Search

4 Abstract: The purpose of this study is to evaluate the performance on the compressive bonding shear strength of ultra-high strength steel fiber reinforced cementitous composites(UHSCC). As a result of compressive bonding shear strength through Direct shear test, It was found that the specimen(150×150×150 ) of NC(Normal concrete) + NC showed similar compressive bonding shear strength at whole experimental level. On the other hand, the specimen of UHSCC+ UHSCC showed decrease of compressive bonding shear strength from after 30 minutes of the retarded placement than 0 minute. As a result of analyzing failure mode of bonding interface, It was found that the specimen of NC + NC showed mixed failure at whole experimental level. In case of the specimen of UHSCC + UHSCC, it showed interface failure from the specimen that are 30 minutes, 60 minutes and 90 minutes of delay of concrete placing. As a result of analyzing XRD test in terms of the placement interface on the specimen of NC and UHSCC, relatively much amount of SiO2 was detected from the specimen of UHSCC than that of NC. It is judged that the most of main components of coating film shown in the specimen of UHSCC is SiO2. In conclusion, it is judged that UHSCC which is made from after 30 minutes of delay of concrete placing is unable to be used as structural member because of deterioration of bonding performance. From later study, it is judged that the improvement of bonding performance from the part of cold joint occurrence is necessary through the interface preparation method.

Increasing costs due to failure and reconstruction highlight the importance of concrete durability research. Carbonation of concrete, which can accelerate corrosion, is one of the major deterioration mechanisms in reinforced concrete structures. Experimental data has been used to develop carbonation prediction models, however, the service life predicted from various models can differ significantly. A potential solution is the application of an artificial neural network algorithm, which simulates the human nervous system, to evaluate concrete carbonation. In this study, the possibility of applying machine learning to predict concrete carbonation behavior is evaluated. A deep learning model, which has the best learning power among various machine learning models, was applied. This model is structured such that hidden layers of hierarchical artificial neural networks are formed in several layers. Existing carbonation experimental data (water-to-cement ratio 0.55 and 0.65, temperature 20 °C, relative humidity 60%, and CO2 concentrations 5% and 20%) was predicted by using the deep learning model which was also compared with the results of two other models – AIJ model and FEM analysis. Under the test conditions, the differences in carbonation rate coefficient between experimental data and the deep learning results ranged from 0.01 mm / year to 0.10 mm / year for the different water-to-cement ratios and CO2 concentrations. These results were comparable though somewhat better than results from FEM analysis, which showed corresponding differences ranging from 0.08 mm / year to 1.04 mm / year . The results were significantly better than the AIJ model, which showed differences ranging from 0.32 mm / year to 2.34 mm / year . These preliminary results suggest that a deep learning algorithm can be used to accurately predict concrete carbonation results.

Reducing the use of natural resources and ensuring proper reuse of industrial wastes are among the most practical potential solutions for sustainable development and a cleaner environment. The generation and disposal of waste materials that cause severe ecological impacts must be inhibited. Based on these ideas, we propose the utilisation of ceramic waste, which is inexpensive, abundant, and environmentally friendly, as a partial replacement for cement and fine aggregates in the preparation of some new types of mortars. This study investigates the long-term performance, mechanical properties, and durability of a mortar comprising ceramic waste as supplementary cementitious material and ceramic particles as fine aggregates. In addition, the environmental benefits of sustainable mortar are assessed. The structure, morphology, and thermal traits of the designed mixes are characterised using scanning electron microscopy (SEM), thermogravimetric analysis (TGA), differential thermal analysis (DTA), X-Ray Diffraction (XRD), and Fourier-transform infrared spectroscopy (FTIR) measurements. The results of this study indicate that the utilisation of ceramic waste as both a binder and a fine aggregate source significantly improved the compressive strength of the mortar and provided higher resistance against adverse environmental conditions. The positive interaction between ceramic waste and fine aggregates enabled a higher level of crystalline formation and, therefore, a reduction in porosity and cracking. In summary, it was demonstrated that ceramic waste blended mortars displayed enhanced performance and energy-saving qualities, which are both technically and environmentally useful and may lead to lower construction costs and increased sustainability.

Palm oil fuel ash (POFA) can be used as a supplementary cementitious material in concrete. In this study, micro and nano POFA were utilized as supplementary cementitious materials to produce high strength blended concrete. The effect of the binders on the fresh and hardened properties was investigated. Hence, the purpose of the study was to optimize the mixture proportions of high strength blended concrete with incorporated micro and nano POFA. The experiments were performed using Central Composite Design under the Response Surface Methodology. The results from the experimental program were used to validate the mathematical models developed from a statistical analysis of the responses. Based on the results, the model predictions were found to closely agree with the experimental data. The lack of a fit test and the high value of the coefficient of determination (R2) proved the adequacy of the regression model to predict the fresh and hardened properties of high strength blended concrete. An optimum mixture can be achieved with 10% micro POFA and 1.50–2.85% nano POFA which satisfies the optimization criteria.

