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To obtain a material that adsorbs nitrogen oxide (NOx) gas with high efficiency, we used sulfuric acid (H2SO4)-treated activated carbon (AC). The proposed H2SO4-treated AC was treated by dipping and spray coating in a H2SO4 solution. For structural analysis, scanning electron microscopy and Brunauer–Emmett–Teller measurements were performed on general and H2SO4-treated ACs. The composition of the atoms on the surface and inner pore structure of both ACs was confirmed through energy dispersive X-ray spectroscopy measurements. From the structural analysis, it was confirmed that the structure of H2SO4-treated AC was similar to that of general AC, indicating that it was not affected by the H2SO4 solution. There was no significant difference in the inner pore structures of general and H2SO4-treated ACs through specific surface area analysis, which indicates that the physical adsorption of NOx gas for the H2SO4-treated AC is similar to that of general AC. Based on the atomic composition analysis, it was confirmed that sulfur ions were largely present on the inner pore structure than the surface of H2SO4-treated AC. These results indicate that the chemical adsorption of sulfur ions and NOx gas in the inner pore structure occurred rather than physical adsorption. The results of this study are expected to be applicable to the field of materials that remove harmful gases.

This study examines the flexural performance of reinforced concrete (RC) columns strengthened through a seismic jacket technique developed using a prefabricated steel bar unit that forms peripheral closed hoops and supplementary V ties, satisfying the design requirements of the ACI 318-14 seismic provisions. Three RC jacketed columns were prepared with a parameter of axial load levels and tested under a constant concentric axial load and cyclic lateral loads. Analytical approaches were also applied to examine the axial load–moment interaction of the RC jacketed columns when considering the confinement effect provided by the jacket section and to investigate the applicability of the previous performance-based design models proposed for virgin seismic columns. The test results show that the developed jacket technique possesses a good potential in enhancing the flexural stiffness, strength and ductility of deficient columns, even under a high axial load. Reinforced concrete jacketed columns possess a higher ductility than that estimated using the ductility parameter model, regardless of the axial load level. Thus, the jacket section including the seismic details of a transverse reinforcement can be conservatively designed, based on the axial load–moment interaction and ductility parameter model for the moment and ductility enhancements required by deficient columns.

The objective of the present study is to examine the applicability of ground granulated powders (GGPs) as a cementitious binding material for soil solidification. The compressive strength gain of t...

Typically, the stress-strain relationship of confined lightweight aggregate concrete (LWAC) exhibits lower stiffness in the ascending branch and more brittleness in the descending branch compared to counterpart confined normal-weight concrete (NWC). To describe the rational stress-strain relationship of confined LWAC according to these trends, the concept of concrete brittleness number (ξb) was introduced. Specifically, ξb values were determined as constants in the existing size effect equation. The constants were fitted via regression analysis of 164 datasets compiled in extant studies. The models of elastic modulus, strength gain factor, strain at maximum stress, and strain at 85% of the maximum stress in descending branch were proposed, including ξb to describe the lower stiffness and more brittle behavior in confined LWAC when compared to those of counterpart confined NWC. Other existing models showed significant differences when compared with the test results in the descending behavior. These differences were significant in LWAC and counterpart NWC. Conversely, the proposed stress-strain relationship of confined concrete was in excellent agreement with the test results, irrespective of concrete type, compressive strength of concrete, and volumetric transverse reinforcement index.

The structural, magnetic and ferroelectric properties of polycrystalline A-site (A = Ho, Pr and Ce of 10%) doped BiFeO3, which were prepared by the solid-state and rapid sintering methods, have been investigated. The powder X-ray diffraction pattern reveals that all the samples show rhombohedral perovskite structure R3c. The Ho-doped BiFeO3 shows that the magnetic property is slightly increased due to compressive lattice distortion and Ho3+ ion doping effect. For the Pr and Ce doped BiFeO3, the remnant polarization and coercive field increased because Pr3+ and Ce3+ ions substitution suppressed oxygen vacancies.

