Application of a Vertical “Electric Sieve” to Mitigate and Prevent Salinization in Coastal Soil

This study explored the application of a Vertical Electrokinetic system (V-EK) with multilayer electrodes in shallow soil to form an “Electric Sieve” to mitigate and prevent the soil salinization caused by salts rising from shallow groundwater in the coastal areas. In the model V-EK system, the electric resistances of soil column, reversely corresponding to salinity, at the applied voltages 4, 10 and 20 V were 266, 487 and 1272 Ω, respectively. Meanwhile, lower electrical conductivity (EC, between 67-230 μs/cm) were observed in the soil within 50 cm below the surface at the voltages of 10 V and 20 V, which was much lower than the minimum value (581 μs/cm) of the control with no current applied. For the control column without EK treatment (0 V), soil in the surface layer had the highest EC value at 1721 μS/cm due to the salts rising from the bottom, and the EC values of soil beneath the surface were in the range of 581-1127 μS/cm. Compared to control column, the level of ions in the surface soil significantly declined after V-EK treatment, especially for the column with voltage at 10 V and 20V. When voltage was at 20 V, Na+ was detected at a range of 0.06-0.08mg/g in the surface soil, a >99% reduction when compared to the controls. Similar efficacy was observed for chloride (Cl-), in the V-EK column with the voltages at 10 V and 20V.

Valorisation of Partially Oxidized Tailings in a Cover System to Reclaim an Old Acid Generating Mine Site

The reclamation of acid-generating mine tailings typically involves building cover systems to limit interactions with water or oxygen. The choice of cover materials is critical to ensure long-term performance, and partly determines the environmental footprint of the reclamation strategy. The objective of this research was to evaluate if tailings pre-oxidized on-site could be used in cover systems. Column experiments were performed to assess the effectiveness of a cover with capillary barrier effects (CCBE), where the moisture retention layer (MRL) was made of pre-oxidized tailings with little to no remaining sulfides (LS tailings). The columns were submitted to regular wetting and drying cycles, and their hydrological and geochemical behaviour was monitored for 510 days. The LS tailings showed satisfying hydrological properties as an MRL and remained saturated throughout the test. The concentrations of Cu in the drainage decreased by more than two orders of magnitude compared to non-covered tailings. In addition, the pH increased by nearly one unit compared to the control column, and Fe and S concentrations decreased by around 50%. Despite these improvements, the leachate water remained acidic and contaminated, indicating that acid drainage continued to be generated despite a hydrologically efficient CCBE.

Performance of Retrofitted Square Reinforced Concrete Column using Wire Mesh and SCC Subjected to Cyclic Load

One way to restore or increase the strength of the structure against earthquakes is to use retrofit method and wire mesh is a material that has high prospects as retrofit material. The purpose of this study was to examine the use of wire mesh as a retrofit material on reinforced concrete columns burdened with cyclic loads. In this study, testing of 3 square column samples of reinforced concrete with dimensions of 300 300 mm. The first specimen is fully retrofit on the entire cross-section of the column, the second specimen is retrofitted on the plastic hinge area of the column and the third specimen is a control column without retrofit. In the first and second specimens were retrofitted with wire mesh size M6 using SCC which was then tested with a cyclic load using displacement control method based on the provisions stipulated in the Indonesian Standard SNI 7834:2012. From the test results and analysis results, it was found that the capacity and ductility of displacement in retrofit specimens increased significantly compared to specimens that were not retrofit. In addition, the decrease in stiffness in retrofit specimens was smaller than in non-retrofit specimens. As for the value of energy dissipation in fully retrofit specimens and in retrofit on the plastic hinge area is almost close. Based on these conditions, the use of wire mesh size M6 and SCC can be used as retrofit material on the column that is burdened with cyclic load. Doi: 10.28991/cej-2021-03091685 Full Text: PDF

Thematic Accuracy Quality Control by Means of a Set of Multinomials

The error matrix has been adopted as both the “de facto” and the “de jure” standard way to report on the thematic accuracy assessment of any remotely sensed data product. This perspective assumes that the error matrix can be considered as a set of values following a unique multinomial distribution. However, the assumption of the underlying statistical model falls down when true reference data are available for quality control. To overcome this problem, a new method for thematic accuracy quality control is proposed, which uses a multinomial approach for each category and is called QCCS (quality control column set). The main advantage is that it allows us to state a set of quality specifications for each class and to test if they are fulfilled. These requirements can be related to the percentage of correctness in the classification for a particular class but also to the percentage of possible misclassifications or confusions between classes. In order to test whether such specifications are achieved or not, an exact multinomial test is proposed for each category. Furthermore, if a global hypothesis test is desired, the Bonferroni correction is proposed. All these new approaches allow a more flexible way of understanding and testing thematic accuracy quality control compared with the classical methods based on the confusion matrix. For a better understanding, a practical example of an application is included for classification with four categories.

Flexural performance of RC columns with FRCC jacketing

A new repair technique consisting on a light jacketing with Fibre Reinforced Cementitious Composites (FRCC) for existing reinforced concrete (RC) buildings has been recently proposed to reduce durability problems of RC members and enhance their capacity. In this work, the effects of FRCC jacketing on the flexural capacity of existing RC columns, with and without a pre-damage, has been evaluated of full-scale specimens under cyclic loading. Digital Imagine Correlation (DIC) was also adopted for understanding the strain distribution in the FRCC jacket. The results shown that the FRCC jacket without a proper anchorage slightly enhanced the flexural capacity of the column. The strengthened column experienced a low damage with respect to control column, but occurrence of premature failures did not allow the achievement of high levels of deformation capacity and ductility.