The principal of molecular structure of cement mortar is important as it shows a component and interaction between cement and additive. By using a themogrativimetric analysis, the phase of mortar structure when exposed to high temperature can be determined. This paper presents the study on influence of epoxy resin without hardener on the microstructure of mortar. Mortar specimens were prepared with mass ratio of 1:3 (cement: fine aggregate), water-cement ratio of 0.48 and 5 to 20% epoxy resin of cement content. All tested specimens were subjected to wet-dry curing; where compressive strength, apparent porosity, thermogrativimetric analysis and fourier transformation infrared spectroscopy were measure. Result shows that, all strength properties of epoxy mortar were significantly higher than control sample and became constant at 10 % of epoxy resin ratio. Thermogrativimetric analysis shows the weight loss of epoxy mortar was almost similar for various percentage of epoxy resin while from fourier transformation infrared spectroscopy test, the component of epoxy mortar and normal mortar was significantly different.

As one of the fastest growing plants on earth, bamboo has a lot of species that range in size from a few centimeters to many meters tall. Bamboo is a unique plant where it can reach their full height up to 30m in a period of 2 to 4 months. Even though bamboo has been used traditionally as a construction material for thousands of years, there are not many studies about the mechanical properties of the bamboo itself. Thus, this paper presents an investigation on tensile and shear strength of four species treated bamboos that are available in Malaysia, which include Bambusa Vulgaris, Dendrocalamus Asper, Gigantochloa Scortechinii and Shizostachyum Grande. All the test was conducted according to the International Standard Organization (ISO-22157-2004). From the test result, Bambusa Vulgaris and Dendrocalamus Asper possess high tensile strength, meanwhile, Gigantochloa Scortechinii shows the highest value of shear strength compared with other species. Moreover, the test result also shows that Shizostachyum Grande possesses the lowest tensile and shear strength. Thus, with the available data on bamboo properties, structural engineers should take the advantages of bamboo to be used as a construction material in modern design buildings.

The electromagnetic pulse (EMP) is a destructive phenomenon which harms the building, telecommunication, and IT based infrastructure. Thus, it is required to reduce the effect of EMP using shielding materials. In the present study, we have used different thickness of concrete walls by incorporating 1 and 5 wt% of carbon black, as well as 100 &micro, m thick Zn&ndash, Al coating using the arc thermal metal spraying method (ATMSM). The EMP was evaluated using waveguide measurement fixture for shielding performance of the concrete wall in the range of 0.85 to 1 GHz frequency. The results reveal that the maximum value, i.e., 41.60 dB is shown by the 5-300-N specimen before application of Zn&ndash, Al coating where the thickness of concrete wall was 300 mm and 5% carbon black. However, once the 100 &micro, Al coating was applied on concrete specimen, this value was increased up to 89.75 dB. The increase in shielding values around 48 dB after using the Zn&ndash, Al coating is attributed to the reflection loss of the metal thermal spray coating. Thus, the Zn&ndash, Al coating can be used for EMP application instead of metallic plate.

Aluminum coating was deposited by arc thermal spraying process onto the steel substrate for the corrosion protection in aggressive environment. However, the arc thermal sprayed coating possesses defects in the coating. Thus, it is important to reduce the defects and enhance the corrosion resistance properties of the deposited coating using post-treatment. In the present study, we have used different concentrations of sodium phosphate mono basic (NaH2PO4) with 0.1 molar (M) calcium nitrate [Ca(NO3)2] as post-treatment solution to fill out the defects of the Al coating. It was observed by scanning electron microscopy (SEM) that 1 M NaH2PO4 with 0.1 M Ca(NO3)2 treated sample exhibited 71% reduction in defects compared to as coated samples. X-ray diffraction (XRD) was performed to determine the phases formed on the coating surface after treatments. XRD confirms the formation of sodium aluminum hydrogen phosphate (Na3Al(OH)(HPO4)(PO4)) and brushite (Ca(HPO4)(H2O)2) as composite oxides on the Al coating. Electrochemical results show that 0.5 M NaH2PO4 with 0.1 M Ca(NO3)2 treated sample has exhibited the highest charge transfer resistance and the lowest corrosion current density after 89 days of exposure in 3.5 wt.% NaCl solution. The enhancement in corrosion resistance of 0.5 M NaH2PO4 with 0.1 M Ca(NO3)2 treated sample attributed to the formation of adherent, sparingly soluble, and stable corrosion products. The volume fraction result of the corrosion products formed on 0.5 M NaH2PO4 with 0.1 M Ca(NO3)2 treated sample after 89 days of exposure in 3.5 wt.% NaCl using XRD confirms the highest amount of Bayerite (&alpha, Al(OH)3) deposition, thus, the corrosion rate of this sample was the lowest.

