We are committed to help solve the deteriorating bridge problem by using our innovative Ultra-High Performance Concrete rehabilitation methods.
Learn about our successfully completed bridge projects addressing the bridge owner’s needs for long-term preservation solutions.
The Delaware Memorial Bridge (DMB) is a twin steel suspension bridge with a length of 10,765 feet and a clearance below of 174 feet. With over 80,000 vehicles crossing daily, it is a vital transportation link in the northeast United States connecting the states of Delaware and New Jersey over the Delaware River. The DMB is the southernmost fixed vehicular structure over the Delaware River. The first span was originally completed in 1951 and a second span was added in 1968 making DMB the world’s second longest twin suspension bridge at that time with a total of eight lanes of traffic. Today, the original suspension span carries the northbound traffic for Interstate 295, whereas the newer span carries the southbound traffic.
After 60 years of continued service, a ‘deck condition’ assessment of the Northbound structure determined that proper rehabilitation of the existing deck would significantly enhance the service life of the bridge. DRBA considered several repair options such as a full deck replacement, UHPC overlays or other traditional overlay materials such Latex Modified Concrete (LMC) or Epoxy Polymer Concrete (EPC). A life cycle cost analysis of the various repair techniques comparing their initial construction costs with their long-term life cycle costs concluded that the benefits of an UHPC overlay outweighed traditional overlay repairs or a full deck replacement. The condition of the existing deck, with a combined delamination and deterioration of approximately 25%, is still at the right age in its life cycle where a preservation solution with a watertight and durable overlay could extend its life expectancy for another 50 years or more without a major repair intervention.
Since previously installed UHPC overlay projects by other US bridge agencies were not large enough to confirm that the UHPC industry would be able to complete a full-scale preservation project across four lanes with minimum traffic interruption, the DRBA decided to perform a pilot project to validate industry installation techniques and construction methods, including traffic control management and the rideability of a UHPC overlay. The DRBA performed a UHPC pilot project over two of the four lanes on two different sections of the northbound bridge and all four lanes in a third section. This encompassed areas on the bridge deck representing the suspension, truss and girder spans. A successful completion of the pilot project will help the DRBA consider a full-scale UHPC overlay preservation of the Northbound structure within the next few years. This project has the possibility of saving significant public funds while also extending the life of the bridge deck by 50 years or more.
For the UHPC pilot project, the DRBA requested a total of 1,000’ long UHPC overlay on three different sections of the DMB; the suspension, truss and girder sections of the bridge. Contractors bidding on the project were required to submit a Qualifications Questionnaire demonstrating that they met minimum requirements for UHPC overlay placement experience and confirming they are capable of furnishing a self-propelled fully automated paving machine that spreads, consolidates, and finishes the UHPC overlay and that is specifically designed and constructed for placing UHPC overlays. The UHPC overlay for each phase needed to be placed within an eight-hour shift without any additional construction joints. The UHPC formulation with 3.25% steel fibers needed to reach 12,000 psi within 48 hours.
Using two onsite mobile batching plants and a Thin Lift UHPC Paver, the project team was able to prove that 90 yd3 of UHPC overlay at a width of 26’ and a depth up to 4” can be installed within an eight-hour shift. This newly developed self-propelled thin lift paver is capable of paving steep slopes and lanes with crowns up to 30’ in width. Its variable and monitored vibration frequency ranges ensure proper consolidation of UHPC even with slopes over 10%. The combination of efficient and high-quality thin lift paving equipment with an experienced workforce are essential to installing a successful UHPC overlay in a fast and cost-effective way, shortening the total construction time of the bridge rehabilitation project. To achieve great rideability and smoothness, the finished UHPC surface was diamond ground and grooved. In total, 328 yd3 of UHPC covering an area of 25,500 ft2 were paved for the 1,000’ DMB pilot project.
To date, this efficient installation time is a new record for the US UHPC industry. The feedback and collective experiences from all members of the project team strengthened the confidence that this pilot project can easily be scaled up for a successful and even more economical full-scale preservation of the northbound structure’s deck within the next few years.
