Sand Surface Research Articles

The effect of liquefaction on mineral breakage physical in the Palu City, Central Sulawesi Province, Indonesia

The Central Sulawesi province had a 7.4 magnitude earthquake in 2018, which was followed by liquefaction in Palu City, Donggala Regency, Sigi Regency, and Parigi Moutong Regency. The boulder sediments, sand, silt, and clay make up the liquefaction material. The extent of mineral damage, mineral surface area, porosity, and sand permeability were all evaluated in this study. By digging a 1 x 1 x 2 m trench at 27 sites, a vertical sampling of liquefaction material was done in both liquefaction-affected and unaffected areas. Smear slides for petrographic investigation were created after the separation of grain sizes. Quartz, biotite, orthoclase, hornblende, plagioclase, and opaque minerals were among the minerals found. Mineral area values in the liquefaction area are lower than in the unaffected area. The Petobo liquefaction area has the highest value of mineral damage, followed by Balaroa, while Sibalaya has the lowest value. In the liquefaction area, where quartz and opaque minerals are less damaged than other minerals, the percentage of mineral damage exceeds 40%. A factor in the deterioration in the carrying capacity of residential land is liquefaction, which causes significant mineral damage but little change in the value of the mineral area. It is suggested that the Petobo and Balaroa areas be designated as green spaces and water catchment areas, while the Sibalaya area can be repurposed as a set of regulated and constrained residential communities.

Effects of Different Surface of Plyometric Training on Speed of Junior Volley Ball Players

The purpose of study was to find out the effects of different surface of plyometric training on speed of junior volley ball players. To achieve the purpose of the study, thirty school girls’ from Jai Gopal Garodia Government higher secondary school, Madhavaram, Chennai, Tamilnadu were selected as subjects at random and their age group range between 12 to 14 years. The study was formulated as pre and post test random group design, in which thirty subject were divided into three equal groups. The experimental group-1 (n=10, SS-PT) underwent sand surface plyometric Training. The experimental group-2 (n=10, NS-PT) underwent normal surface plyometric training and group 3 served as control group (n=10, CG) did not undergo any specific training. In this study, two training programme were adopted as independent variable, i.e., sand surface plyometric training, normal surface plyometric training. The speed was chosen as a dependent variable, it was tested by 30 meters run and scores recorded in seconds. The selected two treatment group’s namely sand surface plyometric training and normal surface plyometric training was performed three days in a week for the period of six weeks, as per the stipulated training program. The selected performance parameters were collected before and after the training period. The collected pre and post data was critically analyzed with apt statistical tool of analysis of co-variance, for observed the significant adjusted post-test mean difference of three groups with respect to each parameter. The Scheffe’s post hoc test was used to find out pair-wise comparisons between groups with respect to each parameter. To test the hypothesis 0.05 level of significant was fixed

Rare species of West Indian aspect in the Holocene of Liverpool Bay and their biogeographic and environmental significance

The Gulf Stream, although not directly responsible for the mild, temperate climate of the British Isles, transports vast quantities of water across the North Atlantic Ocean. An extension of the Caribbean-Loop-Florida current system, this strong current cools and becomes more saline by evaporation as it flows NE across the North Atlantic Ocean. Nevertheless, it is able to transport benthic foraminifera across oceanic distances, the fauna around Bermuda containing many species described from the Caribbean Sea. Examining two cores taken from the shallow middle neritic Holocene Surface Sands Formation of the temperate Liverpool Bay, England, we found rare specimens of eight species recorded also from the neritic of the tropical Caribbean and subtropical Atlantic South Shelf Provinces: Asterigerina carinata, Dyocibicides biserialis, Elphidium discoidale, Nonionoides grateloupii, Quinqueloculina lamarckiana, Reussella atlantica and Sahulia conica. We are confident in our identifications of A. carinata and E. discoidale, but suggest that these names may have been applied to several cryptospecies. Some of these may have been transported on floating phytal debris, A. carinata, which supports algal symbionts, having been recorded at abyssal depths in the eastern North Atlantic. Othersmay have been transported as small propagules (proloculi). Although there may be a constant rain of such specimens into Liverpool Bay, we conclude on the basis of their rarity that the exotic species are unlikely to be able to overwinter there. We suggest, however, that these may have potential as invasive species for Liverpool Bay as climates continue to warm. This is not the earliest instance of transport of exotic species across the North Atlantic. The Late Eocene species Asterocyclina soldadoensis has been recorded from both the southern Caribbean region and offshore Ireland.

