Recommendations for Stabilization of High-Sulfate Soils in Texas

Abstract

In an effort to construct roads more quickly, high-plasticity index soils stabilized with lime are now routinely compacted the day after mixing. With this practice has come an increasing number of heaves due to soluble sulfates reacting with the lime to form ettringite. Soils with sulfate concentrations below 7,000 to 8,000 parts per million (ppm) can generally be treated with lime. This research was performed to identify stabilizers that can be used with sulfate concentrations above 10,000 ppm. The effectiveness of the stabilizers was determined by the measurement of three-dimensional (3-D) swell reduction and unconfined compressive strength. The researchers evaluated 12 stabilizers, including enzymes, polymers, acids, emulsions, fly ash, and ground granulated blastfurnace slag (GGBFS). Three stabilizers significantly reduced volumetric swell. A polymer and an acid reduced swell by about 8%. GGBFS plus lime reduced swell by 10%. GGBFS plus lime was the only stabilizer that reduced swell, increased strength, and was cost-effective enough for the Texas Department of Transportation to consider as an alternative to lime in high-sulfate soils.

Calcium-based stabiliser treatment of sulfate-bearing soils

“…These challenges include: stabilisation of sulfate soils containing larger amounts of sulfates (more than 8000 ppm); methods to screen sulfates in real field conditions; and development of devices that could provide faster screening and assessments of sulfate heave in treated soils. Recent studies reported by Harris et al (2006) introduced a new field testing methodology to screen and determine soluble sulfates and the method has shown early promise. Other challenges are currently under research evaluation and the research results are expected to be reported in the literature over the coming years.…”

Soil treatment with organic non-traditional additives for the improvement of earthworks

“…As for ES, addition of the product modified the behaviour of the soil during the compaction. Nevertheless, field and laboratory testing confirmed the ability of lignosulfonate to be leached out of the soil [11,22,27]. So, it is to be expected that the soil will recover its initial characteristics after a certain period of time.…”

“…However, Harris et al [11] showed that the 3-D swelling potential of a plastic clay (PI = 51) was not modified by the addition of 0.07% of an ES treatment. Another stabilisation mechanism was suggested by Velasquez et al [32], who observed that an ES could have surfactant properties and thus stabilise the soil by improving its compaction ability.…”

“…Additionally, additives have been tested to stabilise erodible soils [33]. Mechanical properties, such as the unconfined compressive strength [23,28] or the swelling potential of plastic soils [11,19], have also been studied.…”

Investigation of Geogrid-Reinforced Flexible Pavement Performance over Expansive Clay

“…Nelson and Miller (1992) classified the soil having linear shrinkage strain over 15 percent as high risky soil to the infrastructure damage. In accordance with the procedure (Harris, 2008), the 3-dimensional swell test was conducted to gauge swelling potential that would cause the soil volume change due to moisture migration. The result indicates that the subgrade soils of sections "S1" and "S2" are more susceptible to swelling than section "S3" soil.…”