The periodic arrangement in metamaterial (MM) should be maintained to ensure the extraordinary properties, but how much periodic irregularity is allowed generally without degrading the properties is not only important for the tolerance in fabrication but interesting scientifically. We introduce the wrecked effect in MM utilizing perfect MM absorber in visible and GHz ranges. The original perfect MM properties turn out to be maintained until MM is destroyed to 10%. In the view of MM absorber, even 40% broken meta-pattern are still good for absorption higher than 93%, the criterion for perfect absorption. The wrecked pattern over 80% result in absorption of nearly 50% in both simulation and experiment, which is even higher than expected. These results can lead to broad applications at the present and in near future through more convenient and cost-effective research and development on MMs.

We simulated a study on a tunable metamaterial absorber using ferrite rubber as a dielectric substrate with ferromagnetic properties. The proposed structure employs ferromagnetic resonance, which utilizes the coupling of an applied magnetic field and an incident electromagnetic wave. As the magnitude of the applied magnetic field increases, it can be seen that the absorption peak moves to a higher frequency. The adjustment of the absorption frequency using the proposed method is expected to be applied to various fields such as sensors, electronic devices and 5G communication antennas.

We studied the adsorption of nitrogen oxides according to various porous materials room temperature, which can effectively to adsorb the nitrogen oxides. Based on results of measuring NOx concentration, the activated carbon materials have been shown to adsorb NOx well, and they have been shown to more efficiently removing NO2, which is very harmful to the environment. In particular, in the case of the coconut activated carbon, the removal efficiency of NO and NO2 was very excellent, and the removal rate of was 30% for 100 minutes and 19.5% for 840 minutes. Our measurement results confirmed that the activated carbon materials have a very large specific surface area and pore volume. In addition, the coconut activated carbon appears to have a large specific surface area and pore volume to remove NOx over a long period of time. Based on the experimental results, it is expected to be used as a material that efficiently removes nitrogen oxides at room temperature.

This study examines the effect of different arrangements of transverse reinforcement in the jacket section on the axial performance of full-scale reinforced-concrete columns strengthened with a seismic section enlargement approach. For the jacket section with seismic details, overlapped channel-shape bars and prefabricated bar units were designed as the closed peripheral hoops, and V-ties or segmented cross-ties were used for the supplementary transverse reinforcement. For the compressive tests of full-scale strengthened columns with a 750 mm square section, a steel loading frame with a 40 000 kN capacity hydraulic jack was specially devised. Test results showed that the strengthened columns without supplementary V-ties in the jacket section possessed lower ductility capacity when compared with that of the existing non-seismic column. At the same level of transverse reinforcement index, the axial ductility ratio obtained from the present full-scale columns was typically lower than that compiled from the scaled-down column specimens with a square section of 200–300 mm. However, the strengthened column with prefabricated bar unit hoops including supplementary V-ties exhibited good ductility, which was comparable to the axial ductility ratios obtained in scaled-down columns, although a size effect potentially induced a more rapid decreasing rate at the descending branch of the stress–strain relationship of the concrete.

Strain F21T, a marine, aerobic, Gram-negative, rod-shaped bacterium, was isolated from seashore sand sampled in Pohang, Republic of Korea. Cells of strain F21T were non-motile, catalase-positive, oxidase-positive, non-spore-forming and formed pinkish-red colonies on marine agar. The strain grew optimally at 37°C, pH 7 and in the presence of 2–3 % NaCl (w/v). Analysis of the 16S rRNA gene sequence of strain F21T revealed that it belonged to the genus Algoriphagus , family Cyclobacteriaceae , with similarity values of 98.1 and 96.8 % to Algoriphagus marincola DSM 16067T and Algoriphagus ornithinivorans IMSNU 14014T, respectively. When comparing the genome sequence of F21 T with those of the type strains of six species of the genus Algoriphagus , the values obtained were below the thresholds for analyses of average nucleotide identity (71.8–92.7 %) and in silico DNA–DNA hybridization using the Genome-to-Genome Distance Calculator (14.7–75.2 %). The DNA G+C content of strain F21T was 42.0 mol%. The chemotaxonomic characteristics of F21T included MK-7 as the predominant isoprenoid quinone, iso-C15 : 0, iso-C17 : 0 3-OH and summed feature 3 (C16 : 1ω6c and/or C16 : 1ω7c) as major cellular fatty acids, and phosphatidylcholine and phosphatidylethanolamine as major polar lipids. On the basis of phenotypic and chemotaxonomic properties, phylogenetic distinctiveness, and genomic data, we named strain F21T as Algoriphagus aquimaris sp. nov. and proposed that strain F21T (=KEMB 2250–007T= KCTC 72106T=JCM 33187T) in the genus Algoriphagus represents a novel species.