Insights from in-situ pore pressure monitoring around a wind turbine monopile

Offshore wind turbine monopiles transfer large bending moments into the soil. Due to the large diameter of the foundation, a significant volume of soil is mobilised to absorb the incoming forces from wind, waves and current. If excess pore pressures are generated during load cycles, the long drainage path length could lead to accumulation of pore pressures and loss of strength and stiffness in the soil. During monopile design, undrained behaviour of the soil during cyclic loading is often assumed to conservatively assess the lateral pile resistance during storms. In-situ monitoring of pore pressures in the soil surrounding a monopile foundation allows the assumption of undrained behaviour to be checked for several episodes during the operational life of the foundation. A 3-year period of monitoring data was analysed for a North Sea monopile which included normal operation, storm episodes and rotor stops. Pore pressure and earth pressure sensors were positioned on the pile at two different depths in the most intensely loaded layer of surface sand. The data provides insight into the amount of excess pore pressure accumulation with storm loading not leading to significant accumulation of excess pore pressure. The only episodes showing a significant development of excess pore pressures were rotor stops with suction pressures being developed on the unloaded side of the monopile. The observed response suggests that significant pile-soil stiffness reductions in the top layer due to cyclic loading are not expected for the monitored location. The study shows the value of monitoring pore pressures in the soil mass surrounding offshore foundations for checking design assumptions.

Adsorption modelling and fixed-bed column study on milk processing industry wastewater treatment using chitosan zinc-oxide nano-adsorbent-coated sandfilter bed.

This study aims to develop a chitosan-zinc oxide nano-adsorbent-coated sand (CZOCS) filter bed for getting rid of milk processing industry wastewater (MPIW) in a safe way. Chitosan zinc oxide nano-adsorbent (CZnO) of 88.35 ± 2.89 d.nm size was used to coat naturally available sand through a calcination process at 200°C for a heating rate of 5°C/min. The characteristics of the diffraction peaks and functional groups are attributed to the nature of CZnO loading on the sand surface. The increase in breakthrough and exhaustion times is caused by the biological oxygen demand (BOD) and chemical oxygen demand (COD) of influent having more time to interact with the adsorbent as bed height increases, resulting in higher reduction efficiencies. Lower bed heights (10cm) which saturate faster than higher bed heights (40cm) result in a shorter mass transfer time. Adsorption capacity at the 95% column exhaustion point increased from 611.04 to 1089.63mg/g for BOD and from 4512.29 to 5600.81mg/g for COD. Different kinds of kinetic models have been used to forecast breakthrough curves employing experimental data. Statistical and error function parameters were used to choose the best-fit model. Among the modelsinvestigated, the Thomas model was shown to be the best-fit with the highest R-square values of 0.9942 and 0.9939. The CZOCS has high reusability and could be used for up to six cycles of organic pollutant adsorption. Aside from that, novel CZOCS could be used to clean real MPIW, andmaking it one of the most promising adsorbents.

Genome assembly of the acoel flatworm Symsagittifera roscoffensis, a model for research on body plan evolution and photosymbiosis.