The draft genome sequence of Halorubrum sp. SAH-A6, isolated from commercial rock salts of the Danakil depression, Ethiopia. The genome comprised 3,325,770bp, with the G+C content of 68.0%. The strain has many genes which are responsible for secondary metabolites biosynthesis, transport and catabolism as compared to other Halorubrum archaea members. Abundant genes responsible for numerous transport systems, solute accumulation, and aromatic/sulfur decomposition were detected. The first genomic analysis encourages further research on comparative genomics, and biotechnological applications. The NCBI accession number for this genome is SAMN04278861 and ID: 4278861 and strain deposited with accession number KCTC 43215.

The carbonation of concrete is the prime deterioration factor in reinforced concrete (RC) structures. During carbonation, the atmospheric CO2 penetrates the concrete and lowers its alkalinity. The problem in predicting carbonation is difficult to address, and a reliable probabilistic carbonation assessment is required to consider different variables such as the concrete quality, the chemistry of the reinforcing steel, and the quality of finishing materials. In the present study, we have used different finishing materials on concrete to minimize the effects of carbonation with a field survey and accelerated conditions. In one experiment, the measurement of the thickness of the concrete cover and the application of the finishing materials were done on-site, whereas, in the other experiment, these were done under accelerated conditions. The carbonation depth and the coefficient of silk wallpaper (SWP) were reduced by half in an accelerated 5% CO2 experiment compared to the plain ordinary Portland cement (OPC), owing to the external physical barrier that reduces the penetration of CO2 through the pores of the concrete. We found that carbonation did not reach the embedded rebar even after 100 years when SWP finishing material was used. The probability model predicted that 51 years would be required for OPC and water paint (WP) to reach a 30% onset of corrosion initiation through accelerated carbonation, while SWP would require 200 years.

Prestressed concrete beams of size 150 × 150 × 1000 mm were designed, and two bonded cold-drawn 7 mm steel wires were stressed at 70% UTS under service conditions before concreting. The beams were cast with M40 grade concrete mix with various percentages of chlorides ranging from 0, 1, 2, and 3% by weight of cement and cured for 28 days. After 28 days, the stretching forces were released, the prestressing steel wire was allowed to regain its original length, the tensile stresses were transformed into a compressive stress in the concrete, and the stress corrosion behavior was assessed. Stress corrosion cracking (SCC) is due to the simultaneous action of stress, corrosive media, and material properties. The stress corrosion behavior of ungrouted pretensioned steel was assessed by using various electrochemical techniques such as electrochemical noise, open-circuit potential measurement, AC impedance, and potentiodynamic polarization measurements. The same experiments were conducted for rebars embedded in the concrete beam with various percentages of chlorides ranging from 0, 1, 2, and 3% by weight of chloride. After 30 days of exposure, the beams were tested for their flexural strength measurements to find out the load-bearing capacity.

A novel extremely halophilic archaeon, designated SAH-A6T, was isolated from a sample of commercial rock salt in Ethiopia. Cells of SAH-A6T were aerobic and pleomorphic. The strain was able to grow at concentrations of 15–30 % (w/v) NaCl (optimum 20–25 % NaCl), at pH 6.0–9.0 (optimum pH 7.0) and in a temperature range of 30–55 °C (optimum 37–45 °C). Mg2+ was not required for growth of SAH-A6T cells. On the basis of 16S rRNA gene sequence analysis, strain SAH-A6T was closely related to Halorubrum halodurans Cb34T (99.1 %), Halorubrum rubrum YC87T (98.9 %), Halorubrum aquaticum EN-2T (98.7 %), Halorubrum cibi JCM 15757T (98.4 %), Halorubrum luteum CGSA15T (97.3 %), Halorubrum lipolyticum 9-3T (97.1 %), Halorubrum tibetense 8W8T (97.1 %), Halorubrum kocurii JCM 1478T (97.1 %), Halorubrum halophilum B8T (97.0 %) and Halorubrum persicum C49T (97.0 %). Phylogenetic analysis based on the rpoB' gene sequences showed that strain SAH-A6T was closely related to Hrr. halodurans Cb34T (99.7 %), Hrr. aquaticum JCM 14031T (99.3 %) and other members of the genus Halorubrum (

It is a known fact that most thermoset resins are very sensitive to hot temperature, which hinders its ability to produce polymer-based products in a large scale. This study aims to investigate the potential of manufacturing polymer concrete in ambient room temperature of 30 ± 2 °C. A laboratory test was conducted with the introduction of polyester retarder additive into polyester resin formulation. All tests were carried out strictly in ambient room temperature (30 ± 2 °C). For comparison purpose, polyester resin without retarder additive was prepared as the control formulation under identical condition. Visual inspection was done on the fresh working life of polyester resin with 0%, 0.1%, 0.15%, and 0.2% of retarder additive in two different types of polyester resin-isophthalic and orthophthalic. Characterization on retarder additive was conducted under X-ray Diffraction (XRD), Fourier Transform Infrared Spectroscopy (FTIR) and, 1H and 13C Nuclear Magnetic Resonance (NMR). Investigation on the effects of polymer retarder additive on the physical and mechanical properties of polymer resin, polymer blended, and polymer concrete showed that the retarder additive had prolonged the working life and improved properties of polymer concrete. These proved the potential of adding retarder additive in polymer concrete in ambient room temperature of 30 ± 2 °C.

