Search

The aim of the present study is to: i) analyze the water absorption capacity of seeds of some Tagetes sp.; ii) compare the water absorption of Tagetes sp. and Lactuca sativa L. seeds in order to assess the potential of genus Tagetes as test object for laboratory screening studies for establishing allelopathic interference in plant communities. Tagetes erecta (local population from Germany), Tagetes patula (local population from Germany), and Tagetes patula variety “Usmivka” (Bulgarian variety) have been included in the study. Equivalence in the water absorption capacity (Ws%) of the seeds of studied Tagetes sp. and Lactuca sativa L. variety “Great Lakes” was found, with the maximum of water absorption occurring at the first hour and stopping by the fourth hour, regardless of the temperature range in which the imbibition takes place. The significant differences in the cumulative values of the average water absorption capacity of the Tagetes sp. seeds compared to Lactuca sativa L. variety “Great Lakes” (Ws% average ranged from +5.68 to +83.27%), indicate that the species of genus Tagetes can be successfully used in laboratory screening studies to establish allelopathic interference under in vitro conditions. Further research is needed to establish seed water absorption capacity (Ws%) of Tagetes sp. depending on the type of aqueous extracts used in allelopathic studies (cold or temperate), as well as of the concentrations applied. [ABSTRACT FROM AUTHOR]

Through the stimulation method of large-scale hydraulic fracturing, the spontaneous imbibition capacity of the water phase in the shale reservoir has great influence on the effect of stimulation. Generally, the lacustrine shale has the characteristics of high clay minerals content, strong expansibility, development of nanopores and micro-pores, and underdevelopment of fractures, which leads to the unclear behavior of spontaneous imbibition of aqueous phase. The lacustrine shale of Da'anzhai Member and marine shale of Longmaxi Formation in Sichuan Basin were selected to prepare both the shale matrix sample and fractured shale sample, and the spontaneous imbibition experiment of simulated formation water was carried out. By means of an XRD test, SEM observation, nuclear magnetic resonance test and linear expansion rate test, the mineral composition, the structure of pores and fractures, the capacity of hydration and expansion of both lacustrine and marine shale are compared and analyzed. The results show that the average spontaneous imbibition rate of lacustrine shale is 60.8% higher than that of marine shale within the initial 12 hours of imbibition. The lacustrine shale has faster imbibition rate than the marine shale in the initial stage of spontaneous imbibition. However, the lacustrine shale has underdeveloped pores and fractures, as well as poor connectivity of pores. Besides, the strong hydration and expansion of clay minerals can easily lead to dispersion and migration of clay minerals on the fracture surface, which will plug up the seepage channels, resulting in poor capacity of spontaneous imbibition. The spontaneous imbibition rate in the middle and late stage of Lacustrine shale is obviously lower than that of the marine shale. The overall spontaneous imbibition rate ability of the lacustrine shale is less than that of the marine shale. According to the characteristics of water imbibition of lacustrine shale, considering the dual effects of hydration expansion of clay minerals on the effective reconstructed volume, the microfractures can be initiated and extended by fully utilizing the hydration of shale. Acidification treatment, oxidation treatment or high temperature treatment can be used to expand pore space, enhance water phase imbibition capacity and improve multi-scale mass transfer capacity of the lacustrine shale.

Many Astragalus species exhibit seeds with physical dormancy (PY), but little is known about the ecological context of this dormancy. We focused on A. maritimus and A. verrucosus, two threatened Sardinian endemic species inside the subgenus Trimeniaeus Bunge. Fresh seeds collected from the only two respective known populations were used to investigate the effect of mechanical scarification, heat shock, and water imbibition processes on PY release and germination. PY can be overcome through mechanical scarification of the water-impermeable seed coats, while no dormancy break was detected, nor a subsequent increase in seed germination due to fire-induced heat. This suggests that fire does not trigger dormancy release and seed germination in these species. The seeds tolerate relatively high heat shock temperatures (up to 120 and 100 °C for A. verrucosus and A. maritimus, respectively), but after 120 °C for 10 min, the number of dead seeds increases in both species. These facts suggest the capacity to develop a soil seed bank that can persist after fires and delay germination until the occurrence of optimal conditions. As regards water imbibition, both Astragalus species did not show the typical triphasic pattern, as germination started without further water uptake. This study emphasizes the significance of understanding germination processes and dormancy in threatened species. In fire-prone ecosystems, PY dormancy plays a crucial role in soil seed bank persistence, and it may be selectively influenced by post-fire conditions. Understanding such adaptations provides useful insights into conservation strategies. [ABSTRACT FROM AUTHOR]

The moisture content of wood is changed during manufacturing processes, such as drying and impregnation. Understanding the water transport in wood is helpful for optimizing the manufacturing technology and improving the durability of wood products. Herein, the one-side imbibition tests of Chinese fir and poplar were carried out via direct contact with a water-saturated sponge. Imbibition amounts and orthotropic kinetics were evaluated by X-ray densitometry, where wood exhibited non-uniform and directional behaviors for water imbibition and there were variations in behavior between Chinese fir and poplar. More water uptake and faster migration were observed for poplar, while water preferentially accumulated at the wetting front for Chinese fir. The effective imbibition height of poplar was significantly higher than Chinese fir, regardless of orientation direction. Within the growth rings, Chinese fir showed heterogeneous water uptake, and faster water migration in latewood was observed. Imbibition height in a single fiber was simulated as a function of cell wall ratio, and the influences of anatomical factors on water movement were explored. These simulation assessments were consistent with the results of the one-side imbibition tests. These findings help to explain the water transport mechanism at the mesoscale and interactions between wood and water. [ABSTRACT FROM AUTHOR]

Many Astragalus species exhibit seeds with physical dormancy (PY), but little is known about the ecological context of this dormancy. We focused on A. maritimus and A. verrucosus, two threatened Sardinian endemic species inside the subgenus Trimeniaeus Bunge. Fresh seeds collected from the only two respective known populations were used to investigate the effect of mechanical scarification, heat shock, and water imbibition processes on PY release and germination. PY can be overcome through mechanical scarification of the water-impermeable seed coats, while no dormancy break was detected, nor a subsequent increase in seed germination due to fire-induced heat. This suggests that fire does not trigger dormancy release and seed germination in these species. The seeds tolerate relatively high heat shock temperatures (up to 120 and 100 °C for A. verrucosus and A. maritimus, respectively), but after 120 °C for 10 min, the number of dead seeds increases in both species. These facts suggest the capacity to develop a soil seed bank that can persist after fires and delay germination until the occurrence of optimal conditions. As regards water imbibition, both Astragalus species did not show the typical triphasic pattern, as germination started without further water uptake. This study emphasizes the significance of understanding germination processes and dormancy in threatened species. In fire-prone ecosystems, PY dormancy plays a crucial role in soil seed bank persistence, and it may be selectively influenced by post-fire conditions. Understanding such adaptations provides useful insights into conservation strategies.

