Sustainable Road Construction for Heavy Traffic Using High Strength Polymeric Geocells, Pokharel et al, 2016
Analysis of recent road projects shows that Neoloy Geocells reduce hauling by 30% and CO2 emissions by 60% to achieve sustainable construction objectives.
Four roads reinforced by Neoloy Geocells in the Oil Sand region of Alberta were evaluated to quantify Neoloy contribution to sustainability objectives. In particular, CO2 emissions were quantified, as the roads were used to access drilling areas, which typically use large amounts of virgin aggregate transported from afar. Because Neoloy Geocell reinforcement enables the use of local infill, these roads were found to cut haulage typically by 30%, reducing CO2 emissions by up to 60%. This represents an important cost saving with the introduction of regulatory carbon tax in Canada. The study also demonstrates additional advantages of Neoloy Geocell reinforcement, including reduced pavement thickness up to 50%, longer life-cycle and lower capital costs.
Challenge – Increase sustainability while maintaining structural integrity
According to a study by Lippiatt, the construction industry accounts for 40% of raw stones, gravel and sand, 25% of raw timber and 40% of energy produced annually in the United States. Although previous studies have demonstrated that Neoloy Geocells increase modulus and bearing capacity, few have validated their quantitative contribution to overall sustainability. All these projects faced the following challenges:
- Lack of nearby gravel
- High cost of hauling and carbon emission
- Extremely soft subgrade and expensive removal and backfill
- Limited rights of way
- Limited construction time (summer months)
- Extremely heavy traffic
Validation – Sustainable access road construction in soft drilling locations
Energy exploration in Canada usually require access through very soft, spongy muskeg ground. The muskeg is often replaced with significant virgin construction material, which is time-consuming, costly and generates a large carbon footprint.
The following four road projects, designed and constructed with Neoloy Geocell reinforcement, were assessed not only for their design, structural performance and their impact on sustainability, but for their reduction in CO2 emissions as well.
MEG Energy Corporation – Temporary access road – P3 Connector
Completed within 1.5 months, this 3.2 km long road was constructed through deep muskeg, using locally available sand and two layers of Neoloy Geocell. It exceeded design expectations and after 3 years of excellent performance, the client requested to extend the road reinforcement.
MEG Energy – Main access road
This 7 km road extension from the original temporary access road, was both widened and made suitable for all-weather use, using NPA Geocell reinforcement on muskeg with local sand infill. After 3 years of excellent operation, almost no maintenance and minimal grading was required.
Creek crossing for major oil company
Located north of Ft McMurray, a road suitable for heavy haulage across a creek was constructed, with instructions not to remove existing muskeg. Neoloy Geocells reinforced local sand, reducing the total thickness of the embankment from 3m to less than 1m.
Township road 762
This 3.2km long stretch in Smoky River is a major access road for the production site of a major oil company. It had experienced a seasonal problem with road break, but was reinforced with Neoloy Geocells on local sand. After 3 years of operation, no maintenance was required, and the thickness of the road was reduced by almost 150 mm.
Results – Less haulage, drastic reduction in carbon emissions
Because Neoloy Geocells can reinforce locally available infill, haulage distances were hugely reduced, in one case from 198km to just 8km. With a 25 ton pay load for the gravel trucks assumed, generating 4.92kg of CO2 per km of hauling, in these 4 projects, calculated savings in CO2 reached 60% based on the respective hauling distance.
In addition, the assessed projects demonstrated that roads reinforced with Neoloy Geocell can save more than 50% in materials. They also require no to minimal aggregate addition, which typically totals 50 mm a year for maintenance of conventional gravel roads.
Benefits – Sustainable and cost-effective roads
The authors concluded that using NPA Geocells is “highly recommended” for engineers and the construction industry, given the following benefits.
- Significantly reduced haulage by 30%, cutting carbon emissions by 60%
- Reduced road thickness by 50% and more, saving both materials and cost
- Less maintenance required, reducing manpower costs
- Longer life-cycle, reducing capital costs