Reused steel gives old bridges an upgrade
In Muskingum County, Ohio (United States), steel beams from bridges which have been replaced are being reused to create new short-span structures. Faced with budget cuts and aging infrastructure, the Muskingum County Engineers Office (MCEO) decided to use salvaged beams to replace the superstructure of the local Green Valley Road Bridge.
The MCEO team first removed the old attachments from the beams before cutting them to the required lengths. A mock-up of the superstructure was created with the reused steel beams so that new cross-frames and stiffeners could be fitted. The entire structure was then disassembled, cleaned, and painted before being transported to the bridge site.
The County estimates that they saved US$51,000 by reusing beams in the new superstructure. The Green Valley Road Bridge is the fifth in Muskingham County to be given a new lease of life through reuse.
Source: Short Span Steel Bridge Alliance
Demonstrating the practicality of reuse in construction
Tata Steel and the Dutch steel promotion institute Bouwen met Staal (Building with Steel) have cooperated on a project at Amsterdam’s Schiphol Airport to demonstrate reuse in construction. The partners adopted a number of new building practices which should facilitate high reuse rates for the steel in Fokker’s new 31,000 square metre distribution centre at Schiphol airport.
A reuse level of between 20 and 40% would reduce the environmental footprint of the steel used in the building by 18 to 36%. This markedly improves the already strong position of steel when it comes to making life-cycle based decisions about material choices for new buildings.
New practices developed for this project include:
- Development of a ‘Building Material Passport’ which contains the specifications of the steel used in the building.
- Demountable connections for beams, columns, and cladding. These connections eliminate on-site welding, and the need for adapted anchor bolts and shot connections.
- Shear stability is provided by horizontal steel trusses instead of flooring.
- The entire building is designed with modular (standard) steel beam and column dimensions, lengths and sizes.
Source: Tata Steel Europe
Sharing by-products lowers emissions, stimulates local employment
China Steel Corporation (CSC) has a steel mill which is part of a larger industrial park in Kaohsiung City. The park houses a range of different factories which buy fuel gases and steam from CSC. In turn, CSC purchases industrial gases and waste fuel from them. The project is part of the District Energy Integration Plan which CSC has been promoting since 1992. As well as reducing the production costs and greenhouse gas emissions from every participating business, the Plan has stimulated local economic development and ‘green’ competitiveness. Socially the project has led to job creation at the different factories. It has also improved safety for the people who work in the industrial park as boilers and other potentially dangerous equipment are not required. Steam is also used to heat CSC’s Group Employee Dormitory and the local swimming pool.
Source: China Steel Corporation
Steelmaking slag stimulates marine environments
Slag is one of the most important by-products in the steelmaking process. As iron ore and recycled steel are melted in the furnace, slag agents and fluxes are added to remove impurities from the iron ore and scrap.
The slags which are formed protect the liquid metal from oxygen and maintain the temperature of the molten metal by forming a lid. As slags are less dense than liquid metal, they float and can be easily removed.
Once removed and cooled, slags have a wide variety of uses in industries ranging from Portland cement production, to road building, and insulation. worldsteel member companies have even created products which are helping to restore marine environments.
In Japan, JFE Steel has created Marine Stone® – a crushed form of slag which is used in environments with poor water circulation. In these areas, oxygen levels at the bottom are low and hydrogen sulphide is produced. As well as creating a foul odour, the hydrogen sulphide can harm fish and shellfish which feed on the sediment.
The crushed slag attracts sea life to the area which helps to suppress production of hydrogen sulphide and remediate the sediment.