In this study, we have introduced a biological dust control technique utilizing a naturally occurring soil microorganism, Sporosarcina pasteurii, which is capable of inducing calcium carbonate precipitation in the environment. To evaluate the dust suppressive potential of this microbial calcite, S. pasteurii was suspended in medium and applied to locally available sand. The treated soil samples were tested via a wind tunnel at intervals and mass losses were measured. In order to identify the optimum conditions of microbial dust suppression, we examined the effects of: a) the concentration of S. pasteurii, b) the temperature and humidity, and c) the soil preparation method (washed or unwashed). Both types of the soil samples treated with S. pasteurii formed a crust-like layer on the surface and showed a significant reduction in mass loss. Our study demonstrated the potential of this microbiallymediated process as an effective, environmentally friendly means of airborne fugitive dust control.

Microbiologically-Induced Soil Stabilization: Application of Sporosarcina pasteurii for Fugitive Dust Control

A selected commercially available sulphonated oil (SO) and a polymer were evaluated for use as soil stabilizers in a laboratory-based investigation. Two naturally occurring soils (Mercia mudstone [MM] and Oxford clay [OC]) and limestone quarry fines (LQF) were treated with the SO, a polymer, and a combination of the SO and the polymer for assessment of changes in their engineering properties. Untreated specimens also were tested to serve as a control condition. Stabilizer performance was evaluated based on the provisions of ASTM D4609-08 (2008). The test results indicated that performance was dependent on both the soil type and the stabilizer dosage. Generally, treatment did not lead to substantial changes in index properties or maximum dry density. However, the optimum moisture content for LQF was substantially reduced (17–35 %) together with improvements in both dry strength (unconfined compressive strength [UCS]: 38 % for MM, 26 % for OC, >500 % for LQF; static flexural strength [SFS]: 60 % for MM and OC, >500 % for LQF) and swell characteristics (20 % for OC, 21–61 % for MM). Applied in the proper context, the stabilizers are suitable for the treatment of soils for low-volume roads.

Soil stabilization using proprietary liquid chemical stabilizers: sulphonated oil and a polymer

Soil improvement using biopolymers has attracted considerable attention in recent years, with the aim to reduce the harmful environmental effects of traditional materials, such as cement. This paper aims to provide a review on the environmental assessment of using biopolymers as binders in soil improvement, biopolymer-treated soil characteristics, as well as the most important factors affecting the behavior of the treated soil. In more detail, environmental benefits and concerns about the use of biopolymers in soil improvement as well as biopolymer–soil interaction are discussed. Various geotechnical properties are evaluated and compared, including the unconfined compressive strength, shear strength, erosion resistance, physical properties, and durability of biopolymer-treated soils. The influential factors and soil and environmental conditions affecting various geotechnical characteristics of biopolymer-treated soils are also discussed. These factors include biopolymer concentration in the biopolymer–soil mixture, moisture condition, temperature, and dehydration time. Potential opportunities for biopolymers in geotechnical engineering and the challenges are also presented.

Biopolymers as Green Binders for Soil Improvement in Geotechnical Applications: A Review

[1] Most wind erosion studies that characterize dust emission potential measure particulate matter smaller than 10 mm (PM10) for air quality purposes or atmospheric modeling. Because the PM10 size fraction is only a portion of the total range of fine‐grained particles potentially emitted from desert landforms, we modified the miniature Portable In Situ Wind Erosion Lab (PI‐SWERL) by adding a new instrument to measure total suspended particulate matter (TSP). The modified PI‐SWERL is capable of measuring TSP with diameters <500 mm emitted from highly erodible surfaces at friction velocities up to 1.28 m s −1 . Undisturbed and artificially disturbed surfaces of six common landforms in the Negev Desert of Israel were studied to evaluate the utility of TSP measurements. These landforms include alluvial fans and plains armored by desert pavements, loessial soils with silt‐rich surficial crusts, fluvial loess with biological crusts, and active sand dunes. The landforms differ in character and surface age, thereby exhibiting a wide range of surface covers, soil properties, and soil strengths. Our results indicate that the magnitude of TSP emission is primarily controlled by geomorphic setting and surface characteristics. TSP and PM10 concentrations measured from dust‐rich loessial soils were significantly correlated, and TSP emission was best predicted at all sites using PM10 content and bearing capacity. Our results demonstrate that further research is needed to determine correction factors for friction velocities related to erodible, anisotropic surface roughness elements and that the modified PI‐SWERL is a promising tool to quantify total potential emission flux from desert landforms.