The effect of high volume nano palm oil fuel ash in the mortar was investigated. This study covers basic properties like the morphology of the composite, the hydration temperature, strength activity index, thermal conductivity and microstructure properties with regards to the variations in the mix design process of mortar. The effects of fineness of the ash on the strength properties of mortar were also investigated. To get a better performance in terms of strength development, the ash used has gone through heat treatment and was ground up to less than 1 μm. The incorporation of more than 80% nano size palm oil fuel ash as cement replacement has produced a mortar having a compressive strength more than OPC mortar at a later age. The overall results have revealed that the inclusion of high volume nano palm oil fuel ash can produce a mortar mix with high strength, good quality and most importantly that is more sustainable.

Chloride attacks concrete structures becoming a primary factor that deteriorates the durability of concrete structures. For this reason, research has been conducted on chloride ion penetration and diffusion. This research produced an accurate durability life prediction through reliability assessments and proposes a prediction method for the chloride ion diffusion coefficient of a concrete applied assessment program for reliability. As a result, test materials were fabricated using different admixtures and chloride ion diffusion coefficient was calculated by applying an RCPT test at each equivalent age. Based on these results, reliability prediction formulas were indicated through the reliability analysis for a durability life design using a Monte Carlo method. In addition, propriety was verified through comparisons and analysis using the proposed formula with the investigated data for chloride ion diffusion.

Recently, the interest in precast voided slab system for buildings is growing up according to the demand for high quality control and the increase in slab thickness. A hollow slab system is widely known as one of the effective slab system which can reduce self-weight of slab. However, in case of conventional precast voided slabs, It is uncertain to apply these slab system to two-way slabs because It have a rectangular shaped void-former. In this study, I-slab system that applies plate type and octagonal pillar type void-former on slim precast slab deck is developed, and then flexural capacity of the I-slab system Is evaluated by 4-pointed banding test. In addition, flexural capacities of I-slab system along the longitudinal and transverse axis are compared to verify the applicability of I-slab system to two-way slabs. Test results showed that I-slab had enough flexural strength and ductility for slab member. In addition, I-slab system Is found to be sufficiently possible to apply on two-way slabs.

Concrete with blast furnace slag (BFS) shows varied strength development properties under general temperature conditions. Therefore, a precise prediction of compressive strength using a full maturity model is desired. The purpose of this study is to predict the compressive strength of concrete with BFS by calculating the apparent activation energy (Ea) for each BFS replacement ratio, applying this activation energy to the equivalent age model, and then using the Carino model. For BFS replacement ratios of 0%, 10%, 30%, and 50%, Eais calculated as 33.475 kJ/mol, 37.325 kJ/mol, 41.958 kJ/mol and 45.541 kJ/mol respectively. Finally, the compressive strength of concrete with BFS is predicted.

Coating for corrosion protection was popular during the past decade. Thermal spray coating played an important role during that time. In recent years, arc thermal metal spray coating became widely used. Arc thermal metal spraying method (ATMSM) provides proven long-term protective coating systems using zinc, aluminum, and their alloys for steel work in a marine environment. This paper provides a review of the latest development in ATMSM by evaluating the current techniques in the industry and by analyzing technical data obtained from an extensive experimental program.

막걸리내 유산균의 특성을 연구하기 위해 알코올 내성이 있는 P. acidilactici K3를 첨가하여 막걸리를 담갔을 때와 시중에 판매되고 있는 생막걸리에 P. acidilactici K3를 첨가하여 한 달간 저장했을 때의 이화학적 변화와 젖산균수의 변화를 조사하였다. 그 결과, P.acidilactici K3를 첨가하여 발효하였을 때의 젖산균 생균수는 이를 첨가하지 않은 막걸리보다 3배 이상 많았으나 알코올 함량은 큰 차이를 보이지 않았으며 당도, 환원당, 총당, 탁도, pH, 산도, 아미노태 질소함량은 큰 차이를 보이지 않았다. 또한 시판되는 생막걸리에 P. acidilactici K3를 첨가하여 저장기간 동안 이화학적 변화를 관찰한 결과, 젖산균 생균수는 P. acidilactici K3를 첨가한 생막걸리는 107 CFU/ml을 유지하였으며, 알코올함량, 탁도, 당도, 환원당, 총당, pH, 총산, 아미노태 질소함량은 큰 차이가 없었다. 본 실험결과, 알코올 내성 젖산균 P. acidilactici K3가 막걸리의 이화학적 성질에 큰 영향을 미치지 않으며, 막걸리 발효균주 및 첨가제로의 응용이 가능함을 확인하였다.