The Bruckner Expressway is a 7-mile-long freeway in the borough of the Bronx in New York City carrying Interstates I-278 and I-95 and connecting several major freeways including the Bronx River Parkway, the Cross Bronx Expressway, the Whitestone Expressway, and the Hutchinson River Parkway. The Bruckner Expressway was completed between 1952 and 1972. Its annual average daily traffic (AADT) is 115,000 vehicles per day on the six-lane I-278 section and approximately 155,000 vehicles per day on the eight-lane I-95 section.
The heavy New York City traffic impact and de-icing salts have resulted in ongoing maintenance projects along the Bruckner Expressway. To prolong the service life of the Expressway and to reduce the need for future maintenance projects, the New York Department of Transportation (NYSDOT) awarded a $204 million project to rehabilitate a half-mile section of the Bruckner Expressway, six connecting ramps between East 141st Street, the interchange with the Major Deegan Expressway and the Robert F. Kennedy Bridge in the Bronx.
During the deck scarification in August 2020, NYDOT noticed a huge void under the approach slab and damaged T-Beams with reduced structural capacity. This was due to accidental grinding off on the ramp across St. Ann’s Avenue. These unexpected findings required a rapid repair method to address and to restore the structural integrity of the damaged T-beams, while traffic remained open with reduced lanes. A traditional repair method with a new layer of rebar for structural continuity was determined to be too time-consuming and too complex. The owner needed a quick, durable solution that could be installed by an experienced contractor one week after finding out of this unexpected challenge.
A two-stage 2” Ultra-High-Performance overlay emergency repair was the chosen method to restore the structural integrity of the damaged T-Beams of the St. Ann’s Avenue Ramp. As this repair was part of an existing rehabilitation project, there was no need for additional surface scarification or additional rebars. UHPC overlays are known to bond well to existing scarified concrete surfaces and to partially exposed
rebars. UHPC’s solution strengthens in days rather than weeks and has great durability resistance to ensure the longevity of the repair.
In total, 14 cubic yards of UHPC were produced and installed in 9 days using two stages in August 2020. We were able to be onsite within one week of providing the repair solution to the owner. One lane of traffic always had to remain open during construction to ensure a continuous flow. The surface of the existing concrete was already prepared and scarified from the originally scheduled repair project. Prior to placing the UHPC material, the existing concrete surface was wetted to achieve a Saturated Surface Dry ( SSD) condition.
Since this bridge only consists of two lanes with rapid moving traffic, the UHPC overlay material was combined with two high shear mixers below the bridge. The freshly mixed UHPC overlay material with 3.25% steel fibers was then lifted in a concrete bucket with a mobile crane onto the top of the bridge deck, where it was transported to the air screed equipment with mobile buggies. A 2” UHPC overlay was installed with the air screed equipment due to the tight and narrow construction site access. In order to prevent any dehydration or potential shrinkage cracking of the freshly paved UHPC overlay, curing compound and plastic tarping were applied.
After two days of curing, the UHPC overlay achieved the minimum required strength of 14,000 psi for allowing surface grinding and grooving. Traffic was flipped over onto the freshly installed UHPC overlay for installation of the second stage, which was completed within four days of the stage one overlay installation. Finally, the overlay surface of the second stage was diamond ground and grooved to meet the road surface requirements for smoothness and micro-texture.
In total, this accelerated bridge preservation method was completed within 9 days of offering the bridge owner a rapid and long-lasting repair solution with minimal interruption to traffic during construction. As an experienced contractor in installing UHPC overlays, we were able to start this project within one week of approval and restored the structural integrity of the damaged T-Beams of this ramp. The newly placed UHPC overlay provides an excellent riding surface for the public and its great durability performance will ensure the longevity of the repair.
The New Jersey Department of Transportation (NJDOT) has been investigating new bridge preservation overlays to enhance the service life of their aging structures. These new overlay procedures utilize more advanced cementitious material than conventional concrete or other traditional overlay materials. The NJDOT has become familiar with the superior strength, durability, flexural and bonding properties of Ultra-High Performance Concrete (UHPC) through various Accelerated Bridge Construction (ABC) projects. Existing bridge decks were replaced with precast deck panels connected with field cast UHPC connections. NJDOT decided to perform a UHPC Overlay Research Project in 2020 to better understand the use of material, installation techniques, construction methods, and performance.