The present study aimed to investigate the significance and limitation for the practical application of high-flexibility glass-fiber (GF) grids as an alternative of conventional steel hoops...

This study examined the effects of the unit weight of concrete (ωc) on the flexural performance of shear walls with different amounts (Ash) of transverse reinforcement in the boundary eleme...

In this paper, we studied the heat flux effect of thermal metamaterials according to the distance of each layer, which can effectively suppress heat propagation and improve an adiabatic property, through the three-dimensional finite-difference time-domain simulation. Based on multiple layers of thermal meta-materials, the heat flux in the propagation direction could be suppressed by thermal meta-layers. The heat flux transferred through the gap between thermal meta-layers could also be efficiently suppressed by controlling the gap of each meta-layer in a concrete block. It was found that the heat transfer characteristics and the thermal insulation efficiency can be adjusted according to the change of the distance in the 5-layers meta-structure. Furthermore, the adiabatic property greatly changed depending on the location of the heat source and the thermal meta-structure transferred into the concrete. The appropriate thickness of each meta-layer should be used to suppress heat transfer and improve adiabatic properties in the concrete structure from the results of the 10-layer meta-structure.

This study examined the effect of the partial prestressing ratio on the flexural behaviour and degree (β) of moment redistribution of two-span lightweight aggregate concrete (LWAC) beams post-tensioned using external strands. The total length of the T-shape beam, between two exterior supports, was 10 600 mm. The unbonded prestressing three-wire strands were arranged with a harped profile of variable eccentricity, using two deviators at the sagging zone in each span and a deviator over the intermediate support. To simulate a uniform load, the top loads were uniformly distributed at four points in each span. Test results revealed that two-span externally post-tensioned LWAC beams typically exhibited smaller incremental stresses (Δfps) in the unbonded strands at the ultimate state and a smaller displacement ductility ratio than those of corresponding internally post-tensioned beams. The safety level of ACI 318-14 equations for Δfps was abruptly reduced for two-span externally post-tensioned beams, indicating non-conservative results for beams with partial prestressing ratios exceeding 0·66. The fib model code significantly overestimated the β values of post-tensioned LWAC beams. The ACI 318-14 code also tended to overestimate the β values of externally post-tensioned LWAC beams, although it yielded a relatively conservative estimate for externally post-tensioned LWAC beams.

Carbon dioxide concentration is steadily increasing in large cities. Consequently, durability evaluation of RC (Reinforced Concrete) structures considering carbonation is becoming a serious issue. Construction joints are used for the effective construction of concrete structures. However, cold joints which are caused by delayed placing and poor surface treatment are vulnerable to shear force and the inflow of carbon dioxide. In this study, an accelerated carbonation test was performed for normal-strength concrete using NPC (Normal Portland Cement) and slag after applying tensile and compressive stresses. The carbonation characteristics were quantified considering the effects of cold joint and the induced stress, and structural analysis was performed using the section laminae approach for a 2-span continuous reinforced concrete T-beam bridge. The service life of top and bottom concretes was evaluated considering the calculated stress, existing carbonation velocity equation, and carbonation function according to the stress. The service life showed a similar trend to that of the applied moment. Changes of 103.6%–64.7% (NPC) and 78.0%–108.8% (slag) were observed on the top surface, whereas changes of 103.8%–65.9% (NPC) and 112.9%–79.6% (slag) were observed on the bottom surface. The service life significantly decreased owing to the increasing carbonation depth for the cold joint in the tension part. This suggests that special care should be taken for cold joints during maintenance.

The present study aims to examine the limitation and significance to develop sustainable lightweight concrete using bottom ash aggregates and preformed foam (LWC-BF). As a positive action for sustainability, ordinary Portland cement (OPC) was replaced by using 50% ground-granulated blast-furnace slag (GGBS) and 20% fly ash (FA), and bottom ash particles were used for entire replacement of natural fine and coarse aggregates. To improve the thermal resistance of concrete, preformed foam was added at the maximum volume fraction of 25%. The test parameters investigated included unit binder content, foam volume fraction, and curing temperature. The different mechanical properties and thermal conductivity for LWC-BF were formulated from the regression analysis using test data. Additionally, the measured compressive strength, thermal conductivity, and air-dried density of LWC-BF were compared with the requirements for precast concrete (PC) insulation panel. Thus, a reliable mixture proportioning for the application to the PC insulation panel could be recommended with the use of unit binder content of 500 kg/m3 and foam volume fraction ranging from 10% to 25%.