Nanometric particles of a model hydrophobic substance curcumin were prepared by a novel method, namely, flash nanoprecipitation from a coarse oil-in-water emulsion. The method employs turbulent co-mixing of water with curcumin-loaded emulsion using manually-operated confined impingement jets mixer. A clear and stable dispersion of nanoparticles was formed in this process, and could be converted to dry, easily water-dispersible powder by spray drying. The mean size of the particles was about 40 nm by DLS, confirmed by Cryo-TEM. The obtained particles contained 20.4 wt% curcumin, X-ray analysis showed it was amorphous. The significant advantages of the studied process are its feasibility, speed and low cost. It does not require any special high-energy input equipment to reduce the droplet size of the initial emulsion as required by the vast majority of other methods, and relies on rapid turbulent mixing and on flow-induced shear stress formed in the simple, manually-operated mixer. Control experiments clearly indicate that employing emulsion, instead of a plain solution and flash nanoprecipitation instead of a simple antisolvent precipitation are advantageous in terms of particle size and stability.

An electromagnetic pulse (EMP) explodes in real-time and causes critical damage within a short period to not only electric devices, but also to national infrastructures. In terms of EMP shielding rooms, metal plate has been used due to its excellent shielding effectiveness (SE). However, it has difficulties in manufacturing, as the fabrication of welded parts of metal plates and the cost of construction are non-economical. The objective of this study is to examine the applicability of the arc thermal metal spraying (ATMS) method as a new EMP shielding method to replace metal plate. The experimental parameters, metal types (Cu, Zn-Al), and coating thickness (100–700 μm) used for the ATMS method were considered. As an experiment, a SE test against an EMP in the range of 103 to 1010 Hz was conducted. Results showed that the ATMS coating with Zn-Al had similar shielding performance in comparison with metal plate. In conclusion, the ATMS method is judged to have a high possibility of actual application as a new EMP shielding material.

In the field of construction, securing the early strength of concrete (on the first and third days of aging) has been an important problem in deciding the mold release time (i.e., shortening the construction time period). Therefore, the problem of reduced compressive strength in the early aging stage caused by mixing granulated blast furnace slag (GBFS) with concrete must certainly be resolved. In this study, we conduct experiments to explore methods for generating a concrete that develops an early strength equivalent to that of 100% OPC. The objective of this study is the development of an early-strength accelerator (ESA) made from an industrial by-product, for a GBFS-mixed cement mortar. This study also analyzes the mechanism of the early-strength generation in the concrete to evaluate the influence of the burning temperature of ESA on the optimal compressive strength of the concrete. According to the results of the experiment, GBFS, whose ESA is burnt at 800 °C, shows an activation factor of 102.6–104.7% in comparison with 100% OPC on the first and third days during early aging, thereby meeting the target compressive strength. The results of the micro-analytic experiment are as follows: ESA showed a pH of strongly alkaline. In addition, it was found that the content of SO3 was high in the chemical components, thus activating the hydration reaction of GBFS in the early age. This initial hydration reaction was thought to be due to the increase in the filling effect of the hydrate and the generation of C-S-H of the early age by the mass production of Ettringite.

Pediococcus acidilactici strain S1, a lactic acid-fermenting bacterium, was isolated from makgeolli-a Korean traditional fermented alcoholic beverage. Here we report the 1,980,172 bp (G + C content, 42%) genome sequence of Pediococcus acidilactici strain S1 with 1,525 protein-coding sequences (CDS), of which 47% could be assigned to recognized functional genes. The genome sequence of the strain S1 might provide insights into the genetic basis of the lactic acid bacterium with alcohol-tolerant.

Concrete carbonation damages the passive film that surrounds reinforcement bars, resulting in their exposure to corrosion. Studies on the prediction of concrete carbonation are thus of great significance. The repair of pre-built reinforced concrete (RC) structures by methods such as remodeling was recently introduced. While many studies have been conducted on the progress of carbonation in newly constructed buildings and RC structures fitted with new repair materials, the prediction of post-repair carbonation has not been considered. In the present study, accelerated carbonation was carried out to investigate RC structures following surface layer repair, in order to determine the carbonation depth. To validate the obtained results, a second experiment was performed under the same conditions to determine the carbonation depth by the Finite Difference Method (FDM) and Finite Element Method (FEM). For the accelerated carbonation experiment, FDM and FEM analyses, produced very similar results, thus confirming that the carbonation depth in an RC structure after surface layer repair can be predicted with accuracy. The specimen repaired using inhibiting surface coating (ISC) had the highest carbonation penetration of 19.81, while this value was the lowest for the corrosion inhibiting mortar (IM) with 13.39 mm. In addition, the carbonation depth predicted by using the carbonation prediction formula after repair indicated that that the analytical and experimental values are almost identical if the initial concentration of Ca(OH)2 is assumed to be 52%.

