Material innovation is a key component of bridge construction, reducing costs and maintenance expenses. Engineers tinker with iron to produce refined versions that are ductile and strong in both compression and tension.
Steel bridge fabricators offer prefabricated options that reduce installation time and minimize disruption during construction. Their light weight also allows for smaller abutments and less expensive construction equipment.
Refined Iron
Iron is a strong and durable metal that can be used to build structures such as bridges. Its tensile strength is greater than many other materials and it resists stress, strain, heat and corrosion. However, iron also rusts easily when it comes into contact with damp air. Rusting can decrease the strength and other properties of iron and reduce its lifespan.
When engineers design bridges, they must consider several factors, including the material to be used. Engineers also have to think about how the bridge will be used, what type of vehicles will use it and where the bridge will be located. Then they have to consider how much weight the bridge will carry.
In the past, wrought iron was the preferred material for monumental construction due to its superior structural properties and the fact that it could be assembled using traditional hot-riveting techniques. However, most of these old structures are now suffering from fatigue damage due to a combination of factors.
One of the key issues is that wrought iron tends to develop stress concentrations at joints. As a consequence, these structures are particularly sensitive to high cycle fatigue. Furthermore, the wrought-iron bridges are often subject to environmental loadings that cannot be controlled such as road traffic, deliberate sabotage or war incidents (in French structures mostly related to the two world wars).
Self-Healing Concrete
Researchers have developed self-healing concrete that repairs cracks and other damage autonomously. It is inspired by the way the human body heals itself. This cutting-edge material incorporates healing agents that remain dormant until triggered by environmental conditions, such as exposure to water and air.
These healing agents are encapsulated in microcapsules that are mixed into regular concrete mixes. When the concrete is damaged, a capsule ruptures and the healing agent is released to repair the crack. This approach has been tried with a variety of bacteria but in their trials scientists found that bacterium bacillus pseudofirmus worked best.
Other researchers have focused on incorporating fungi into concrete. The fungi form a natural fiber that can cover exposed cracks and recover mechanical properties of the concrete. The fungi fiber also prevents water ingress and mitigates the corrosion caused by deicing salts.
In addition to extending the lifespan of structures, self-healing concrete reduces maintenance costs by minimizing the need for repairs. It also helps to reduce the carbon footprint of buildings and other infrastructure systems, aligning with global sustainability goals.
Taking into account the huge economic, environmental and social impacts of bridge collapses, self-healing concrete is an important new technology to consider for future projects. It could help reduce the risk of structural failures and save lives. It will also allow structures to be constructed using 30 to 40% less reinforced concrete, which is a significant saving in terms of materials and construction time.
Composite Materials
While traditional materials like steel and concrete have long held a stronghold in bridge construction, composites are making a major impact in this space. These advanced materials feature a high strength-to-weight ratio and are corrosion resistant, providing long life and low maintenance costs. As a result, they can save time and money during construction while delivering significant cost savings in the long run.
Composite materials are composed of long fibers embedded in a resin matrix that gives them their strength and durability. Typically, the fibers are sourced from glass or carbon fibre and the resin is a polymer such as polyester, epoxy or vinyl ester. The composite material is then cured under heat and pressure.
These types of materials are used to strengthen existing bridges as well as for new construction. For example, the Blackfriars Bridge in London is being restored with composite materials to support heavy vehicular traffic without overstressing the structure. As a result, the composite deck system will reduce deterioration of the bridge while providing a stable platform for vehicles to travel over.
Many fabricators and suppliers of advanced materials are working to spread awareness about the benefits that these materials offer in infrastructure projects. They’re finding that conversations with civil engineers are moving away from resistance to change and skepticism about the capabilities of these materials to a more fair consideration of their overall value.
Smart Technology
In order to maintain bridges at an optimal condition, meticulous inspection is essential. However, while some parts of a bridge can be visually inspected on-site, the integrity of other areas is difficult to assess without special equipment. For example, a time-lapse camera has been developed to monitor the movement of bearings under temperature differences and live traffic loads. The device can be powered by batteries or solar energy. This smart inspection technology can provide a new tool for assessing the structural integrity of bridges.
A wide range of smart bridge sensors are also being developed to allow for better facility inspections. These smart sensors can measure the performance of bridges, such as vibrations and temperature, to identify signs of deterioration. For instance, the University of Michigan is developing a sensing “skin” that can be incorporated into paint or concrete to detect cracks or other anomalies.
The sensor data can then be used to develop a virtual model of the bridge and compare it with actual measurements, allowing technicians to find out when repairs are needed. This smart monitoring system can reduce the amount of time it takes to carry out inspections and maintenance, as well as help to prevent critical failures in advance. Sophia Fox-Sowell covers artificial intelligence, cybersecurity and government regulation for StateScoop. She earned a bachelor’s degree in anthropology from Wagner College and a master’s in media innovation from Northeastern University.