Water Absorption Curves Research Articles

Examining Mechanical Property Differences in Concrete with Natural and Synthetic Fiber Additives

The rapid growth of Natural Fiber Laminate (NFL) innovation is a direct response to environmental challenges, positioning these materials as superior alternatives to synthetic fiber composites. This paper delved into the outcomes of an extensive experimental study investigating the influence of sisal fiber (SLF), banana fiber (BF), and glass fiber (GF) on the mechanical and microstructural characteristics of concrete. The water absorption curves were established for sisal fiber concrete (SLFC), banana fiber concrete (BFC), and glass fiber concrete (GFC). Furthermore, Scanning Electron Microscope (SEM) observations were conducted to perform microanalysis and failure analysis of the tested specimens. The results revealed significant improvements in the concrete containing fibers compared to its counterpart in fiber-free concrete. For mixtures with a water-to-binder (W/B) ratio of 0.3, the most optimal mix (GF-30-135) showed improvements in compressive strength, flexural strength, and splitting tensile strengths by 4.13%, 8.93%, and 10.10%, respectively. On the other hand, for W/B of 0.4, mix GF-30-135 showed improvements of 5.05%, 8.55%, and 11.60%, respectively. Furthermore, as the fiber content increased, microscopic analyses revealed a weakening of the bond between the fibers and the rest of the matrix, contributing to the deterioration of the mechanical properties.

Embebição e germinação de sementes de chincuya (Annona purpurea Moc e Sessé Dunal) sob efeito de ácido giberélico e pH da água em imersão

Abstract: Germination is influenced by several factors, among them pH. Two experiments were conducted to determine the effect of imbibition-water pH on the water absorption curve of chincuya seeds and germination. The results were contrasted to the known effect of gibberellic acid imbibition. In the first year of fruit collection and evaluation, imbibition curves were constructed per treatment. The seeds of this evaluation were divided into two lots: the first at the initial moisture content (39.9 %) and the second at the moisture content of 34.1 % after three days of drying in the laboratory. The seeds were imbibed for 84 h in distilled water at three pH levels (5, 7, and 9) and kept in a water bath at 30 °C. In the second year of collection and evaluation, the pH treatments were repeated, and an imbibition treatment with gibberellic acid at 350 mg L-1 (pH 3.9) was added. A control treatment contained distilled water at pH 6.1. For both years, treated seeds were incubated on paper towels and placed under controlled conditions at a 12-hour photoperiod and alternating day and night temperatures (30 °C:25 °C). The three imbibition curves showed similar behavior and no statistical significance. Seeds with a higher moisture content did not gain weight after imbibition. The imbibition curves increased constantly in the seeds at 34.1 % moisture, and weight gain reached almost 46 % with the pH 9 treatment. However, there were no statistical differences among treatments. The highest rate of water absorption occurred in the first six hours in the open-air, dehydrated seeds, and after 72 hours, the weight of the seeds did not increase. Average daily germination kinetics indicated a slow and poor germination process. Gibberellic acid significantly promoted germination, causing 43 % germination. The absolute control reached 5.7 %, while the rest of the treatments did not promote germination.

Investigating the influence of PVA and PP fibers on the mechanical, durability, and microstructural properties of one-part alkali-activated mortar: An experimental study

Alkali-activated materials (AAMs) have gained significant attention in recent years due to their potential for sustainable construction and outstanding strength and durability characteristics. However, their wide application is constrained by their weak behavior under flexure and tensile loading, leading to brittleness. This study examines the formulation of an alkali-activated fiber-reinforced mortar, using fly ash and hydrated lime as main precursors, and investigates the capacity when reinforced with polyvinyl alcohol (PVA) and polypropylene (PP) fibers. The performance was measured through experimental investigation in terms of flowability, setting time, compressive strength (CS), water absorption, flexure strength (FS), and load-displacement curve under flexure loading. The durability was assessed through acid and sulfate attack tests after 120 days. The findings showed that adding both types of fibers improved the mechanical and durability performance of the one-part AAM. The highest CS of 44.95 MPa and 42.04 MPa and FS of 7.8 MPa and 6.9 MPa were achieved for PVA and PP fibers at a 1.5% fiber content. The FS was increased by 18.94% and 28.2% for PP1.5 and PVA1.5 fibers respectively. The control sample, PP 1.5 and PVA 1.5 recorded 31.1%, 12.5%, and 11% loss in CS after the acid attack test, respectively, after 120 days. A reduction of 15.3% and 13.3% was recorded in flow diameter with the addition of PP and PVA fibers at 2%. Overall, mortars reinforced with PVA fibers have shown better flowability, mechanical strength, and chemical resistance than PP fibers.

