Mixed Sand Research Articles

Kinetics of CO2 hydrate formation in clayey sand sediments: Implications for CO2 sequestration

Hydrate-based CO2 sequestration beneath oceanic sediments is an emerging technique that involves the injection of CO2 into the hydrate stability zone (HSZ) beneath the seabed, forming hydrate cap that structurally traps the injected CO2 and reduces the risk of leaking CO2 from the storage sediment. Gas hydrates are adequately stable in sand sediments saturated with fresh water; however, the salinity of oceanic water impairs hydrate formation kinetics, stability, and CO2 storage capacity. In addition to sandstones, marine sediments are composed of many clay minerals that could affect hydrate formation. Therefore, this study experimentally simulates CO2 injection into sand and clayey sand sediments to assess the potential of CO2 hydrate formation. CO2 hydrates are formed inside a high-pressure reactor, which contains unconsolidated sediment bed/pack (silica sand; mixed sand with bentonite clay: 5 wt% and 10 wt%), saturated with de-ionized water or brine (3.3 wt% NaCl). Hydrate formation experiments were performed at 4 MPa pressure and 274.15 K temperature. Results show that CO2 hydrate formed within the sand sediment, with induction times of 6 and 8.5 h, for the de-ionized and brine systems, respectively. CO2 gas mole uptake in the de-ionized system was 71.54 mmol/mol however, in the brine system the gas uptake was 56.95 mmol/mol. Hence this 20.4% reduction in the gas uptake indicated the inhibition effect of salinity. In contrast, in the brine-saturated 5 wt% clay-sand sediment, the induction time was 6.5 h, indicating the promoting effect of the nano-sized clay particles. However, the gas uptake in this brine-saturated clay-sand sediment was reduced by 45.51% compared to the brine-saturated sand sediment. Increasing the clay content to 10 wt% prevented CO2 hydrate formation due to porosity reduction. Moreover, de-ionized water in clayey sand sediments prevented hydrate formation due to clay swelling. Finally, CO2 hydrate formation at the end of each experiment was visually confirmed.

Quantitative Assessment of Sand Particulates in Gas-Water Slug Flow Using Deep Learning

Summary The weak collision response excited by micrometer-scale sand particulates is prone to overmixing with strong slug noise, significantly reducing the characterization and monitoring accuracy of sand particulate information in slug flows. Therefore, we developed a quantitative assessment method for sand particulates in slug flow that combines triaxial vibration monitoring and deep learning. First, a migration behavior characterization method of sand particulates is proposed combining nonlinear statistics, multifrequency coherence, and multiscale time frequency. The multifrequency response characteristics corresponding to the multiscale flow behavior of the sand-carrying slug flow were successfully characterized on the 2D time-frequency plane, namely, the mixed sand migration behavior [Intrinsic Mode Function 1 (IMF1)], liquid slug sand carrying (IMF2), forward liquid film and Taylor bubble sand carrying (IMF3), and reflux liquid film sand carrying (IMF4). Furthermore, the influence mechanism of gas superficial velocity (1.5–3.5 m/s), liquid superficial velocity (0.95–2.14 m/s), and sand content (0–20 g) on the triaxial vibration response of slug particulate flow with different migration behaviors is elucidated. Finally, a convolutional neural network (CNN)-gated recurrent unit (GRU)-self-attention mechanism (SATT) model for sand content assessment is developed based on the characterized multiscale migration behavior information and achieves an average recognition accuracy of 95.55% for data sets representing different sand migration behaviors in slug flow. This provides a new method for precisely identifying and monitoring sand production information of multiphase pipe flow.

