Throughout history, bridges have always been important, valuable structures in their own right. By their very nature, bridges are built in a variety of areas where the topography, ground conditions, or other existing structures and developments are unsuitable for conventional pathways, roads or railway construction. Therefore, bridges are found in the most challenging, exposed environments.
Modern bridges built using reinforced concrete or steel often require a service lifespan of more than 100 years. Recent surveys in Europe and North America have shown that the majority of existing bridges already exhibit significant degrees of degradation. Many of them are therefore in need of substantial and often urgent repair and refurbishment.
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Sika provides full support to bridge owners, architects, engineers, and contractors with necessary technical advice and assistance to ensure a successful project. In particular for refurbishment projects, this includes assistance throughout the process, from the initial survey and assessment, root cause diagnosis, specification writing, detailing, method statements, on-site quality control, and practical application assistance. For new construction, Sika can offer support to design structures for long service life. Sika’s expertise can make a significant contribution to minimizing the total project cost over the full defined service life-cycle.
Sika today provides a complete range of innovative products and systems specially designed to solve all challenging requirements in differing bridge projects anywhere in the world.
Concrete admixtures
Watertight joint systems
Liquid applied waterproofing membranes
Concrete repair systems
Corrosion inhibitors
Post-tensioning systems
Bridge Exposures
Water can penetrate naturally through the capillary pore structures of reinforced concrete. In areas of carbonated concrete, or where there is a high chloride content on the surface of the steel reinforcing bars, reinforcement corrosion, cracks or spalling can occur on the surface.
Overloading due to increasing traffic loads, inadequate design, damage to the structure, stress/fatigue failure, earthquake effects, or any other mechanical impact such as vehicle impact, can all exceed or reduce the load capacity of the structure.
By their nature and locations, bridges are subjected to a wide variation of temperatures between day and night/winter and summer conditions, or between different sides or surfaces of the structure. These frequent cycles result in thermal stresses and movement in the concrete structure that can also result in cracks.
Carbon Dioxide (CO²) reacts with the Calcium Hydroxide (Ca(OH)²) in the pore liquid of the cement matrix of concrete structures and deposits as calcium carbonate (CaCO³). This process known as carbonation reduces the protection of embedded steel reinforcement, when the process reaches the reinforcement bars.
Chlorides come from de-icing salts used in winter, or from saltwater in marine environments. They can penetrate the concrete structure and once they reach the reinforcement bars, they can locally destroy the passivation film causing fast pitting corrosion.
The freeze-thaw process creates stresses in the concrete matrix due to the expansion of free water in the capillary pores during freezing conditions; this can result in the scaling of the surface of poor quality concrete. This action is also greatly accelerated by the presence of chlorides in the water.
Concrete elements submerged in water such as the bridge piers or columns are continuously exposed to erosion and abrasion of their surfaces. Damage occurs from the action of fast-flowing water, and the particles of sand or other solid materials in the water.
Fire due to traffic accidents, for example, can result in a reduction of the structural integrity of any of the concrete elements including the columns, decks or precast segments, etc.
What Causes Damage and Deterioration to Bridges?
| Type of Deterioration | Root Cause |
|---|---|
| Steel Reinforcement Corrosion |
|
| Structural Steel Corrosion |
|
| Deck Corrosion (Reinforced concrete or steel deck) |
|
| Leaching / Efflorescence |
|
| Concrete Spalling |
|
| Structural Cracks |
|
| Non-Structural Cracks |
|
| Scaling of Concrete Surface |
|
1. Concrete Technology
Concrete structures such as bridges can be exposed to a broad range of forces and strains, starting internally with mechanical stresses resulting from the construction type and extending to various external attacks. Enormous stress on the concrete include such factors as extreme hot or cold temperature conditions and fluctuations, aggressive water or chemicals, continually rolling, abrading or pulsating strains on surfaces, or even in extreme cases the impact of fire. Therefore, a highly durable concrete is necessary for the construction or repair of a bridge.