Real-Time Experimental Monitoring for Water Absorption Evolution Behaviors of Sandstone in Mogao Grottoes, China

Rock mass has typical pore structure, and the induced coupling effects of fluid and solid matrix appear in the disaster evolution process of deep energy exploitation and overground rock hydration. As a representative case, influenced by the water absorption environment, the surrounding rock and murals of Mogao Grottoes produce hydration diseases, which may be related to unclear interaction mechanisms between the surrounding rock and water. In this study, the self-developed physical experimental system for real-time experimental monitoring was applied to test the water absorption evolution behaviors of sandstone. The experimental results showed that the water evaporation of the rock sample during the process of water absorption could be measured through this well-designed physical experimental system, and the actual water absorption of the rock sample is the difference between the decrease of water in the water storage bucket, measured by the balance and the water evaporation in the process of experiment; by drawing the actual water absorption curve of the rock sample, the time when the water absorption of the rock sample reaches saturation could be determined accurately; and the curve of water absorption with time could be expressed as an exponential function. The experimental techniques and methods in this study provide a feasible research idea for studying the water absorption evolution behaviors and mechanisms of the surrounding rock weathering when it meets water, and have significance for revealing the disease mechanisms of the surrounding sandstone in Mogao Grottoes, China.

Hygrothermal aging effect on the water diffusion in glass fiber reinforced polymer (GFRP) composite: Experimental study and numerical simulation

Understanding the water diffusion process in glass fiber reinforced polymer (GFRP) is critical to bridging the gap between the long-term degradation performance of GFRP composite and the retained strength of glass fibers under water attack. In this study, the water diffusion in GFRP with consideration of defects is systematically investigated through experimental and simulation methods. The water diffusivity of GFRP decreased from 6.60 × 10−7 to 2.05 × 10−7 mm2/s as glass fiber volume fraction increased from 0 to 50.21%. In addition, the diffusivity increases slightly with the presence of voids, and significantly with matrix cracking, debonding and fiber erosion, while it is insensitive to fiber size. Furthermore, the square or hexagonal fiber arrangement models produce similar results to random fiber arrangements in the actual situation. GFRP water absorption curves are found to be underestimated and overestimated respectively for models without and with defects taken into consideration. Finally, the simplified and refined FE models are supposed to be employed to rapidly estimate the water absorption of GFRP composite.

Method for Predicting the Water Absorption of External Insulating Silicone Rubber

The intrusion of moisture may induce an abnormal increase in temperature or may even cause fractures in insulation equipment. Therefore, the hygroscopicity of rubber materials must be characterized. However, the existing methods for weighing organic polymer materials, such as silicone rubber, for moisture-absorption tests are time-consuming. In this article, a practical method for testing the moisture-absorption performance of silicone rubber materials for external insulation is proposed. The basic characteristics of the Langmuir diffusion equation for the water-absorption characteristics of silicone rubber are analyzed. A Langmuir curve fitting method based on the contraction–expansion (C–E) algorithm is developed, and its fitting effect is preliminarily verified by combining the experimental errors obtained from the experiment. Results show that the fitting effect has a strong relationship with the initial range of diffusion coefficient, bonding coefficient, and debonding coefficient. The time-consuming process of directly applying the fitting method is reduced from 70 to 50 days. The initial ranges of diffusion, bonding coefficient, and debonding coefficient are determined via the results of molecular simulations and experiments combined with an analysis of the literature. A prediction model is optimized and then validated against the experimental data from the recent literature on the water-absorption characteristics of silicone rubber at different temperatures. The experimental time required to reach saturated water absorption is remarkably reduced from 70 days to 1 day. Therefore, the method developed herein is feasible for engineering applications. Moreover, the entire water-absorption curve can be possibly plotted with an error of not greater than 5% via this prediction method.

Experimental Study on the Mechanical Properties, Water Absorption, and Fiber Degradation of Naturally Aged Glass Fiber and Polypropylene Fiber-Reinforced Concrete.

