Sustainability Publications

CO2 Reduction

Innovation Solutions for Sustainable Road Construction

Norouzi, M., Poharel, S.K.,
Breault, M., Breault, D.
Canadian Society of Civil Engineers Annual Conference

The industrial and infrastructural developments in the past mainly focused on economic development. After
the Brundtland commission report on sustainable development it was realized that the development should
happen considering the future of the Planet Earth and the lives of our successors. In the recent years Kyoto
Protocol and Paris summit have put even more emphasis on sustainable development. With the
understanding of what causes the impact on our natural environment, CO2 emission has been accepted as
one of the quantitative measures defining sustainability of a project. Road construction activities are a large
contributor to CO2 emissions in Canada. Conventional practices, as discussed, are result oriented and
focus only on providing the required structural capacity of roads and highways for the expected traffic
condition. Nowadays there are innovative technologies that offer the same structural capacity while using
less amount of material and activity required to build the roads which in turn will result in less CO2 emission.
This paper discusses an innovative solution utilizing Geocells made from nano polymeric alloy to build
roads. Two design options, one the conventional method and the other using high strength polymeric
Geocells reinforcement are discussed. The findings from the research illustrate that by using the high
strength Geocells reinforcement, both the cost of road construction and corresponding CO2 emissions are
greatly reduced compared to the conventional construction alternative. It is illustrated in detail how using
innovative geosynthetic alternatives can save up to 20% of CO2 emissions during the life cycle of a road

Sustainable Road Construction for Heavy Traffic Using High Strength Polymeric Tough-Cells

Norouzi, M., Poharel, S.K.,
Breault, M., Martin, I.
CSCE Resilient Infrastructure

Four roads reinforced by Neoloy Tough-Cells 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 Tough-Cell 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 Tough-Cell reinforcement, including reduced pavement thickness up to 50%, longer life-cycle and lower capital costs.

High-Modulus Geocells for Sustainable Highway Infrastructure

Kief, O., Schary, Y., Poharel, S.K.,
Indian Geotechnical Journal: Special Issue on Transportation Geotechnics

Technological innovation in geosynthetics such as high modulus (stiff) geocells (cellular confinement systems) can help achieve a more sustainable highway infrastructure. Research, testing, field trails, and case studies demonstrate how geocells increase pavement performance on one hand, while achieving sustainable goals on the other. Recent published research and testing of high-modulus Novel Polymeric Alloy (NPA) geocell-reinforced bases are briefly reviewed in this paper. NPA geocells improved strength and rigidity of flexible pavements as indicated by: increased modulus of structural layers, reduced stresses to the lower layers and decreased surface degradation. Field trials validate that NPA geocells improve the modulus of road base layers, even while reducing the structural thickness and utilizing on-site or recycled materials for structural infill. Sustainable roads can be built with less virgin resources and a smaller environmental footprint, while extending the pavement service life and decreasing maintenance.

Recycled Aggregate

A Large Test Box Study on Geocell-Reinforced Asphalt Pavement [RAP] Bases over Weak Subgrade under Cyclic Loading

Thakur, J.K., Han, J., Pokharel, S.K., Parson, R.L.

ASCE Geocongress

Currently, great emphasis is placed on sustainable construction and infrastructure with green technologies. As a result, the demand for sustainable and environmental friendly roads is increasing day by day. More technologies for sustainable roadway construction are needed. One way to construct environmentally sound roads is through the use of recycled asphalt pavement (RAP) materials as a base course. However, limited research has been done to quantify its structural capacity with engineering properties. It is expected that RAP base courses may have excessive deformation under traffic loading due to the existence of asphalt in RAP. It is believed that geocell confinement can reduce the permanent deformation and improve the performance of RAP bases. In this study, three-dimensional novel polymeric alloy (NPA) geocell was used to confine RAP bases. To investigate the effect of geocell confinement on the performance of road bases, unreinforced and geocell-reinforced RAP bases were constructed over weak subgrade (target CBR of 2%) in a large geotechnical test box (2 m x 2.2 m x 2m high) and tested under cyclic loading. The test results showed that geocell confinement reduced the permanent deformation and vertical stress distribution at the interface between base and subgrade, and increased percentage of elastic deformation as compared with the unreinforced base.

