Sand Stabilization Research Articles

Influence of the physico-chemical properties of root mucilage and model substances on the microstructural stability of sand

Root mucilage (RM), a soil-born biohydrogel, affects the physical stability of the rhizosphere. One reason for this is attributed to the present polysaccharides which contribute to the formation of aggregates by acting as interparticulate glue. The aim of this study was to explore how physico-chemical properties of polymers of interparticulate gels influence this gluing and thus soil microstructural stability. We hypothesized that the microstructural stability of sand increases with the viscosity of the amended biohydrogel, which depends on the content of carbohydrate polymers and non-esterified uronic acids which themselves determine the amount of absorbed calcium. Therefore, natural RM of maize and wheat were compared with higher viscous chia seed mucilage (SM) as a widely used model for RM, and with industrial pectin rich in uronic acids partially methylated. Results show that additionally to Ca binding by uronic acids, binding by proteins is a further possible mechanism of Ca adsorption in RM. Upon Ca addition, the viscosity increased upon intermolecular associations (pectin) and decreased upon suppression of intermolecular charge–charge repulsion (chia SM, maize RM). Amount of high-molecular weight material in the amendment affected strongly soil microstructural stability. Results further suggest the creation of gel micro-zones upon Ca addition, which increase the viscosity of interparticulate gel and sand microstructural stability. Finally, the study outlines several physico-chemical mechanisms through which interactions between biotic (roots and seed) and abiotic components (mineral particles) influence soil structure, which control the water, air and nutrient flow through the rhizosphere and is, thus, an important soil quality parameter.

Life history response of Echinops gmelinii Turcz. to variation in the rainfall pattern in a temperate desert.

BackgroundCurrent and future changes in rainfall amount and frequency may particularly impact annual plants in desert ecosystems. The winter annual Echinops gmelinii Turcz. is widely distributed in the desert habitats of northern China and is a dominant pioneer annual plant following sand stabilization in the Tengger Desert. This species plays a vital role in dune stabilization during spring and early summer, when wind erosion is the most severe and frequent. However, seedling emergence and regeneration in sandy soil are mainly determined by rainfall patterns. Therefore, understanding the life history response of this species to rainfall variation is necessary for understanding the change of population dynamics under the future climate change.MethodsA field simulation rainfall pot experiment using rainout shelter was conducted that included five amounts and five frequencies of rainfall based on historical and predicted values to monitor the life history responses of E. gmelinii in a near-natural habitat.ResultsWe found that rainfall amount and frequency significantly affected seedling survival, growth and reproduction. The plant height, biomass, capitula number, seed number, seed mass and reproductive effort, but not the root/shoot ratio, significantly increased with increasing rainfall. Further, these traits exhibited the greatest response to low-frequency and larger rainfall events, especially the optimal rainfall frequency of 10-day intervals. Offspring seed germination showed increasing trends with decreasing rainfall, suggesting that the maternal effects may have occurred.ConclusionsOur study shows that the plasticity in growth and reproduction of E. gmelinii in response to rainfall variations may help it to gain dominance in the harsh and unpredictable desert environment. Furthermore, population development of this winter annual species should be promoted under the likely future scenarios of large rainfall events and increasing cool-season precipitation in temperate desert.

Investigation of various gram-positive bacteria for MICP in Narmada Sand, India

ABSTRACT In lieu of the conventional carbon-intensive and expensive cement-based ground improvement methods, microbially induced calcite precipitation (MICP) method has gained prominence recently as a sustainable approach to improve the engineering properties of soil. MICP involves calcification by microbial processes, inducing cementation effect in granular soil particles. Several studies have demonstrated the use of Sporosarcina pasteurii bacteria to improve density, stiffness, shear strength, and liquefaction resistance of sand. However, the effects of different bacteria on calcite formation have not been systematically examined in the Indian context. This study investigates MICP in poorly graded, liquefiable Narmada sand, using gram-positive bacteria (i.e. Sporosarcina pasteurii, Bacillus subtilis, and Bacillus sphaericus). Several controlled microbial and cementation media concentrations were tested in sand-filled tubes. Calcite precipitation was analyzed using SEM, FTIR, XRD, and calcimeter. Bacillus subtilis and Bacillus sphaericus resulted in calcite precipitation comparable to that of Sporosarcina pasteurii and can be utilized for sand stabilization.