Mixed superoleophilic/superoleophobic hard granular media for coalescence of oil-in-water-emulsion

To enhance the coalescence separation efficiency of oil/water emulsions, the coalescence mechanism of oil droplets between two media of opposite wettability was investigated. A coalescent-bed comprising a mix of superhydrophobic and superoleophilic quartz sand, along with superhydrophilic and underwater superoleophobic quartz sand, was constructed in a coalescer. Single-factor and response surface experiments were used to study the effects of oleophilic/oleophobic sand mixing ratio, apparent velocity, initial oil concentration, bed thickness, sand particle size on coalescence-separation performance, and to determine the optimal experimental conditions. Employing the extended Derjaguin-Landau-Verwey-Overbeek (XDLVO) theory, the agglomeration mechanism of oil droplets within the mixed particle bed was analyzed based on interfacial energy dynamics. Results indicate that the mixing ratio of the two sands significantly influences coalescence separation performance. An optimal oleophilic/oleophobic sand mixing ratio of 1:1 yielded a mass factor of 0.69 kPa−1, showcasing superior coalescence separation efficiency and an optimal balance of separation efficiency and pressure drop. Under the optimal conditions of apparent velocity of 2.7 m/h, initial oil concentration of 471.9 mg/L, bed thickness of 12.6 cm and mixed sand particle size of 0.5 mm, the oil/water separation efficiency reached 98.08 % ± 0.87 %, with effluent oil droplet size being 2.5 to 3 times larger than at the inlet. Analysis of the oil droplet coalescence mechanism revealed a synergistic effect between the two quartz sands, enhancing oil removal performance. The strong affinity of oil to the superhydrophobic and superoleophilic sand surface increases oil droplet wetting and coalescence efficiency, while the water attraction on the superhydrophilic and underwater superoleophobic sand surface forms a stable water film, improving the flux of the continuous water phase and reducing pressure drop across the bed. This study demonstrates that combining quartz sands of opposite wettability not only overcomes the limitations of single-wettability surfaces in coalescing oil removal but also achieves high efficiency and low energy consumption in oil removal.

Study on mechanical properties and corrosion damage mechanism of mixed sand concrete

In order to address the excessive utilization of river sand resources in Inner Mongolia, an investigation is being conducted on the utilization of wind-blown sand and machine-made sand for the production of mixed sand concrete. A study is conducted to examine the influence of including mixed sand in concrete on its mechanical qualities, working performance, and erosion resistant durability. The findings suggest that when the proportion of wind-blown sand in the mixed sand mixture increases, the compressive strength of the mixed sand concrete exhibits a general pattern of initially increasing and subsequently dropping. At a ratio of 1:1 between wind-blown sand and machine-made sand, there is a maximum point. Nevertheless, the capacity for stretching under tension, resilience, and the strength of the connection all demonstrate a consistent decline. The wind-blown sand content of 50 % in the mixed sand is the critical value. When the wind-blown sand content exceeds 50 %, the tensile deformation capacity, toughness, and bond strength experience a steep decline. Utilizing a combination of different types of sand diminishes the efficiency of concrete. Nevertheless, the efficacy of concrete can be enhanced by modifying the water-cement ratio and the quantity of water-reducing admixtures. It is worth mentioning that although the work performance can be improved, there might be a little reduction in the mechanical qualities of the concrete. The erosion depth in mixed sand concrete has a growth rate that is 0.027 mm/d lower compared to ordinary river sand concrete under erosion conditions. The compressive erosion resistance coefficient and saturated surface dry water absorption rate show significantly reduced damage in mixed sand concrete compared to standard river sand concrete. Moreover, when erosion-freeze-thaw coupling circumstances are present, the structural deterioration of mixed sand concrete is less significant in comparison to ordinary river sand concrete. By using a mixture of sand, the concrete's ability to withstand erosion is improved, resulting in a longer lifespan. This discovery establishes a theoretical foundation for the secure utilization of concrete in aquatic environments in Inner Mongolia.

