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From the Perspectives of the Heavy Highway Contractor and the Transportation Research Engineer
April 2022

So much of the attention on the subject of chemical soil stabilization and base course treatment is given to laboratory test data and what the materials engineers have to say on the topic. What is missing from that limited perspective are the observations of the lead civil and geotechnical engineers and project managers from the heavy highway construction firms that have built billions of dollars of domestic and international highway projects in the recent decades. These are the people that have a handle on the actual behavior and performance of the various stabilizer products as highway construction working platforms, on ease of application and productivity rates and on the length of the time delays related to delivery schedules and curing time requirements. And finally – they have a vested interest in tracking how the pavement sections that they constructed above subgrades stabilized with the various stabilizer products maintained their integrity and ride quality (IRI test results) over time. What is also missing from that limited perspective are follow-up studies conducted by independent transportation research organizations documenting pavement smoothness after highway projects constructed above stabilized subgrades have been in service over a decade or longer. Pavement smoothness is the internationally recognized standard for evaluating performance over time. Following are reports that fill in the missing perspectives.

“..pavements placed over EMC SQUARED System
stabilization treatments are performing better than the pavements
placed over conventional stabilizer products.”

— Abel Ortiz

We have a particularly relevant testimonial to share involving some of the most famously problematic soils for construction purposes in the country, along with the feedback from one of the largest heavy highway construction companies regarding their experience in stabilizing these problem soils on three highway projects in Texas. This troubling soil trend runs north-south through Central Texas, through the Dallas–Fort Worth area and the Austin–Round Rock area south to San Antonio and west to the Rio Grande River. In addition to highly expansive clays soils rich in organic and sulfate content, this trend includes the notorious Eagle Ford Shale Group, another group of soils that cement, fly ash and lime, the three conventional calcium-based products, have failed to effectively stabilize, or worse, actually induced heaving and cracking of asphalt and concrete pavements placed above. At one point in time, the Dallas District Office of the Texas Department of Transportation (TxDOT) estimated that, because of this problem, the use of the calcium-based stabilizers was heaving and cracking the pavements and causing $23 million in annual pavement damage in the Dallas District alone. TxDOT funded a two-year study at the Texas Transportation Institute (TTI) that recommended the use of the EMC SQUARED System stabilizer products for effectively treating these problem soils and eliminating the risk of pavement heaving.

Reporting From The Heavy Highway Contractor

Following the release of the TTI report and additional field testing, TxDOT awarded three contracts to Zachry Construction where the EMC SQUARED System stabilizer products were selected and successfully installed by the contractor without any reported problems and extremely positive reviews. Nine years later Mr. Abel Ortiz, a Project Manager for Zachry Construction Corporation in the Dallas-Fort Worth area, conducted a study after years of observing the field performance of these three projects while managing the construction of other major highway projects in the area. He reported that the pavements constructed over the subgrades stabilized with the EMC SQUARED System products were obviously performing better than the pavements constructed over other subgrade options (cement, fly ash and lime). He also provided the names of other lead Zachry staff involved in these projects that he conferred with during this study regarding their experience with the EMC SQUARED System stabilizer products, including their Corporate Quality Control Manager, their Corporate Project Controls Director, a Vice President and Project Manager, and two Dirt Superintendents responsible for EMC SQUARED Stabilizer installations. In summary, he reported “The consensus at Zachry is that when we applied the EMC SQUARED System stabilization treatment at our projects in Dallas, we found that it provided a stable working platform at a reduced cost over conventional stabilization methods and without any significant application challenges. Visiting the projects several years later (twelve years after highway construction) confirmed to me that the pavements placed over EMC SQUARED System stabilization treatments are performing better than the pavements placed over conventional stabilizer products.”

Zachry Construction is not alone among contractors that have seen EMC SQUARED System stabilizers outperform cement, fly ash and lime products at a much lower cost and with improved productivity. For more information on the EMC SQUARED highway projects constructed in the Dallas-Fort Worth area by Zachry Construction and other heavy highway contractors, see https://stabilizationproducts.net/docs/18468.pdf

Reporting From The Transportation Research Engineer

The current national and international field testing standard for evaluating pavement performance is the International Roughness Index, or IRI. The U.S. DOT’s Federal Highway Administration (FHWA) requires all state department of transportation organizations to conduct field testing of their federally funded highway networks on an annual basis and report their IRI results. The Austin area office of transportation research engineering firm Applied Research Associates, Inc. (ARA), was responsible for analyzing and reporting the annual IRI test results for the Dallas area highway projects under the jurisdiction of the Texas Department of Transportation (TxDOT) and the North Texas Tollway Authority (NTTA). ARA was subsequently tasked with summarizing the IRI test results for the pavements constructed above subgrade soils stabilized with the EMC SQUARED System stabilization treatments, and reporting on the condition of the pavements approximately eighteen years after the stabilization and highway construction work was completed. Five of these highway projects were constructed without major drainage problems affecting the performance of the pavement structural sections and evaluated in Synthesis Summary of Projects in Dallas, Texas – Use and Performance of Advanced Soil Stabilization, ARA Report No. 003563-1, as summarized at right. In spite of the famously problematic soil conditions in this area of Texas, the IRI ratings for these sections of highway all remained in the GOOD classification and the average Surface Condition was reported as EXCELLENT. The study was conducted by Harold Von Quintus, P.E., ARA’s Principal Transportation Engineer who has previously served as a Principal and Co-Principal Investigator on various projects sponsored by the FHWA, NCHRP and other transportation agencies as well as being a participant in research studies associated with the implementation of Mechanistic- Empirical (ME) Pavement Design.

 

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