Artificial Clay Research Articles

Decomposing an elevational gradient in predation by insectivorous birds

AbstractInsectivorous birds have ecologically important effects on prey abundance, behavior, and evolution, and through top‐down control, birds indirectly reduce herbivory and promote plant growth. While several studies sought to characterize biogeographic patterns in top‐down control by birds, variation in bird predation along elevational gradients is not well characterized in terms of both its commonness and the mechanisms underlying such variation. Here, we characterized variation in bird predation along a 700‐m montane elevation gradient using artificial clay caterpillars, assessing the roles of variation in aridity, other elevational effects not associated with aridity (e.g., most notably growing season length), and bird abundance and diversity. Multivariate models revealed increasing attack rates with aridity (when controlling for the effects of elevation) and elevation (when controlling for aridity). Because aridity declines with elevation, elevational patterns were not detectable in a univariate analysis. Bird abundance (but not diversity) decreased with elevation (but not aridity) and did not provide an explanation for our results, suggesting that the underlying mechanisms were behaviorally based. We speculate that the declining abundance of insect prey with elevation and aridity leads to increased bird foraging efforts and thus the likelihood of attacking clay caterpillars. If widespread, these dynamics have important consequences for both the interpretation of predation bioassays generally and our understanding of the multivariate drivers of variation in top‐down control by predators and predation risks experienced by prey.

Thermo-mechanical behaviour of a kaolin-based clay soil

The thermal behaviour of KSS, a low-plasticity artificial clay made with kaolin clay, silt and sand, was investigated in a series of temperature-controlled oedometer tests, at temperatures between 5°C and 70°C, and at vertical pressures up to 2·4 MPa. The experiments investigated the effect of overconsolidation ratio (OCR), pressure level and repeated thermal cycling on thermally induced volume change. Thermal volumetric strains were found to be dependent not only on OCR but also on pressure level, contradicting previous experimental findings and highlighting the importance of even a small dependency of compression index Cc on temperature. Furthermore, thermal volumetric strains were irreversible on heating and cooling even for highly overconsolidated samples. Although irreversibility at high OCR values has been attributed to particle rearrangement and plastic accommodation in the past, an alternative explanation is put forward here, as yielding on the Hvorslev surface is expected to occur on unloading under one-dimensional (1D) conditions. The tests also revealed evidence of thermal creep for the initially normally consolidated samples. The influence of both current temperature and temperature history on the reloading response of mechanically overconsolidated KSS was tested and quantified in terms of their effect on the measured pre-consolidation pressure. The results from these tests were compared to results from the available literature referring to clays of similar and higher plasticity and the comparison highlighted that although soil plasticity can explain the observed quantitative differences between high-plasticity soils to a large extent, mineralogy, in addition to structure, may also play an important role for low-plasticity soils.

Isolation, Identification, and Application of Pigment-Producing Actinobacteria from Stingless Bee Hives for Handicraft Production

Actinobacteria are distributed in natural habitats and produce a vast variety of natural pigments that are different in colour shades and applied in textile industry and others. The extracted actinobacterial pigments are used as eco-friendly natural dyes and colour and non-toxic to living organisms and environments compared with chemical or synthetic colours. In order to produce actinobacterial pigments for handicraft making, eight strains of the pigmented producing actinobacteria were isolated from stingless bee (Tetragonilla collina Smith, 1857) hives. Based on deep colour shades presented, 4 actinobacterial strains were chosen to prepare various colour for handicrafts, including yellow, violet, green, and pink. To identify actinobacterial strains selected, phylogenetic identification was carried out. The phylogenetic results indicated that strain C2 phylogenetically shared the 16S rDNA sequence 99.6 % similarity with its closest species, namely Streptomyces cellulosae. Strain C4 had the phylogenetic relationship close to Streptomyces californicus (99.9% similarity of 16S rDNA). Strain E1 was a closest member belonged to Streptomyces chartreusis (99.9% 16S rDNA sequence similarity), and strain E2 was phylogenetically closely related to Streptomyces aureoversilis with 99.2% 16S rDNA sequence similarity. To produce the handicraft colour, we cultivated four actinobacterial strains on broken-milled rice, and actinobacterial pigments were extracted using ethyl acetate. The crude extracts obtained were mixed with white flower clay that was used for handicraft making, and the artificial clay flowers were made. This study is the first to report the use of natural colours obtained from pigment-producing actinobacteria in handicrafts in Thailand and other countries. Future research will explore the application of actinobacterial pigments in various fields, including fine arts, the ceramic industry, and others.