The development and production of innovative concrete mix designs using special admixtures has been a core Sika business since 1910. Our technology and high-quality products have been continuously developed during this century of experience. Sika provides the most complete range of admixture technologies and products for the efficient replacement of highly durable concrete.
Increasing the durability of concrete by using:
SikaControl® SRA to minimize shrinkage of concrete
SikaControl® AER to increase the frost and freeze/thaw resistance
SikaFume® silica fume to increase the density of the matrix
Sika® FerroGard® corrosion inhibitor to prevent the corrosion of steel reinforcement
Sika® Antisol® for controlled curing of the concrete for significantly enhanced durability
SikaFiber® for increasing the ductility, tensile strength and resistance to concrete spalling in high temperatures
High early strength concrete for reduced closure times is achieved by:
High range water reduction and plasticizing with Sika® ViscoCrete® and SikaPlast® technology, to provide enhanced strength development and precisely controlled concrete workability
Hardening or set acceleration to speed up the hydration process using SikaRapid® technology
Casting concrete with maximum flowability for specific periods of time without the need for vibration by the addition of:
Sika® ViscoCrete® and Sika ViscoFlow® technology for highly flowable and workable concrete with optimized raw material usage, based on powerful water reduction with extended workability time
Sika® Stabilizer VMA for improved stability of the self compacting concrete, even with inferior quality aggregates
SikaFume® silica fume to provide increased density and durability of the matrix, with enhanced fresh concrete stability
Two-component, structural epoxy bonding agent Sikadur®-32 to bond fresh concrete to hardened concrete
2. Concrete Repair
Repairing damaged concrete is one of the primary requirements in the maintenance of concrete bridges. Localized spalling or full surface scaling of concrete surfaces has to be repaired with durable concrete repair materials. A sound and correctly repaired concrete substrate is also the basic requirement for any additional waterproofing, protection or strengthening systems to be applied.
Sika provides an extensive range of thoroughly tested and proven repair materials and systems based on different technologies for each specific requirement and situation. These include bonding and corrosion protection primers, hand and machine applied repair mortars, suitable for the vertical and overhead application, semi-fluid mortars for efficient bridge deck repairs, plus combined surface leveling and protection mortars, not requiring additional protective treatments (EpoCem®-technology).
Thin-layer repair system for bridge decks:
Bonding bridge primer for large area repairs (where relevant): SikaTop® Armatec®-110 EpoCem®
Semi-fluid repair mortars for large area repairs: Sika MonoTop®-432 N
Thixotropic repair mortars for local patch repairs: Sika MonoTop®-412 series
Self-levelling, epoxy modified, cement-based levelling mortars: Sikafloor®-81/-82 EpoCem®
Structural concrete repair system for columns and beams:
Bonding primer (where relevant): Sika MonoTop®-910 N or SikaTop®Armatec-110 EpoCem®
Hand or wet spray machine applied repair mortars: Sika MonoTop®-412 /-352 series
Surface levelling and fairing mortars: Sika MonoTop®-723 N or Sikagard®-720 EpoCem®
Structural concrete repair systems for soffits and other surfaces under live dynamic loading:
Bonding bridge primer: SikaTop® Armatec®-110 EpoCem®
Hand or machine applied repair mortar: Sika MonoTop®-412 series
Surface levelling mortar: Sika MonoTop®-723 N
With the application for installation and performance testing of repair mortars under live dynamic loading, SikaTop® Armatec®-110 EpoCem® and Sika MonoTop®-412 N fulfill the requirements of German Standard ZTV-SIB, TL BE-PCC, 1999.
3. Structural Strengthening
If the existing steel reinforcement is reduced in capacity due to corrosion, if the traffic loads are increased (i.e. permissible axle weights), or if the structural design or seismic resistance needs improvement, then reinforced concrete bridges have to be strengthened.