Carbonation may potentially lead to corrosion of steel bars in reinforced concrete. This concern presents a major barrier against the implementation of sustainable low-clinker cementitious materials in the design of reinforced concrete structures. Various studies have documented the relationship between different equilibrium moisture states in carbonated concrete and the corrosion rate of the embedded steel. However, limited attempts were focused on visually observing the dynamic (time-dependent) behavior of moisture penetration into concrete and the related corrosion state and rate. Moreover, there is a lack of data on the local moisture state in the cementitious matrix in the steel-concrete interfacial zone. In this study, liquid water uptake in carbonated mortar was in-situ and over time monitored by neutron imaging. The corrosion state of embedded steel was monitored by means of electrochemical measurements. This combined experiment revealed that the arrival of the waterfront at the steel surface led to a sharp decrease of the steel potential. The corrosion rate increased from negligibly low values (

Wood permeability is a macroscopic property resulting from complex pathways at the cellular level. In this study, high-resolution X-ray CT scans were performed during longitudinal imbibition in Norway spruce to investigate the role of wood rays and tracheids network in liquid migration. A customized setup was designed to maintain the bottom face of a wooden cylinder in contact with water, without vibration, despite the sample rotation required during each scan. The results highlighted a contrasted role of latewood and earlywood in water migration. Liquid imbibition was fast in latewood, because the bordered pits are less prone to aspiration than in earlywood, due to their smaller diameter and larger cell wall thickness. In earlywood, the migration pattern was complex due to pit aspiration that isolate tracheids clusters. Indeed, the images revealed a significant contribution of wood rays in the migration pathways. Consequently, tracheids were not progressively filled in the longitudinal direction from one tracheid to the next, but they were filled laterally with water coming from wood rays at different heights of the cells. This explained entrapped air bubbles in the lumens and led to a 3D heterogeneous liquid distribution. [ABSTRACT FROM AUTHOR]

In order to study the deformation characteristics of water imbibition of coal body containing gas, a self-designed pressure-bearing gas natural water absorption test platform was used to carry out isobaric natural water absorption experiments in coal gas adsorption equilibrium pressures at 0.5, 1.0, 1.5, 2.0 MPa. The test results showed that: in the gas adsorption stage, with the increase of pressure, the horizontal and vertical deformation of the coal body showed a trend of increase, the vertical strain was about twice as the horizontal strain. In the natural water absorption stage, the transverse and longitudinal deformation of coal body is greater than that of pure gas adsorption under the same gas pressure. The ambient pressure of the experimental system increased slightly, and the maximum value of pressure increase was 0.013 MPa, indicating that the water imbibition was accompanied by gas desorption process. At the stage of gas desorption and water drainage, under different gas pressures, the water content of coal were 0.98%, 1.05%, 1.51%, 2.24%. The volume strain was secondarily related to the initial gas pressure, the residual deformation value of coal body strain was large, and it showed the irreversibility and destructiveness of gas-containing coal deformation after water imbibition.

Drought and temperature stresses are known as primary factors limiting germination and seedling growth. Seed priming with plant growth regulators is one of the popular approaches to minimize adverse environmental stresses. This study was carried out to examine the role of seed priming with 5-aminolevulinic acid (5-ALA) at different levels (0, 25, 50, and 100 mg L-1) in germination and seedling growth of three wheat (Triticum aestivum L.) 'Emam', 'Gomria', and 'Zakia' under high temperature and drought stresses using a range of temperatures (25, 30, and 35 °C) and water potentials (0.0 and -0.5 MPa). Water uptake, germination and early seedling growth attributes were measured. Drought stress and high temperature decreased germination%, germination index, and shoot fresh weight by 39.2%, 35.4%, and 48.6%, respectively, as compared with 0.0 MPa and 25 °C. Seeds of 'Zakia' primed with 50 mg L-1 5-ALA at -0.5 MPa, and 35 °C increased fresh and dry weights of the root by 19.8% and 68.4% relative to 0 mg L-1. For interaction between variety and 5-ALA, the highest germination% (90.3%) was recorded in 'Emam' with 50 mg L-1 5-ALA. Treatment 100 mg L-1 5-ALA decreased mean germination time by 24.5% and 28.9% at 25 and 35 °C, respectively; 50 mg L-1 5-ALA increased seedling vigor index by 16.3% as compared with 0.0 mg L-1 at -0.5 MPa and 35 °C. The 5-ALA enhanced water imbibition of the three varieties under drought and temperature stresses. This study suggested that seed priming with 5-ALA is a possible way to mitigate the negative effects produced by drought and temperature stresses on germination and early seedling growth of wheat. [ABSTRACT FROM AUTHOR]

Sclerophyll forest in Mediterranean central Chile has been subjected to severe degradation due to anthropic disturbances and climate change and is in need of restoration. Since direct seeding is usually unsuccessful, we need to research seed propagation to produce plants for restoration. Our objective was to assess pre-germination treatments for six native woody species (Acacia caven, Lithraea caustica, Quillaja Saponaria, Porlieria chilensis, Kageneckia angustifolia, and Ceratonia chilensis) of the sclerophyll forest, considering its operational applicability and consequences for nursery plant production. Treatments were selected according to previous studies, and operational applicability in nurseries. Germination and level of seeds water imbibition were assessed. Results indicate that time for seed water imbibition is critical for germination in A. caven, P. chilensis and K. angustifolia, with an average germination of 90.2 ± 2.0%, 85.0 ± 4.7%, and 47.4 ± 2.3%, respectively. Gibberellin did not improve germination compared to water soaking in Q. Saponaria, K. angustifolia and P. chilensis. In addition, physical scarification is a suitable treatment for L. caustica and C. chilensis, instead of chemical scarification, avoiding handling toxic and corrosive compounds in nurseries. We recommend assessing seed water imbibition rates as a key factor for proper germination processes.