The effects of clay mineralogy and crack properties on elastic properties of dry and water-saturated transversely isotropic rocks

The causes of the intrinsic elastic anisotropy of shales are very complicated, and clay mineralogy and crack properties are critical for rock-physics models and geomechanics applications in shales, but they are still poorly understood. Further, it is difficult to directly measure the elastic properties of single-crystal clays due to their small particle size. To reduce the multiparametric influence factors caused by complex components in natural shales, two sets of artificial rocks with different clay minerals are fabricated, and their porosity, permeability, and ultrasonic velocities are measured under different pressure conditions. The results suggest that clay mineralogy can significantly affect physical and elastic properties and their pressure sensitivity, and the permeabilities of the sample composed of kaolinite are much higher than those of the sample composed of smectite due to the larger particle size of kaolinite compared with smectite. Further, the type of clay can cause a difference in “intrinsic” velocity and anisotropy. The microcrack can enhance the velocity anisotropy on the basis of intrinsic anisotropy, and crack properties such as maximum dip angle and normal-to-tangential compliance ratio are obtained by a theoretical model, which is also affected by clay type, causing the difference in the pressure sensitivity of elastic properties. Water has a significant influence on the elastic properties and anisotropy of artificial clay samples, which can reduce the S-wave velocity and increase the P-wave velocity driven by multiple competing factors. Water reduces the velocity anisotropy because the presence of water narrows the difference between the velocity parallel and perpendicular to the axis of symmetry. The normal-to-tangential compliance ratio of cracks is also affected by water as a stiffer fluid can reduce the normal compliance of cracks at the grain scale.

Ageing/thixotropy effects on strength and compressibility in Leda clay and polymer-amended clayey tailings

Evidence of ageing has been reported in natural deposits of sedimentary clays, dredged sediments, and in clay-rich oil sands tailings, and such time-dependent behaviour has been observed to influence their long-term settlement and strength development characteristics. The ageing phenomenon can, therefore, have important implications for the reclamation of such deposits. This research investigated ageing in polymer-amended tailings and Leda clay monitoring relatively small (10 cm high) laboratory samples for over 100 days. Both tailings and natural clay were found to develop increased strength, sensitivity, and higher pre-consolidation pressure and reduced compressibility. The correlation between fall cone shear strengths and pre-consolidation pressures was strong for both the natural clay and the clayey tailings, though this ratio was different in the tailings and the clay. The Leda clay appeared to reabsorb some of its bleed water, which was found to be due to the transition of some free water to absorbed water after 80 days. Using a concept developed from ageing experiments in artificial clays, it was found that shear strengths measured after an “early equilibrium state” correlated strongly with shear strengths measured near the end of ageing. This is promising for quantifying the potential for ageing on compressibility without having to resort to year-long experiments.

Undrained strength of clay determined from simple shear test

The undrained shear strength of clay is an important parameter for the design of embankments, shallow foundations, and pile foundations. Among the various methods of testing undrained strength, the simple shear is essential when the shearing mode of the soil surrounding the pile is similar to that in a simple shear test. This study employs a series of undrained strength tests with a Berkeley simple shear apparatus. Three reconstituted natural clays and one artificial clay were tested with a range of coefficients of consolidation. The influence factors, including sample pre-consolidation pressure, saturation back pressure, shearing rate, height of specimen, consolidation stress, and lateral stress ratio, were investigated in undrained simple shear tests. The failure mode in simple shear and corresponding strength parameters are also examined. Based on the test data set, models for describing the undrained strength with simple shear for high plasticity clays are developed and compared to test data for normally consolidated reconstituted clay. Good agreement between models and intact Onsoy clay is also observed when allowance is made for the coefficient of consolidation and strength parameters of undisturbed clay and in situ stress state.

Importance of color for artificial clay caterpillars as sentinel prey in maize, soybean, and prairie

AbstractThe use of artificial clay caterpillars to measure predation pressure under real field conditions is one method that has garnered recent support for quantifying ecosystem services that beneficial insects provide. Here, we focus on color and ask whether it is an important variable that should be considered in studies using clay caterpillars as sentinel prey. We deployed a total of 1920 brown, cream, green, gray, terracotta, and white clay caterpillars onto maize, soybean, and prairie plants to test if lighter colored caterpillars will be attacked and retrieved more than caterpillars with darker colors. As hypothesized, color was a significant predictor with green and terracotta caterpillars performing best, whereas brown and gray caterpillars performed the worst. Interestingly, clay caterpillars were also attacked proportionally to the number of insects in the surrounding habitat. Combined, we suggest artificial clay caterpillars could be useful for rapid ecosystem function assessments, but only when their color is considered.

