding surface is hand finished.
Case 1:
Adjacent concrete paving lane is available as height reference.
The adjacent concrete lane will establish line and grade.
Meet Requirements for Height, Azimuth and Level Setting Jig
Min. of 2 ft (0.6 m)
Rebar Cage
Conduit Light
Base
Adjacent Concrete Lane
Subgrade
Secure Jig Firmly
Subbase
Concrete Anchor
Case 3:
Concrete pavement is avail- able for height reference.
Typical where core, cut, or partial slab removal is used to install base in existing pave- ment, or boxout method is used to install base in new concrete pavement.
Meet Requirements for Height, Azimuth and Level
Min. of 2 ft (0.6 m)
Rebar Cage
Conduit
Adjacent Concrete Pavement
Subgrade
Secure Jig Firmly
Subbase
Concrete Anchor Adjacent
Concrete Pavement
Setting Jig Light
Base Secure Jig
Firmly Case 2:
Adjacent concrete paving lane is not available as height reference. Base is “set in space”.
Line and grade is more difficult to establish. Varia- tion in concrete pavement height must be accommo- dated.
Meet Requirements for Height, Azimuth and Level
Setting Jig
Rebar Cage
Conduit Light
Base
Subgrade
Secure Jig Firmly
Subbase
Concrete Anchor zimuth
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Figure 8.12. Diagram of light can placement for the coring and cookie cutter methods.
PAVING ALERT
Implications of Im- properly Installed Light Bases:
There are benefits to the paving contractor that are measured in time and cost savings when light base installa- tion deficiencies are de- tected before concrete paving. It is relatively cost free to check a light base before paving; it is an expensive proposi- tion to remove a light base after the pavement is placed and finished.
The height setting of a light base is the most common cause of a de- ficient installation. When the light base is set too high, there is no satis- factory mitigation other than remove and re- place. Therefore, check- ing the height before concrete paving is a crit- ical step.
Chapter 8 – Concrete Placement, Finishing, Texturing and Curing
Pavement surface quality in the proximity of an in-pavement light is important. Poor hand finish- ing usually results in corrective action or re- placement of the concrete in the vicinity of the