Sika has been involved in structural strengthening since the development of the technology in the 1960’s using bonded steel plates. Since 1991, Sika has also been a pioneer with the development of carbon fiber reinforced polymer (CFRP) based structural strengthening systems. As a leader in strengthening all types of reinforced concrete structures, Sika provides a full range of fully tested and approved strengthening systems.
Strengthening systems for shear strengthening of beams and columns, consisting of Sikadur® structural epoxy adhesives and:
Prefabricated L-shaped plates – Sika CarboShear L for application on rectangular T-beams
SikaWrap® fabric strengthening system based on unidirectional carbon and glass fibers, for application on beams and beam-column joints
Structural strengthening systems for the flexural strengthening of bridge decks, beams, and girders, consisting of Sikadur® structural epoxy adhesives and:
The carbon fiber reinforced polymer-based, pultruded plate system Sika CarboDur®, available with different E-moduli and in various dimensions, for external application
The carbon fiber reinforced polymer-based Sika CarboDur® NSM system for application in near-surface slits
Structural strengthening system for the post-tensioned strengthening of bridge decks and beams, consisting of:
Tendon based on CarboDur® plates and special CarboStress® anchorage heads
End-anchorage solutions based on project needs
Strengthening system for axial strengthening of columns (column confinement), consisting of Sikadur® epoxy adhesives and:
Unidirectional SikaWrap® fabrics, based on carbon and glass fibers, available in a range of area weights
4. Waterproofing
Bridges are an essential part of modern infrastructure and are often subject to the harshest weather that climates have to offer. In order to maintain the durability over its design life, special attention should be given to the waterproofing and protection of exposed elements and critical areas such as the bridge deck itself, to prevent serious damage to the concrete and structural reinforcement.
Due to constant movement, the deck waterproofing system must be able to accommodate dynamic traffic loads and bridge cracks whilst still maintaining a strong bond with both the substrate and asphalt road surface. Bonding failure can lead to loose or rucked road surfaces allowing water, chlorides and chemicals to attack the structure, reducing the design life.
New technology with Sikalastic®-851 waterproofing membrane, liquid applied membrane based on polyurethane or polyurea, together with innovative Sikalastic®-827 pellets-system for high bond and shear strength (see "Bonding Asphalt Overlays") make a reliable bridge deck protection system.
SikaShield® bituminous membranes have high resistance to puncture, durability and heat compatibility, making it suitable for systems subjected to traffic. It is certified according to EN 14695 - reinforced bitumen membranes for waterproofing concrete bridge structures and other concrete surfaces subject to traffic.
New innovative Sikalastic®-827 pellets bond asphalt overlays to Sika waterproofing systems by expanding and melting, forming a mechanical and chemical bond at the interface. This dramatically increases both shear and tensile bond strengths, thus increasing safety to heavy traffic braking and long term durability.
Waterproof, anti-slip systems for bridge decks:
Epoxy-urethane system: System consisting of an appropriate substrate primer with Sika® Elastomastic® TF tough, elastic waterproof wearing layer. Approved and certified according to German regulation ZTV-RHD-ST for riveted and welded, directly trafficable, orthotropic steel decks with low to medium traffic. With a suitable primer, the system can also be used for waterproofing and protection of pedestrian and bicycle bridges made of concrete.
Pure polyurea spray-applied system: Fast-curing pure polyurea membrane with aggregate injection system in accordance with German regulation ZTV-RHD-ST, consisting of a primer and Sikalastic® One Shot system, suitable for waterproofing and protection of concrete decks.
Optional color stable top coats from the Sikafloor® range are suitable for both systems.
Structural bonding and flexible watertight injection systems for crack sealing in concrete structures:
For the surface sealing of bridge decks: Flexible polyurethane and acrylic resin-based injection systems – Sika® Injection systems
For structural cracks and void repair: Sikadur®-52 and Sika® Injection 451 low viscosity, epoxy resin-based systems
5. Joint Sealing
Bridges are complex and demanding structures. There are many joints that need waterproofing, from simple saw cut contraction joints to exposed movement and connection joints. These joints are exposed to thermal movement, constant vibrations, extreme weathering, mechanical impact from the traffic and chemical impact from spillage or de-icing.