Stabilization of silty sand using bentonite‑magnesium-alkalinization: Mechanical, physicochemical and microstructural characterization

This paper investigates the mechanical, physicochemical, and microstructural characterization of treated silty sand using a novel additive. The additive from a mixture of bentonite, magnesium chloride, and alkaline solution was introduced for stabilization of soil. Atterberg limits, compaction, pH, and unconfined compressive strength (UCS) tests were used to assess the mechanical and physicochemical properties of the stabilized soil. Further investigation results on the optimum designed sample are discussed based on microstructural analysis using X-ray powder diffraction (XRD), field emission scanning electron microscopy (FESEM), Energy Dispersive Spectroscopy (EDS), and Fourier transform infrared spectroscopy (FTIR). Two curing types: unheated and heated at 60 °C for 24 h, were observed at 7, 14, 28 and 60 days in ambient temperature. Overall, it was found that the chemical additive improved the compressive strength of the soil and the heated curing tests showed significant strength improvement. The mechanical and physicochemical results revealed an optimum mix to improve silty sand strength using the addition of 40% bentonite with an alkaline activator (SS/SH) ratio of 0.5, an alkaline activator-to-MgCl2 (L/S) ratio of 0.7, and 3% MgCl2 by dry weight of the soil under heat curing condition at 60 °C for 24 h. The microstructure analysis confirmed the formation of the cementitious products, such as calcium aluminium silicate hydrate (C-(A)-S-H) and magnesium silicate hydrate (M-S-H) in the treated sample.

The Physical and Chemical Properties of Soil Crust in Straw Checkerboards with Different Ages in the Mu Us Sandland, Northern China

Straw checkerboards, as a mechanical sand barrier, are one of the most important engineering measures for sand control and vegetation restoration. In this study, we characterized the physical and chemical properties of soil crust treated with straw checkerboard in the Mu Us Sandland, Northern China, and investigated the mechanism of sand stabilization and revegetation in the arid area. We collected soil crust from 1.0 × 1.0 m straw checkerboards after revegetation intermittently over 10 years, and then measured properties such as soil particle size composition, bulk density, soil nutrients, pH, and other indicators in the laboratory. During the progress of straw checkerboard treatment, the results showed a significant decrease in percentage of soil crusts sand and a corresponding increase in the portion of silt and clay with straw checkerboard treatment years. The age of straw checkerboard treatment was positively correlated with soil nutrients, such as organic matter, total N, total P, total K, available N, available P, and available K. While pH showed a slightly rising trend, electrical conductivity (EC) was negatively correlated with crust life. The number of plant species has significantly changed, herbaceous vegetation succession being replaced by shrubs over 10 years, and vegetation coverage peaked at the sixth year. This study can represent a successful example of restoration in arid desert regions, thereby supplying more theoretical basis for sand fixation and dessert restoration.

Mechanisms of soil moisture availability in vadose zone of a sand dune system: Linking soil physical properties and rainfall patterns

AbstractSand dune systems in the arid region of north‐western China are maintained by sand‐stabilizing vegetation, which provides critical ecosystem services. Limited knowledge of soil moisture recharge in these systems hinders sand stabilization efforts. To increase the understanding of soil moisture response to rainfall, we analysed soil water transport in the desert vadose zone of sand dunes and dune slacks following four natural rainfall events during the growing season of 2017. Rainfall was dominated by small rain events (<5.0 mm), accounting for 58% of total rainfall events. Soil moisture at 5–25 cm depth in dune slacks was significantly higher and more variable to 60 cm depth than in sand dunes. Soil moisture at 5 cm depth was replenished with rainfall amounts of <5 mm in dune slacks, but not in sand dunes. When rainfall amount reached 20 mm, soil moisture in dune slack and in sand dune increased, but was much higher in dune slack than in sand dune at depth of 5 cm; after the rain, soil moisture remained at a relatively high level in dune slack but not in sand dune. This was possible because dune slacks had higher silt contents and root biomass, which played a key role in improving soil water holding capacity or accelerating rainfall infiltration at 0–25 cm depth. Overall, the rainfall‐driven hydrological regime coupled with soil physical factors regulated spatial and temporal variability of soil moisture in a sand dune system.