We evaluated the applicability of metal spray coating as a waterproofing/corrosion protection method for a concrete structure used for water purification. We carried out an ozone resistance test on four metal sprays and evaluated the water permeability and bond strength of the metals with superior ozone resistance, depending on the surface treatment method. In the ozone resistance test, four metal sprays and an existing ozone-proof paint were considered. In the experiment on the water permeability and bond strength depending on the surface treatment method, the methods of no treatment, surface polishing, and two types of pore sealing agents were considered. The results showed that the sprayed titanium had the best ozone resistance. Applying a pore sealing agent provided the best adhesion performance, of about 3.2 MPa. Applying a pore sealing agent also provided the best waterproofing performance. Scanning electron microscope analysis showed that applying a pore sealing agent resulted in an excellent waterproofing performance because a coating film formed on top of the metal spray coating. Thus, when using a metal spray as waterproofing/corrosion protection for a water treatment concrete structure, applying a pore sealing agent on top of a film formed by spraying titanium was concluded to be the most appropriate method.

A new technique was accepted to fill the porosity of Al coating applied by arc thermal spray process to enhance corrosion resistance performance in artificial ocean water. The porosity is the inherent property of arc thermal spray coating process. In this study, applied coating was treated with different concentrations of ammonium phosphate mono basic (NH4H2PO4: AP) solution thereafter dried at room temperature and kept in humidity chamber for 7d to deposit uniform film. The corrosion resistance of Al coating and treated samples have been evaluated using electrochemical impedance spectroscopy (EIS) and potentiodynamic techniques with exposure periods in artificial ocean water. Electrochemical techniques, X-ray diffraction (XRD), Raman spectroscopy, atomic force microscopy (AFM) and field emission-scanning electron microscopy (FE-SEM) indicated that phosphate ion would have been retarding corrosion of Al coating effectively. The formation of AHP (Ammonium Aluminum Hydrogen Phosphate Hydrate: NH4)3Al5H6(PO4)8.18H2O) on Al coating surface after treatment with AP is nano sized, crystalline and uniformly deposited but after exposure them in artificial ocean water, they form AHPH (Aluminum hydroxide phosphate hydrate Al3(PO4)2(OH)3(H2O)5) that is very protective, adherent, uniform and plate like morphology of corrosion products. The AHPH is sparingly soluble and adherent to surface and imparted improved corrosion resistance.

The relative performances of mechanical, permeability, and corrosion resistance properties of different concrete types were compared. Concrete types were made from ordinary Portland cement (OPC), Portland pozzolana cement (PPC), and Portland slag cement (PSC). Compressive strength test, effective porosity test, coefficient of water absorption, short-term accelerated impressed voltage test, and rapid chloride permeability test (RCPT) were conducted on M30 and M40 grades of concrete designed with OPC, PPC, and PSC cements for 28- and 90-day cured concrete types. Long-term studies such as microcell and electrochemical evaluation were carried out to understand the corrosion behaviour of rebar embedded in different concrete types. Better corrosion resistant properties were observed for PSC concrete by showing a minimum current flow, lowest free chloride contents, and lesser porosity. Besides, PSC concrete has shown less coefficient of water absorption, chloride diffusion coefficient (CDC), and lower corrosion rate and thereby the time taken for initiation of crack extended.

Concrete contains cement, which is known to emit large amounts of CO2 in production, absorbs a certain amount of CO2 by triggering a carbonation reaction with atmospheric CO2. However, this CO2 absorption is generally neglected when evaluating the CO2 emission from concrete. Thus, it is necessary to discover and consider ways to quantitatively evaluate the CO2 absorbed by concrete. To this end, a carbonation model that can accurately predict the carbonation depth of concrete is necessary. However, the existing carbonation prediction equation is a simple regression equation that merely considers factors such as water–cement ratio and CO2 concentration, and has a drawback as the results vary considerably form one researcher to another. Meanwhile, currently the use of fly ash, which is effective in reducing both of hydration heat and CO2 emission and enhancement of long-age strength, is increasing. Thus, in the present study, a method for measuring CO2 absorption by fly-ash-blended concrete structures using a carbonation model based on fly-ash-blended hydration was developed and evaluated. An apartment complex in which fly-ash-blended concrete was used is evaluated for its CO2 absorption by using the developed method in this study. As a result, carbonation depth, amounts of CO2 emission and absorption of fly-ash-blended concrete structure by design strength was obtained. The CO2 absorbed by service life is approximately 3.79–8.47 % of the CO2 emitted during the manufacturing of the concrete structure.