The sealants must reliably prevent water from entering the structure and causing decay of concrete and steel components through corrosion. Durable waterproofing has a significant impact on the life expectancy of the bridge.
High performance watertight joint sealing systems for use on bridge decks, parapets, and other elements:
For facade and parapet joint waterproofing: Sikadur® Combiflex® SG system
For bridge deck and deck waterproofing edge terminations: Sika® Dilatec® B, R and E edge systems
For facade joint waterproofing: Sikaflex® joint sealants
The rapid completion of construction and refurbishment works has been a driver of innovation since many years. Examples are reduced curing times of concrete and application over a wider temperature range, application on humid substrates or fast curing of sealants, adhesives and coatings.
The fast curing of a sealant can be achieved by adding a booster. Sikaflex®-406 KC is a single component sealant that is accelerated with a booster, Sikaflex®-406 KC Booster. The Sikaflex®-406 KC system unites the advantages of a one- and two-component systems.
The system including Sikaflex®-406 KC with Sikaflex®-406 KC Booster is designed for:
- Connection joints between steel, defined asphalt types, concrete, granite, rails in track superstructure
- Movement joints in road and airport pavements, parking decks, driveways, pedestrian and traffic areas
- Joint dimensions 10 – 70 mm
Advantages:
- Rapid release to traffic: Recessed and broadcasted joints can be opened to traffic after 3 hours
- High movement capability of ±25%
- High mechanical and chemical resistance
Sikasil®-728 SL is designed to seal saw cut and expansion joints in pavement on highways, airports, bridges, garages, and car park top decks as well as driveways. Application can be executed in cold and hot temperature conditions. Sikasil®-728 SL withstands an exposure from -40°C to +150°C, high UV radiation and severe weather conditions.
Advantages:
- Very high movement capability
- Very good adhesion, especially to concrete
- Very long service life due to outstanding UV resistance
- Very good flexibility for use in extremely high and low temperatures
The EMSEAL BEJS is a traffic-durable bridge and roadway expansion joint which provides a primary watertight seal preventing and decreasing maintenance costs to bridge bearing pads and support structures. It is designed for new construction and refurbishment of old or failed bridge expansion joint systems to handle harsh environmental conditions and features great movement capability, very good low temperature flexibility and high temperature stability.
Non-invasive anchoring provides for quick turnaround and repairs. The system is composed of a pre-compressed, silicone-foam hybrid installed into field-applied adhesive on the joint faces, with the silicone bellows locked to the joint faces with a silicone sealant band.
The EMSEAL BEJS is designed for:
- Concrete-to-concrete substrates
- Rebuilt joint faces, where demolition and removal of existing embedded metal angles is not feasible or affordable
- As a lasting replacement for all failed liquid-sealant joints in parapets, sidewalks or jersey-barriers.
Advantages:
- EMSEAL systems enable watertight expansion joints in all kind s of substrates delivering continuity of seal for bridge and highway conservation
- Ability to adjust to varying joint gap widths
- Easy installation, because system is delivered in pre-compressed form smaller than the gap
- Staged installation preserves traffic flow
6. Concrete Protection
To improve the performance and durability of reinforced concrete surfaces on bridge structures, additional protection systems are frequently required, particularly in refurbishment situations. Typical concrete protection systems for bridges can be classified as hydrophobic impregnations, sealing impregnations, surface coatings, or corrosion inhibitors. These are designed for use in different situations or collectively in alternative combinations, to greatly reduce damage to the concrete surfaces, to stop or reduce the rate of steel reinforcement corrosion and prevent significant structural damage.