The impact of Acacia saligna and the loss of mobile dunes on rodent populations: a case study in the Ashdod-Nizzanim sands in Israel

The Mediterranean coastal dune habitat of Israel is diminishing rapidly, mostly due to massive urbanization, changes in habitat characteristics caused by dune stabilization and the presence of Acacia saligna, an invasive species brought to Israel for the purpose of dune stabilization. In this study we document the effect of sand stabilization on the composition of small mammal communities in the Ashdod-Nizzanim sands, Israel. We analyzed differences in species diversity and abundance for species of rodents in four types of habitat: unstable (mobile) sand dune, semi-stabilized dune, inter-dune depression and a plot of the invasive Acacia saligna. Rodent communities were found to undergo gradual changes concurrently with the stabilization of the sands. The mobile dune was the only habitat in which the strict psammophiles Jaculus jaculus and Gerbillus pyramidum were captured in abundance. No species commensal with human were captured neither in the mobile nor in the semi-stabilized dunes. However, in the inter-dune depression there was quite a large representation of Mus musculus, a rodent commensal with humans. The Acacia saligna plot had the lowest number of captures and the lowest rodent biomass calculated, with Mus musculus composing nearly half of the captures. The results of this study demonstrate that stabilization of the sands in Ashdod-Nizzanim area is associated with the disappearance of psammophile rodents and the appearance of species commensal with humans. In order to preserve the habitat for psammophile rodents, measures should be taken to halt the spread of acacia and the continuing stabilization of the sands.

Microbial Induced Carbonate Precipitation Using a Native Inland Bacterium for Beach Sand Stabilization in Nearshore Areas

Microbial Induced Carbonate Precipitation (MICP) via urea hydrolysis is an emerging sustainable technology that provides solutions for numerous environmental and engineering problems in a vast range of disciplines. Attention has now been given to the implementation of this technique to reinforce loose sand bodies in-situ in nearshore areas and improve their resistance against erosion from wave action without interfering with its hydraulics. A current study has focused on isolating a local ureolytic bacterium and assessed its feasibility for MICP as a preliminary step towards stabilizing loose beach sand in Sri Lanka. The results indicated that a strain belonging to Sporosarcina sp. isolated from inland soil demonstrated a satisfactory level of enzymatic activity at 25 °C and moderately alkaline conditions, making it a suitable candidate for target application. Elementary scale sand solidification test results showed that treated sand achieved an approximate strength of 15 MPa as determined by needle penetration device after a period of 14 days under optimum conditions. Further, Scanning Electron Microscopy (SEM) imagery revealed that variables such as grain size distribution, bacteria population, reactant concentrations and presence of other cations like Mg2+ has serious implications on the size and morphology of precipitated crystals and thus the homogeneity of the strength improvement.

Population dynamics of Echinops gmelinii Turcz. at different successional stages of biological soil crusts in a temperate desert in China.

The effects of biological soil crusts (BSC) on vascular plant growth can be positive, neutral or negative, and little information is available on the impacts of different BSC successional stages on vascular plant population dynamics. We analysed seedling emergence, survival, plant growth and reproduction in response to different BSC successional stages (i.e. habitats: bare soil, cyanobacteria, lichen and moss crusts) in natural populations of Echinops gmelinii Turcz. in the Tengger Desert of northwest China. The winter annual E. gmelinii is a dominant pioneer herb after sand stabilisation. During the early stages of BSC succession, the studied populations of E. gmelinii were characterised by high density, plant growth and fecundity. As the BSC succession proceeded beyond moss crusts, the fecundity decreased sharply, which limited seedling recruitment. Differences in seedling survival among the successional stages were not evident, indicating that BSC have little effect on survival in arid desert regions. Moreover, E. gmelinii biomass allocation exhibited low plasticity, and only reproductive allocation was sensitive to the various habitats. Our results further suggest that the negative effects of BSC succession on population dynamics are primarily driven by increasing topsoil water-holding capacity and decreasing rain water infiltration into deeper soil. We conclude that BSC succession drives population dynamics of E. gmelinii, primarily via its effect on soil moisture. The primary cause for E. gmelinii population decline during the moss-dominated stage of BSC succession is decreased fecundity of individual plants, with declining seed mass possibly reducing the success of seedling establishment.

In vitro synthesis of bio-brick using locally isolated marine ureolytic bacteria, a comparison with natural calcareous rock

Microbially Induced Calcite Precipitation (MICP) using ureolytic bacteria has emerged as a promising technology with several applications in geotechnical engineering. In the current study, bacterial isolates from marine environment (coastal sandstones) have been investigated for their calcification potential. The isolated ureolytic bacterial strains NIOT-1 exhibited high urease activity and identified as Sporsarcina pausterii, were selected for further studies. The laboratory tests revealed that Sporsarcina pausterii NIOT-1 precipitated calcite crystals between the sand particles through the enzymatic hydrolysis of urea, which increased the ammonium concentration to the maximum of 366.54 mM and pH of 8.32. The petrological analysis of the samples indicated that the dominant carbonate phase was calcite. This precipitation of calcite crystals between the sand particles resulted in the physical stabilization of sand leading to the unconfined compressive strength to 3950 kpa. The strength of the laboratory made calcareous sandstone was comparatively higher when compared with the naturally formed calcareous sand rocks (3100 kpa (Uvari) and 1000 kpa (Pudumadam)) along the coasts, but the naturally formed ferrugineous sandstone belongs to Vepalodai was higher compared to all (30500 kpa). This has been envisaged by adopting MICP techniques in preventing the beach sand movement to protect eroding shoreline and to protect coastal populace at critical pockets of the coast as a nonconventional coastal protection measure.