Symsagittifera roscoffensis is a well-known member of the order Acoela that lives in symbiosis with the algae Tetraselmis convolutae during its adult stage. Its natural habitat is the eastern coast of the Atlantic, where at specific locations thousands of individuals can be found, mostly, lying in large pools on the surface of sand at low tide. As a member of the Acoela it has been thought as a proxy for ancestral bilaterian animals; however, its phylogenetic position remains still debated. In order to understand the basic structural characteristics of the acoel genome, we sequenced and assembled the genome of aposymbiotic species S. roscoffensis. The size of this genome was measured to be in the range of 910-940 Mb. Sequencing of the genome was performed using PacBio Hi-Fi technology. Hi-C and RNA-seq data were also generated to scaffold and annotate it. The resulting assembly is 1.1 Gb large (covering 118% of the estimated genome size) and highly continuous, with N50 scaffold size of 1.04 Mb. The repetitive fraction of the genome is 61%, of which 85% (half of the genome) are LTR retrotransposons. Genome-guided transcriptome assembly identified 34,493 genes, of which 29,351 are protein coding (BUSCO score 97.6%), and 30.2% of genes are spliced leader trans-spliced. The completeness of this genome suggests that it can be used extensively to characterize gene families and conduct accurate phylogenomic reconstructions.

Raman imaging towards in-situ visualisation of perchlorate adsorption

Raman imaging can directly visualise perchlorate adsorption, and even enables in-situ monitoring, because water has a low Raman activity and generates almost no interference, which is demonstrated herein. The Raman signal enhancement of perchlorate on the porous silver surface provides a possibility to monitor the adsorption of perchlorate at low level. From this initial adsorption assembly of (i) porous silver-perchlorate, we test several more, including (ii) porous silver-perchlorate-sand, (iii) porous silver-perchlorate-microplastic-sand, (iv) porous silver-perchlorate-microplastic-sand-river water etc. The introduction of microplastic, another emerging contaminant, can provide extra insights into the co-adsorption process. Particularly the composite structure of microplastic-sand can simultaneously visualise the adsorption of perchlorate on the silver surface, the plastic/organic surface and the sand surface. We note that the water can modify the configuration of perchlorate in-situ towards the adsorption on silver surface; the adsorption of perchlorate can benefit from co-adsorption with organic matter, and the rough surface plays an important role as well. Overall, Raman imaging provides an effective approach to directly visualise the adsorption of emerging contaminants.

Effect of substratum types on the growth of assimilators and stolons of <italic>Caulerpa okamurae</italic> (Bryopsidales, Chlorophyta)

To examine the effects of substratum types on the growth of Caulerpa okamurae, sand surface and sand burial experiments were conducted. Five assimilators (erect fronds) per replicate were cultured for 15 d on the surface of three different treatments: fine sand (200 μm), coarse sand (600 μm), and no sand (control). Also, three stolons and three assimilators were buried by fine grain or coarse grain sands and incubated for 15 d. In both experiments, other culture conditions included 25°C, 30 μmol photons m-2 s-1, and 16 : 8 h L : D (light : dark). In both experiments, stolon + assimilator-, assimilator-, and stolon-weights were measured. Relative growth rates (RGRs) of stolon + assimilator weights ranged from 0.43 to 1.95% d-1 at no sand and fine sand treatment, respectively. RGRs for the weight of stolon + assimilator and new assimilators were significantly greater on the fine- and coarse sand surface than the control. In the burial experiments, RGRs of stolons (4.28% d-1 at coarse sand and 5.57% d-1 at fine sand, respectively) were significantly greater than those of assimilators (1.38% d-1 at fine sand and 1.82% d-1 at coarse sand, respectively). When stolons were buried, RGRs for assimilators were greater at the fine sand than at the coarse sand treatment. On the other hand, RGRs of buried assimilators for total frond weights and for newly produced stolons were significantly greater at the coarse sands than at the fine sands. In conclusion, C. okamurae grew well with all substrates of sands and showed better growth on fine sands than coarse ones. This result suggests that the growth of stolons and assimilators of C. okamurae is stimulated after stable attachment to the sand substrates by rhizophores. In addition, stolons showed higher growth rates than the assimilators in the sand burial states, indicating that stolons are more tolerant to low light than assimilators of C. okamurae.

