Structural engineering can help solve a problem that’s getting a lot of attention today: waste. Plastic in the waterways, the “trash island” in the middle of the Pacific Ocean, landfills getting full — society in general is becoming more alarmed about waste. That’s bringing pressure to bear on politicians and businesses to reduce waste. Cities in the United States have already banned plastic bags and plastic straws, and the pressure is not going to let up.
Structural engineering decisions have a major impact on the amount of waste generated in construction, as well as the end of a building’s lifespan. Additionally, structural engineering decisions that reduce waste can also save energy and costs for erecting and disassembling buildings.
Recycled materials in construction
Using recycled materials diverts them from the waste stream, reducing the amount of material going to landfills or, worse, into the wider environment.
Steel, copper and aluminum are widely used and re-used, and contain a high amount of recycled basic material. Steel is easily recycled and reused for structural purposes, and copper is readily reused for wire and other applications.
A range of roofing materials contain recycled copper and other materials. They can be less expensive than traditional roofing tiles, and last longer with less maintenance over the roof’s life cycle.
Innovative structural engineering professionals know about recycled flooring materials, such as engineered wood and tile products. A variety of carpet materials are made from recycled bottles and fibers.
Gypsum from drywall can be recycled and used for new drywall, cement components, even agricultural uses.
Rubber from tires can be recycled and reused for a range of applications. One is as a flexible, safe ground covering for playgrounds.
A company in Norway demonstrated a product called NewspaperWood. It rolls recycled newsprint and other paper with solvent-free glue and presses the material into log shapes. These can be then cut and used in the same way as real wood.
Plasphalt is a material made by adding unsorted plastic waste with concrete and bitumen as an alternative form of asphalt. Experiments and studies of plasphalt show that it lasts longer than regular asphalt, reducing maintenance costs for roads.
And of course, everyone with any knowledge of structural engineering knows that concrete can be ground down and reused as filler in new concrete construction.
Structural engineering at demolition
Rethinking structural engineering can also help reduce waste and the amount of material going to a landfill at the end of a building’s life cycle, during demolition.
First, it requires a wider understanding of what is available to be reused, re-purposed or recycled. As stated, steel, aluminum, copper and concrete are readily recyclable, and there are many options available.
Wood, tiles, drywall, asphalt pavement, paper and glass can all be recycled or repurposed in various ways, as well. Tiles, cladding and floor covering can be sold or re-used in another building.
Structural engineering benefits
The benefits of using recycled materials in construction, and focusing on recycling at the demolition stage, are wide-ranging. First is the cost savings of having less material to transport to a landfill or dispose of in other ways. Energy savings are important, as well.
Using recycled materials is also a criterion for a building to be recognized in the Leadership in Energy and Environmental Design program, or LEED, by the U.S. Green Building Council. This recognition provides considerable public relations value for the building owner, tenants and builders.
Considering using recycled and repurposed materials in construction of new buildings also opens up new possibilities in structural engineering: new materials, new design choices, and new ways to reduce energy use and waste production through the building’s lifespan.