Partial replacement of Portland cement by slag can reduce the energy consumption and CO2 emission therefore is beneficial to circular economy and sustainable development. Compressive strength is the most important engineering property of concrete. This paper presents a numerical procedure to predict the development of compressive strength of slag blended concrete. This numerical procedure starts with a kinetic hydration model for cement–slag blends by considering the production of calcium hydroxide in cement hydration and its consumption in slag reactions. Reaction degrees of cement slag are obtained as accompanied results from the hydration model. Gel-space ratio of hardening slag blended concrete is determined using reaction degrees of cement and slag, mixing proportions of concrete, and volume stoichiometries of cement hydration and slag reaction. Furthermore, the development of compressive strength is evaluated through Powers\'gel-space ratio theory considering the contributions of cement hydration and slag reaction. The proposed model is verified through experimental data on concrete with different water-to-binder ratios and slag substitution ratios.

We examine a process of preparing oil-in-water nanoemulsions by quenching (diluting and cooling) precursor microemulsions made with nonionic surfactants and a cosurfactant. The precursor microemulsion structure is varied by changing the concentration of the cosurfactant. Water-continuous microemulsions produce initial nanoemulsion structures that are small and simple, mostly unilamellar vesicles, but microemulsions that are not water-continuous produce initial nanoemulsion structures that are larger and multilamellar. Examination of these structures by cryo-electron microscopy supports the hypothesis that they are initially vesicular structures formed via lamellar intermediate structures, and that if the lamellar structures are too well ordered they fail to produce small simple structures.

Steam curing is necessary to be used in the manufacturing of precast concrete, thus, a large amount of energy is consumed and the turnover of forms is low. This practice leads to reduction in productivity. This paper focuses paper focuses on developing early stage strength for precast concrete of more than 10 MPa after 6 h of curing at room temperature without steam curing. Various micro-analysis tools such as TG/DTA, Conduction Calorie Meter, XRD, SEM and MIP were conducted on concrete and cement paste with the amount used of calcium-based hardening accelerator (CHA) for tricalcium silicate (C 3 S). Results show that the reaction effect of the CHA was terminated before reaching 12 h, the initial setting of concrete was in 80 min with 3% of CHA. The rate of heat evolution is increased in the mechanism of developing the compressive strength in early age and the yield of Ettringite, Ca(OH) 2 and C–S–H is increased at early age due to the fact that the CHA stimulates tricalcium aluminate (C 3 A) and C 3 S in high early strength cement when using calcium-based hardening accelerator into high early strength cement. Additionally, the pore volume of range of 20–100 nm decreased with the CHA content.

The depth of chloride ion permeation from a concrete surface can be monitored in reinforced concrete structures. The purpose of this study is to develop and apply a thin-film sensor based on the measurement of changes in electrical resistance of the sensing elements in order to follow the chloride ion penetration in mortar. The proposed thin-film sensors were placed in mortar specimens intrinsically containing chlorides, and mortar specimens impregnated with chloride solutions then subjected to accelerated corrosion in a NaCl solution. For making a film sensor, a screen printer machine was used. Silver (Ag) paste and iron (Fe) powder were coated on the thin-film sensor that reacts to chloride ion in mortar. As a result of experimental testing, the appropriate ratio of Ag to Fe was >1:2. The electrical resistance of the sensors increased with the degree of corrosion behavior of thin-film sensor. The time to the first change in electrical resistance decreased along with the degree of corrosion as the distance from the mortar surface decreased. The proposed thin-film sensors are thus confirmed to be capable of monitoring the depth of chloride permeation in mortar with sufficient accuracy.

This paper presents the experimental results on the behavior of fly ash geopolymer concrete incorporating bamboo ash on the desired temperature (200 &deg, C to 800 &deg, C). Different amounts of bamboo ash were investigated and fly ash geopolymer concrete was considered as the control sample. The geopolymer was synthesized with sodium hydroxide and sodium silicate solutions. Ultrasonic pulse velocity, weight loss, and residual compressive strength were determined, and all samples were tested with two different cooling approaches i.e., an air-cooling (AC) and water-cooling (WC) regime. Results from these tests show that with the addition of 5% bamboo ash in fly ash, geopolymer exhibited a 5 MPa (53%) and 5.65 MPa (66%) improvement in residual strength, as well as 940 m/s (76%) and 727 m/s (53%) greater ultrasonic pulse velocity in AC and WC, respectively, at 800 &deg, C when compared with control samples. Thus, bamboo ash can be one of the alternatives to geopolymer concrete when it faces exposure to high temperatures.

Global demand for cement in construction industry is expected to increase to 400% by year 2050 hence, contributes to the increasing global CO2 emission. One of the alternative options that considered realistic to reduce usage of cement is using the blended concrete which replacing cement with other waste materials that contain cementitious properties. In this study, the engineering properties of high strength blended concrete such as workability, compressive, splitting tensile and flexural strengths were investigated. To achieve the aim, a total of 126 concrete specimens were produced that consist of concrete cubes, cylinders and prisms. Ten different mixes of blended concrete with the cement replacement of 0 to 30% of the 45-micron size of POFA and 1-3% of nano POFA. The hardened properties of blended concrete were determined at the age of 7, 28 and 90 days. The findings revealed that, the enhancement of the 2-3% of nano POFA improved the concrete workability with 5 to 10 mm increment of slump height. At all age of curing, the blended concrete consists of 10% of micro POFA and 1 to 3% of nano POFA showed a higher strength compared with the plain concrete. The highest enhancement strength of compressive, splitting tensile and flexural were 4%, 10% and 11% respectively at certain age of curing. These results showed the improvement of the engineering properties of the blended concrete with enhancement of the nano POFA.

