Original article Neotectonic formation and localization conditions of groundwater reserves in over-deepened sections of the Kitoy River valley

The purpose of the study is to identify the main neotectonic formation features of over-deepened valleys where fresh groundwater is localized. The object and the subject of the study is the Kitoy deposit of drinking groundwater located in the U-shape valley of the Kitoy river, which is composed of constratal alluvium, as well as hydrogeological and hydrogeochemical conditions of the deposit. The study of the over-deepened alluvial dislocation is carried out based on the analysis of the works performed at the Kitoy fresh groundwater deposit for the period from 1956 to 2020. The deposit is located at the southern margin of the Siberian platform within the Irkutsk-Cheremkhovo plain. The article studies the origin of the dislocation formed by the intersection of waves of pitching and subsidence of the Baikal and Sayan directions accompanied by the groundwater localization. The described over-deepened valley is 9-39 m thick. It is represented by boulder-gravelpebble material with sandy aggregate. The average filtration coefficient for the deposit is 122 m/day, the average water permeability coefficient is 3400 m2 /day, whereas beyond its limits the indicators decrease. The qualitative composition of groundwater meets the standards, but some areas feature increased mineralization, high content of iron and manganese due to the inflow of groundwater from the underlying Jurassic aquifers. The authors made a generalization on the variations of the effective thickness of the aquifer and analyzed the favorable conditions for the formation of fresh groundwater within the depression structure for the purpose of water supply for drinking and household uses.

Mechanical Properties and Durability of Recycled Aggregate Permeable Concrete

The recycled aggregate permeable concrete made of reused construction wastes is very important for realizing the sustainable development of the construction industry, it can alleviate the adverse impact of surface runoff during storm and the urban heat island effect. Therefore, this paper studied the mechanical properties and durability of recycled aggregate permeable concrete. At first, a few properties of the target material, including bulk density, moisture content, water absorption, compressive strength, and water permeability coefficient, were tested respectively. Then, based on the orthogonal test, the performance of the target material was analyzed, and the analysis steps of the range analysis method and the variance analysis method in the orthogonal test were given. At last, the mechanical properties and durability of the target material were tested via experiments, and the relevant test results and analysis were elaborated.

Influence of Heat Reflective Coating on the Cooling and Pavement Performance of Large Void Asphalt Pavement

To reduce the temperature of asphalt pavement in summer, and alleviate the urban heat island effect, a comprehensive method of combining a heat reflective coating and large void asphalt pavement was proposed. Using the developed coating cooling test equipment, the cooling effect of the coating on a large void asphalt mixture was studied in six different proportions, four different colors, and four different dosages, and the durability of the coating was verified by abrasion tests. Finally, the best dosage of the coating was recommended through an adhesion test of the coating, and a water permeability and anti-skid performance test of the pavement. The results show that the reflectivity of the coating can be improved by adding functional fillers, of titanium dioxide and floating beads, into the coating. The order by reflectivity and cooling effect of the four color coatings was green > red > gray > blue, and the maximum cooling value of the green coating reached 9.7 ℃. The cooling performance of the coating decreased with the increase of wear time, and the rate of decrease was fast, then slow, and finally tended to be stable after 20,000 times wear. The coating reduced the anti-skid performance and the water permeability coefficient of large void asphalt pavement, but still maintained a high level. The green coating with 15% titanium dioxide and 10% floating beads is recommended as the cooling coating for large void asphalt pavement, and its dosage should be controlled at about 0.4–0.8 kg/m2.

Performance Assessment of SWRO Spiral-Wound Membrane Modules with Different Feed Spacer Dimensions

Reverse osmosis is the leading process in seawater desalination. However, it is still an energy intensive technology. Feed spacer geometry design is a key factor in reverse osmosis spiral wound membrane module performance. Correlations obtained from experimental work and computational fluid dynamics modeling were used in a computational tool to simulate the impact of different feed spacer geometries in seawater reverse osmosis spiral wound membrane modules with different permeability coefficients in pressure vessels with 6, 7 and 8 elements. The aim of this work was to carry out a comparative analysis of the effect of different feed spacer geometries in combination with the water and solute permeability coefficients on seawater reverse osmosis spiral wound membrane modules performance. The results showed a higher impact of feed spacer geometries in the membrane with the highest production (highest water permeability coefficient). It was also found that the impact of feed spacer geometry increased with the number of spiral wound membrane modules in series in the pressure vessel. Installation of different feed spacer geometries in reverse osmosis membranes depending on the operating conditions could improve the performance of seawater reverse osmosis systems in terms of energy consumption and permeate quality.

Permeability of Concrete and Correlation with Microstructure Parameters Determined by 1H NMR

Water and gas permeability coefficients of concrete with different water-binder (w/b) ratios and admixtures were measured by a self-designed test device based on the steady-state flow method for liquid and the method of differential pressure in stability for gas, respectively. In addition, the micropore structure of concrete was determined by 1H nuclear magnetic resonance (NMR). Results indicated that there are good correlations between water and gas permeability of concrete with different w/b ratios, with correlation coefficient greater than 0.90. Better correlations between water permeability and segmental contributive porosity ranged from 10 to 100 nm and 100 to 1000 nm can be identified, but the gas permeability is more relevant to the segmental contributive porosity ranging from 100 to 1000 nm. Moreover, the correlation between water permeability and contributive porosity for each pore diameter is always better than that of gas permeability. The influence of admixtures on the relationship between permeability and pore size distribution of concrete is significant. Moreover, water permeability coefficient is one or two orders of magnitude lower than the gas permeability coefficient.