Investigation on Swelling Performance of Oil Sands and Its Impact on Oil Production during SAGD Processes

SAGD (Steam Assisted Gravity Drainage) is used in Canadian fields where there are interlayers that impede steam chamber development and thus impede production. Many experiments have been conducted on the effect of interlayers on oil recovery. However, the swelling characteristics of interlayers under different conditions, as well as the possible clay mineral transformation and particle migration of clay particles at high temperatures, are rarely studied. In this paper, the swelling characteristics of natural oil sands and artificial clay samples were studied by high temperature hydration swelling experiments to obtain a better comparison. The effects of temperature, pressure and solution type on the swelling rate of oil sand were studied. The uniaxial compressive strength of the core in the presence of clay was studied by the scribe test. In addition, before and after the aging test at 220 °C and 2.5 MPa, the clay mineral composition was studied by the X-ray diffraction method, and the mineral transformation was proved. Finally, the impact of clay swelling on oil production is investigated by simulating the particle migration effect while considering the swelling effect. The results show that the swelling rate of oil sand increases with the increment of temperature and the decrement of pressure. The swelling rate of an artificial clay sample in distilled water is the highest, while a 1% KCl + 1% CaCl2 solution has the best swelling inhibition effect. This study aims to provide new insights into reservoir damage research during SAGD development.

Parameterization of the Model of Artificial Clay Freezing Considering the Effect of Pore Water Salinity

This paper considers the artificial freezing of an argillite-like clay layer containing a NaCl salt solution in its pore space. The experimental results of the thermophysical properties of the clay with various salinities and water content in soil samples are presented. We determine the parameters of the soil freezing characteristic curves, the dependences of the specific heat capacity, and thermal conductivity based on temperature and salinity. These parameters are used in the formulation of a simple thermodynamic model for the artificial freezing of a clay layer with a single freezing pipe. The model includes diffusive transfer of heat and salt concentration, as well as salt precipitation when the eutectic point is reached. The motivation for using the simplified model is to understand the general patterns of soil freezing when considering the effect of salinity, as well as to test the proposed numerical finite-difference algorithm for solving the problem of freezing a clay layer based on the method of equivalent heat capacities. Using the algorithm, we analyzed the regularities of the redistribution of dissolved and precipitated salt in frozen soil, and also evaluated the effect of diffusive salt transfer on the numerical solution.

Evolution of blowouts in artificial foredunes on Pingtan Island, China

AbstractThe appearance of a blowout can be an obvious sign of accelerated coastline retreat or dune erosion and in response to serious coastal erosion, an increasing number of artificial foredunes are being built. However, over time, numerous blowouts have also developed on artificial foredunes. To our knowledge, no studies have been reported on the evolution of blowouts in artificial foredunes, and in response we explore the aerodynamics and morphodynamics of artificial blowouts at different stages, by conducting field experiments on the Changjiang Ao coast of Pingtan Island, China. Where a foredune was built on an artificial clay structure, with topography and wind fields around three blowouts in different developmental stages measured, preliminary results revealed that: (1) the blowout morphology and airflow patterns show distinct seasonal changes; (2) the development of blowouts in artificial foredunes involves five stages, in contrast to the four stages observed in natural foredunes; and (3) blowout development is controlled by a two‐way feedback between aeolian processes and blowout morphological development, and the artificial structure can interfere with this feedback mechanism by altering the path of blowout development. The findings enhance our understanding of geomorphic process–response systems in artificial foredunes and provide a reference for coastal management and dune stabilization policy and practice.

Mechanical properties and freeze-thaw resistance of lightweight aggregate concrete using artificial clay aggregate

Abstract This work intends to make structural lightweight aggregate concrete by using artificial expanded clay aggregate with different replacement levels from normal coarse aggregate and improve it with a high-performance superplasticizer to increase its strength. The mechanical characteristics covered in the present work were compressive strength, flexural strength, and splitting tensile strength in addition to freezing and thawing resistance. Different densities were found for all mixes ranging between normal and lightweight concrete and that depends on the replacement of normal aggregate with lightweight aggregates. Mixes with replacement exceeding 25% give compressive strength less than 17 MPa and cannot be regarded as structural lightweight concrete. Modified mixes give higher values of mechanical properties, and also some non-structural lightweight concrete mixes were improved to structural lightweight concrete by using PC-superplasticizer in this study. The research also includes freezing and thawing cycles on reference mixes and lightweight mixes. Lightweight mixes give high durability against freeze-thaw cycles where the reduction in compressive strength was 6.2, 4.6, and 5.5% for 10% rep, 15% rep, and 20% rep mixes, respectively, compared with 32.2% reduction for reference mix.