Bridge NJ 159 WB over the Passaic River was one of three bridge structures to be rehabilitated as part of the UHPC Overlay Research Project Contract A (North) by NJDOT. This straight 4-span bridge, consisting of pre-stressed concrete I-girders and a reinforced concrete deck, was originally built in 1939 and accommodates about 11,700 vehicles per day (A.D.T) crossing the Passaic River. The impact from trucks and de-icing salts has resulted in the deterioration of the existing bridge deck. Since the remaining structure was still in good condition an exposed UHPC overlay was the ideal preservation solution to support the enhanced service life and the avoidance of future maintenance repairs. Another purpose of this project was to assess the speed of construction and to validate this repair technique as an ABC method for future preservation bridge projects.
An exposed 2.75” UHPC overlay was selected to be installed in two phases while maintaining traffic in a reduced lane. The UHPC overlay was installed with Thin Lift UHPC paving equipment specifically designed for the North American bridge preservation market. A Thin Lift UHPC paver can provide proper consolidation and surface uniformity of the UHPC overlay while accelerating the installation time during construction.
A total of 65 yd3 of UHPC were installed in two stages in October 2020. After removal of the existing 2.5” asphalt overlay, approximately ½” of the existing concrete deck was scarified using hydrodemolition. This concrete surface preparation technique is known to provide superior bonding of UHPC to existing concrete. Prior to installing the UHPC overlay, the existing concrete surface was wetted to achieve a Saturated Surface Dry (SSD) condition.
A thixotropic UHPC material with 3.25% steel fibers was mixed on-site using two high shear mixers and transported in buggies to the Thin Lift Paving equipment. This self-propelled paving equipment has a variable frequency range, so it is ideal to properly consolidate thixotropic UHPC by liquefying a very low flow material and shaping it into place. A Thin Lift UHPC Paving equipment is easily capable of paving lanes with crowns, cross-slopes, grades of over 10%, and lanes ranging in widths from 8’ to over 30’.
Each stage required approximately 36 yd3 of UHPC and was easily installed within 6 hours. On average, the UHPC overlay had a thickness of 2.75” with a 2% grade and up to 4% cross-slope. To prevent any dehydration or potential shrinkage cracking of the freshly paved UHPC overlay, a curing compound and plastic tarping were applied. After two days of curing, the UHPC overlay achieved the minimum required strength of 12,000 psi. This minimum strength was necessary to allow for the transition of traffic onto the freshly installed UHPC for Phase 2 of the project, as well as to start diamond grinding and grooving of the entire UHPC overlay after completion of Phase 2. Diamond grinding and grooving of the UHPC overlay provide a very smooth textured riding surface that is very similar to a newly constructed concrete deck. In total, the entire bridge deck was repaired within two weeks.
Preserving the NJ 159 WB bridge deck with an exposed UHPC overlay will provide the NJDOT with a durable, long-lasting bridge deck that could extend the service life of this structure for another 50 years. When installed properly with Thin Lift Paving equipment and an experienced workforce, UHPC overlay construction methods can minimize traffic interruptions and shorten the total construction time. This offers an accelerated and competitive solution during the initial construction process for future New Jersey bridge preservation projects.
The New Jersey Department of Transportation (NJDOT) has been looking for a new overlay preservation system for aging bridge decks that would enhance and extend the service life of their existing structures. The NJDOT was familiar with the exceptional strength and durability properties of Ultra-High Performance Concrete (UHPC), which uses field cast connections for precast bridge decks to replace existing bridge decks. However, the NJDOT had not used UHPC as a bridge deck overlay. To better understand the use of the material, installation practices, and performance of a UHPC overlay, the NJDOT decided to perform a UHPC Overlay Research Project.
As part of the UHPC Overlay Research Project Contract A (North) by NJDOT, bridge I-280 WB, which spans over the Newark Turnpike, was one of three bridge structures to be rehabilitated with an UHPC overlay and UHPC expansion joints. This curved, 3-span bridge with steel girders and a reinforced concrete deck was originally built in 1979 and is an important westbound ramp feeding approximately 29,500 vehicles per day (A.D.T) from the New Jersey Turnpike onto the Interstate I-280. The heavy traffic and the impact of de-icing salts have resulted in corrosion of the reinforcing steel in the existing bridge deck, as well as the deterioration of all abutment and pier expansion joints.