Growth stimulant influence on biometric indicators of oak seedlings in the Bukovyna Sub-Carpathian region

The use of growth stimulants for the cultivation of oak seedlings in the Bukovyna Sub-Carpathian region allows to accelerate their development and increase their sustainability in an environment where there is no natural forest regeneration. The aim of the study was to evaluate the effect of growth stimulants at different multiplicity of treatments during the growing season on the biometric parameters of Quercus robur L. Seedlings were grown in Ecotherm containers in the glasshouse of the base nursery. The composition of the substrate for filling the containers is a mix of peat, sand and black soil in equal proportions with mycorrhiza from under the forest canopy of oak stands. The results of the effect of growth stimulants on the biometric parameters of one-year-old seedlings of common oak with a closed root system are presented. Plant growth stimulants were used for spraying and irrigation seedlings during their cultivation. The results of the research indicate a positive effect of the use of growth stimulants on the seedlings of common oak. All experimental variants showed a positive effect on the biometric parameters of one-year-old oak seedlings at three, six and nine times of feeding with growth stimulants during the growing season. The difference in the variants with the use of plant growth stimulants compared to the control in height is up to 27%, in the length of the root system – up to 43%, and in the total length – up to 29%, accordingly, depending on the dose of the stimulants and the frequency of treatment during the growing season. Refined data on the biometric parameters of one-year-old seedlings of common oak with a closed root system grown in closed ground conditions were obtained. The data obtained are useful for forest restoration in regions with damaged or degraded ecosystems where natural regeneration is limited

Effect of rubber particles on mechanical properties of calcareous sand under large displacement shear

To reveal the influence of rubber particles on the mechanical properties of calcareous sand under the large-displacement shear effects of earthquakes and waves, indoor ring shear tests were conducted on rubber particle-calcium sand mixtures. The effects of rubber particle size and content on the mechanical properties of calcareous sand were studied via indoor ring shear test. Then, based on PFC3D, a numerical model of a ring shear test that can restore the shape of calcareous sand particles is established, and a mesomechanical analysis of mixed sand is carried out. The results showed that the effect of the rubber particle content on the crushing characteristics and strength of calcareous sand was significant and that the effect of the particle size was small. The rubber content causes a gradual decrease in the peak strength and particle crushing rate and increases the deformation stability of the mixed sand. The softening coefficient and relative crushing rate were significantly reduced to 0.01–0.06 and 0.28–1.2%, respectively, at 40% rubber content. The numerical simulations and experimental results were in good agreement. An increase in the rubber content significantly influences chain development, which explains the macroscopic mechanical properties of mixed sand at the fine level.

Stay on trails: Detrimental effects of recreational activities on soil compaction and infiltration

Bromo Tengger Semeru National Park (BTS-NP) in East Java, Indonesia showcases a breathtaking volcanic landscape and cultural allure, drawing hundreds of thousands of domestic and international visitors. Recreational activities involving human and animal trampling and motorized-vehicle traffic caused soil disturbance along their networks of paths, trails, or roads, potentially having a detrimental long-term effect on the tourism industry and environmental services provided by the national parks. However, the extent of the impact of these disturbances on soil properties remains unclear. This study assessed the impact of different disturbance intensities, consisting of undisturbed locations as a control (zone 1), low to medium- (zone 2), and high- (zone 3) disturbance intensities on five different BTS-NP tourism hotspots, including Entrance Wonokitri (EW), Whispering Sand (WS), Parking Temple (PT), Teletubbies Hill (TH), and Entrance Bromo Stairs (EB), on soil properties, including soil compaction represented by soil penetration resistance, and soil infiltration. This study revealed that the higher severity impact of recreational activities on soil compaction was parallel with higher disturbance intensity, particularly in EW and TH. In these particular locations, higher soil compaction is significantly linked to lower soil infiltration, thus needing extra attention and protection. Meanwhile, in WS, PT, and EB, soil infiltration was more controlled by the establishment of a cemented topsoil layer consisting of mixed sand, sulfur, and water. Better management strategies, such as the use of proper trails and road infrastructures, particularly on EW and TH, might be relevant to minimize the impact of recreational activities on these ecologically, economically, and culturally important areas.

