The Geosynthetic Institute had a particularly busy 2018 with White Papers, issuing five of them. All of them are worth reading. One that particularly caught our eye, however, was the 30 November 2018 release of White Paper 40. The document, “Status of Pavement Design Methods Used by U.S. DOTs and Inclusion of Geosynthetics Therein,” provides a concise survey of practices throughout the US. It identifies if states have their own design methodology or if they use AASHTO, the Mechanistic-Empirical Pavement Design Guide, or some other approach. The survey further breaks down if geosynthetics are included in the guidance, what types of geosynthetics, and if they are used for performance or thickness reduction in a road system.
GSI WHITE PAPER 40 ON GEOSYNTHETICS IN PAVEMENT DESIGN
The authors write:
“Regarding the use of geosynthetics in the states’ pavement designs, all but four states use geotextiles or geogrids within or directly beneath the gravel base course. Geotextiles are slightly more commonly used than geogrids. Interestingly, the purpose of the geosynthetic inclusion is almost always improved performance. It is assumed that this comes about by either improved durability or better rideability. Only three states used the inclusion to reduce the thickness of the gravel base course. Lastly, other uses of geosynthetics in the pavement cross section was solicited. These results were as follows:
- Prevention of reflective cracking – eight states
- Separators between the base course and soil subgrade – fourteen states
- Reinforcement of weak soil subgrades – nine states
- Other purposes – eight states
Within this last group, we feel that many states use geotextiles as underdrain filters, however, our survey was not sufficiently explicit in this regard.”
Geosynthetica recommends readers working in transportation engineering download a copy of GSI White Paper 40. The information contained in the paper’s large Table 2 is particularly insightful for current practice.
Learn more about the Geosynthetic Institute’s work, membership, and opportunities at www.geosynthetic-institute.org.
CALLING ALL TRANSPORTATION ENGINEERS! GAP 2019 brings together FHWA, FRA, FAA, USACE – ERDC and YOU to