06 Jul 2022 |
Research article |
Infrastructure and the Built Environment , Sustainable Development, the Circular Economy and Environmental Issues
Moving Towards Sustainability
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Each year, as the snow melts, temperatures rises and Canadian motorists come across numerous potholes that can wreak havoc on their vehicle’s suspension. In fact, the 2019 Canadian Infrastructure Report Card estimated that nearly 350,000 km of r ads were in very poor, poor or fair condition. This number represents the entire road network of Quebec or half the distance between the Earth and the Moon.
Repairing or, more often than not, patching these roads inevitably entails substantial costs. However, less known is the resulting environmental impact. It is estimated that the construction, renovation, and demolition sectors generate 41% of waste materials produced in Quebec.
That being said, what can be done to build better roads, increase their lifespan and reduce their environmental impact? At the Laboratoire des chaussées et mélanges bitumineux (LCMB), researchers are exploring several avenues, including a technique called full depth reclamation (FDR).
Full Depth Reclamation
The FDR technique is commonly used throughout the world. Full-depth reclamation is a pavement rehabilitation technique that is carried out in situ, by reusing materials from the existing pavement. The upper portion of the pavement is pulverized, bituminous and hydraulic binders are mixed in place to obtain a new so-called stabilized pavement foundation. After the curing period, a layer of asphalt is applied on top producing a pavement that will easily last 15 years.
Full Depth Reclamation
This technique has many benefits. To begin with, the stabilized foundations offer thickness of a greater bearing capacity than conventional foundations. The surface layer of asphalt can therefore be reduced. This technique can also reduce maintenance costs by 16% to 50% over a 50-year period, depending on specific site conditions. Be that as it may, what makes this method unique is that all the old material is reused in road rehabilitation—nothing goes to landfills. As an example, applying this technique on a 1.6 km two-lane road resulted in the following savings:
- 168 trucks;
- 4,200 tonnes of material consumed;
- 2,060 cubic metres of landfill space
- 11,400 litres of fuel.
Unfortunately, the FDR technique is rarely used because there is little or no implementation oversight, quality control or performance monitoring in Canada.
The LCMB researchers are on a mission to develop design and quality control tools to increase the utilization potential of this rehabilitation technique. To this end, they will be working on three topics:
- Developing design tools based on material characteristics;
- Developing guidelines to improve curing monitoring;
- Identifying simple and effective means of quality control.
Multifunctional Polymer Roof Deck Tiles
Another project targeted by the researchers is the design of roof deck tiles that are part of a circular economy context. Typically, roof deck tiles are made of concrete, which makes them difficult to transport and install, and they exert additional weight on the structure. LCMB Researchers are exploring the possibility of making them out of polyurethane and fibreglass, using recycled materials from old wind turbine blades and production scrap. In addition to being thinner and lighter, these tiles could combat urban heat islands by reflecting light, which reduce the heat absorption.
A Sector that Must Increase its Circularity
The achievable gains in sustainability in construction are huge, provided that we make room for innovation in both the materials used and the techniques deployed in the field. The impact of the construction sector is such that we cannot think of reducing our ecological footprint by maintaining the status quo.
Éric Lachance-Tremblay is a professor in the Department of Construction Engineering at ÉTS.
Program : Construction Engineering
Research laboratories : LCMB – Pavements and Bituminous Materials Laboratory