The 8th Giroud Lecture: Transforming Concrete Pavements Through Geosynthetics

At the opening of the 13th International Conference on Geosynthetics (13ICG) in Montréal, Dr. Jie Han delivered the 8th Giroud Lecture, exploring how geosynthetics could transform the design and construction of concrete pavements.

Titled Transforming Concrete Pavements: Innovative Geosynthetic Solutions for Improved Sustainability and Resilience, the lecture brought together laboratory research, field monitoring and practical case studies to demonstrate the potential of three technologies: geogrids, wicking geotextiles and geocells.

Dr. Han, Roy A. Roberts Distinguished Professor at the University of Kansas, began by recognizing Dr. J.P. Giroud’s vision, leadership and profound contribution to the geosynthetics discipline. He also reflected on Dr. Giroud’s mentorship and the important role it has played in his own research and professional journey.

A largely unexplored application

Geosynthetics are already widely used in unpaved roads, asphalt pavements and overlays. Their application beneath and within concrete pavements, however, has received significantly less attention.

Concrete pavements must withstand traffic loading while also responding to changing moisture and temperature conditions. Water pumping, erosion and freeze-thaw cycles can weaken the pavement foundation, cause a loss of support beneath the concrete slabs and contribute to cracking and faulting at joints.

Dr. Han’s lecture examined how geosynthetics can address these underlying problems, helping pavements withstand disruption, recover more effectively and remain in service for longer.

Geogrids: strengthening the pavement foundation

The first part of the research focused on using geogrids to stabilize the aggregate subbase beneath concrete slabs.

Through interlocking with the aggregate, the geogrid limits particle movement and creates a stiffer, more stable foundation. Laboratory testing presented during the lecture showed that geogrid stabilization increased the modulus of subgrade reaction—an important measure of foundation support—by two to five times, with its benefits becoming particularly significant after erosion had occurred.

The research also found that geogrids:

• Minimized the loss of support beneath concrete slabs
• Improved load transfer across pavement joints
• Helped prevent the cracking and breaking of slabs
• Increased the number of allowable axle loads by approximately 2.5 to 3.3 times in a design case analysis

A field application on Interstate 5 in Santa Clarita, California, demonstrated how a geogrid-stabilized recycled concrete aggregate base could achieve a 55% reduction in base thickness while providing a substantially higher foundation modulus.

The results show how geogrids can support both resilience and sustainability: strengthening pavement performance while reducing the volume of aggregate required and enabling greater use of recycled materials.

Wicking geotextiles: managing one of the greatest threats to pavements

Water is one of the most persistent challenges affecting pavement performance. It can enter a pavement through surface infiltration, capillary action, a rising groundwater table or seepage from higher ground. Once present, it can weaken the soil, contribute to erosion and pumping, cause the migration of fines and intensify freeze-thaw damage.

Unlike conventional drainage materials, which generally reduce moisture only to field-capacity conditions, wicking geotextiles use specialized fibers to transport water away from the pavement through both drainage and evaporation.

Laboratory and field studies presented by Dr. Han found that wicking geotextiles could:

• Reduce soil moisture below its field capacity
• Provide hydraulic and mechanical improvement
• Increase soil modulus by more than five times following rainfall
• Reduce permanent deformation by more than 50%
• Provide separation, filtration and stabilization alongside their drainage function

Field monitoring of reconstructed pavement on US Route 169 in Kansas further demonstrated how wicking geotextiles could mitigate problems associated with a high groundwater table and freeze-thaw conditions.

The technology offers an important shift in approach: instead of simply accommodating water within the pavement structure, it actively removes moisture and helps the pavement foundation retain its strength.

Geocells: combining the benefits of rigid and flexible pavements

The final solution examined was geocell-reinforced concrete pavement.

In this application, geocells confine the concrete and distribute loads over a wider area. They can also eliminate conventional formwork and steel reinforcement, control cracking and shrinkage, accelerate construction and allow localized repairs.

Experimental results showed that, compared with both aggregate and geocell-reinforced aggregate sections, geocell-reinforced concrete pavement:

• Reduced the pressure transferred to the subgrade by approximately 80%
• Increased load capacity by approximately 250%
• Reduced deformation by more than 80%
• The system also behaved progressively under loading, combining characteristics of rigid and flexible pavements.

A project in Huila, Colombia, illustrated the system’s practical potential. Faced with heavy vehicles and a hot, wet tropical climate, the project required a climate-resilient alternative to conventional asphalt or reinforced concrete pavement. Geocell-reinforced concrete offered a faster and more economical solution capable of supporting the required loads.

Designing for future conditions

A central message from the lecture was that pavement resilience cannot be assessed solely against present-day conditions. Designs must account for increasing traffic loads, changing temperatures and higher or more variable moisture levels.

Geosynthetics can contribute throughout the life of a road by reducing excavation, enabling the use of on-site and recycled materials, limiting performance loss, supporting faster recovery after disruptive events and extending the pavement’s service life. Collectively, these benefits can reduce costs and carbon emissions while improving long-term infrastructure performance.

Looking ahead, Dr. Han identified several opportunities for the next decade, including recyclable and bio-inspired materials, sensor-enabled geosynthetics, climate-resilient transportation systems, AI-assisted design and new installation methods.

His lecture demonstrated that geosynthetics should no longer be viewed only as additions to conventional pavement systems. Supported by appropriate testing and design methods, they have the potential to fundamentally change how concrete pavements are designed, constructed and maintained.

Read Dr. Jie Han’s short Giroud Lecture paper

A full paper expanding on this work will be published in Geosynthetics International at a later date.