The curing of soil specimens treated with a liquid polymer soil stabilizer of styrene acrylic family was studied through an extensive laboratory testing program. First, the effect of different curing environments including air, water and heating on the unconfined compressive strength (UCS) of stabilized sand was studied to identify suitable curing environments. Furthermore, a parametric study was conducted through which the liquid content of the specimens (i.e., polymer + water) was varied and the overall performance of treated specimens of sand and sulfate-rich high plasticity clay was assessed. The optimally treated specimens (i.e., with the best curing environment and optimal stabilizer dosage) were evaluated for their (1) short-term performance, (2) swelling potentials of treated high plasticity clay, and (3) durability after 24 wet–dry or freeze–thaw cycles. The results suggested that heating can significantly expedite the curing; conversely, soaking the specimens in water showed a detrimental effect in terms of the resultant strength. The strongest specimens were achieved when no extra water in addition to the liquid stabilizer was added when treating the soil. As to clay, the liquid polymer showcased excellent performance in reducing the swelling potential but the strength of the specimens was highly decreased by to moisture and freeze–thaw cycles.

In recent years, alternative soil stabilizers to supplement to cementitious soil stabilizers have been attempted for some applications and provided promising results. This study focuses on the application of a low viscosity liquid polymer for shallow soil improvement. The mixing method of soil specimens treated with the liquid polymer soil stabilizer, which belongs to Styrene Acrylic family, was studied through an experimental testing program. The tested soils included poorly graded sand and sulfate-rich clay. The water, liquid polymer and dry soil were mixed with different sequence to assess the effect on strength. The specimens were cured in controlled environment for up to 35 days before tested. It was found that the curing of the polymer stabilizer in sand and clay were time consuming and took to a month to reach their full strength. The mixing method did not show tangible difference for stabilized sandy specimens and demonstrated significant effect on stabilized clay specimen. Specifically, as to clay, when water was added after the dried soil and polymer were thoroughly, no improvement was observed.

Polymer-infused plant roots can be created without soil excavation by infusing polymer into the roots of plants through the easily accessible above-surface plant stems. Efficacy of this technique for use in soil stabilization applications involves assessing the durability of polymer-infused plant roots. Polymer content was determined for infused Artemisia annua plant roots. Durability of these polymer-infused roots was evaluated by mass loss resistance and strength loss resistance of acid-treated samples. Durability in the context of soil stabilization applications was determined by comparing the shear strength of aged samples. Polymer infusions improved the durability of the plant material. Infused plant stems incubated in acid for 15 weeks lost 29% mass, whereas noninfused stems lost 60% mass. Infused roots incubated in acid for 24 h retained a tensile strength of 25 MPa, whereas noninfused acid-treated roots had a tensile strength of 12 MPa. In comparison to plant roots that provided no enhance...

Concentrations of indicator bacteria, such as E. Coli, fecal coliform, and Enterococci were measured from upstream, underneath, and downstream of a bridge over the Guadalupe River near Kerrville, TX, to evaluate the effect of direct droppings of birds residing under the bridge structures on the bacterial loading in the underneath water. The bacterial loadings in all sampling locations increased as soon as the migratory birds started nesting on the bridge. The concentrations of bacteria in water beneath the bridge were significantly higher than those in upstream water. The concentrations of bacteria in downstream water were slightly higher than those in upstream water and significantly lower than those in water underneath the bridge due to dilution and decay. The probability analysis of the concentration of bacteria in water underneath the bridge showed that the concentrations of E. Coli, fecal coliform, and Enterococci are likely to remain within the Texas Commission on Environmental Quality specified contact recreation limit for 71, 68, and 35 percent of the time, respectively, during the nesting season.