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Recent Projects

Featured Projects

Naval Air Station

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shim_trans  Summery
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shim_trans  Objective
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shim_trans  Project Background
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shim_trans  Scope of Work
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shim_trans  Bravo 25 Description
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shim_trans  Overview
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shim_trans  Crane Rail Removal
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shim_trans  Loss of Transverse
 Negative Moment
 Capacity over the
 Outboard Crane Rail
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shim_trans  Concrete Repair
 Materials
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shim_trans  Top Deck
 Repair Procedure
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shim_trans  Under Deck Repairs
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shim_trans  Cathodic Protection
 System
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shim_trans  Cathodic Protection
 System Installation
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shim_trans  Grout Resistivity
 Measurements
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shim_trans  Reinforcing Steel
 Lead Wire Installation
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shim_trans  Upgrade Reinforcement
 Introduction
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shim_trans  Analysis of Bravo-25
 Load Response
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shim_trans  Calculation of
 Bravo 25 Resistence
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shim_trans  Modes of Failure
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shim_trans  Bravo 25
 Upgrade Design
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shim_trans  Concrete Surface
 Preparation
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arrow_right  Embedded
 Reinforcement
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shim_trans  Wet Lay-up
 Composite Laminate
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shim_trans  Proof Tests using
 Impact Load Method
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shim_trans  Costs
 Acknowledgements
 References
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Turbine Deck Load Capacity Restored


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Home > Recently Completed Projects > Featured Project > Pearl Harbor

Featured Project

 

Embedded Reinforcement

Embedding pultruded carbon/epoxy composites as negative reinforcing is particularly attractive for the top surface of the deck where exposed external reinforcement would be subject to mechanical and environmental damage and would require protective cover. It also precludes some of the surface preparation steps. The contractor selected DFI pultruded carbon composite rods to meet the rod specifications. These smooth rods contain 65 percent high strength carbon fibers (700 ksi (4830 mPa) ultimate strength) in an epoxy matrix. The rods were encapsulated in Sikadur 32?, a two-part amine epoxy, in slots that were cut in the concrete surface. The manufacturer removed the epoxy surface “sheen” on the rods to ensure better bond to the epoxy encapsulant. The epoxy encapsulant was required to have significant tensile and interlaminar shear strength. It was also desirable to have a glass transition temperature well above the highest temperature expected in the deck.

 

In preparation for rod installation, the contractor cleaned the deck surface, removed all loose material, and applied a two-part, penetrating epoxy primer/sealant (Sikadur 55©) over the areas to be reinforced. The contractor laid out the reinforcing pattern after the primer had set, and NFESC made adjustments to avoid drains, rails, cleats, and other obstacles (Figure 51). One of the key functions of the primer was to penetrate microcracks and strengthen the concrete surface to minimize damage when cutting slots. The contractor used a diamond blade and cut each slot with a single pass (Figure 52). NFESC set the depth and width of the slots to ensure that the carbon reinforcing would be completely encased in epoxy with enough clearance to allow for variances in the concrete finish (Figure 53). NFESC required at least a 1/4-inch (6 mm) clear cover and 1/16-inch (1.5 mm) clearance between the reinforcing and the slot walls. The minimum spacing of the slots was 4 inches (10 cm) on center. Existing reinforcing steel was well below the bottom of the slots and was not encountered. The slots were thoroughly cleaned and abrasive blasted using copper slag under 200 psi (1.4 mPa) pressure (Figure 54). Slot surfaces were primed with Sikadur 55? (Figures 55 and 56).

 

Slots were filled with Sikadur 32? epoxy up to ¼ inch (6 mm) of the surface and the bars were laid and pressed in place in the slot (Figures 57 through 60). Sikadur 32? has excellent wetting capabilities. Its tensile strength exceeds 5,500 psi (38 mPa) and its shear strength exceeds 5,000 psi (35 mPa). Its Young’s modulus is 250,000 psi (1,770 mPa). Stainless steel clips were used to hold the rods in place where the concrete surface was not planar (Figures 61 and 62). After placing the rods into partially filled slots, the slots were “topped-off” with a sand/epoxy (Sikadur 22©) grout for ultra violet (UV) protection (Figures 63 and 64). The UV protection grout was specified as two parts 60 grit sand to one part epoxy. The contractor varied the amount of sand from 1.25 to 2 parts to 1 part epoxy. More sand provides more UV protection but is more difficult to place.

 

Strain gauges were attached to 12 rods prior to encapsulation for post construction proof test monitoring. The gauges were positioned at crucial points above the transverse and pile girders where outrigger load response would be greatest. The strain gauges were 1/2-inch (13 mm), 350-ohm foil gauges. Bridge completion units were externally added to the strain gauge circuits during proof tests.

 

The contractor used copper slag to abrasive blast the rod slots. It is the most effective abrasive NFESC has encountered. However, the contractor did not have any means of recycling the abrasive and it became an environmental pollutant.

 

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Figure 51. Layout detail of reinforcing
upgrade on primed concrete surface areas.
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Figure 52. Saw cutting
slots on deck surface.
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Figure 53. Detail of embedded
high strength carbon rod.
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Figure 54. Abrasive blasting slots for priming.
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Figure 55. Applying primer to slots in negative moment region over pile girder. Rods in foreground.
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Figure 56. Priming slot surfaces with Sikadur 55©.
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Figure 57. Lilly pumping system for mixing, pumping, and applying two-part epoxies.
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Figure 58. Placing Sikadur 32 LPL© in slots using Lilly pump.
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Figure 59. Placing Sikadur 32© epoxy encapsulant in slots and embedding pultruded carbon rods.
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Figure 60. Filling slots from small containers and placing pultruded reinforcement rods.
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Figure 61. Stainless steel clip to hold and bend rod over curved surface.
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Figure 62. Installing clip to hold rod in place while encapsulant cures.
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Figure 63. Applying sand-filled Sikadur 22© to top 1/8-inch of slot for UV protection.
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Figure 64. Finished rod installation in negative moment region over transverse girder on outside track slab.

 

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ACE Restoration & Waterproofing, Inc.
620 E. Walnut Ave.
Fullerton, CA 92831
714.526.7366
Fax: 714.526.7965

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  ACE Restoration and Waterproofing Quick Service Overview:
  Concrete repair; concrete restoration, structural upgrade, epoxy injection,
  waterproofing, and more concrete technologies in Fullerton California (CA)
  by ACE Restoration and Waterproofing.

  Concrete Repair, Concrete Restoration, Epoxy Injection, Waterproofing

http://www.acerestoration.net/

 

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