Although the uniaxial tensile strength (ft) of concrete is one of the most essential properties in designing and analyzing the tensile performance of a concrete member, a rational consensus...

Since a concrete structure exposed to a sulfate environment is subject to surface ion ingress that yields cracking due to concrete swelling, its service life evaluation with an engineering modeling is very important. In this paper, cementitious repair materials containing bacteria, Rhodobacter capsulatus, and porous spores for immobilization were developed, and the service life of RC (Reinforced Concrete) structures with a developed bacteria-coating was evaluated through deterministic and probabilistic methods. Design parameters such protective coating thickness, diffusion coefficient, surface roughness, and exterior sulfate ion concentration were considered, and the service life was evaluated with the changing mean and coefficient of variation (COV) of each factor. From service life evaluation, more conservative results were evaluated with the probabilistic method than the deterministic method, and as a result of the analysis, coating thickness and surface roughness were derived as key design parameters for ensuring service life. In an environment exposed to an exterior sulfate concentration of 200 ppm, using the deterministic method, the service life was 17.3 years without repair, 19.7 years with normal repair mortar, and 29.6 years with the application of bacteria-coating. Additionally, when the probabilistic method is applied in the same environment, the service life was changed to 9.2–16.0 years, 10.5–18.2 years, and 15.4–27.4 years, respectively, depending on the variation of design parameters. The developed bacteria-coating technique showed a 1.47–1.50 times higher service life than the application of normal repair mortar, and the effect was much improved when it had a low COV of around 0.1.

Ultra-High Performance Concrete (UHPC) has been increasingly widely applied in civil and infrastructure engineering because of its outstanding properties in strength and durability. In particular, the research and application of UHPC in structures requiring high load-bearing capacity and high impact resistance, such as manhole covers, will have great practical significance. This paper presents experimental results of some properties of UHPC and uses the finite element method (FEM) to analyze and design two types of UHPC manhole covers according to the requirements for BS EN 124 classes A15 and B125. The research results show that the UHPC manhole covers need only 30 mm thickness without steel bar can ensure class A15.However, to meet the requirements of class B125,the UHPC manhole covers with a thickness of 60 mmneed a steel mesh of diameter size 10 mm reinforcement. The test results prove that the load-bearing capacity of the UHPC manhole covers from the experiments is consistent with the theory.

The objective of this study is to assess the shear friction characteristics of lightweight aggregate concrete (LWAC) prepared using artificially expanded bottom ash and dredged soil granules. A total of 37 concrete mixtures were prepared under the classification of three series. In the first and second series, the natural sand content for replacing lightweight fine aggregates and the water-to-cement ratio varied to obtain different densities and compressive strengths of concrete. The third series was designed to estimate the effect of the maximum aggregate size on the friction resistance along the shear crack plane of the monolithic interfaces. The frictional angle of the LWAC tested was formulated as a function of the ratio of the effective tensile and compressive strengths of concrete through the expansion of the integrated mathematical models proposed by Kwon et al., based on the upper-bound theorem of concrete plasticity. When predicting the shear friction strength of LWAC, the present mathematical model exhibits relatively good accuracy, yielding the mean and standard deviation of the ratios between experiments and predictions of 1.06 and 0.14, respectively, whereas the empirical equations proposed by the AASHTO provision and Mattock underestimated the results. Ultimately, an advanced modification factor for shear design of LWAC is proposed as a function of the density and compressive strength of concrete and the maximum size of aggregates.