Stabilisation of crustal sand layer using biocementation technique for wind erosion control

Abstract This paper examines biocementation via the microbial-induced carbonate precipitation (MICP) process as an appropriate and promising new technology for stabilisation of loose sand and silty sand deposits as a method to mitigate wind erosion. The technique involves spray treating the sand surface layer with a mixture of cementation and bacterial-cell solutions, the ensuing reactions causing calcite precipitation to occur between the sand grains, thereby lightly cementing them together over time. The bench-scale experimental programme presented investigates the proposed technique’s effectiveness for stabilisation of silica and carbonate sands with different gradations, determination of the optimal reagent concentrations, the time-dependent shear strength development for the crustal sand layer following single- and double-MICP spray treatments, as well as wind tunnel experiments. Of particular novelty were investigations of the effect of dew formation on crustal shear strength development with curing period and the efficiency of the MICP treatment for the outdoor environment compared to laboratory-controlled test conditions. The wind tunnel experiments demonstrated that 28-day cured singly MICP-spray-treated crustal sand layers were stable to simulated 20 m·s −1 winds measured at 20 cm above the layer surface.

Dynamic Characterization of Sand Stabilized with Cement and RHA and Reinforced with Polypropylene Fiber

AbstractThis paper introduces rice husk ash (RHA) as an acceptable replacement for cement in the chemical stabilization of sand, with economic and environmental benefits. Unconfined compression str...

New sand stabilization index of sand encroachment around green belts in Gourara, southwest of Algeria

In the Saharan regions of Algeria, the phenomenon of sand encroachment is the main cause of the degradation of the physical environment as well as the biological resources. It represents an impediment against all forms of socio-economic activities. In the past, fighting sand encroachment in the region of Gourara (southwest of Algeria) was carried out through ancestral processes like fences and small clay walls. Since 2007, this region has witnessed the plantation of several green belts, planted by the forest services as a part of the biological fight against this phenomenon. The present study evaluates the effectiveness of these green belts in the fight against sand encroachment by the application of a new index of sand stabilization (ISS). The calculation of this index is performed with two factors: the rate of recovery and the height of sand accumulations stabilized inside the green belts. In addition, the status of this index was determined by two parameters: the calculated index value and the field of observation. Thus, a positive validation of effectiveness of this index has been found after its application on different cases of green belts. The multivariate analysis (PCA) of 60 sand encroachment surveys on the three studied green belts (BVO, BVD, BVG) enabled to distinguish three groups of surveys, according to both the values recovery rate and the height of sand accumulations. This new index has allowed to represent the sand stabilization situation of each green belt. Thus, three situations were found: weak, average, and strong stabilization.

Stabilization of aeolian sand with combined use of geofiber and synthetic fluid

Aeolian sand is very common in arid and semi-arid regions. Without proper improvement, this soil lacks desirable engineering characteristics for use for pavement base courses, subbase courses, subg...

К синтаксономии псаммофитной растительности памятника природы «Дьяковский лес» (Саратовская область)

К синтаксономии псаммофитной растительности памятника природы «Дьяковский лес» (Саратовская область)

LIVING SHORELINE DESIGN USING NUMERICAL AND PHYSICAL MODELS TO CREATE A PUBLIC PARK IN EUCLID, OHIO

The shoreline of Euclid, Ohio consists of silty-clay cliffs that are naturally eroding into Lake Erie, supplying sediments to the littoral system. Updrift stabilization and entrapment of sands along the shoreline have led to accelerated deterioration of Euclid’s cliffs along a thousand meter stretch of lakefront. Due to the cliffs’ unstable nature and privately held ownership, long stretches of shoreline are inaccessible and only a few property-owning residents have visual access to the lake. Through state funding and creative negotiations, the City of Euclid and SmithGroupJJR were given permission to create a recreational waterfront park using both hard and soft engineering techniques designed to dynamically adapt to the forces of Lake Erie and not impede natural littoral transport. A series of numerical and physical modeling studies were undertaken to optimize a natural design that will remain stable throughout extreme events. This design married revetments, headland habitat beaches, offshore breakwaters, vertical structures, submerged structures, tee-groin breakwaters, recreational sand beaches, and natural plant stabilization techniques to achieve a stable, resilient waterfront park that can be enjoyed by the public.