How Weather Affects over Time the Repeatability of Spectral Indices Used for Geological Remote Sensing

Geologic remote sensing studies often targets surface cover that is supposed to be invariant or only changing on a geological timescale. In terms of surface material characteristics, this holds for rocks and minerals, but only to a lesser degree for soils (including alluvium, colluvium, regolith or weathered outcrop) and not for vegetation cover, for example. A view unobstructed by clouds, vegetation or fire scars is essential for a persistent observation of surface mineralogy. Sensors with a continuous multi-temporal operation (e.g., Landsat 8 OLI and Sentinel-2 MSI) can provide the data volume needed to come to an optimal seasonal acquisition and the application of data fusion approaches to create an unobstructed view. However, the acquisition environment always changes over time, driven by seasonal changes, illumination changes and the weather. Consequently, the creation of an unobstructed view does not necessarily lead to a repeatable measurement. In this paper, we evaluate the influence of weather and resulting soil moisture conditions over a 3-year period, with alternating dry and wet periods, on the variance of several “geological” spectral indices in a semi-arid area. Sentinel-2 MSI data are chosen to calculate band ratios for green vegetation, ferric and ferrous iron oxide mineralogy and hydroxyl bearing alteration (clay) mineralogy. The data were used “as provided”, meaning that the performance of the atmospheric correction and geometric accuracy is not changed. The results are shown as time-series for selected areas that include solid rock, beach sand, bare soil and natural vegetation surfaces. Results show that spectral index values vary not only between dry and wet periods, but also within dry periods longer than 45 days, as a result of changing soil moisture conditions long after a last rain event has passed. In terms of repeatability of measurements, an overall low soil-moisture level is more important for long-term stability of spectral index values than the occurrence of minor rain events. In terms of creating an unobstructed view, we found that thresholds for NDVI should not be higher than 0.1 when masking vegetation in geological remote sensing, which is lower than what usually is indicated in literature. In conclusion, multi-temporal data are not only important to study dynamic Earth processes, but also to improve mapping of surfaces that are seemingly invariant. As this work is based on a few selected pixels, the obtained results should be considered only indicative and not as a numerical truth. We conclude that multi-temporal data can be used to create an unobstructed view, but also to select the data that give the most repeatability of measurements. Images selection should not be based on a certain number of days without rain in the days preceding data acquisition but aim for the lowest soil moisture conditions. Consequently, weather data should be incorporated to come to an optimal selection of remote sensing imagery, and also when analyzing multi-temporal data.

Injection strategy for effective bacterial delivery in bioaugmentation scheme by controlling ionic strength and pore-water velocity

For the in-situ remediation of the contaminated subsurface environment, the injection of nutrients and microorganisms changes chemical and physical conditions, which control the delivery and immobilization of microorganisms. We investigated the injection strategy for effective bacterial delivery in a bioaugmentation scheme by controlling ionic strength (IS) and pore-water velocity (v). A set of bacterial transport tests was conducted using the saturated sand column to mimic the saturated subsurface environment. The effectiveness of the injection strategies was evaluated by applying solutions with different ionic strengths into the sand column with different pore-water velocities. The deposition and delivery of bacteria through the sand column were analyzed using the first-order deposition model. The deposition and delivery of bacteria injected by various strategies were numerically simulated considering the variable deposition rate. The breakthrough curves from column experiments revealed that the bacterial deposition on the sand surface was increased by an increase in the ionic strength and by a decrease in the pore-water velocities. The rates of bacterial deposition (k1) on sand could be determined as a function of ionic strength and pore-water velocity, and it was applicable to simulate the delivery of bacteria under dynamic groundwater conditions. The numerical case study considering various injection strategies showed that the nutrient concentration controlled the bacterial delivery to the target area more significantly than the injection flow rate. Injection of bacterial solution with lower nutrient concentration could be increased the deposited bacterial concentration at the target point (Stp) by 6.2–7.1 times higher. Short pulse injection with a high injection rate decreased Stp by 67–78%. The efficiency of bacterial delivery (Ed) could be increased three times higher by lowering nutrient concentration in the injection solution. The process of evaluating the efficiency of bacterial delivery could be a prominent approach to determining the injection strategy for in-situ remediation considering variable conditions of a contaminated site.

