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Mitigation of High Sulfate Soils in Texas

Project Summary

In TxDOT research project 0-6618, two new treatment methods to mitigate high sulfate-induced soil heave were tested on U882 in Paris District. Three test sections consisting of one control and two test sections were constructed on U582 near Bells in Grayson County. The Control Section (Test Section 3) consisted of lime treated soil in normal practice. The other two sections (Test Sections 1 and 2) are lime-fly ash treated and lime treated sections. Both sections were constructed with extended mellowing period of 7 days. It is important to evaluate the effectiveness of different chemical treatments for providing better stabilization of high sulfate soils in actual field conditions as many pavement projects are built on high sulfate soils in various districts.

Current chemical stabilization practices for high sulfate soils have resulted in high maintenance costs due to the increasing roughness and distress that these pavements have experienced. Many districts have to partially or completely rehabilitate these pavements built on high sulfate soils within a few months to three to four years after original construction, in many cases, the repairs will include a complete restoration of the pavement lanes for several miles, which can be translated to losses of entire pavement infrastructure for those miles of pavement. Continuous monitoring and verifying the two test sections currently built as a part of field monitoring task of 0-6618 will provide tangible and practical solutions of stabilizing high sulfate soils. Two of the treatment methods considered in these sections will focus on different mellowing practices and use of a combined lime treatment with fly ash.

If proven effective in the field validation studies, the stabilization solutions could prolong the life of pavements by 30 to 40% built on high sulfate soils with minimal distress and this potentially means significant maintenance dollars savings for each district. Considering a $100 million worth of pavement construction projects built on high sulfate soils, these savings could amount to $100 million or more (100% of original construction costs) as there will be no need for complete rehabilitation of the pavements. Also, safety will be enhanced as roughness coming from heave bumps will be drastically reduced. This will provide smooth riding conditions with minimal pavement roller coaster type bumps and valleys. All these will lead to significant improvements to pavement infrastructure assets currently serviced by TxDOT.

Project Number

5-6618-01

Status

Completed

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