The main objective of this study is to better understand the performance changes of naturally aged glass fiber-reinforced concrete (GFRC) and polypropylene fiber-reinforced concrete (PPFRC), especially the degradation of fibers, which is of great significance for evaluating the durability of structures using these two types of composite materials. The mechanical properties, water absorption, and microstructures of GFRC and PPFRC at a curing age of three years, including their compressive strength, full curves of water absorption, fiber-matrix interaction, and fiber degradation, were systematically studied, and the related properties were compared with those at the curing age of 28 days. The degradation of fibers after freeze-thaw cycles was also studied. The results revealed the following. The water/binder ratio (w/b) affects the rate of increase of the long-term compressive strength of naturally aged concrete. In general, the water absorption of fiber-reinforced concrete (FRC) at the curing age of three years was found to be significantly reduced, but with the increases of w/b and the fiber content to the maximum values, the water absorption of the specimens cured for three years was higher than that of the specimens cured for 28 days. Moreover, with the increase of the curing age, the optimal glass fiber (GF) contents for reducing the water absorption decreased from 1.35% to 0.90% (w/b = 0.30), and from 0.90% to 0.45% (w/b = 0.35), respectively. The GF surface was degraded into continuous pits with diameters of about 200 to 600 nm, and the surface of the pits was attached with spherical granular C-S-H gel products with diameters of about 30 to 44 nm. The freeze-thaw cycles were found to have no significant effect on the pits on the GF surface and the granular C-S-H gel products attached to the pits, but caused a portion of the cement matrix covering the GF to fall off. The interfacial bonding between the polypropylene fiber (PPF) and the cement matrix exhibited almost no change in the PPFRC after three years of curing as compared with that after 28 days of curing. Furthermore, the cement hydration gel on the PPF surface was not significantly damaged by 150 freeze-thaw cycles.

Effect of Slurry Coating Modified Methods on Water Absorption of Recycled Coarse Aggregate

Water absorption rate of the recycled coarse aggregate is higher than the natural ones. Until now, there is no test method to record the instantaneous value of the water absorption although this could help us to understand the recycled coarse aggregate better. This paper developed a new device that can record the water absorption continuously and calculate the water absorption rate automatically. The water absorption curve from 0 min to 60 min can be plotted smoothly. The performances of modified recycled coarse aggregate and concretes with recycled coarse aggregate have also been studied. The result shows that the water absorption rate increases fast and about 90% water has been absorbed during the first 10 min. The slurry of silicon nitride with 500 nm particle size can reduce the 10 min water absorption rate of the recycled coarse aggregate from above 4.5% to below 2.5%. A recycled coarse aggregate wrapped with wet slurry is better than the ones wrapped with dry slurry shell for the slump of concrete. Compared to the concrete without any recycled coarse aggregate, the compressive strength and the splitting tensile strength of the concrete with recycled coarse aggregate modified by fresh cement slurry have been increased by more than 20%.

Durable mechanical properties of unidirectional flax fiber/phenolic composites under hydrothermal aging

Natural fibers show great potential in polymer composites reinforcement, it remains challenging to tackle the mechanical stability of the composites under moist/water condition for long-term outdoor applications. Herein, unidirectional flax fiber reinforced phenolic (FFRP) composites were developed to systematically study the effects of water absorption on their mechanical properties. Water absorption tests were conducted by immersing composite specimens into distilled water at three different temperatures (23, 37.8, and 60 °C) for a period up to 3 years. Water absorption curves indicate FFRP achieved adsorption equilibrium within 64 days, exhibiting diffusion coefficients (D) of 7.3 mm2/s and maximum moisture contents (Mm) of 18.3%, which reveal the water absorption by FFRP composites in the initial stages followed Fickian behavior. After aging for 3 years, the mean values for tensile strength and Young's modulus were 57 MPa and 15 GPa, respectively, 77.7 and 47% lower, respectively, and the shear strength decreased by about 71.7% compared to the unaged specimens. The effects of hydrothermal aging on the tensile and interlaminar shear characteristics of the composites Long-term hydrothermal aging was found to weaken interlaminar shear characteristics of the composites, causing degradation/deformation of the flax fibers and degradation of the phenolic matrix. A hydrothermal aging mechanism defined as “swelling-debonding-matrix degradation-fiber degradation” at molecular scale is proposed for FFRP composites, promising to steer the future design and exploitation of natural fiber reinforced polymer composites to accommodate the prolonged adaptability at water conditions.

Effects of Temperature, Scarification, Stratification, Phytohormones, and After-Ripening on the Dormancy and Germination of Eucommia ulmoides Oliv. Seeds

Eucommia ulmoides Oliv., the only member of the family Eucommiaceae, is endemic to China and has great development and utilization prospects. The seeds of E. ulmoides show dormancy but the underlying mechanism remains unknown. The aim of this study was to determine the cause of the seed dormancy and provide fundamental knowledge for the breeding, genetic improvement, and conservation of the germplasm resources of this species. According to the seed dormancy classification system developed by Jerry M. Baskin and Carol C. Baskin, we compared the germination percentage between intact seeds and isolated embryos, constructed water absorption curves, and evaluated the germination of seeds treated with scarification, cold/warm-moist stratification, after-ripening during dry storage, and gibberellic acid (GA3). The results showed that the intact seeds germinated only at 10 °C with a low germination percentage of 13.3% whereas the isolated embryos had a high normal germination percentage among a wider range of temperatures. According to the results from the scarified seeds, half seeds, and intact seeds, the seed coat significantly restricted the embryo water absorption. The scarification, after-ripening, cold/warm-moist stratification, and GA3 treatments promoted seed germination. Among them, cold-moist stratification was the most effective method and the temperature range of seed germination increased in both directions from 10 °C with prolonged stratification. The germination percentage increased significantly at constant temperatures with the highest germination percentage of 93.7 ± 0.3% at 10 °C and a light/dark cycle after 90 days of cold-moist stratification. Therefore, the freshly harvested E. ulmoides seeds exhibited a combinational dormancy comprising physical and Type 3 non-deep physiological dormancy, causing limited embryo water absorption by the seed coat and a low embryo growth potential. Given the unique phylogenetic characteristics and utility of E. ulmoides, our findings should promote studies of seed dormancy evolution and the development and application of E. ulmoides germplasm resources.