Influence of biochar incorporation on the collector surface properties and the transport of silver nanoparticles in porous media

Biochar is widely used as a soil amendment due to its environmental friendliness and convenient availability. It is believed that the presence of biochar in porous media can influence the transport of colloidal and solute contaminants. In this study, different mass ratios of biochar were added to packed sand with a rough or smooth surface to determine the significance of biochar on the retention and release of silver nanoparticles (AgNPs). The results showed that biochar reduced the transport of AgNPs in rough and smooth sands under different solution conditions. A small amount of biochar (0.1–1% in mass percentage) can significantly enhance the retention of AgNPs due to the alteration in collector surface roughness and chemical heterogeneity that potentially reduce the energy barrier for retention. Furthermore, the retention of AgNPs in rough sand was always higher than that in smooth sand under the same experimental conditions. The presence of biochar also produced nonmonotonic retention of AgNPs mainly due to the changes in collector surface roughness. Additionally, the AgNPs retention associated with biochar tended to be irreversible due to the charge heterogeneity, while the reversible retention could mainly occur on a rough sand surface via shallow primary minima. This work highlights the significance of collector surface roughness that needs to be considered in the process of biochar amendment for practical applications to effectively immobilize colloidal contaminants in soil or groundwater.

Role of tailing colloid from vanadium-titanium magnetite in the adsorption and cotransport with vanadium.

The geochemical cycling of vanadium (V) in mining areas has attracted much attention. However, little knowledge was about the effects of tailing colloids on the fate and transport of vanadium in tailing reservoirs which was ignored before. This study investigated the interactions of tailing colloids from vanadium-titanium magnetite with vanadium. Colloid characterization, tailing leaching, adsorption, and column experiments of single and cotransport of tailing colloid with V were conducted. Results show that 98.08% V in the vanadium-titanium magnetite tailing was in the residual state with limited leachable V under various conditions. The adsorption of V to the tailing colloid was via electrostatic attraction and surface complexation on the heterogeneously distributed sorption sites on the colloid surface. The adsorption control step was the diffusion of V into the tailing colloid pores. The increase in pH and the decrease in ionic strength (IS) promoted the single transport of tailing colloid and V in quartz sand columns. In cotransport scenarios, V promoted the transport of tailing colloids via the surface coating effect. In contrast, the transport of V was retarded by the adsorbed tailing colloid on the quartz sand surface. The pre-adsorbed V in the column enhanced the subsequent transport of tailing colloids by electrical repulsion, while the pre-adsorbed tailing colloids facilitated the subsequent transport of V via cotransport of the released colloids with V. The high mobility of the tailing colloid and V and their cotransport in the porous media highly demonstrated the potential V pollution pathways that need to be taken into account.

Transport of nanoscale zero-valent iron in saturated porous media: Effects of grain size, surface metal oxides, and sulfidation

Knowledge of the fate and transport of nanoscale zero-valent iron (nZVI) in saturated porous media is crucial to the development of in situ remediation technologies. This work systematically compared the retention and transport of carboxymethyl cellulose (CMC) modified nZVI (CMC-nZVI) and sulfidated nZVI (CMC-S-nZVI) particles in saturated columns packed with quartz sand of various grain sizes and different surface metal oxide coatings. Grain size reduction had an inhibitory effect on the transport of CMC-S-nZVI and CMC-nZVI due to increasing immobile zone deposition and straining in the columns. Metal oxide coatings had minor effect on the transport of CMC-S-nZVI and CMC-nZVI because the sand surface was coated by the free CMC in the suspensions, reducing the electrostatic attraction between the nZVI and surface metal oxides. CMC-S-nZVI displayed greater breakthrough (C/C0 = 0.82–0.90) and higher mass recovery (84.9%–89.3%) than CMC-nZVI (C/C0 = 0.70–0.80 and mass recovery = 70.9%–79.6%, respectively) under the same experimental conditions. A mathematical model based on the advection-dispersion equation simulated the experimental data of nZVI breakthrough curves very well. Findings of this study suggest sulfidation could enhance the transport of CMC-nZVI in saturated porous media with grain and surface heterogeneities, promoting its application in situ remediation.