Low-temperature plasma treatment of wheat seeds was performed by a plasma jet and dielectric barrier discharge, both at atmospheric pressure. The influence of the plasma treatment on the growth parameters such as root and shoot dry weight and length as well as on the mean germination time was investigated. Stimulation of germination and an increase of the mean germination time were achieved for the shortest plasma exposure time. The ability of water imbibition by wheat seeds was found to increase by 20–30%. These phenomena were explained by the enhancement of hydrophilicity of the seed surface, which resulted in the reduction of the apparent contact angle. The positive effect of the plasma treatment was also achieved for biomass parameters such as average length, dry weights of roots and sprouts, and other. Thus, the plasma treatment can prove to be an effective alternative to traditional pre-sowing seed treatments used in agriculture. [ABSTRACT FROM AUTHOR]

During the fracturing fluid imbibition into shale reservoirs, partial minerals could dissolve and diffuse into the fracturing fluid.However, few studies are conducted on the effects of ion diffusion on shale oil migration, especially in salt-rich shale oil reservoirs. The salt-rich shale oil reservoirs are regarded as the potential hot targets for shale oil exploration in China. In this study, a series of water imbibition and ion diffusion experiments are conducted on salt-rich shale samples. The nuclear magnetic resonance method is used to monitor the oil migration and demonstrate the effects of ion diffusion. The experimental results show that the salt-rich shale contains a large amount of halite, resulting in a much higher salt ion diffusion capacity than conventional shale (about 15–45 times higher). Salt ion diffusion can induce lots of pores, caves and fractures that can act as channels for oil migration. However, the dimensionless imbibition rate has a negative relationship with ion diffusion capacity, indicating that too many salt crystals cannot contribute to the oil production. The salt crystals dissolution may block matrix pores and generally reduce the oil migration rate, despite these new migration channels. This study can help understand the effects of fracturing fluid retention on oil production in salt-rich shale oil reservoirs [ABSTRACT FROM AUTHOR]

The Callovo Oxfordian clay-rock (COx) is studied in France for the disposal of radioactive waste, because of its extremely low permeability. This host rock is governed by a hydromechanical coupling of high complexity. This paper presents an experimental study into the mechanisms of water uptake in small, unconfined, prismatic specimens of COx, motivated by the comprehension of cracking observed during concrete/COx interface sample preparation. Water uptake is monitored using both X-ray tomography and neutron radiography, the combination of these imaging techniques allowing material deformation and water arrival to be quantified, respectively. Given the speed of water entry and crack propagation, relatively fast imaging is required: 5-min X-ray tomographies and 10-s neutron radiographs are used. In this study, pairs of similar COx samples from the same core are tested separately with each imaging technique. Two different orientations with respect to the core are also investigated. Analysis of the resulting images yields with micro- and macro-scale insights into hydromechanical mechanisms to be obtained. This allows the cracking to be interpreted as a rapid breakdown in capillary suction (supposed large both to drying and rebound from in situ stress state) due to water arrival, which in turn causes a loss of effective stress, allowing cracks to propagate and deliver water further into the material. [ABSTRACT FROM AUTHOR]

The water adsorption into pore spaces in brittle rocks affects wave velocity and transmitted amplitude of elastic waves. Experimental and theoretical studies have been performed to characterize moisture-induced elastodynamic variations due to macroporous effects; however, little attention has been paid to the manner in which wetting of nanopores affects elastic wave transmission. In this work, we extend our understanding of moisture-induced elastic changes in a microcracked nanopore-dominated medium where 80 % of the surface area exhibits pore diameters (also include microcrack widths) below 10 nm. We study acousto-mechanical response resulting from a gradual wetting on a free-standing intact Herrnholz granite specimen over 98 h using time-lapse ultrasonic and digital imaging techniques. Linkages between ultrasonic attributes and adsorption-induced stress/strain are established during the approach of the wetting front. We find that Gassmann theory, previously validated in channel-like nanoporous media, does not work properly in predicting the P-wave velocity increase of microcracked nanopore-dominated media at ultrasonic frequency. However, squirt flow – a theory recognized to characterize wave velocity increase and attenuation in microcracked macropore-dominated media at the pore scale – also accounts for the observed increase of P-wave velocity in microcracked nanopore-dominated media. The transmitted amplitude changes in direct P waves are explained and predicted by the elastic wave propagation within P-wave first Fresnel zone and reflection/refraction on the wetting front. • Acousto-mechanical response of a free-standing intact specimen to gradual wetting. • Squirt flow dominates P-wave velocity increase in microcracked nanoporous media. • Amplitude changes are explained by elastic wave propagation around Fresnel zone. [ABSTRACT FROM AUTHOR]

Spontaneous water imbibition plays an imperative role in the development of shale or tight oil reservoirs. Spontaneous water imbibition is helpful in the extraction of crude oil from the matrix, although it decreases the relative permeability of the hydrocarbon phase dramatically. The dynamic pore-scale network modeling of water imbibition in shale and tight reservoirs is presented in this work; pore network generation, local capillary pressure function, conductance calculation and boundary conditions for imbibition are all presented in detail in this paper. The pore network is generated based on the characteristics of Barnett shale formations, and the corresponding laboratory imbibition experiments are matched using this established dynamic pore network model. The effects of the wettability, throat aspect ratio, viscosity, shape factor, micro-fractures, etc. are all investigated in this work. Attempts are made to investigate the water imbibition mechanisms from a micro-scale perspective. According to the simulated results, wettability dominates the imbibition characteristics. Besides this, the viscous effects including viscosity, initial capillary pressure and micro-fractures increase the imbibition rate, while the final recovery factor is more controlled by the capillarity effect including the cross-area shape factor, contact angle and the average pore-throat aspect ratio.

Tight matrix has relatively low permeability and porosity, with abundant micro/nano pores. The capillary force in these pores are relatively strong, making the wetting liquid easier to be imbibed in the matrix. This process is called spontaneous imbibition. The complexity of pore structure is identified as one of the key factors influencing the imbibition process, but the detailed mechanism is not clear. Thus, in this work, a method is proposed to evaluate the influence of pore structure on imbibition process. Pore structure has fractal properties in a specific scale. By using the fractal theory, an imbibition model is provided to analyze the influence of microscopic structures on spontaneous imbibition, considering the pore size distribution and pore connectivity. Also, based on this model, the influencing factors on dimensionless imbibition and diffusion rate are discussed. Results show that the pore structure has more branches, larger and shorter sub-throats has higher chance to gain a high imbibition rate. Finally, a 3D imbibition parameter cube is constructed to determine the parameter combinations in favor of strong water diffusion potential. By utilizing the analysis method based on the fractal theory, we can effectively evaluate the imbibition potential. It is helpful to provide a guidance to evaluate the water imbibition to gas production.