Structural Behavior of Unbalanced Section self-compacting reinforced concrete axially Loaded columns

Eight (120 mm) square and (1 m) long reinforced concrete columns were tested under axial load to large inelastic deformations. The main purpose of this research was to investigate the behavior of column sections confined by rectilinear ties. Major variables considered in this program included: (1) Distribution of longitudinal and lateral steel, including unbalanced section due to the asymmetric distribution of reinforcing steel bars (2) type of concrete; normal concrete and self-compacting concrete. Finite element model was performed to validate the experimental results of this investigation. Test results indicate that a asymmetric distribution longitudinal bars results in desired performance of columns. Unsupported longitudinal bars and its number effective only at large deformations and result in rapid deterioration of column behavior at a later stage. There is 8.75% and 35.65% decrease in ultimate capacity under the control column, asymmetric distribution of reinforcing steel bars appears a more brittle while symmetric bars yields more elastic than brittle, it adds safety when failure happens.

Hemoadsorption of high-mobility-group box 1 using a porous polymethylmethacrylate fiber in a swine acute liver failure model

Background: High-mobility-group box chromosomal protein 1 has been identified as an important mediator of various kinds of acute and chronic inflammation. In this study, we aimed to develop a column that effectively adsorbs high-mobility-group box chromosomal protein 1 by altering the pore size of the fiber. Materials and methods: First, we produced three types of porous polymethylmethacrylate fiber by altering the concentration of polymethylmethacrylate dissolved in dimethylsulfoxide. We then selected a fiber based on the results of an in vitro incubation test of high-mobility-group box chromosomal protein 1 adsorption. Using the selected fiber, we constructed a new column and tested its high-mobility-group box chromosomal protein 1 adsorption capacity during 4-h extracorporeal hemoperfusion in a swine acute liver failure model. Results: Electron microscope observation showed that the three types of fibers had different pore sizes on the surface and in cross section, which were dependent on the concentration of polymethylmethacrylate. In the in vitro incubation test, fiber with moderate-sized pores demonstrated the highest adsorption capacity. In the in vivo hemoperfusion study, the ratio of the high-mobility-group box chromosomal protein 1 concentration at the outlet versus the inlet of the column was significantly lower with the new column than with the control column during 4-h extracorporeal hemoperfusion. The normalized plasma level of high-mobility-group box chromosomal protein 1 at 12 h after the completion of hemoperfusion was significantly lower with the new column than with the control column. Conclusion: The newly developed polymethylmethacrylate column adsorbs high-mobility-group box chromosomal protein 1 during hemoperfusion in swine ALF model.

In Vitro Study of Endotoxin Adsorption by a Polymyxin B-Immobilized Fiber Column

Background: Polymyxin B-immobilized fiber (PMX-F) columns are used as therapeutic interventions for septic shock. The clinical efficacy has been reported for 2-h applications, but their ability to adsorb endotoxin over longer treatments has not been fully elucidated. We hypothesized that PMX-F columns are capable of endotoxin removal for more than 2 h. Method: We designed closed circuits incorporating either a PMX-F column with an 8.5-mL priming volume (PMX-01R) or a sham-control column, and used inactivated fetal bovine serum as the circulating perfusate. Endotoxin was continuously injected at a fixed rate for 24 h, and perfusate endotoxin concentrations were measured at fixed time points. PMX-01R endotoxin adsorption was calculated from the difference in the endotoxin concentrations. Results: PMX-01R endotoxin adsorption increased continuously in a virtually linear manner. Conclusions: The PMX-01R column showed sustained endotoxin adsorption for at least 24 h. This indicated that PMX-F columns would be capable of clinical endotoxin removal for 24 h.

Strength and Ductility of RC Columns Retrofitted by FRP under Cyclic Loading

Rapid increasing of population and limited city area as well as better awareness on the green open area of the city, which is ideally about 30 percent, have forced the development of the buildings vertically. The increasing number of high-rise buildings and skyscrapers are the evidence that the development of the buildings in the cities of Indonesia are heading towards the over-ground space. However, the vertical development is known to be highly vulnerable to earthquake hazard. The revised Indonesian seismic map has increased the seismic load in most of the seismic zones in Indonesia. To create a safe and healthy city, a comprehensive urban planning and design is required. A good urban planning and code-based design must also be adopted to assure a safe building structure for the dwellers. This study is intended to observe the possibility of using alternative materials to improve the performance of the existing buildings which have not followed the existing earthquake-resistant building code through the implementation of Fiber Reinforced Polymer (FRP) wrap on structural members. The strength and ductility enhancements of the columns retrofitted with external confinement using FRP are found when compared with the unconfined control column. The results indicated that the maximum loads of each confined columns have increased by 33.52, 54.97, 36.61, and 40.73 percent, respectively, for columns C-1G, C-1C, C-1RC, and C-1RG. The ductility of columns C-1C and C-1G have increased by 122.73 and 53.30 percent, but decreased by 15.24 and 66.31 for columns C-1RG and C-1RC when compared with the unconfined control column C-1, respectively. This is due to the unintended premature failure at the upper end of the column C-1G and an indication that the secondary fiber direction which was placed vertically has contributed to the longitudinal steel of C-1RC in increasing its capacity.