Lactic acid bacteria (LAB) are a representative group of probiotics and used in many fermented foods and beverages. Several recent studies have shown that LAB are present in makgeolli which is a traditional Korean alcoholic beverage. However, most LAB are intolerant of more than 6% (v/v) alcohol concentrations. For this reason, alcohol-tolerant LAB are isolated from kimchi, makgeolli and nuruk using alcohol containing selective media. After being cultured in MRS broth containing 13% (v/v) alcohol, the two strains which showed the highest increasing O.D values, were finally selected. As results of 16S rRNA gene sequencing and biochemical characterization using an API kit, the two species were identified as Pediococcus acidilactici K3 and S1. In addition, the identified two strains produced bacteriocins against Staphylococcus aureus. When compared with the P. acidilactici type strain, the two selected strains possessed two to three time higher growth on 12-13% (v/v) alcohol containing MRS broth. The viability of P. acidilactici K3 and S1 when inoculated in makgeolli and stored at did not decrease through a period of one month indicating that the selected strains can be used for LAB containing makgeolli.

Archaea are prokaryotic organisms distinct from bacteria in the structural and molecular biological sense, and these microorganisms are known to thrive mostly at extreme environments. In particular, most studies on halophilic archaea have been focused on environmental and ecological researches. However, new species of halophilic archaea are being isolated and identified from high salt-fermented foods consumed by humans, and it has been found that various types of halophilic archaea exist in food products by culture-independent molecular biological methods. In addition, even if the numbers are not quite high, DNAs of various halophilic archaea are being detected in human intestines and much interest is given to their possible roles. This review aims to summarize the types and characteristics of halophilic archaea reported to be present in foods and human intestines and to discuss their application as well.

Flash nanoprecipitation (FNP) is a process that, through rapid mixing, stabilizes an insoluble low molecular weight compound in a nanosized, polymer-stabilized delivery vehicle. The polymeric components are typically amphiphilic diblock copolymers (BCPs). In order to fully exploit the potential of FNP, factors affecting particle structure, size, and stability must be understood. Here we show that polymer type, hydrophobicity and crystallinity of the small molecule, and small molecule loading levels all affect particle size and stability. Of the four block copolymers (BCP) that we have studied here, poly(ethylene glycol)-b-poly(lactic-co-glycolic acid) (PEG-b-PLGA) was most suitable for potential drug delivery applications due to its ability to give rise to stable nanoparticles, its biocompatibility, and its degradability. We found little difference in particle size when using PLGA block sizes over the range of 5 to 15 kDa. The choice of hydrophobic small molecule was important, as molecules with a calculated water-octanol partition coefficient (clogP) below 6 gave rise to particles that were unstable and underwent rapid Ostwald ripening. Studies probing the internal structure of nanoparticles were also performed. Analysis of differential scanning calorimetry (DSC), cryogenic transmission electron microscopy (cryo-TEM), and (1)H NMR experiments support a three-layer core-shell-corona nanoparticle structure.

The purpose of this research is to verify the performance of hardening accelerator in cement paste through mechanical performance evaluation and micro structure analysis on hardening accelerator for development of super high early strength concrete. The research results showed that hardening accelerator produced when hydrated with cement, enhancing the degree of saturation of Ca ion by using differential thermal analysis. Moreover, porosity was reduced rapidly as capillary pores were filled by hydration products of . According to the experiment using hydration measurement testing, when 1% and 3% of accelerator were mixed, hydration rate increased toward the second peak point compared to high early strength cement, before the first peak point disappeared. It turned out that adding accelerator accelerated the hydration rate of cement, especially . The shape of C-S-H is shown depending on the amounts of accelerator added and the production and age of by using SEM to observes hydration products. Therefore, it`s evident that hardening accelerator used in this research increases amounts of and accelerates , it is effective for the strength development on early age.

To select a most desired mix proportion that meets required performances according to the quality of recycled aggregate, a large number of experimental works must be carried out. This paper proposed a new design method for the mix proportion of recycled aggregate concrete to reduce the number of trial mixes. Genetic algorithm is adapted for the method, which has been an optimization technique to solve the multi-criteria problem through the simulated biological evolutionary process. Fitness functions for the required properties of concrete such as slump, density, strength, elastic modulus, carbonation resistance, price and carbon dioxide emission were developed based on statistical analysis on conventional data or adapted from various early studies. Then these fitness functions were applied in the genetic algorithm. As a result, several optimum mix proportions for recycled aggregate concrete that meets required performances were obtained.