Influence of Partial Replacement of Cement and Sand with Coal Bottom Ash on Concrete Properties

An experimental study was accomplished to study the effect of replacement of both cement and sand with coal bottom ash (CBA) on the properties of the concrete. Control mix was prepared without coal bottom ash replacement and nominated as series A. The mixes of series B were prepared with20 % replacement of cement with 30 hours ground coal bottom ash (GCBA). Mixes of series C were prepared with four percentages (5,10,15,20) of CBA as partial replacement of sand. Mixes of Series D mixes were prepared as a combination of series B and C. Slump flow, compressive strength, and water permeability properties were investigated. Series D mixes showed lower workability compared to the series C mixes and control mix. Compressive strength of series D mix gained slightly higher strength compared to the control mix but lower than series C strength. Series C mixes absorbed more water compared to control mix concrete. Series D mixes achieved lower water permeability coefficient compare to series C which showed lower water permeability than the control.

Effect of Compaction and Hydraulic Gradient on Subbase Layer Permeability

In order to prevent or at least reduce the deformation of road surface, it is necessary to ensure adequate water permeability of the structural layers and control of groundwater level. In geotechnical engineering, the water permeability of the mineral aggregates or soils is determined using a constant head water permeability apparatus. In order to assess the suitability of the results, it is necessary to take into account particle size distribution of the test object and perform the test at different hydraulic ramps. The aim of this research is to define and clarify unbound mineral aggregate mixtures hydraulic gradient and compaction level of road layer impact on water permeability. The following properties have been determined during the tests: particle size distribution, particle density, Proctor density, optimum water quantity, water permeability under different compaction and hydraulic slopes. Based on the results of the research, low-dustiness non-bonded mineral materials are recommended for frost resistant layers. For the water-permeability coefficient test, it is recommended that the test layer should be compacted to a design compaction ratio and the hydraulic gradient should not be higher than 1.0. Other conclusions and recommendations for further research and for improvement of water permeability functionality in the road pavement are presented.

Estimation of Recycled Concrete Aggregate’s Water Permeability Coefficient as Earth Construction Material with the Application of an Analytical Method

Creating models based on empirical data and their statistical measurements have been used for a long time in the economic sciences. Increasingly, these methods are used in the technical sciences, such as construction and geotechnical engineering. This allows for reducing the costs of geotechnical research at the design stage. This article presents the research carried out on Recycled Concrete Aggregate (RCA) material with is reclaimed crushed concrete rubble. Permeability tests were carried out using the constant head method. Tests were conducted on blends of RCA with the following particle size ranges: 0.02–16 mm, 0.05–16 mm, 0.1–16 mm, and 0.2–16 mm. The gradients used during the tests were between 0.2 to 0.83, which corresponds to gradients encountered in earth construction and are below the critical gradient. Directly from the tests, the flux velocity for the range of tested gradients were calculated based on filtered water volume measurements. The values of the permeability coefficient (k) were then recalculated. Finally, statistical methods were used to determine which physical parameters of the tested material affect the permeability coefficient. The physical parameters selected from the statistical analysis were used to create a model describing the phenomenon. The model can be used to determine the permeability coefficient for a mixed RCA material. The article ends with conclusions and proposals concerning the use of models and the limits of their applicability.

Out of the blue; Phototropins of the leaf vascular bundle sheath mediate the blue light regulation of the leaf hydraulic conductance

ABSTRACTThe leaf vascular bundle sheath cells (BSCs), which tightly envelop the leaf veins, constitute a selective dynamic barrier to water and solutes radially entering the mesophyll and play a major role in regulating the leaf radial hydraulic conductance (Kleaf). Recently, we showed that the BSCs’ plasma membrane H+-ATPase, AHA2, increases Kleaf by acidifying the xylem sap. Since BL reportedly increases Kleaf and we found the blue light (BL) receptor genes, PHOT1 and PHOT2 expressed in the Arabidopsis BSCs, we hypothesized that, similar to the guard cells (GCs) BL signal transduction pathway, the BSCs’ PHOT1 and PHOT2 activate the BSCs’ H+-ATPase and thus regulate Kleaf. Indeed, under BL illumination, the Kleaf in the knockout mutant lines phot1-5, phot2-1, phot1-5phot2-1 and aha2-4 was lower than in WT. BSCs-directed complementation (using the SCR promoter) of phot1-5 and aha2-4 respectively by PHOT1 and AHA2, restored the BL-induced Kleaf increase. BSCs-specific silencing of PHOT1 or PHOT2 (using the SCR promoter) abolished the BL-induced Kleaf increase. Xylem-fed PHOT inhibitor, tyrphostin 9, also abolished the BL-induced Kleaf increase in WT. Moreover, in WT plants, white light (WL) acidified the xylem sap compared to dark, but did not acidify the xylem sap of the phot1-5 mutant. BSCs-specific complementation of phot1-5 by SCR: PHOT1, restored the WL-induced xylem acidification. On a cellular level, BL hyperpolarized the BSCs, which was prevented by tyrphostin 9. In addition, the osmotic water permeability coefficient (Pf) of the BSCs was higher under WL treatment. Our results link the blue light control of water fluxes from the xylem to the mesophyll via the BSCs in the following model:BL →BSCs’ PHOTs activation →tyrosine phosphorylation→BSCs’ H+- ATPase activation →BSCs hyperpolarization, xylem acidification →Pf elevation → Kleaf increase. Thus, this study is the first to demonstrate an independent BL signal transduction pathway regulation of the vascular tissue.