Effects of Four Weeks of Plyometric Training Performed in Different Training Surfaces on Physical Performances in School Children: Age and Sex Comparisons.

Short- to middle-term plyometric training has been shown to be an effective method to promote youth fitness and health. However, there is no knowledge of previous studies that investigated the sex and age effects on physical fitness following different PT surfaces (i.e., firm vs. sand) in schoolchildren. This study examined the effects of age and sex on explosive and high-intensity responses following plyometric training (4 weeks, twice/week) performed on firm vs. sand surfaces in untrained schoolchildren. Ninety girls and ninety boys (under 8: age = 7.1 ± 0.5 and 7.1 ± 0.4 years; under 10: age = 9.0 ± 0.4 and 9.0 ± 0.5 years; under 12: age = 11.0 ± 0.5 and 11.0 ± 0.5 years, respectively) participated in a randomized and parallel training design with pre-to-post testing. Participants were allocated (i.e., 30 boys and 30 girls for each group) into either two experimental groups (firm group: performing plyometrics on a clay surface and sand group: performing plyometrics on a dry surface of 20 cm deep sand) or a control group (CG, habitual physical education classes) within their corresponding age groups. Children were tested for sprint, jumping and change of direction speed performances before and after 4 weeks of plyometric training. Both experimental groups induced more significant improvements in all assessed variables than CG (p < 0.0001; effect size > 0.80), whereas both surfaces induced similar improvements (p > 0.05). Older boys achieved better performances than their younger counterparts (p < 0.05) and older girls (p < 0.0001), respectively. This finding showed that age and sex could affect explosive and high-intensity performances during childhood after a short-term plyometric training. In contrast, the training-induced fitness changes were not influenced by the type of surface.

Sand/Polyethyleneimine Composites with Enhanced Sorption/Desorption Properties toward Pollutants

The direct deposition of polyethyleneimine (PEI), a weak polycation with a large content of amino groups, onto sand fractions with different sizes (F70, F100, F200, and F355), resulted in versatile core-shell sorbents for water cleaning. Herein, PEI and the weak polyanion poly(acrylic acid) (PAA) were directly precipitated as an nonstoichiometric polyelectrolyte complex ([PEI]:[PAA] = 2:1) onto a sand surface followed by cross-linking with glutaraldehyde (GA) at three molar ratios ([CHO]:[amine] = 1:10; 1:5; 1:1 = r). Non-crosslinked polyelectrolyte chains were washed out in strongly basic (pH 14) and acidic (pH 0) media. The sand/PEI-GA composites were evaluated to determine the organic shell stability using swelling experiments and X-ray photoelectron spectroscopy. The sorbed/desorbed amount of two model pollutants (copper ions and bromocresol green) in column experiments depended on the sand fraction size and cross-linking degree of the PEI shell. The maximum recorded values, after five loading/release cycles of pollutant species onto F70/PEI-GAr, F100/PEI-GAr, F200/PEI-GAr, and F355/PEI-GAr, were situated between the 0.7–5.5 mg Cu2+/mL column and 3.7–15 mg BCG/mL column. Sand/PEI-GAr composites could act as promising sorbents, low-cost and eco-friendly, which could be applied for water purification procedures.