Effects of different segments in polyurethane on the performance of sand stabilization

ABSTRACTSynthetic polymers have recently drawn increasing attention to chemical sand stabilization (CSS). The relationship between the molecular structure and the fixing effect, however, is rarely reported aside from the performance. In this article, different segments of waterborne polyurethane dispersions (PUDs) are discussed with respect to their influence on stabilizing sand. We prepared five PUDs by controlling parameters including the diisocyanate‐to‐polyol ratio (R) and the molecular weight and characterized them with Fourier transform infrared spectroscopy and laser particle analysis. The unconfined compressive strength (UCS), a key criterion in CSS, was used to evaluate the performance of the PUDs. We found that a biggerRgave the polyurethane (PU) film a higher strength than the smallerRbut did not do the same to the sand mold. This indicated that homogeneity was a primary property of the sand mold. Taking the details of the crushed sand molds and the PU films into account, we concluded that the soft segments played a major role in the homogeneity. Force analysis showed that four modes of breaking occurred at the interface of the sand and cured PU. We concluded that whereas the hard segments in PU determined the ceiling of the UCS, the soft segments determined the floor by benefiting adsorption. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci.2019,136, 47267.

Strength and Deformation Characteristics of Silty Sand improved by Gravel

Silty sand is a poor filler of highway and railway subgrade, and various physical and chemical improving methods have been applied to increase the strength and stability of silty sand. Adding gravel to silty sand is a routine physical improving method. In this paper, large-scale triaxial tests were carried out on silty sand and improved soil which is obtained by adding 4 different proportions of gravel into the silty sand in order to analyze the strength and deformation characteristics of the improved soil. The stress-strain relations obtained from tiaxial tests were analyzed and the effect of coarse particles and fine particles on the strength and deformation of the specimen were also analyzed. The test results show that with more coarse particles and under a higher confining pressure, a greater deviator stress is required to produce the same axial strain. The increase of coarse particles helps to enlarge the angle of internal friction and cohesion, while the increase of fine particles decreases the angle of internal friction and cohesion. Under low confining pressure, the soil specimens with more coarse particles exhibit evident shear dilation. Under high confining pressure, the soil specimens produce a greater volume strain. Adding appropriate amount of gravel into the silt soil can increase its strength and restrain its deformation, but excessive amount of gravel may produce too much volume deformation.

Inner relationship between the damping property and the sand‐fixing durability of polymer materials

ABSTRACTThis article for the first time reveals the impact of the damping property of materials on its sand‐fixing durability. Based on the turbulence of wind, it could be regarded as a kind of periodic mechanical force. So, when polymers are used to fix sand, they would constantly perceive a periodic force of wind. And, this force would give rise to yielding fracture and fatigue of polymer, so that the sand‐fixing durability of material could be weakened significantly. To impair the periodic force of wind and extend the durability of sand‐fixation polymer materials, we, for the first time, introduce the designing principle of macromolecular damping material, that can transform external mechanical force into own thermal energy, into the preparation of sand‐fixing materials. In this work, poly(vinyl acetate) (PVAc) emulsions with different dangling chain have been synthesized successfully in order to improve their damping properties. The effects of the prepared PVAc with gradually growing dangling chain length have been investigated on their damping properties, on the sand stabilization strengths and sand‐fixing durability. And the relationship between the damping property and the sand‐fixing property of PVAc was built by simulating wind tunnel test. The experimental results show that, introducing the dangling chain could significantly improve the damping temperature range and extend the anti‐wind erosion time of PVAc. It has to be noticed that, introducing the dangling chain, will provide a double effects for the sand stabilization strength of materials, i.e., it can improve both the flexibility of the side‐chain and the internal friction of the molecular chains. Wind tunnel test verified that introducing the dangling chain can raise the damping performance of material and convert more periodic force of wind into the friction heat of molecular chain, and thus impair the damage of wind on the materials and improve their anti‐wind erosion properties. These findings suggest that the damping material applied in sand fixation is a bright idea and successful method for improving the sand‐fixing durability. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019, 136, 47208.

Microbial Sand Stabilization Using Corn Steep Liquor Culture Media and Industrial Calcium Reagents in Cementation Solutions

Abstract In this research, the potential of using the microbial-induced carbonate precipitation method was considered for the stabilization of sand using corn steep liquor, the byproduct of Glucosa...