Sika provides a wide range of tested and well proven concrete protection systems based on different technologies including hydrophobic or sealing impregnations, rigid and elastic surface coatings, galvanic anodes, and surface applied corrosion inhibitors. All of these Sika products and systems fully comply with various standards and regulations.
Liquid, surface applied corrosion inhibitor: Sika® FerroGard®-903 Plus
Galvanic protection systems: Sika® FerroGard® galvanic anodes
Deep penetrating hydrophobic impregnations Sikagard® -705 L/-706 Thixo
For invisible protection of fair-faced concrete, count on Sika's solutions with cost effective products which cause no change in the structure's appearance. For facades, beams, columns and all areas of the bridge superstructure, Sika provides durable, deep penetrating, protective hydrophobic impregnations with a unique and complete concrete protection system, including:
Sika® FerroGard®-903 Plus corrosion inhibitor
Hydrophobic impregnations: cream silane-based Sikagard®-706 Thixo and liquid silane-based Sikagard®-705 L
Rigid, continuous film-forming, protective concrete surface coatings:
High performance, solvent dispersed, acrylic resin coating Sikagard®-680 S BetonColor
Water dispersed, protective acrylic resin coating Sikagard®-675 W ElastoColor®
High build, film-forming protective concrete coating system with crack-bridging abilities:
Water dispersed, high build, acrylic resin-based, elastic intermediate, and surface levelling coating: Sikagard®-545 W Elastofill®
Water-based, high build, elastic crack-bridging, colored, protective top-coating: Sikagard®-550 W Elastic
Water-based, protective coating Sikagard®-555 W Elastic - high dynamic and static crack-bridging ability, even at subzero temperatures, not requiring intermediate coat. Applicable from 300 to 600 g/m2 per coat according to the desired level of crack bridging.
7. Grouting and Fixing
Remedial works on concrete bridge structures often include the requirement for void filling, fixing and sealing or bedding and grouting with free-flowing materials. Typical examples are concrete repairs using formwork, high precision grouting under bridge bearing plates, or for cable duct grouting. Additionally flowable resin and cement grouts are used to fix manholes or other steel frames and equipment, where rapid hardening materials are usually required to reduce closure times.
Sika provides a wide range of tested and well proven grouts and fixing materials based on all of the different technologies available including cement, epoxy, polyurethane and PMMA. For many decades, Sika has also provided special products for high precision applications such as bearing plates, rail tracks and duct sealing.
Materials for grouting under bridge bearing plates and to fill voids, holes, and cavities or for embedding drainage pipes and other elements:
Cement-based, high precision grouting products: SikaGrout®-300 series
Epoxy resin-based, rapid hardening, high strength grouting products for use under dynamic loading: Sikadur®-42 series
PMMA resin-based, grouting products for application at low temperatures down to -10 °C: Sikadur®-12 Pronto
Sika® FastFix® systems for road construction and maintenance works:
Fixing and bedding of manhole frames and mechanical joint
hosing: Sika® FastFix®-138 TP or Sika® FastFix®-4
Concrete curb bedding and jointing: Sika® FastFix®-1 TP
Block paver and stone set pavement bedding and jointing: Sika® FastFix®-133 TP
Rail fixing, damping and bedding solutions for all types of rail track systems to be installed on bridge decks:
Discrete fixing solutions: Icosit® KC range
Direct rail track fixing and bedding solutions: Icosit® KC range
8. Structural Bonding
Structural adhesives are used for many bonding applications in new construction and refurbishment. The bond must allow the transfer of high loads without deformation and creep. The main function of structural adhesives is in the bonding of similar or dissimilar materials together (i.e. concrete to steel, steel to composites etc). Dependent on their design, structural adhesives can not only bond the elements together, but they can also fulfil additional functions such as waterproofing, sealing, concrete protection or even vibration dampening.