Effect of gravel pack permeability on horizontal well productivity loss under secondary methane hydrate formation: Experimental optimization of 3D randomly distributed mixed sand pack

Horizontal well productivity is limited by secondary hydrate formation (temperature drop results from endothermic of hydrate dissociation) during production. Seepage capacity as one of the key indexes for evaluating production efficiency, and efficiency is declined by sand production. Sand control is achieved by using gravel pack technology (selected sands for hindering the sediments particles migration), which extends the production time. However, forecasting the productivity decline trend from quantifying the permeability of the gravel pack after secondary formation remain challenges. To address these issues, a randomly distributed 3D normalized permeability (Kr) model was developed to describe the seepage capacity of gravel pack composed by various particle sizes of mixed glass beads. The theoretical modelling was established by observing micro spatial structure of glass beads with hydrate formation. The new model considered three consolidation modes of hydrate in pores (cementing + bearing, pore filling, and grain coating) and linked them with the productivity ratio equation of a horizontal gas well. To confirm the viability of the model, a series of permeability measurement experiments with various size ratios (α) from 1 to 10 were conducted. Finally, errors comparison and all parameters of the model were analyzed. The results showed that the productivity ratio declined clearly after saturation is >0.79, when α = 4. For long-term production, α = 10 would be better. The new model can help hydrate horizontal wells increase production from laboratory to industrial exploitation. KeyPoints•Secondary hydrate formation permeability model in gravel pack was established.•After secondary saturation's effect on horizontal well production was developed.•Gravel pack was simulated by random non-coincident particles with varies size ratios.•When the size ratio is 4, productivity ratio of horizontal well was extended.

Experimental study and prediction of the long-term strength development of high-flowability concrete made of mixed sand and high-content fly ash

To comprehensively utilize the abundant solid wastes of superfine river sand and fly ash, a mixed sand of superfine river sand with coarse manufactured sand and high-flowability concrete made of mixed sand and high-content fly ash were developed. To address the critical question about the long-term strength of this new concrete, this paper presents an experimental study on the long-term development of cubic compressive and tensile strengths of the concrete over a curing age from 7 days to 360 days. In the study, the mixed sand was a hybrid of 40 % superfine river sand and 60 % coarse manufactured sand, and the fly ash content varied from 30 % to 75 % of the total binders by weight. The law of strength development of concrete with fly ash content was analyzed, combined with explanations of the mechanism and observations of hydration exotherms and microstructures of the concrete. Equations were proposed for predicting the long-term development of cubic compressive and tensile strengths, incorporating coefficients to reflect the effects of fly ash on the binder’s compressive strength and the development tendency of concrete strength. The validity of the proposed prediction equations was verified against the test results and compared with the extended application of the equation specified in CEB-FIP MC 2010.

Suppressing interfacial reactions and burn-on defects in sand casted 13Cr9Mo1VNb steel castings. Part I: a novel MgO-chromite hybrid material

Addressing the significant issues of sand burn-on defects and interfacial reaction in sand casted 13Cr9Mo1VNb steel castings, which notably compromise the quality of the steel castings, remains a persistent challenge. The interfacial behaviors between the novel mixed sands and the steel grade were investigated under various sands. The sintering behavior of the sands was also studied without liquid steel at various holding time. In the absence of the influence of molten steel, sintering of mixed chromite-MgO does not undergo solid-solid reaction, with no detected presence of liquid phase and 2MgO·SiO2. The mixed sands undergo sintering reactions upon contact with molten steel, yet no liquid phase is detected. This is primarily attributed to the chemical reaction between MgO and the liquid phase, resulting in the formation of forsterite, leading to the near-complete liquid phase consumption. Magnesia grains can suppress the liquid phase sintering of chromite by 13Cr9Mo1VNb, thus weakening its sintering performance. The presence of 2MgO·SiO2, which exhibits excellent resistance to slag (liquid phase) and steel liquid corrosion, impedes the rising of the liquid phase. Consequently, this reduces the thickness of the adhesive layer and suppresses metal penetration. The production of 2MgO·SiO2 diminishes with the escalation of MgO addition, which increases adhesive thickness and metal penetration as the magnesia content rises. Within the scope of this study, the incorporation of 20 % MgO is suggested to mitigate burn-on defects, which may represent an advantageous selection.