To maintain traffic flow during construction, a two- stage 1.5” UHPC overlay with field cast UHPC headers at the abutment and pier joints was selected as part of the preservation strategy for this I-280 WB bridge structure. After removal of the existing 3.25” asphalt overlay, approximately ½” of the existing concrete deck was scarified using hydrodemolition. The deteriorated expansion joints at both piers and both abutments were removed using hydrodemolition. A new expansion joint solution consisting of 1’-8” x 1’-8” field cast UHPC headers on each side of the joint was installed. Since UHPC is impervious to de-icing salts, the surface of the headers remained fully exposed.
Hydrodemolition was specified as the concrete surface preparation technique because it is known to provide superior bonding of UHPC to existing concrete. The finished UHPC overlay was covered with 2.25” asphalt, an adopted common practice for UHPC overlays in Europe.
A total of 124 yd3 of UHPC were installed in two stages for the entire project during the fall of 2020. With its length of 340’, the I-280 WB UHPC overlay is currently the longest continuous overlay installation in North America. The need to always have one lane open for continuous traffic flow on this ramp structure during construction resulted in a very narrow and tight construction work zone, especially during Phase 1. The UHPC material was mixed on site using two high shear mixers stationed in the extended work zone, well past the higher elevated bridge abutment.
For each stage, the headers of the expansion joints were cast with a self-consolidation UHPC with 2% steel fibers to ensure proper material consolidation around the rebars within the headers. As soon as the headers reached 12,000 psi, a thixotropic UHPC overlay with 3.25% steel fibers was installed. A thixotropic formulation is designed to have a very low flow so that the material will stay in place on a sloping bridge deck. The vibration of the paving equipment causes the material to liqueify and level out following the grade and cross-slope set by the equipment. This bridge deck was built on a curve with a 2% grade and a 4% crowned cross-slope. Due to the raised headers, tight work zone, and closeness to live traffic adjacent to the working zone, a vibrating air screed was utilized to install the UHPC overlay. The freshly placed material was sprayed with curing compound, covered with plastic for curing, and reached 12,000 psi within two days.
The designers’ idea of replacing the expansion joints with UHPC headers was successful given that the UHPC raw materials and mixing equipment were already on site for the UHPC overlay. Only the admixture and fiber dosages needed to be adjusted, highlighting that UHPC is a very versatile material that can easily be adapted to different types of applications with varying installation methods.
Preserving the I-280 WB bridge deck with a UHPC overlay will provide the NJDOT with a durable, long-lasting bridge deck and will extend the service life of this structure.
The 25’ long, simply supported NJ 57 bridge consists of hollow-core prestressed concrete slabs with a 12” thick (maximum) concrete slab and 2.25” asphalt overlay and supports approximately 10,900 vehicles per day (A.D.T). Continuous traffic flow, the impact from vehicles, and challenging environmental conditions due to de-icing salts and freezing-thawing cycles contribute to deterioration. The remainder of the structure was still in good condition, making this bridge deck an ideal candidate for an Ultra-High Performance Concrete (UHPC) overlay preservation solution to enhance its service life and long-term performance.
The New Jersey Department of Transportation (NJDOT) has had prior experience with UHPC by replacing existing bridge decks with precast deck panels connected with field-cast UHPC connections. Only recently, other US transportation agencies started to install thin bonded UHPC overlays for aging bridge decks to repair, preserve, and improve their condition. To study and better understand the use and performance of UHPC for bridge overlays, the NJDOT decided to perform a UHPC Overlay Research project where this NJ 57 bridge structure was bundled into Contract A (North).
To maintain traffic flow during construction, a two-stage, 1.5” UHPC overlay installation was selected, replicating a common and proven European preservation strategy. After removal of the existing 3.25” asphalt overlay, approximately 0.5” of the existing concrete deck was scarified using Hydrodemolition, exposing a superior surface for bonding UHPC to the existing concrete. This project followed the commonly established European practices for UHPC overlays by using a stepped longitudinal UHPC construction joint between the two construction phases and by covering the completed UHPC overlay surface with 2.25” asphalt.