Microscopic and spectroscopic investigations of uranium(VI) reduction by <i>Desulfosporosinus hippei</i> DSM 8344

Abstract. Clay formations are potential host rocks for the long-term storage of high-level radioactive waste in a deep geological repository. Bentonites are supposed to serve as backfill material, not only for a final disposal site in clay formations but also in crystalline rock. For a long-term safety assessment, various aspects must be taken into account. Besides geological, geochemical and geophysical considerations, naturally occurring microorganisms also play a crucial part in the environment of such a repository. In the event of a worst-case scenario when water enters the disposal site, they can interact with the radionuclides and change for example the chemical speciation or the oxidation state (Lloyd et al., 2002). Desulfosporosinus spp. are an important representative of anaerobic, sulfate-reducing microorganisms, which are present in clay formations as well as in bentonites. Various studies have shown that they play a major role in the microbial communities of these surroundings (Bagnoud et al., 2016; Matschiavelli et al., 2019). A closely related microorganism to the isolated species is Desulfosporosinus hippei DSM 8344, which was originally found in permafrost soil (Vatsurina et al., 2008). This bacterium was used to investigate its interactions with uranium(VI) especially regarding the reduction to the less mobile uranium(IV). Time-dependent reduction experiments in artificial Opalinus Clay pore water (Wersin et al., 2011) (100 µM uranium(VI), pH 5.5) showed the removal of about 80 % of the uranium(VI) from the supernatants within 48 h. Corresponding UV/Vis measurements of the dissolved cell pellets exhibited an increasing proportion of uranium(IV) in the cell-bound uranium. Calculations with the inclusion of extinction coefficients led to a ratio of 39 % uranium(IV) after 1 week. Therefore, a combined sorption-reduction process is a possible interaction mechanism. Time-resolved laser-induced luminescence spectroscopy verified the presence of two uranium(VI) species in the supernatant. A comparison with reference spectra led to an assignment to a uranyl(VI) lactate and a uranyl(VI) carbonate complex. The species distribution showed a decrease of the proportion of the lactate species with time, whereas the proportion of the carbonate species remained almost constant. Uranium aggregates are formed on the cell surface during the process, as determined by transmission electron microscopy (TEM). Furthermore, uranium occurs inside and outside the cells as well as vesicles containing uranium. These findings help to close existing gaps in a comprehensive safeguard concept for a repository for high-level radioactive waste in clay rock. Moreover, this study provides new insights into the interactions of sulfate-reducing microorganisms with uranium(VI).

Interaction between cement clinker constituents and clay minerals and their influence on the strength of cement-based stabilized soft clay

The strength of cement-based stabilized clay is less than that of concrete and mortar and shows a distinct variability owing to the existence of various clay minerals. To better understand the cement–clay reactions and the strength generation, two artificial clays with the unique clay mineral and major strength-producing constituents of cement clinker were investigated via mechanical, compositional, and microstructural analyses. Results show that C3A-stabilized clay gains strength rapidly in the first 3 days, but this favourable tendency vanishes over time. After 90 days of curing, the strength of C3S-stabilized clay is about four times that of the corresponding C3A-stabilized clay, indicating the remarkable long-term stabilization efficiency of C3S. Furthermore, clay minerals primarily draw into strength evolution in the reaction process. Despite that bentonite is more reactive than kaolin as long as the highly alkaline conditions persist, it has a higher probability to flocculate into large aggregates during the mixing process, which may impair the reaction efficiency and even brings adverse stabilization effects, suggesting the importance of uniformity control.