Water mobility in coal plays an important role in achieving the high performance of coalbed methane (CBM) recovery from coal. To better understand this phenomenon, a systematical investigation of water imbibition and drainage was conducted experimentally using high rank coals collected from Qinshui Basin of China. The results show the shapes of the T 2 spectrum for water imbibition and drainage experiments generally distribute with the bimodal pattern with a higher left peak around 1 ms and a lower right peak around 50–100 ms. The cumulative imbibition water content ranges from 3.09 to 6.54 vol% under the 0 MPa saturated hydraulic pressure at vacuumed state, which is accounting for 58.30–91.07% of total imbibition water content, and grows exponentially with the increasing of saturated hydraulic pressure. The cumulative drainage water content ranges from 0.53 to 1.71 vol%, and residual water content varies from 3.47 to 6.73 vol%, which latter is accounting for 72.1–88.46% of the total imbibition water content. The imbibition and drainage water contents increase with the total pore volume increasing. The well-developed macropores and mesopores increase the drainage water content and rate, while the micropores mainly contribute to the residual water content. The cumulative imbibition water content is positively related to inertinite content but negatively related to ratio of vitrinite to inertinite and ash yield, whereas it is just the opposite for drainage water content and rate. As it is expected, the increasing wetting angle generally increases the drainage water content and rate. [ABSTRACT FROM AUTHOR]

• Aqueous formate solutions were tested at high concentrations up to 30 wt%. • Such solutions were tested for wettability alteration of carbonate rocks. • Wettability alteration occurred with high-concentration formate solution. • The wettability alteration by formate did not require an acidic pH. • Calcite dissolution and the resulting formate species played the key roles. This paper presents an experimental study of the injection of aqueous formate solution into oil-wet carbonate porous media at different formate concentrations and acidity levels. The research was motivated by the potential use of aqueous formate solution as a wettability modifier in enhanced oil recovery and/or a carbon carrier in geological carbon storage in carbonate reservoirs. However, the wettability alteration of carbonate rocks by formate has not been tested at elevated concentrations of formate or in any coreflood. The experimental program in this research consists of aqueous stability, wettability alteration, and three dynamic imbibition experiments with fractured carbonate cores with varying formate concentrations up to 30 wt% and initial pH between 6 and 7. With an excess amount of calcite powder, the 20 wt% formate solution in 15000 ppm NaCl brine showed essentially the same pH history as the base NaCl brine, where calcite dissolution caused the solution pH to increase to a stable value near 9. None of the samples studied in this research showed solid precipitation. Material balance of dynamic imbibition data indicated that the imbibition of formate into the matrix was most significant in coreflood #1, in which 30 wt% formate solution was injected into a fractured carbonate core. A large gradient in formate concentration between the fracture and the matrix likely caused the rapid mass transfer. Then, calcite dissolution and the resulting formate species caused wettability alteration to enhance water imbibition, which in turn expelled the oil in the matrix. The incremental oil recovery factor was 9.1 % for 30 wt% formate (pH = 7; coreflood #1), 2.9 % for 5 wt% formate (pH = 7; coreflood #2), and 7.0 % for 5 wt% formate + HCl (pH = 6; coreflood #3). A greater oil recovery factor resulted from a greater concentration of formate and a reduced pH. This is the first time corefloods were performed with aqueous formate solution at elevated concentrations up to 30 wt%. [ABSTRACT FROM AUTHOR]

In tight oil reservoirs, water imbibition is the key mechanism to improve oil production during shut-in operations. However, the complex microstructure and composition of minerals complicate the interpretation of oil migration during water imbibition. In this study, nuclear magnetic resonance (NMR) T2 spectra was used to monitor the oil migration dynamics in tight oil reservoirs. The factors influencing pore size distribution, micro-fractures, and clay minerals were systematically investigated. The results show that the small pores corresponded to a larger capillary pressure and a stronger imbibition capacity, expelling the oil into the large pores. The small pores had a more effective oil recovery than the large pores. As the soaking time increases, the water preferentially entered the natural micro-fractures, expelling the oil in the micro-fractures. Subsequently, the oil in the small pores was slowly expelled. Compared with the matrix pores, natural micro-fractures had a smaller flow resistance and were more conducive to water and oil flow. Clay minerals may have induced micro-fracture propagation, which can act as the oil migration channels during water imbibition. In contrary to the inhibitory effect of natural micro-fractures, the new micro-fractures could contribute to the oil migration from small pores into large pores. This study characterized the oil migration characteristics and provides new insight into tight oil production.

Hot-water injection can enhance oil recovery in naturally fractured reservoirs by altering wettability from oil- or intermediate-wet to more water-wet in the matrix. This process can reduce residual oil saturation in the matrix where, as a result, the relative permeability curves and capillary pressure will change. Therefore, the trapped oil in the matrix can flow into the fracture network. Part 1 described the wettability alteration process from hot-water imbibition along with the numerical model development and 1D examples. Part 2 presents the results from a series of 2D models and sensitivity study for both light-oil and heavy-oil cases in naturally fractured reservoirs. [ABSTRACT FROM AUTHOR]

The alteration of wettability can be a key mechanism for additional oil production from hydrocarbon reservoirs worldwide. This paper models thermally-induced wettability alteration from hot-water imbibition in naturally fractured reservoirs (NFRs). Hot-water (or steam) enhanced oil recovery (EOR) in fractured reservoirs can lead to increased oil recovery by enhancing water imbibition into matrix blocks, rendering the formation more water-wet. This will increase recovery as a result of decreased oil-water interfacial tension and reduced residual oil saturation. Modeling and evaluating production mechanisms in such a process in NFRs requires an understanding of multiphase flow parameters. In this work, numerical simulation codes with finite-difference formulations were developed to couple fluid flow and heat transfer for 1D and 2D flow geometries in spontaneous imbibition. This paper examines the effect of elevated temperature on wettability by considering various initial and boundary conditions. This approach results in more accurate simulation results as the relative permeability and capillary pressure curves are updated at each time step and for each grid (or each rock-type). The results from this study confirmed: a) the rate of recovery in co-current is generally higher than that in counter-current imbibition in a hot-water imbibition process, b) changing the wetting state in matrix from intermediate- or oil-wet to more water-wet proved to increase the ultimate recovery by reducing the residual oil saturation, c) updating the k r and P c curves vs. temperature in simulating a hot-water injection process in NFRs can be more accurate than the commercial simulators where the relative permeability and capillary pressure curves are updated based on solely their end-points. [ABSTRACT FROM AUTHOR]