For the entire project, a total of 6 yd3 of UHPC with 3.25% steel fibers were installed in two stages during the fall of 2020. Since one lane always had to remain open, the construction zone was very narrow and tight for both phases during rehabilitation. After cleaning the hyrdodemolished surface, the substrate was watered to a saturated-surface-dry (SSD) condition before applying the UHPC overlay to ensure the best bonding. The UHPC material was mixed on-site using a high shear mixer and then transported in mobile buggies to a vibrating air screed.
Due to the restricted lane and tight worksite access, a vibrating air screed was utilized to install this 1.5” UHPC overlay with a centerline crown and a 2% cross-slope. The longitudinal construction joint between the paved lanes was a stepped UHPC joint with galvanized rebars, replicating a common European practice. To prevent any dehydration or potential shrinkage cracking of the freshly paved UHPC overlay, curing compound and plastic tarping was applied. After two days of curing, the UHPC overlay achieved the minimum required strength of 12,000 psi, allowing for the next step in the construction cycle to proceed. The completed UHPC overlay was covered with 2.25” asphalt.
As part of the UHPC Overlay Research project, the rehabilitation system applied to the NJ 57 bridge deck will provide the NJDOT with great insight on the installation techniques, construction methods, and long-term performance for a historically well-proven UHPC preservation solution from Europe. This preservation solution will provide the NJDOT with a durable, long-lasting bridge deck that will extend its service life much longer than other traditional overlay materials.
The Ellison Avenue Design-Build project involved the replacement of a 115-year-old multi-span bridge over the LIRR Main Line in Westbury, NY. The project scope included the design and reconstruction of the bridge from the abutment footings up, including installing a new single-span precast prestressed concrete superstructure with integral wearing surface. Shear Keys for the precast superstructure were filled with 30 CY of 20 KSI UHPC followed by diamond grinding to achieve the final roadway profile. The project was situated in a residential neighborhood, limiting site access and linearizing construction progress.
Construction on the project was challenging because of limited space at the worksite and work over an active commuter rail line main corridor. Design complexities included engineering a new roadway profile that neared maximum permissible grading limits heavy profile in the roadway and engineering a new approach sidewalk and parapet that did not impart additional loads on existing substructures of unknown capacity.
Site logistics and access issues were solved by installing temporary access ramps from the roadway down to the LIRR Right-of-Way below, allowing ease of access to track level for equipment and workers. This also facilitated work during the two weekend outages allotted on the project, for which planning began at the onset of the project to ensure continuity of LIRR operations. Construction means and methods were optimized to minimize work that required track outages, resulting in returning tracks back to service ahead of schedule.
Roadway grading design issues were solved by selecting a shallow precast prestressed concrete beam superstructure, reducing the height of the bridge. The use of a precast superstructure also minimized impacts to LIRR rail traffic below. Helical piles were utilized to transfer loads from a new approach sidewalk & parapet through existing crib-type retaining walls along the bridge approaches, eliminating the need for a costly and intrusive replacement of the crib walls
In total, 30 cubic yards of UHPC were produced and installed during a single casting day. The precast bridge units were prepared for the UHPC material by casting with an exposed aggregate finish which provides an excellent bond with UHPC. Utilization of PBE with UHPC shear keys allowed the shutdown of rail traffic below the bridge to be shortened to two weekend closures. This reduced the impact of the bridge work to a LIRR trains and the traveling public. The use of UHPC joints and PBE also allowed a reduction in the height of the bridge which corrected an existing bridge profile issue.
The bridges were originally constructed for a new grade separated interchange on State Route 1 (SR-1) at Bower Beach Road. Two 120 ft long and 42 ft wide bridges were constructed with a cast-in-place concrete deck on steel girders.
After the initially completed concrete bridge decks were surveyed, it was determined that the cambers of the steel beams were not even. This resulted in having the top rebar mat in the center of the bridge deck with insufficient concrete cover and protection. DelDOT was in search of a solution that would provide enough protection of the top rebar mat, while keeping the designed cross slopes and horizontal curve of the bridges.