Volume change behavior of reconstituted marine clay: effect of initial and leaching pore fluid salinity

Because the salinity of marine clay changes continuously in response to the migration of seawater toward land or freshwater from river to sea, the intrinsic pore fluid salinity of the clay-water system may change periodically. Recent studies indicate that pore-water salinity changes the intrinsic properties of reconstituted homoionic artificial clay. However, the effect of seawater on the intrinsic properties of marine clay is unknown. The aim of this study was to investigate changes in the compression parameters of marine clay for the leaching salinity of seawater with respect to tap water. The results show that ratio $${e}_{0}/{e}_{\mathrm{L}}$$ is more sensitive to salinity than $${e}_{100}^{*}$$ . Although the Iv − log p for all samples at different intrinsic/leaching salinities were located on the intrinsic compression line (ICL); some deviation from the ICL was observed at low-stress levels. In high-salinity reconstituted samples, the osmotic gradient caused the low-salinity water to penetrate the clusters and separate individual particles, increasing the size of intra-cluster pores and settlement during consolidation. The distance between the particles at any stress level was larger than in diffuse double layer theory because of a deviation from the assumed parallel fabric in the theory.

Model Test and Back Analysis of Shield Tunnel Load Distribution in Soft Clay

Combined with the soft clay layer of Foshan metro, a back‐analysis method combining model test and numerical simulation is developed. First, the similitude criterion for the model used in this study was derived from similarity theory and elasticity mechanics equations. Artificial clay is prepared by mixing kaolin, bentonite, loess, and river sand in proportions of 4 : 2: 3 : 1. Gypsum, water, and borax are mixed in proportions of 1 : 0.7 : 0.015 to simulate the tunnel lining. The model tests were carried out based on four load modes: the combination of mode 1, vertical load distribution and horizontal load linear distribution, mode 2, vertical load distribution and horizontal load parabolic distribution, mode 3, vertical load parabolic distribution and horizontal load linear distribution, and mode 4, vertical and horizontal load parabolic distribution. Then, the calculation model corresponding to the four load modes is established using ABAQUS, and the measured data is back‐analyzed as the known quantity. The specific load values obtained were 359 kPa, 380 kPa, 361 kPa, and 368 kPa by the load‐internal force curve. The bending moment and axial force are calculated by substituting the back‐analysis load values back into the model and comparing the results with the measured values; it was found that the internal forces under the back‐calculation load still deviated by varying degrees. By using the comprehensive error function E to evaluate the advantages and disadvantages of the four distribution modes, the comprehensive errors are 4.3%, 1.7%, 6.5%, and 5.9%, respectively. That is, the error of load distribution of mode 2 (the combination of vertical load distribution and horizontal load parabolic distribution) is the lowest and is highly consistent with the measured value, which is the closest to the characteristics of the load pattern of the stratum.

The elastic properties and anisotropy of artificial compacted clay samples

Clay minerals are a major component of hydrocarbon reservoir rocks, and they are known to play important roles in the physical and elastic properties of rocks. However, it is difficult to directly measure these properties of single-crystal clays due to their small particle size. Therefore, we have constructed three sets of artificial clay samples with different compaction stresses to investigate the effect of the compaction stress and clay mineralogy on their elastic properties and anisotropy. All of the dry samples are measured by the pulse-transmission method. The results indicate that the compaction stress and clay mineralogy have a significant influence on the physical and elastic properties of the clay samples. The microstructures of clay samples indicate that the clay platelets are aligned almost perpendicularly to the direction of compaction stress, and the ultrasonic velocity analysis validates the assumption of transverse isotropy of our clay samples. The velocities increase with the compaction stress, especially at low stress, which corresponds to the rapid porosity reduction at low stress levels. Velocity anisotropy parameters increase with increasing of compaction stress due to the increase of texture sharpness for clay minerals during the compaction process. The elastic moduli of the clay samples display a significant stress sensitivity and a strong directional dependence, with the Young’s moduli increasing and the Poisson’s ratios decreasing with the compaction stress. A simple theoretical template is used to quantify the orientation distribution functions (ODFs) of clay platelets, and the generalized Legendre coefficients of ODF increase with the increase of compaction stress, especially at low stress. Further, the compressional-wave (P-wave) and shear-wave anisotropy increase with the ODF coefficients [Formula: see text] and [Formula: see text], especially P-wave anisotropy.