BACKGROUND The importance of the effect of phytochemical accumulation in wheat grain on grain physiology has been recognised. In this study, we tracked phytochemical concentration in the seed coat of purple wheat during the water-imbibition phase and also hypothesised that the speed of germination was only relevant to its initial phytochemical concentration. RESULTS The results indicate that the speed of germination was significantly reduced in the darker grain groups within the purple wheat. Total phenol content was slightly increased in all groups compared to their initial state, but the levels of other phytochemicals varied among groups. It is revealed that anthocyanin was significantly degraded during the water imbibition stage. Also, the activities of peroxidase, ascorbate peroxidase, catalase, glutathione S-transferase, glutathione reductase, and glutathione peroxidase in each grain colour group did not correlated with germination speed. Overall antioxidant activity was reduced as imbibition progressed in each group. Generally, darker grain groups showed higher total antioxidant activities than did lighter grain groups. CONCLUSION These findings suggested that the reduced activity of reactive oxygen species, as controlled by internal antioxidant enzymes and phytochemicals, related with germination speed during the water imbibition stage in grains with greater depth of purple colouring. © 2016 Society of Chemical Industry [ABSTRACT FROM AUTHOR]

Sequentially prepared semi-interpenetrating polymer network (semi-IPN) has been developed here via Michael type addition of acrylic acid (AA) and 2-acrylamido-2-methylpropane sulfonic acid (AMPS) on to starch. The semi-IPN hydrogel have proficiency in fast water imbibition towards gel network and swelling tunable character with pH alteration in ambient condition. The synthesized gel has been characterized by Fourier transformed infrared spectroscopy (FTIR) to confirm Michael type grafting of monomers on to starch. The surface morphology, observed from Scanning Electron Microscopy (SEM) exhibited corrugated rough surface on hydrogel which enhances the fast water uptake feature by anomalous Fickian case II diffusion mechanism. Grafting reaction also improves its thermal stability which has been confirmed by thermogravimetric analysis (TGA). Biodegradation study with hen egg lysozyme medium reveals the accelerated enzymatic scission of the starch backbone and progressive mass loss. Degradation of the hydrogel around 60% of its primary mass has been observed within 7 days. The physicochemical characterizations of this hydrogel suggest this as a promising pH-tunable, biodegradable candidate for control drug delivery vehicle. [ABSTRACT FROM AUTHOR]

Herbal medicines are in great demand for preliminary health care due to their wide medicinal value, with no side effects. Since many species are used in the system of traditional medicine, scientists have great opportunities to develop appropriate packages of practices for their multiplication and conservation. Abrus precatorius is the native plant of India and used in many ways in the Indian Ayurvedic system of medicine. This seeds of the species is dormant due to hard seed coat. So the aim of the study is to remove seed dormancy and enhance germination capacity within a short period. To overcome the problem of dormancy, seeds were scarified by seed scarifier and sand paper and also treated with acid (H2SO4) and hot water just before sowing. 60-95% germination was achieved under different treatment conditions while the seeds without any treatment fail to germinate. The highest (95%) germination was observed just 12 days after sowing in seeds treated with concentrated H2SO4 for 120 minutes. 70-75% germination was achieved when the seeds were treated with acid for 105 and 135 minutes. Seeds treated with con. H2SO4 for 150, 90 and 60 minutes and also scarified by sand paper showed similar results with 60-65% germination. The seeds scarified by a mechanical scarifier and treated with hot water did not show more than 32.5% germination.

Some heavy oil reservoirs in Canada and Venezuela show anomalous behavior under solution gas drive. However, although foamy oil can improve the performance of solution gas drive in heavy oil, only approximately 5–15% OOIP can be recovered during primary production. In this study, micromodel flood experiments and sandpack flood tests were performed to evaluate the potential of water flooding to enhance the recovery of heavy oil after solution gas drive. The micromodel test indicates connected gas channels were created in the micromodel when the pressure was lower than the pseudo-bubblepoint pressure during the solution gas drive; the injected water moves initially through low-viscosity gas channels and through the micromodel during subsequent water flooding. A large number of gas bubbles were found to be dispersed in the oil at the end of the solution gas drive. Heavy oil with dispersed gas bubbles was driven by injected water, forming a flow where water displaced the foamy oil present. The sandpack tests results show that the performance of the subsequent water flooding was significantly affected by the conversion pressure. The conversion pressure was the pressure at the end of the solution gas drive, and the subsequent water flooding was conducted when the pressure was reduced to the conversion pressure after solution gas drive. As the conversion pressure decreasing, the oil recovery of the solution gas drive increased, and the oil recovery of the subsequent water flooding decreased. The optimum conversion pressure of water flooding was found to be the pseudo-bubblepoint pressure. For the water flooding with the convertion pressure lower than the pseudo-bubblepoint pressure, most oil was produced in the high water cut period. Water imbibition caused by capillary forces was the main mechanism leading to the recovery of heavy oil at the high water cut period. The effect of water imbibition on the recovery was more significant at lower injection rate, leading to the higher recovery. [ABSTRACT FROM AUTHOR]

En este estudio se evaluó el efecto de la alta presión hidrostática (APH) en la imbibición de agua, tiempos de cocción y la microestructura de los cotiledones y la cubierta de granos de Phaseolus vulgaris. Los tratamientos a 275, 410, 550 ó 690 MPa a 25ºC por 5 min incrementaron la velocidad de imbibición de agua alcanzando la saturación en la mitad del tiempo. La APH redujo los tiempos de cocción (TC) de los granos sin remojar en un 25% a 39% comparable al de los granos remojados en agua por 3 h. Las fotografías con microscopía de barrido (MEB) demostraron una agregación de la matriz proteica, hinchamiento de las paredes celulares y de los gránulos de almidón en las células de los cotiledones de los granos de Phaseolus vulgaris tratados con APH. La cubierta externa perdió su suavidad y las capas celulares se hincharon, comportamiento similar al observado cuando los granos se remojan. La APH parece ser una alternativa para reducir los largos tiempos de preparación del Phaseolus vulgaris.Effect of high hydrostatic pressure on water imbibition, cooking times and microstructure of Phaseolus vulgaris. The effect of high hydrostatic pressure (HHP) on water imbibition, cooking times, and microstructure of cotyledons and seed coats of black beans was evaluated. High pressure treatments at 275, 410, 550 or 690 MPa and 25°C for 5 min increased the rate of water imbibition of black beans. The saturation degree of HHP treated black beans was reached 50% faster than the saturation degree of untreated black beans. High hydrostatic pressure treatments reduced the cooking times (CT) of unsoaked black beans by 25% to 39%, similar to black beans soaked for 3 h. The microstructure of HHP treated beans exhibited protein aggregation in cell protoplasm and swelling of cell walls and starch granules. Seed coats of HHP treated black beans were less smooth than seed coats of untreated black beans. The swelling of palisade, hourglass, and parenchyma cells was also observed in HHP treated black beans such as soaked beans. High hydrostatic treatment is an alternative for reducing the preparation long times of Phaseolus vulgaris.