First report of Phytophthora niederhauserii causing root rot of carob tree (Ceratonia siliqua L.) in Spain.

Carob tree (Ceratonia siliqua L.) is a crop native to the Mediterranean Basin mainly being used as livestock feed, in pharmaceutical industry, and also a valuable source of human food due to the high dietary fibre and sugar contents. In January 2023, one-year-old 'Duraio' carob trees grafted on 'Rojal' rootstock on pots showing dark brown to necrotic lesions on the secondary roots, decline symptoms and leading to the death of some plants, were detected in a nursery located at the Valencian Community region in Spain. Disease severity was 40 to 50% of root area and disease incidence was approximately 50% on approximately 1000 plants. Six representative plants were randomly collected. Roots were washed under running tap water to rinse the soil away, and small symptomatic pieces were cut, disinfected with 70% ethanol, and then dried on absorbent paper. Two-mm-long segments were plated on CMA-PARBPH, a Phytophthora-selective medium, and incubated at 25ºC. After 2-3 days, growing colonies were transferred to potato dextrose agar (PDA) medium. A Phytophthora-like organism was consistently isolated (50% of root segments, n= 120). Colonies were whitish with irregular margins, had coenocityc mycelium, irregularly branched hyphal swellings, and chlamydospores were absent. Sporangia were non-papillate, persistent, ellipsoid and measuring 25 to 40 × 50 to 90 μm (average: 35.5 × 74.7 μm, n = 50). They proliferated internally with both nested and extended proliferation. These morphological features were similar to those of Phytophthora niederhauserii (Abad et al., 2014). Internal transcribed spacer (ITS) and cytochrome c oxidase I (COX1) regions of a representative isolate CF3 were sequenced to confirm the identity. Both sequences were deposited in GenBank under accession numbers OR763816 for ITS and OR783697 for COX1. OR763816 showed 99.87% sequence identity to P. niederhauserii strain Ex-type MG865552 and OR783697 showed 99.85% sequence identity to P. niederhauserii strain Ex-type MH136944 (Abad et al., 2023). Pathogenicity test was performed on one-year-old carob tree seedlings (Duraio/Rojal) grown in 13 cm-diameter pots to fulfill Koch's postulates. The inoculum was prepared in 1 L glass flasks with a mixture of 200 ml vermiculite, 20 ml oat grains, and 175 ml of V8 broth (20% V8 juice and 0.2% of CaCO3 in demineralized water) (Jung et al., 1996). Glass flasks with vermiculite/oat/V8 mixture were autoclaved three times for 20 min at 120 ºC. These mixtures were inoculated with the isolate CF3 which was previously grown on V8 agar medium and incubated for six weeks in the dark at room temperature (Pérez-Sierra et al., 2013). For inoculation, twenty-gram inoculum were mixed with 200 g autoclaved potting mix (peat, vermiculite and sand; 1:1:1, v/v/v), and added to the pots to plant the seedlings. Seven plants were inoculated and non-infested vermiculite/oat/V8 mixture was used to prepare seven control plants. Two months after inoculation one of the inoculated plants died. Six months after inoculation, only the inoculated plants showed decline symptoms with dry leaves and root necrosis. Isolates resembling P. niederhauserii were recovered by plating the roots from all inoculated plants on CMA-PARBPH, and the identity of the isolates was confirmed as P. niederhauserii based on ITS and COX1 sequencing. To our knowledge, this is the first report of P. niederhauserii causing root rot on carob tree. The detection of this pathogen in nurseries is relevant because its dissemination to orchards could have a negative impact in carob crop production.