Application potential of granite cutting waste and tunnel excavation rock as fine aggregates in cement-based materials based on surface characteristics

To alleviate the shortage of river sand (RS) and recycle abandoned resources, two recycled manufactured sands (RMSs) produced from tunnel excavation rock (tuff manufactured sand, TS) and granite cutting waste (granite manufactured sand, GS) are studied and compared with standard sand (SS) and RS. The aim is to identify the application potential of the two RMSs in cement-based materials. This is done by analyzing their influences on the mortar properties based on their surface characteristics and establishing a correlation between the surface characteristics of RMS and mortar properties. For the parent rock, petrographic analysis is performed and the uniaxial compressive strength is measured. For sand, the physical properties are evaluated and X-ray diffraction is used for analyzing the chemical composition. Digital image processing, nitrogen adsorption, and X-ray computed tomography are employed to determine the surface characteristics of sand particles. For the mortar, the fluidity, mechanical strength, water absorption, early total shrinkage, and accelerated expansion ratio are measured. The microstructure of the mortar interface transition zone is examined. Mercury intrusion porosimetry and thermogravimetric analysis are conducted to study the internal mechanism. The results indicate that compared with SS, the two RMSs reduce the fluidity of fresh mortar. In addition, TS is beneficial for the flexural, compressive, and tensile strengths of hardened mortar because of its denser internal pore structure and high degree of hydration caused by the properties of sand. The mechanical strength of the GS mortar can reach a similar or slightly higher level than that of the SS mortar. Furthermore, the fluidity and mechanical strength are well correlated with two parameters of sand, namely, roundness and specific surface area. The tensile strain capacity of the RMS-based mortar is superior to those of the SS and RS mortars. However, RMS increases the early total shrinkage. Although the TS mortar has the highest tensile strain capacity, it also has the largest early total shrinkage among the four mortar mixtures. Comparing the escalations in tensile strain capacity and early total shrinkage, the TS increases the risk of shrinkage cracking in the early stages. The effect of GS on the mortar tensile strain capacity is slightly greater than that on the early total shrinkage; thus, there is no significant influence on the risk of early shrinkage cracking in the GS mortar. In the accelerated expansion test, the TS shows potential alkali-silica reaction (ASR) risk in accordance with ASTM C1260 , however , the GS indicates no potential for expansion damage. Based on the performance of various sands and mortars, GS has a better application value than TS. As for the TS mortar, it is necessary to consider the shrinkage cracking risk and ASR hazard in practical applications. • Application potential of granite cutting waste and tunnel excavation rock as fine aggregates is analyzed. • The surface characteristics of sands are the focus of the discussion. • Correlations between the surface characteristics of recycled manufactured sands and mortar properties are established. • The risk of early shrinkage cracking of recycled manufactured sand mortar is studied.

Digital image-based performance evaluation of GCL-sand interfaces under repeated shearing

Inadequate shear strength mobilization at the interfaces results in translational failures in Geosynthetic Clay Liners (GCL). Periodic addition of solid waste into the landfill causes additional normal and shear stresses in GCLs. The mechanical response of GCLs and fibre strength are highly time-dependent. Hence the interface shear resistance reduces under the application of repeated shear cycles. To simulate these conditions, a repeated interface shearing test was conceptualized in this study. A natural river sand and a manufactured sand of identical gradation were used in experiments. Each GCL-sand interface was subjected to eight cycles of shearing in dry and hydrated conditions under three different static normal stresses. Results showed that the variation of the peak interface shear stress has different phases, governed by different mechanisms. Digital image analysis of tested GCL surfaces after each shearing cycle provided important clues for this response. Entrapment of sand particles into GCL surfaces is beneficial initially because of increased friction at the interface and this benefit is more pronounced in the case of manufactured sand, due to the irregular shape of particles. Quantification of sand particle entrapment and surface changes to GCL helped in understanding these micro-level interaction mechanisms.