The impact of cold radiofrequency air plasma on the wetting properties and water imbibition of beans (Phaseolus vulgaris) was studied. The influence of plasma on wetting of a cotyledon and seed coat (testa) was elucidated. It was established that cold plasma treatment leads to hydrophilization of the cotyledon and tissues constituting the testa when they are separately exposed to plasma. By contrast, when the entire bean is exposed to plasma treatment, only the external surface of the bean is hydrophilized by the cold plasma. Water imbibition by plasma-treated beans was studied. Plasma treatment markedly accelerates the water absorption. The crucial role of a micropyle in the process of water imbibition was established. It was established that the final percentage of germination was almost the same in the cases of plasma-treated, untreated, and vacuum-pumped samples. However, the speed of germination was markedly higher for the plasma-treated samples. The influence of the vacuum pumping involved in the cold plasma treatment on the germination was also clarified. [ABSTRACT FROM AUTHOR]

Sclerophyll forest in Mediterranean central Chile has been subjected to severe degradation due to anthropic disturbances and climate change and is in need of restoration. Since direct seeding is usually unsuccessful, we need to research seed propagation to produce plants for restoration. Our objective was to assess pre-germination treatments for six native woody species (Acacia caven, Lithraea caustica, Quillaja Saponaria, Porlieria chilensis, Kageneckia angustifolia, and Ceratonia chilensis) of the sclerophyll forest, considering its operational applicability and consequences for nursery plant production. Treatments were selected according to previous studies, and operational applicability in nurseries. Germination and level of seeds water imbibition were assessed. Results indicate that time for seed water imbibition is critical for germination in A. caven, P. chilensis and K. angustifolia, with an average germination of 90.2 ± 2.0%, 85.0 ± 4.7%, and 47.4 ± 2.3%, respectively. Gibberellin did not improve germination compared to water soaking in Q. Saponaria, K. angustifolia and P. chilensis. In addition, physical scarification is a suitable treatment for L. caustica and C. chilensis, instead of chemical scarification, avoiding handling toxic and corrosive compounds in nurseries. We recommend assessing seed water imbibition rates as a key factor for proper germination processes. [ABSTRACT FROM AUTHOR]

Herbal medicines are in great demand for preliminary health care due to their wide medicinal value, with no side effects. Since many species are used in the system of traditional medicine, scientists have great opportunities to develop appropriate packages of practices for their multiplication and conservation. Abrus precatorius is the native plant of India and used in many ways in the Indian Ayurvedic system of medicine. This seeds of the species is dormant due to hard seed coat. So the aim of the study is to remove seed dormancy and enhance germination capacity within a short period. To overcome the problem of dormancy, seeds were scarified by seed scarifier and sand paper and also treated with acid (H2SO4) and hot water just before sowing. 60-95% germination was achieved under different treatment conditions while the seeds without any treatment fail to germinate. The highest (95%) germination was observed just 12 days after sowing in seeds treated with concentrated H2SO4 for 120 minutes. 70-75% germination was achieved when the seeds were treated with acid for 105 and 135 minutes. Seeds treated with con. H2SO4 for 150, 90 and 60 minutes and also scarified by sand paper showed similar results with 60-65% germination. The seeds scarified by a mechanical scarifier and treated with hot water did not show more than 32.5% germination. [ABSTRACT FROM AUTHOR]

Several procedures can be used to evaluate the physiological potential of soybean seeds, but it is fundamental that reliable procedures are associated with the field performance of the seed lots. This research aimed to evaluate the physiological potential of soybean seed lots with quick tests, as well as vigor assessment, seedling field emergence and the computer image analysis system (SVIS®), to identify the most efficient procedure for classifying soybean seed lots. The physiological potential of five seed lots of 'BRS Valiosa RR ' and 'CD 208' was evaluated for two periods (before and after cold room storage) by the germination test (paper and sand), rapid evaluation tests (water imbibition and pH exudates), vigor tests (accelerated aging and electrical conductivity), seedling field emergence and the computer image analysis system (SVIS®). Germination (sand substrate), electrical conductivity and water imbibition tests were effective in separating the seed lots of both cultivars, but only the water imbibition test allowed classification in both evaluation periods. The water imbibition test is therefore considered as promising for evaluating physiological potential during seed production and storage. [ABSTRACT FROM AUTHOR]

This study investigates fines migration and mineral reactions as a mechanism for CO 2 residual trapping. We perform imbibition experiments using a sintered glass core and seven Berea sandstone cores. The cores receive four injection stages: water, CO 2 -saturated water, water-saturated CO 2 , and finally water or CO 2 -saturated water. During the second injection stage, the quantity of CO 2 -saturated water is altered to induce various degrees of fines migration and mineral reactions. These effects are found to yield residual CO 2 saturations of 16%, 22% and 23% for zero, 25 and 50 pore volumes of CO 2 -saturated water injection, respectively. These percentages are 6–7% greater than if neither fines migration nor mineral reactions were present. This is attributed to pore plugging caused by fines migration and mineral reactions, impeding the imbibing water from displacing CO 2 in the plugged pores. In addition, CO 2 -saturated water imbibition is found to increase residual CO 2 saturation by 26–30% over that resulting from water imbibition. This is attributed to the CO 2 dissolution effect during water imbibition. We therefore conclude that fines migration and mineral reactions is a CO 2 residual trapping mechanism during CO 2 sequestration. [Display omitted] • Experiments are performed on glass and Berea cores to study CO 2 residual trapping. • Fines migration and mineral reactions lead to plugging of pores. • Pores plugged by fines migration and mineral reactions trap CO 2. • Both water and CO 2 -saturated water imbibition experiments are performed. • Water imbibition yields less residual CO 2 due to dissolution. [ABSTRACT FROM AUTHOR]