Experimental study of rate-dependent uniaxial compressive behaviors of two artificial frozen sandy clay soils

The rate-dependent uniaxial compressive behavior of frozen clay soil is strongly affected by its minerals, void ratio, stress history, and pore fluid salinity. Previous studies show that an extremely low deformation rate applied on a clay soil tends to result in a lower bound compressive strength. However, the lower bound stress-strain behavior of frozen clay soil under the uniaxial compressive condition was not studied. A thorough understanding of the rate-dependent behavior of frozen clay and its relationship with temperature requires a large number of specimens with similar compositions and micro-structures. In this study, a series of laboratory tests were carried out on artificial frozen sandy clay soils to measure the rate-dependent uniaxial compressive behavior at temperatures ranging from −15 °C to 0 °C. We used two types of artificial frozen clay soils with pre-determined clay fraction, clay mineralogy, stress history, and moisture content. Our results conclude that a low temperature and a high deformation rate tend to generate brittle failure with post-peak softening behavior. A temperature close to the freezing temperature and a low deformation rate result in a diffuse failure associated with strain hardening. Temperature-dependent uniaxial compressive mechanical properties were measured and modeled using empirical relations, which are highly dependent on the applied deformation rate. A series of step-loaded relaxation tests were carried out on those artificial clay soils and creep parameters were estimated using relaxation test results and a power law creep model. A new approach of deriving the lower bound of stress-strain curve of frozen soil is proposed accordingly. The idea of determining the lower bound of stress-strain curve is based on the isotache concept, which was previously used in the soil consolidation theory.

Developmental costs of yellow colouration in fire salamanders and experiments to test the efficiency of yellow as a warning colouration

Abstract Warning colouration reduces predation risk by signalling or mimicking the unpleasantness of prey and therefore increases survival. We tested in two experiments the evolutionary costs and benefits of the yellow colour pattern in fire salamanders (Salamandra salamandra), which display a yellow/black colour pattern usually associated with toxic alkaloids. Our first experiment aimed to test whether the development of colouration is condition dependent and thus related to developmental costs, i.e. influenced by resource availability during the developmental process. Therefore, we reared fire salamander larvae under different nutritional conditions and compared the relative amount of yellow they developed after metamorphosis. Fire salamander larvae reared under limited food conditions had a lower proportion of yellow following metamorphosis than control larvae reared under superior food conditions. In a second experiment we tested whether the proportion of yellow has an impact on the risk of being attacked using artificial models. We tested, in salamander-free and salamander-occupied natural habitats, whether artificial clay models with different proportions of yellow and black receive different attack rates from potential predators (birds, mammals, insects). In clay models the proportion of yellow and the site had a significant effect on predation risk. Models with larger amounts of yellow had fewer bite marks from predators such as carabid beetles and birds, but only in sympatry with salamanders. In conclusion, the early expression of conspicuous colouration seems to be condition dependent and therefore potentially costly. Furthermore, the yellow colouration of fire salamanders act as a signal that potentially reduces their risk of being attacked by predators. Thus, the yellow colouration of fire salamanders seems to represent an adaptive trait that reduces the risk of predation, which can be expressed in higher quantity by individuals of a certain condition.

Gold clay from self-assembly of 2D microscale nanosheets

Nature has always demonstrated incredible ability to create amazing materials such as soft clay which are built from nanoplatelet packing structures. It is challenging to produce artificial clays owing to the difficulty in obtaining large volume fractions of nanoplatelets and the lack of structural control in layer-by-layer packing. Here, single-crystalline Au nanosheets are synthesized by controlled growth in the bilayer membranes of succinic acid surfactants. Then, a self-assembly strategy is used to make {111}-oriented gold nanostructures at the liquid−liquid interface. The stiffness of the nanosheet assemblies are six orders of magnitude softer than bulk gold. The Au nanosheet aggregates show high plasticity and deformable into macroscale free-standing metallic architectures. They show a stress/strain-dependent conductivity owing to morphological changes. Our study provides valuable insights on the chemical synthesis of 2D nanostructures as well as for the self-assembly strategy on fabrication of mouldable metals for producing free-standing metallic architectures with microscale resolutions.

Lightweight SFRC Benefitting from a Pre-Soaking and Internal Curing Process.

The presented research program is focused on the design of a structural lightweight fiber-reinforced concrete harnessing an internal curing process. Pre-soaked waste red ceramic fine aggregate and pre-soaked artificial clay expanded coarse aggregate were utilized for the creation of the mix. Copper-coated steel fiber was added to the mix by volume in amounts of 0.0%, 0.5%, 1.0%, and 1.5%. Test specimens in forms of cubes, cylinders, and beams were tested to specify the concrete characteristics. Such properties as consistency, compressive strength, splitting tensile strength, static and dynamic modulus of elasticity, flexural characteristics, and shear strength were of special interest. The achieved concrete can be classified as LC12/13. A strength class, according to fib Model Code, was also assigned to the concretes in question. The proposed method of preparation of concrete mix using only pre-soaked aggregate (with no extra water) proved to be feasible.