Evaluation of Growth, Yield and Bioactive Compounds of Ethiopian Kale (Brassica carinata A. Braun) Microgreens under Different LED Light Spectra and Substrates

Microgreens are innovative vegetable products whose production and consumption are gaining popularity globally thanks to their recognized nutraceutical properties. To date, the effects of lighting conditions and growing substrate on the performances of Brassica carinata microgreens (indigenous to Africa) remain underexplored. The present study aimed at providing insights into the influence of different lighting treatments provided by LEDs, namely monochromatic blue (B), red (R), cool white (W) and a combination of three color diodes (B + R + W), and substrates (cocopeat, sand and cocopeat–sand mix (v/v) (1:1)) on the growth, yield and bioactive compounds of B. carinata microgreens. Seeds were germinated in dark chambers and cultivated in growth chambers equipped with LED lighting systems for 14 days under a fixed light intensity of 160 ± 2.5 µmol m−2 s−1 and photoperiod of 12 h d−1. The best performances were associated with the spectrum that combined B + R + W LEDs and with substrate resulting from the cocopeat–sand mix, including the highest yield (19.19 g plant−1), plant height (9.94 cm), leaf area (68.11 mm2) and canopy cover (55.9%). Enhanced carotenoid and flavonoid contents were obtained with B + R + W LEDs, while the B LED increased the total amount of chlorophyll (11,880 mg kg−1). For plants grown under B + R + W LEDs in cocopeat, high nitrate levels were observed. Our results demonstrate that substrate and light environment interact to influence the growth, yield and concentration of bioactive compounds of B. carinata microgreens.

Mechanical and Physiochemical Characteristics of Sandcrete Blocks Produced with Sustainable Biomaterials

The quest for sustainable construction materials is rapidly increasing; due to health hazards associated the traditional construction items. This research goal is to investigate how sugarcane bagasse ash (SBA), crushed periwinkle shells (CPS) and cassava starch (CS) incursion affects the engineering performance of sandcrete blocks, and the physiochemical qualities of their leachate. SBA was incorporated at a rate of 5, 10, 15 and 20% as substitution for cement; treated CPS (TCPS) and untreated CPS (UCPS) were add at a rate of 10, 15, 20 and 25% as partial replacement for sand; while 1% CS was added as integrity enhancer. A consistent cement–sand mix ratio of 1:8 and corresponding water–cement (w/c) ratio of 0.55 were employed across all 17 experimental units; and the blocks were cured using the irrigation technique. Likewise, the blocks were subjected to leaching condition (immersion in water) to collect their leachate. Chemical compositions of the SBA, sand, cement, CS and TCPS and UCPS were examined using the x–ray fluorescent technique, while the mechanical and physiochemical parameters of the blocks were studied in harmony with the American Society for Testing and Materials standards. The results obtained revealed that the mechanical and physiochemical qualities of the blocks were dependent on the volume of the bio–materials incorporated into the sandcrete. Furthermore, the findings showed that an environmentally friendly high–strength lightweight sandcrete blocks, meeting international requirement of 3.45 N/mm2 can be produced by incorporating 10% SBA, 15% TCPS and 1% CS into the sandcrete block. The research highlights the possibility of using agricultural waste materials in achieving sustainable materials for the housing industry.