[Display omitted] • Introducing, for the first time, a magnetic resonance imaging method for shales. • The imaging method can provide water and oil images on a macroscopic scale. • Water and oil saturations depend on the macroscopic scale heterogeneity of bedding planes. • T 1 - T 2 ∗ technique permits differentiating shale fracture and matrix pore water. • Monitoring shale water imbibition using a combination of MR Imaging and T 1 - T 2 ∗ techniques. Fluid storage and transport in shale and clay formations is important in many areas of application, including hydrocarbon recovery from, and waste fluid storing in, these reservoirs. The multiscale heterogeneous nature of shales is largely responsible for these rocks being considered unconventional and complicated. Researchers often rely on imaging methods to provide spatial information to characterize their heterogeneity. SEM and nano-CT are powerful methods that have been used to give images of shale nanopores with fields of view (FOV) of 100 μ m. However, this limited FOV has raised questions about the validity of simulations based on these methods to scale up and represent macroscopic shale properties. Here, we have used, for the first time, SPRITE Magnetic Resonance Imaging (MRI) methods to give core plug size shale images. The imaging method resolves water and oil signals to give separate images of each in shales. "As received" shale samples were used to acquire 1D and 3D oil and water images to characterize natural fluid distribution. Water uptake experiments were conducted to probe fluid displacement in shales. Measurements included gravimetric, Magnetic Resonance (MR) T 1 - T 2 ∗ relaxation correlation, and SPRITE imaging methods. Water and oil images showed that sample scale heterogeneities are imposed by the shale beddings. Water uptake experiments (1) showed the capability of the T 1 - T 2 ∗ method to identify MR signals from shale fracture water and matrix pore water, and (2) illustrated wettability control of spatial water distribution in shales during spontaneous imbibition. [ABSTRACT FROM AUTHOR]

There is still debate on how shutting fractured wells for a period of time can affect the well performance. In this study, we combined two approaches to better understand the effects of shut-in time on well performance. First, we analyzed flowback and post-flowback production data from a horizontal well drilled in the Montney Formation, which was fractured with water containing a microemulsion (ME) additive. After the shut-in time for 7 months, the oil and solution gas rates significantly increased by 750% and 671%, respectively. However, the free gas rate decreased by 95% in 65 days, before it started to build up again to exceed the values at the start of the production. Second, we performed a series of imbibition oil-recovery, dynamic liquid-liquid contact angle, and interfacial tension measurements to investigate how the interplay of (i) capillary suction and (ii) osmotic pressure affects oil production from core plugs during the counter-current imbibition tests. Combined analyses of field and laboratory results suggest that the increase in oil production rate after the shut-in period is due to combined effects of (i) free-gas dissolution into the oil (ii) capillary imbibition of fracturing water containing ME solution into the rock matrix driven by wettability alteration and osmotic pressure, and (iii) reduction in phase trapping near fracture face due to interfacial tension reduction. • The self-EOR process during the shut-in period can lead to enhancement in hydrocarbon recovery. • Adding a microemulsion system to the fracturing water enhances imbibition oil recovery from oil-saturated core plugs. • Osmotic pressure is a key driving force for enhancing imbibition oil recovery. [ABSTRACT FROM AUTHOR]

We investigated both the distribution of protein, ash and starch in legume (chickpeas, smooth and wrinkled peas) cotyledons, and the soaking and cooking characteristics, including gelatinization and retrogradation, of the starch. There were large differences in composition between different types of legumes and also between the outer and inner parts of legume cotyledons. Wrinkled peas exhibited much higher water absorption during prolonged soaking and there were higher hardness value determined for cooked seeds compared with chickpeas and smooth peas. While the hardness of cooked seeds decreased continuously as cooking time increased to 110 min, all legume starch was fully gelatinized after cooking for 70 min. [ABSTRACT FROM AUTHOR]

• Significant shrinkage cracking was revealed in the repair mortar bonded with a pre-dried substrate. • Large discontinuity was found around the interface between repair mortar and pre-saturated substrate. • Progressive increase of water content around interface was noticed during imbibition. • Shrinkage cracks can significantly promote water imbibition in repair and old mortar. Appling fresh mortar onto the surface of old concrete has been a common repair and reinforcement method. In this work, the influence of initial moisture conditions of old mortar on the microstructure of repair mortar was checked. Two types of composites were prepared by bonding fresh repair mortar with a pre-dried or a water-saturated old cement mortar. By analyzing X-ray CT images, severe shrinkage cracking was found in the repair mortar bonded with a pre-dried old mortar. A large discontinuity was revealed between repair mortar and pre-saturated old mortar by X-ray CT images. Various porosities in the repair mortar were identified by Mercury Intrusion Porosimetry tests. Dynamic water imbibition in the two types of composites was followed by neutron radiography. Shrinkage cracks in repair mortar can significantly promote water infiltration in both repair mortar and substrate, which poses a threat to the durability of the repair system. [ABSTRACT FROM AUTHOR]

Behavior of spun rayon fabric treated by the poly-set process was investigated in comparison with cotton and polynosic fabrics reported earlier. There was no significant difference between the process steps as regards dry wrinkle recovery of spun rayon fabric. Unlike cotton and polynosic fabrics, the wet wrinkle recovery showed a high, significant difference between process steps, as observed for cotton and plynosic fabrics, although the difference was not big enough to classify them into two distinctly separate groups. The dominant influence of the water-sensitive links was observed for the dry state of spun rayon. Treatment based on the simple assumption that the difference in the dry and wet wrinkle recovery angles is a criterion of water-sensitive links showed the same tendency as for polynosic fabrics. The relationships between the various physical properties and wrinkle recoveries were investigated. [ABSTRACT FROM PUBLISHER]

Data are reported on the moisture regain, water of imbibition, tear strength, elastic properties, and flame resistance of chemically modified viscose rayon fabrics.The data reveal that THPC behaves as if it were a derivative of formaldehyde. Under moderate curing conditions, substitution of hydroyxy groups in cellulose occurs, but when curing conditions are more severe, cross-linking takes place. Both triethanolamine and urea inhibit the reaction of THPC with cellulose and reduce acid degradation. Treatment of fabric with THPC-urea or THPC-melamine resins also leads to polymer deposition, especially at high curing temperatures. Both in the presence and absence of urea, when substantial quantities of triethanolamine are added, THPC decomposes, and the amount of phosphorus fixed is reduced. Triethanolamine appears to act in a complex manner; its effect is due not solely to its alkalinity. Only in the presence of urea does the fabric acquire flame resistance, although phosphorus is fixed even in the absence of urea. Fabric aminized with 2-amino ethyl sulfuric acid is on subsequent treatment with THPC, also flameproofed. Due to the presence of amino groups in the fabric, however, THPC reacts with fewer hydroxyl groups, and the losses in tear strength are less. [ABSTRACT FROM PUBLISHER]