The roles of Fe oxyhydroxide coating and chemical aging in pyrogenic carbon nanoparticle transport in unsaturated porous media

Pyrogenic carbon (PyC) nanoparticles are widespread in the environment, which is important to global carbon cycle. PyC can exist for millions of years and undergo various environmental aging processes. To better understand the roles of Fe oxyhydroxides and water content on the pristine and aged PyC transport, adsorption and column experiments were conducted under three saturations (100%, 70%, and 40%) and three pH (5, 7, and 9) in both clean and Fe oxyhydroxide-coated sand. At high water saturations (100% and 70%), the mobility of both the pristine and aged PyC was enhanced at high pH due to strong electrostatic repulsion, and the aged PyC showed higher mobility than the pristine PyC because of its more negative charge and hydrophilic surface. The coating of Fe oxyhydroxides on sand decreased the mobility of both the pristine and aged PyC due to weak electrostatic repulsion, large specific surface area, and high roughness. At low saturation (40%), solution pH showed little effect on both the pristine and aged PyC mobility, and water saturation became the main factor affecting PyC mobility. Almost no pristine or aged PyC transported out from the Fe oxyhydroxide-coated sand column because Fe oxide increased the roughness of the sand surface, which led to a sharp increase in the air-water-solid interface and retention sites. This study demonstrates that water content, environmental aging, and Fe oxyhydroxides are significant in the fate and transport of PyC nanoparticles in environments, which provides a good fundamental understanding for the assessment of pyrogenic carbon application in environmental protection and carbon sequestration.

Field Test on Soybean-Urease Induced Calcite Precipitation (SICP) for Desert Sand Stabilization against the Wind-Induced Erosion

Soybean-urease induced calcite precipitation (SICP) is an effective method for the improvement of sand, which forms a biocemented layer on the desert sand surface to resist erosion induced by the wind. Under this study, field tests were carried out to determine how the SICP approach may enhance the resistance of the desert to wind-induced erosion and the durability of SICP treatment in southeastern margin of Tengger Desert, Ningxia Hui Autonomous Region, China. The experimental results demonstrated that the erosion resistance of desert sand was significantly enhanced due to the SICP treatment, and the improvement effect was enhanced with the increase of the biocement solution concentration and dosage and the number of treatment cycles. Furthermore, it was also found that the resistance of SICP-treated sand to erosion induced by the wind reduced as the development of time reduced. Based on the test results in this paper, larger biocement solution concentration and dosage and multiple treatment cycles are proposed in the areas where severe wind-induced erosion takes place in order to improve the ductility of SICP treatment.

Model experiments on hydraulic properties around multiple piers with reproduced 3D geometries

The effects of multiple piers with 3D geometries on water levels during floods, as well as riverbed fluctuations and local scour after floods were examined via hydraulic model experiments. The Kintaikyo Bridge in Japan, a world-famous historical triple-wooden-arch bridge, was modeled at a scale of approximately 1/276. The number of model piers was set to four, as in the real bridge, and they were 3D printed and installed in the sand layer of an open channel. To provide adequate information on the pier installation conditions and hydraulic response, four cases were studied in the experiments, primarily considering present pier conditions; the previous conditions of the Kintaikyo Bridge were also considered. The experimental conditions in these four cases depended on whether foundations were present, the piers were skewed against the flow center, and the shape was spindle or similar to that of the present case. In the current bridge condition where foundations are present and there is no skew, water level rise, riverbed fluctuation, and local scour were suppressed. Furthermore, the statistical analysis of the results suggested that riverbed fluctuations are more stable after flooding. The two piers with foundations had smaller scour areas than those without. Further, those with foundations generally had lower mean scour at the pier perimeters. Regarding those without foundations, there were no differences in riverbed fluctuations or local scour due to the skewed pier angle. In addition, the representative length of the pier with a 3D geometry was determined by dividing the projected area of the pier below the initial sand surface in the main flow direction by the pier height, and the relationship between the Froude number or the mean water depth and the maximum scour depth was investigated.