River-mouth lagoon dynamics on mixed sand and gravel barrier coasts

River-mouth lagoon dynamics on mixed sand and gravel barrier coasts

Study of mechanical and microscopic properties using hybridized waste glass and manufactured sand in cement mortar

The production of waste glass in China was more than 20 million tonnes, but the current recycling rate was only around 30%. How to recycle this glass was a problem that urgently needed to be solved. This study used green glass and TFT-LCD glass to replace manufactured sand in 20%, 40%, 60% and 80%. Different proportions of mixed sand were composed to prepare cement-based specimens to investigate the effect of varying waste glass on the strength and pore structure of the cement-based materials through the mechanical test, porosity and water absorption test, resistivity test, mercury intrusion porosimetry. Finally, the hydration products generated in the interfacial transition zone were observed through scanning electron microscopy (SEM) to explain the mechanism of the action of waste glass on cement-based materials containing manufactured sands. The test results showed that adding the two types of glass sands reduced the flowability of the cement-based materials while adversely affecting the flexural strength of the cement-based materials. The compressive strength reached the optimum at 20% substitution, higher than the compressive strength of river sand and manufactured sand groups. From the SEM observations, the specimen mixed with 20% glass sand generated more types of hydration products than the manufactured sand group at three days and optimized the pore structures. At 28 days, the compressive strength of GG20 specimens was 8% higher than that of the RS group. Therefore, the replacement amount of GG up to 20% had optimum admixture.

The impact of supplementary cementitious materials on the rheological and mechanical properties of mortars based on quarry waste sand

Mineral substances used as additives in cement plants or as additives in the making of concrete contribute through their physical, hydraulic, and pozzolanic activity to improving the behavior of cements in both the fresh and hardened states. Several types of additions are well known, such as natural pozzolans, fly ash, blast furnace slag, and silica fume. These products become more active in the alkaline solutions of cement and give rise to new hydrates that impart greater mechanical strength and better durability to concretes. Through their surface activity and granular distribution, they play a fundamental role in the rheological and mechanical behavior of mortars and concretes. Quarry waste sand (QWS) is generally stockpiled to be eventually sold at very low prices. For this reason, its use in the production of concrete and mortar is increasingly becoming a necessity to protect the environment and meet the needs of the construction and public works sector.This study aims to investigate the effect of using both supplementary cementitious materials (SCM) and quarry waste sand(QWS) to improve some properties of mortar. Ordinary cement is replaced by 10%, 20% and 30% of silica fume (SF), natural pozzolan (NP) or ground blast-furnace slag (GBFS) by weight and the properties of the QWS sand -based mortar are compared to those of natural sand (NS) based mortar. In this study, the slump, superplasticizer requirement, rheological parameters, mechanical strength, and water absorption are investigated. The results obtained show that QWS sand mix has the best workability and requires less superplasticizer dosage. When SCM were used, a drop-in workability is shown and more superplasticizer is required. Also, QWS sand makes the mortar strength 2 and 1.5 times higher than that of NS and becomes 42% higher with 10% SF. Adequate relationships have been established to predict mechanical strengths as a function of test parameters with high correlation coefficient and low root mean square error.

Impact of Biochar on Pathogenic Bacteria and Bermuda Grass (Cynodon dactylon) Growth in Soil Treated with Chicken Manure

Chicken manure plays an important role in soil amendment by improving soil properties for plant growth. However, the high levels of pathogens can have an adverse effect on humans when used for sports turf. This study was conducted to 1) determine the pathogenic bacteria in chicken manure-amended soil, 2) identify the appropriate decomposition stage of manure associated with reduced number of pathogenic bacteria, 3) assess the effect of different rates of biochar on pathogenic bacteria in the amended soil and 4) determine the effect of biochar on the growth of Bermuda grass. The design used for the laboratory experiment was 3˟3 factorial in Completely Randomised Design (CRD) and it was replicated three times. The factors involved were: decomposition stages of chicken manure (3 levels) and the different rates of biochar (3 levels). The best combination of biochar and chicken manure at the percentages of 0, 5, 10, and 15 were then used together with soil and sand mix at a ratio of 100:00 and 70:30 to plant Bermuda grass. This experiment showed that E. coli was present in chicken manure and that increasing the decomposition period had a significant effect on the E. coli by reducing its load. Also, the addition of biochar to the chicken manure resulted in a significant reduction of E. coli count (p<0.01). The soil amended with the biochar and manure also supported very well the growth of Bermuda grass with the 10% and 15% biochar manure mix in 70 to 30 ratio of topsoil and sand giving the best grass growth in terms of spread, thickness, height, and color. A regression analysis given by the equation Y(coverage)=176.857-23.0402(sprouting) (R2=0.99), indicated that sprouting significantly affected grass coverage such that 99% variation in the grass coverage was attributed to the sprouting. At the end of the study, it was concluded that well-composted chicken manure should be used together with biochar on sports fields to help remediate the problem of E. coli infestation and also improve the growth of grass on fields. Furthermore, biochar with chicken manure-amended soil could be ideal for vegetable garden to help reduce foodborne diseases caused by E. coli infestation.