Spontaneous water imbibition plays an imperative role in the development of shale or tight oil reservoirs. Spontaneous water imbibition is helpful in the extraction of crude oil from the matrix, although it decreases the relative permeability of the hydrocarbon phase dramatically. The dynamic pore-scale network modeling of water imbibition in shale and tight reservoirs is presented in this work; pore network generation, local capillary pressure function, conductance calculation and boundary conditions for imbibition are all presented in detail in this paper. The pore network is generated based on the characteristics of Barnett shale formations, and the corresponding laboratory imbibition experiments are matched using this established dynamic pore network model. The effects of the wettability, throat aspect ratio, viscosity, shape factor, micro-fractures, etc. are all investigated in this work. Attempts are made to investigate the water imbibition mechanisms from a micro-scale perspective. According to the simulated results, wettability dominates the imbibition characteristics. Besides this, the viscous effects including viscosity, initial capillary pressure and micro-fractures increase the imbibition rate, while the final recovery factor is more controlled by the capillarity effect including the cross-area shape factor, contact angle and the average pore-throat aspect ratio. [ABSTRACT FROM AUTHOR]

Tight matrix has relatively low permeability and porosity, with abundant micro/nano pores. The capillary force in these pores are relatively strong, making the wetting liquid easier to be imbibed in the matrix. This process is called spontaneous imbibition. The complexity of pore structure is identified as one of the key factors influencing the imbibition process, but the detailed mechanism is not clear. Thus, in this work, a method is proposed to evaluate the influence of pore structure on imbibition process. Pore structure has fractal properties in a specific scale. By using the fractal theory, an imbibition model is provided to analyze the influence of microscopic structures on spontaneous imbibition, considering the pore size distribution and pore connectivity. Also, based on this model, the influencing factors on dimensionless imbibition and diffusion rate are discussed. Results show that the pore structure has more branches, larger and shorter sub-throats has higher chance to gain a high imbibition rate. Finally, a 3D imbibition parameter cube is constructed to determine the parameter combinations in favor of strong water diffusion potential. By utilizing the analysis method based on the fractal theory, we can effectively evaluate the imbibition potential. It is helpful to provide a guidance to evaluate the water imbibition to gas production. [ABSTRACT FROM AUTHOR]

As an effective enhanced oil recovery (EOR) technique in tight reservoirs, cyclic water injection has been extensively studied recently. However, very few studies have considered the impacts of loading-path dependent fracture deformation, i.e. deformation hysteresis. In this study, an efficient coupled two-phase flow and geomechanics model is developed to simulate cyclic water injection in a tight oil reservoir with the consideration of fracture deformation hysteresis. The embedded discrete fracture model (EDFM) is applied to handle complex fracture geometries. Different loading-path dependent constitutive models are used to describe the deformations of hydraulic fractures and natural fractures, respectively. Then simulation studies are performed to demonstrate the impacts of deformation hysteresis of hydraulic fractures and natural fractures on EOR performance. The sensitivities to injection rate, depletion pressure and soaking time are examined. The results show that the deformation hysteresis of hydraulic fracture has significant effect on oil production, while that of natural fracture has negligible impact. The effects of fracture deformation hysteresis are more pronounced under high injection rate and depletion pressure, but less sensitive to soaking time. [ABSTRACT FROM AUTHOR]

• Sol-gel hybrid silica coatings: Long lasting antireflection and water-repellence. • The coatings have a microporous structure with hydrophobic pore surfaces. • Coatings preserve their advantageous properties after soaking in neutral aqueous media. • The effect of acidic or alkaline aqueous media can be reversed via heat-treatment. • Soaking resulting in matrix swelling helps to preserve the antireflective property. Bifunctional hybrid silica sol-gel coatings were synthesized, which showed both increased light transmittance and water-repellence. The as-prepared coatings of variable thickness (100–175 nm) were found to have low refractive index (1.250–1.275), high porosity (36%–42%), and maximum light transmittance up to 99.8%. Water-repellence of the surface was due to high water contact angle (90°) and low contact angle hysteresis (1–2°). Ellipsometric porosimetry and transmission electron microscopy measurements confirmed the microporous structure of the coatings. A systematic investigation for studying the durability and the deterioration of optical and surface properties was studied during aqueous soaking tests at different pH. During these experiments atomic force microscopy showed that the morphology of the surface did not change. The changes in the wetting properties were also confirmed by surface free energy measurements and an increase of the polar component was observed. The optical properties could be regenerated completely or partially after the soaking via heat treatment at 400°C. The light transmittance of the samples remained high after the soaking, most likely due to the swelling of the solid matrix. The light transmittance and the water-repellent properties of the coatings showed long-term stability up to a year of storage. [ABSTRACT FROM AUTHOR]

Rock is a typical porous and heterogeneous geological medium, and water imbibition has a great influence on its mechanical properties. The degree of water imbibition in rock heavily depends on the internal fissures of rock and the soaking time. Here, sandstone specimens were soaked in a red ink solution for different amounts of time, and then cross sections were photographed to obtain RGB images of the water distribution in the rock. Next, the correlation between the water distribution in the rock specimens and the RGB values of the images was established to characterize the water distribution in the sandstone specimens. Finally, the water imbibition in rock was quantified with the diffusion equation, which was applied to determine the diffusivity of rock when the quantitated water distribution was matched to the observed wetted ring in the laboratory. This study quantifies the evolution of unsaturated moisture distribution in sandstone with soaking time and the variation of uniaxial compression strength as it is affected by the water distribution. The results from this study can be used as the scientific bases to study the rock weakening mechanism in a water environment. [ABSTRACT FROM AUTHOR]

Capillary absorption of C15, C15H1 and C15H2 concretes. • This research is exploring the performance of two water repellent surface treatments (H1 and H2) on one type of concrete (C15). • The water repellents were found to significantly reduce the water absorption kinetics. • However, this reduction was shown to be temporary, what makes the originality of this research work. • As shown in the following Figure, the surface treatments slow down the water transfer but when the water passes through the physical barrier, the kinetics capillary absorption becomes similar to that of non-treated concrete. Indicators of durability are nowadays key-parameters in the design of reinforced concrete structures. One way to guarantee durability is usually to design concrete mixtures with low porosity and low transfer properties. An alternative or in addition to this performance-based approach is the use of treatments such as water repellent, applied on surface of both new and existing concrete structures. The aim of the present study is to evaluate the efficiency of two water repellents with respect to water capillary absorption. Both studied water repellents were applied on a concrete with relatively low mechanical performances (28-day compressive strength equal to 20 MPa). Porosity, pore structure and capillary absorption kinetics were determined according to the AFREM recommendations (Arliguie et al., 2008) for both treated and non-treated concrete samples. The water repellents were found to significantly reduce the water absorption kinetics. However, this reduction was shown to be temporary. The surface treatments slow down the water transfer but when the water passes through the physical barrier, the kinetics capillary absorption becomes similar to that of non-treated concrete. A pore network model was used to support this explanation of the observed absorption kinetics and to model the effect of water-repellent. [ABSTRACT FROM AUTHOR]