A Gram-stain-negative, non-motile, mesophilic, short rod-shaped, aerobic bacterium designated as 318-1T was isolated from a marine sediment collected from Masan Bay, South Korea. Strain 318-1T grew optimally at pH 6–7, at 30 °C and in the presence of 2–3 % (w/v) NaCl, tolerant of up to 8 % (w/v) NaCl, and accumulated poly-β-hydroxybutyrate (PHB). A comparative analysis of 16S rRNA gene sequences revealed that strain 318-1T formed a distinct phyletic lineage in the genus Ruegeria (family Rhodobacteraceae , class Alphaproteobacteria ) and showed high sequence similarity to Ruegeria halocynthiae DSM 27839T (96.5 %) and Shimia haliotis DSM 28453T (96.3 %). Comparing the genome sequence of 318-1T with those of the type strains of seven species of the genus Rugeria and two species of the genus Shimia : the values obtained were below the thresholds with analysis of average nucleotide identities (ANI, 71.6–76.8 %) and in silico DNA–DNA hybridisation, genome-to-genome distance calculator (GGDC, 18.5–20.6 %). The DNA G+C content was 65.75 mol%. Chemotaxonomic data [predominant quinone ubiquinone Q10; polar lipid profile consisting of major compounds phosphatidylcholine (PC), phosphatidylglycerol (PG), an unidentified aminolipid and an unidentified lipid; major fatty acids summed feature 8 (C18 : 1ω7c and/or C18 : 1ω6c)] supported the affiliation of strain 318-1T to the Genus Ruegeria . Genomic, chemotaxonomic, and phenotypic differentiation of strain 318-1T from the members of the genus Ruegeria support as a novel species. On the basis of the results in this study, a novel species, Ruegeria lutea sp. nov., is proposed. The type strain is 318-1T (=JCM 30927T=KEMB 7306-525T=KCTC 72105T).

The objective of this study is to evaluate the sulfuric acid resistance of the concrete coated with bacterial-glycocalix-based biomimetic coating mortar. The variation of the compressive strength and mass of the coated concrete since the specimen was immersed into an aqueous solution of 5 % sulfuric acid were 0.88 and 12 % at the age of 56 days, respectively, showing a superior deterioration resistance. As a result, it can be concluded that the developed biomimetic coating mortar possesses a great potential for enhancing the deterioration resistance performance of concrete.

In this study repeated cyclic loading tests were carried out on seven shear wall specimens, which were fabricated in a real scale. The purpose of these experiments is to investigate the difference on the seismic performance of the wall depending on two methods of confining longitudinal bars at the wall boundaries and propose relaxed bar arrangement details that could be used in a moderate to high seismicity zone. The results showed that the seismic performance of special shear walls using overlapping loops as transverse reinforcement of the boundary element was similar to that of special shear walls using a closed hoop in strength, stiffness, and energy dissipation. This means the former can serve as an alternative for rational seismic design for moderate to high seismicity zones using overlapping hoops.

This paper proposes an integrated concrete surface treatment with surface enhancement via silicate impregnation and surface spraying with TiO2 (a photocatalyst). In this work, two types of silicate-based materials, sodium alumina silicate (SAS) and colloidal silica (COS) were used. Various tests were carried out to characterize the silicate properties and engineering performance of the impregnated concrete. In addition, the purification performance in concrete sprayed with TiO2 was investigated. Concrete impregnated with silicate and sprayed with TiO2 showed an improvement in the durability and mechanical performance because of the addition of the CSH gel and TiO2 barrier. After impregnation, the TiO2 applied by spraying retained good performance for the removal of acetaldehyde and methyl orange.

Electric arc furnace oxidizing slag (EOS), in the fine aggregate form, can effectively be utilized as a construction material. However, its engineering properties vary with the manufacturing processes employed and the producing district, thereby causing observed differences in material performance. In this study, EOS was obtained from steel manufacturing plants in South Korea, and engineering properties of standalone EOS, as well as in combination with cement mortar were separately evaluated. Test results demonstrate that EOS primarily comprises CaO, SiO2, and FeO in combination with 18.2% larnite, which possesses β-C2S crystal structure with a similar cement mineral. The EOS mortar combination demonstrated increasing compressive strength with an increase in EOS content due to the effect of a considerable amount of β-C2S present in EOS. The EOS-based mortar with electric arc furnace reduction slag (ERS) demonstrated unsatisfactory results in accordance with a criterion set for the length rate of change. This implies that more consideration is required toward the use of mixed ERS and EOS in cement mortars due to the swelling effect of ERS on dimensional stability.