The Concrete Masonry and Hardscapes Association (CMHA) is conducting research to update the Mechanistic Empirical (M-E) design methodology for interlocking concrete pavements (ICPs).

The M-E design method utilizes engineering analysis, laboratory testing, computer modeling and actual material properties to predict pavement performance under specific traffic loads, soil conditions, weather conditions, climates and material combinations prior to construction, according to a CMHA press release. Meanwhile, more traditional pavement design methods heavily rely on formulas based on historical road tests.

The new M-E methodology under development will support engineers in better evaluating alternative pavement structures, the use of recycled materials and how pavements will perform under unique project conditions using state-of-practice engineering tools.  With this more flexible design process, engineers can more accurately optimize pavement systems, evaluate innovative materials and confidently specify ICPs for a wide range of commercial, municipal and transportation projects, the press release states.

Through its research, CMHA confirmed that the paver and bedding layers function as one “highly coherent structural system” rather than as independent layers. This knowledge improves the accuracy of pavement design models and provides engineers with a deeper understanding of how complete pavement systems will perform under load.

For the past three decades, the design of ICPs has relied on the AASHTO-93 flexible pavement design method, which is incorporated into ASCE 58-16. While the method has proved to deliver durable, high-performing pavements, the developing methodology will support a better understanding of a wider range of pavement structures.

“We’re not replacing a design method that works,” said Robert Bowers, P. Eng., vice president of engineering, hardscapes for CMHA. “We’re building on decades of successful performance with modern engineering tools that give designers more flexibility, encourage innovation and increase confidence in specifying interlocking concrete pavements.”

The next step for the research initiative will be to achieve full-scale validation using a heavy-vehicle simulator to test the performance of six different pavement structures under millions of simulated truckloads, according to the press release. The pavement structures will represent a variety of material combinations, including recycled concrete, concrete base, different aggregates and varying aggregate configurations.

Once completed, the research will inform updates to ASCE 58-16, revised CMHA technical guidance, updated design tables and future digital design tools. The final recommendations are expected in 2028.

The research project is industry-funded and expected to cost $1 million.

Source: CMHA