https://agupubs.onlinelibrary.wiley.com/doi/pdf/10.1029/2011JF001965

Total suspended particulate matter emissions at high friction velocities from desert landforms

Over the past 50 years, oil mulching has been a common technique for sand dune stabilization in the southwest of Iran (Khuzestan province). However, concerns over the release of heavy metals from oil mulching have led to the search for alternative mulches that are capable of stabilizing sand dunes without environmental hazards. This study investigates the feasibility of using sugarcane residues for producing environment-friendly mulches. Dunder, Press Mud, and clay soil from the surrounding area near the sand dunes were used to make sugarcane mulches for comparison with the traditional oil mulch. A sand dune was selected as a sample bed for applying the mulch. To select the proper ingredients and treatments, Dunder, Press Mud, and clay soil were mixed with water by a trial-and-error method. The selected batch mix was then used to make the desired mulch and sprayed on a sand dune bed. Shear strength of surface soil (SSS), penetration resistance (PR), soil surface shear resistance (SSR), and erodibility of selected treatments were measured by the shear torvane, hand penetrometer, Zhang’s surface shear device, and the wind tunnel. The treatments were arranged in a factorial experiment within a completely random design with the factors including mulch type (seven sugarcane mulches and one traditional oil mulch), thickness (1 or 2 layers), and rainfall (rain and no rain). The results indicate that SSS and PR increased with mulch thickness; the average values of SSS and PR obtained with the two-layer treatments were 1.27‒1.33 and 1.13‒1.15 times as great as the single-layer treatments. Increasing fraction of sugarcane residues significantly increased the SSS and PR. Higher concentrations of organic matter, CaCO3, and electrolyte in the sugarcane mulches may have helped the bonding of soil particles and increased the SSS and PR. However, the oil mulch had the lowest SSS but the highest PR. This might be due to the lower viscosity of oil mulch that allows it to penetrate sand dunes more easily than sugarcane mulches do.

http://iar.shirazu.ac.ir/pdf_3446_153fe91a865c9105a02027fea61a2f43.html

The influence of sugarcane mulch on sand dune stabilization in Khuzestan, the southwest of Iran

Laboratory evaluations were performed on several commercially available polymer emulsions to provide comparisons of these materials for stabilization of silty sand. Portland cement stabilized specimens were prepared and tested to provide a conventional stabilizer control. Results indicate that some polymer emulsions achieve compressive and retained wet strengths on the same order as the cement stabilized soils at lower additive levels. Toughness values reveal that some soil polymers exhibit significantly higher values for both the wet and dry testing condition than soil cements, indicating significantly higher strains were attained at yield (defined as the point of maximum applied stress. No significant differences in the retained wet strength and toughness were found between the polymers and cement soil additives. Cure time behavior of several soil polymers indicates that these systems may not have reached ultimate physical properties after 28 day cure times.

Stabilization of Silty Sand Using Polymer Emulsions

An evaluation of commercial and experimental dust palliatives was conducted to determine their effectiveness for mitigating fugitive dust on roads in arid climates. Several types of chemicals were tested including polymer emulsions, lignosulfonates, chloride salts, synthetic fluids, an asphalt emulsion, a polysaccharide solution, a polyacrylamide, and a guar gum. Each product was placed in an individual test section at a rate of 3.8 L∕ m2 using an admix construction method (grade/spray/till/compact/spray). Fourteen test sections were constructed and observed at 30-day intervals to monitor product performance. Data from both stationary and mobile particle collectors were analyzed to determine the ability of each product to suppress dust for extended periods. Several products are recommended for use on roads in arid climates as a result of this evaluation.

Tim McCaffrey

Papers

Stabilization of Silty Sand Using Polymer Emulsions

Evaluation of dust palliatives for unpaved roads in arid climates