A UHPC overlay was selected as the preferred alternative repair method due to its great durability resistance and water tightness. The UHPC overlay functioned as grade repair, waterproofing element and road surface. In addition, it can function as a structural element under compression but this was not considered in the design of the repair method. The UHPC overlay thickness varied between 1¾” to up to 5” in local areas with an overall average thickness of approximately 3”.
The surface of the existing concrete was prepared using hydrodemolition at a depth of ¼” in order to ensure sufficient bond of the UHPC overlay to the concrete substrate.
Given the low temperatures in February 2019, heating was required to prevent the thin UHPC overlay from freezing and allowing the UHPC overlay to bond properly to the existing concrete deck. This heating was accomplished with forced air and hydronic systems placed below and above the bridge deck.
In addition, heating of the UHPC premix and mixing water was required to maintain proper UHPC workability during placement.
The selected material was a Lafarge Holcim Ductal overlay formulation with 3.25% steel fibers. In order to achieve proper strength development, the freshly placed UHPC overlay was tented and heated immediately after installation.
Twenty-four hours later, the tent was removed and hydronic heating hoses were placed for three days of curing. Using this curing procedure, the UHPC overlay reached strengths between 11,000 psi and 13,000 psi almost achieving the design strength of 14,000 psi within this short time period.
Staging of the overlay construction included 3 paving lanes (18 ft, 12 ft, 12 ft) and construction joints were located between the road lanes. The final road surface preparation included diamond grinding of the UHPC surface in order to meet the road surface requirements for smoothness and microtexture.
In 2017, Cramer & Associates Inc. of Grimes, IA was awarded the main contract to rehabilitate the deck of Floyd River Bridge as part of a large bridge rehabilitation package. WALO Iowa LLC was chosen as a sub-contractor for the UHPC overlay project, due to our expert know-how and experience with the material. WALO has successfully completed a variety of UHPC applications in Europe, most significantly the 2.3-mile-long Chillon Viaducts, alongside Lake Geneva in Switzerland. Recognized by the American Concrete Institute (ACI), the Chillon Viaduct rehabilitation was the first ever project to use a machine to install a UHPC layer on bridge decks.
The 9,020 sq. ft UHPC overlay job was completed in less than ten workdays, by our construction team and with support from Cramer & Associates Inc. and LafargeHolcim North America.
One lane of the bridge remained open for public at all times for the course of the project to minimize traffic disruption to the traveling public.
The Chillon viaduct is located in Switzerland, over the east end of Lake Geneva, south-east of Montreux. It comprises two parallel 1.4 mile long prestressed concrete box girder bridges, bearing the east and westbound lanes of the Swiss A9 highway.
Built in the 1960s, it was one of the most significant works in prestressed concrete for many years, so it was of great historical value to the area. Originally designed to sustain an estimated volume of 10,000 vehicles per day, it is currently being used by 60,000 vehicles daily.
The bridge was scheduled for deck rehabilitation, but an inspection of the viaducts revealed that they were significantly damaged and deemed structurally deficient. In various places, the concrete’s reinforcing bars had been corroded and the concrete itself was betraying signs of Alkali-Silica Reaction (ASR). On closer inspection, following hydrodemolition tests, Alkali-Aggregate Reactions (AAR) were also detected, which meant the mechanical properties of the concrete were compromised. If repairs were not undertaken, it is likely the structure would have needed complete rebuilding.
With an ever-increasing number of vehicles using the bridge, a solution was required to increase the shear, bending and fatigue resistance of the deck slab. The structure also needed any damage caused by ASR and AAR to be reversed, as well as waterproofing to prevent future damage and a significant improvement of its structural properties.
A thin steel rebar-reinforced Ultra-High Performance Fiber Reinforced Cement-based Composite (UHPFRC or UHPC) overlay was selected as the best and most cost-effective solution to meet the complex needs of the structure. The material has extraordinary strengthening and waterproofing qualities and, with the right skills and machinery, it is possible to place it extremely quickly, meaning that the carriageway could be closed for the least amount of time possible, minimizing disruption and costs.