Experimental Evaluation of Recycled Asphalt Pavement Bases Reinforced by Geocells under Cyclic Plate Loading

Thakur, J.K., Han, J., Pokharel, S.K., Parson, R.L.

TRB 91st Annual Meeting 

Geocells, one type of geosynthetics manufactured in a form of three-dimensional interconnected cells, have been reported to effectively provide lateral confinement to infill material to increase the modulus and bearing capacity of base courses. Most studies so far have been focused on the behavior of geocell-reinforced bases under static loading. Geocells used for pavement applications are subjected to repeated loading. Limited studies have been conducted so far to investigate the performance of geocell-reinforced bases under repeated loading. In this study, single and multiple geocell-reinforced granular bases with three types of infill materials (Kansas River sand, quarry waste, and AB-3 aggregate) were tested and compared with the unreinforced bases under repeated loading. This study experimentally investigated the effect of the geocell reinforcement on the permanent deformation and percentage elastic deformation of the granular bases. The test results showed that the geocell reinforcement reduced the permanent deformation and increased the percentage elastic deformation of the granular bases. Multiple geocell-reinforced sections demonstrated even better performance as compared with single geocell-reinforced sections.

Performance of Geocell-Reinforced RAP Bases over Weak Subgrade under Full-scale Moving Wheel Loads

Han, J., Pokharel, S.K., Manandhar, C., Yang, X.M., Leshchinsky, D., Halahmi, I., Parsons, R.L.

ASCE Journal of Materials In Civil Engineering

Recycled asphalt pavement (RAP) has been increasingly used as an energy efficient and environmentally friendly paving material and is currently the most reused and recycled material in the United States. RAP has been used in new hot mix asphalt (HMA) mixtures and in base courses for pavement construction. When RAP is used as a base course material, the presence of asphalt in RAP may cause excessive deformation under traffic loading. Geocell, three-dimensional (3D) polymeric geosynthetic cells, was proposed in this study to minimize the deformation by confining the RAP material. Full-scale accelerated pavement tests were conducted to evaluate the effect of geocell reinforcement on RAP base courses over weak subgrade. Two types of RAP were used and a total of seven geocell-reinforced and unreinforced RAP sections were tested under full-scale traffic loads. The road sections were excavated and examined after each moving wheel test. The benefits of geocell reinforcement were evaluated in rut depths for a specific number of passes of the wheel load and the angle of stress distribution from the surface to the base course-subgrade interface. The test results demonstrated that the novel polymeric alloy geocell reinforcement improved the performance of unpaved RAP sections by widening the stress distribution angle and reducing the rut depth if the base courses were equally compacted in unreinforced and reinforced sections.

Validation of Geocell Design for Unpaved Roads

Norouzi, M., Pokharel, S.K.,
Breault, M., Martin, I.
IFAI [ATA] Geosynthetics Conference

Based on cyclic plate load and moving wheel tests Pokharel (2010) proposed a design method for unpaved roads using Neoloy based Geocell with a theoretical base from the Giroud and Han (2004) design method for planar reinforcement. To validate it under real time traffic, unpaved haul roads, well pads, and logging yards were designed. To the possible extent locally available cheaper poorly graded but environmentally friendly materials were used as infill. In case of extremely soft subgrades, construction layer of poorly graded sand reinforced with Geocell provided a driving surface for the construction equipment. The performance of the structures was evaluated on the rutting criteria, maintenance requirement, and visual serviceability after one year of service. This paper discusses the design method used in a number of projects in Western Canada including the Oil Sands region that face extreme cold weather conditions. The limitations of the design method are also discussed.