Sika has been a pioneer in the use of resin adhesives for structural bonding of precast concrete elements since the 1960’s. Sika’s epoxy adhesives have now been used to bond segmental bridge structures all around the world. This extensive experience has allowed the development of a wide range of additional structural bonding products and systems for unique applications. In the 1990’s Sika also introduced a complete range of cartridge applied resin anchoring adhesives for many different applications.
Segmental bridges are built in short sections (called segments) one piece at a time, whereby traditional methods build a bridge in very large sections. Segmental bridges are made of precast concrete, which is manufactured at another location and then transported to the final location for placement within the complete structure. They are very economical for long spans (over 100 meters), especially when access to the construction site is restricted, and also allow for special design features to enhance the beauty of the structure.
Sika offers Sikadur-31 SBA: Range of thixotropic, structural two-part adhesive specially formulated for segmental bridge construction; available in different grades to suit different applications and environmental conditions. All grades present advantages including: meets and/or exceeds internal and national standards (FIP, BS, AASHTO, ASTM, etc.), high strength, high modulus of elasticity, no primer required and more.
With high mechanical strength and durability, no shrinkage, good chemical and fatigure resistance and much more, Sikadur®-30 epoxy adhesive is perfectly suited for structural bonding of Ultra High Performance Concrete (UHPC) precast elements.
Epoxy adhesives for bonding different elements or components to concrete, steel or bituminous substrate:
Sikadur®-30 for high-performance bonding of steel plates on to concrete
Sikadur®-31 CF for multi-purpose bonding such as precast concrete or natural stone curbs onto concrete or asphalt surfaces
Special structural adhesives tested according to European or US-standards for anchoring all types of fittings and equipment to bridge structures, such as for the installation of cable trays or other services, crash barriers, drainage pipes, inspection access equipment, catch nets, reinforcing steel, and more.
ETA and AC approved, structural resin anchoring adhesive Sika® AnchorFix®-2, for installation of threaded rods and rebar at temperatures as low as -5 °C.
ETA approved, structural resin anchoring adhesive Sika® AnchorFix®-2+, for installation of threaded rods and rebar, including cracked concrete and seismic testing. With different hardener grades (arctic and tropical), suitable at temperatures from -10°C/-25°C up to 40°C.
AC approved, structural resin anchoring adhesive Sika® AnchorFix®-2020, for installation of threaded rods and rebar including cracked concrete and seismic testing.
ETA and AC approved, high performance, epoxy resin based, structural anchoring adhesive Sika® AnchorFix®-3001/-3030, for installation of threaded rods and rebar even into damp substrates, including cracked concrete and seismic testing.
Special epoxy mortars for the bedding, bonding, and dry-packing of many different types of fixtures and fittings, including steel frames and parapet railings, etc.:
Three-component, non-shrink, epoxy resin-based mortars Sikadur®-41 CF and Sikadur®-43 HE
9. Wooden or Masonry Bridge Repair
Generally, wooden or masonry bridges are old structures and may suffer from decays over the ages, which is most often due to a lack of deck waterproofing or other structural component failure. On some occasions, the design load no longer complies with new traffic regulations, and structural strengthening is required. An invisible solution is often required in order to maintain the appearance of old, historical or iconic structures.
Sika offers expertise in the rehabilitation of masonry or wooden bridges. As a specialist in waterproofing, masonry protection, and structural strengthening, Sika offers a full range of systems to prevent water ingress and to increase the structural capacity of these old structures.
Old masonry structures shall retain their visual appearance and any treatment shall not affect the breathing capacity of the structures.
Liquid siloxane emulsion Sikagard®-703 W
High-performance cream siloxane Sikagard®-730 Thixo
Functionality and durability of masonry or wooden bridges can be improved by structural strengthening, while still keeping the outward appearance of the structure.
Externally bonded or near-surface mounted Sika CarboDur® CFRP strengthening system
Textile reinforced mortar for masonry strengthening
The durability of masonry bridges can be improved by injections:
Sika InjectoCem®-190 for filling the joint
Sika Injection®-304 for rising damp treatment
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