Wettability alteration of quartz sand using Z-type Langmuir–Blodgett hydrophobic films

This paper presents the results of a study of the effect of sand treatment on its filtration and wetting properties by applying Langmuir multimolecular film coatings of fatty acids. It has been established that the coefficient of water filtration through sand treated with a 2% solution of stearic acid in chloroform is reduced by 82%. It is shown that a change in the filtration properties of sand is associated with an alteration in the wettability of sand from water-wet to oil-wet due to the formation of oriented Z-type Langmuir–Blodgett hydrophobic films on the surface of sand grains. The effective permeability of sand for water decreases after the formation of hydrophobic Langmuir–Blodgett Z-type films and waterflooding becomes more effective. Treatment of sand with palmitic and oleic acids, as well as simple mixing of sand with a 2% solution of stearic acid in chloroform, has little effect on the filtration properties of sand. COMSOL multiphysics simulation of filtration process and oil displacement in treated and untreated sand with fatty acid was used.

Creating landscape‐appropriate habitat restoration strategies: success of a novel nesting habitat design for imperiled freshwater turtles

Turtle nesting habitat can be created as a restoration strategy to increase habitat availability or provide suitable habitat away from threats. Traditional nest habitat restoration consists of creating nesting mounds using a mix of sand and gravel. However, nesting mounds do not resemble natural turtle nesting habitat in a rock barren landscape where turtles nest in crevices and cracks in the bedrock. Therefore, our objective was to design and evaluate the success of a landscape‐appropriate design for turtle nesting habitat in a rock barren landscape. To evaluate success of the nest habitat design, we assessed the (1) survival of transplanted moss and lichen cover on created nest sites, (2) ecohydrological and physical conditions at created and natural sites, and (3) turtle egg hatching success at created and natural sites using a split‐clutch experiment. We found no difference in productivity between lichen transplants and natural sites, indicating that intact lichen transplants were successful. Moss transplant success was more variable due to moisture stress because transplants were conducted during dry conditions. In general, created nest habitat tended to have a more stable thermal and moisture regime compared to natural sites. When accounting for maternal effects, the odds of an egg hatching successfully was 6.6 times higher in a created site than a natural site. Overall, the success of our nest habitat design in the first few years suggests that this landscape‐appropriate design will be a useful restoration strategy for increasing turtle nesting habitat in rock barren landscapes.

Study on the Mechanical Properties of Two General-Purpose Cement-Lime Mortars Prepared Based on Air Lime.

It is believed that the use of mortars based on air lime in the construction and renovation of brick buildings has a number of advantages, especially those closely related to the durability and strength of the structure. However, there is still a noticeable difference in the mechanical properties of these materials. This research investigated the mechanical characteristics of a mixed cement-lime mortar with the two most popular proportions of an air lime, cement, and sand mix: 1:1:6 and 1:2:9 (by volume). Mechanical tests were performed on standard and non-standard samples to assess compressive strength, tensile strength, flexural strength, and fracture energy. The obtained results indicate the possibility of using these mixtures in modern masonry construction, as well as in the aspect of sustainable development. Additionally, lime mortar with a higher lime content can be used in non-load-bearing walls and in renovation and repair works.