Thermal and moisture performance parameters of high toughness engineered cementitious Composite(ECC) with PVA fibers

PVA fibers-reinforced engineered cementitious composite (PVA-ECC) has good mechanical properties and broad application prospects in construction. But researches on the performance of it as a building envelope are limited. To provide a basis for the study of the heat and moisture transfer performance of PVA-ECC as a building material, this work investigated the thermal and moisture properties of PVA-ECC by experimental methods. The dry density and porosity, capillary water absorption curve, isothermal moisture absorption curve and the relationship between water vapor permeability and relative humidity were measured. The results show that the dry density of PVA-ECC is 1715 kg/m 3 , and the porosity is 20%. The capillary water absorption coefficient of PVA-ECC is 9 × 10 − 3 k g ⋅ m − 2 ⋅ s − 0.5 , and the capillary saturated moisture content is 59.84 k g ⋅ m − 3 . The water vapor permeability of PVA-ECC is 3.21 × 10 −9 kg/(m·s·Pa) in the relative humidity range of 15%–33%, while it is 1.196 × 10 −8 kg/(m·s·Pa) in the relative humidity range of 81%–100%. Different empirical adsorption isotherm models are used to fit the isotherm adsorption curve of PVA-ECC. The BET model shows the best effect among these models. The variation of the thermal conductivity of PVA-ECC affected by moisture content is studied and the applicable fitting expression is obtained. The results show that as the moisture content increases, the thermal conductivity gradually increases, but the growth rate decreases. Over all, PVA-ECC has low water absorption, vapor permeability and thermal conductivity. Combined with its advanced mechanical properties, It can be speculated that the PVA-ECC has the potential to be used as a building envelope material. • The dry density and porosity of PVA-ECC materials were measured. • The capillary water absorption curve of PVA-ECC was obtained and analyzed. • Fitting effect of different models for the isothermal moisture absorption curve is investigated. • Influence of mass moisture content on thermal conductivity is evaluated.

Modification of the Hygroscopic Properties of Textile Materials Containing Polyurethane Threads

The article discusses the influence of the presence of polyurethane (elastomeric) threads in the composition of a textile material on the effect of plasma modification of hygroscopic properties. The objects of the study were textile (knitted) fabrics based on cotton fibers with the addition of Dorlastan threads. The samples were processed in the plasma of a high-frequency capacitive discharge at a reduced pressure, as the plasma-forming gas was used air. Experiments have shown that the water absorption of the samples after plasma treatment is increased by an average of 1.5 times. The presence of Dorlastan thread does not significantly affect the result of the plasma modification, since the samples are completely immersed in water and the elastomeric threads do not limit the water absorption of its cotton component. The degree of capillary rise, on the contrary, depends on the presence of polyurethane threads. In samples made of 100% cotton, the increase occurs up to 190-. According to these samples, polyurethane threads prevent the capillarity of water by about 4 times. Kinetic curves of water absorption are given. The results suggest that other processing treatments are required to render the polyurethane threads hydrophilicity by plasma treatment. This should be considered in the development of plasma methods for treating textile materials, including in terms of matrix for composite materials.

Controlled Water Uptake in Fuel Cell Membranes with Dual Chemistry Confinement

Nafion is one of the most commonly used materials for proton exchange membranes in polymer-electrolyte fuel cells (PEFC) due to its stability and high ion-transport capabilities. However, its dehydration problem as well as dimensional instability limits its application in high-temperature, low-humidity environments. In this paper, we propose a potential solution to this problem by introducing nanoscale confinements to the Nafion chains. In particular, a coarse grain molecular dynamics model is developed that reproduces the water absorption curve of the pristine Nafion membrane. The model enables us to perform systematic studies on the effects of confinement to the absorption behavior of the Nafion membrane at different activities. Confinement of different chemistries and sizes has been introduced in the simulation system in order to investigate its effects on water absorption on different activities. It is found that confinement of dual chemistry (consisting of both hydrophobic and hydrophilic confinements) offers a solution to its drawbacks. The hydrophobic confinement helps flatten the absorption curve and decrease the water absorption at high activity, while the hydrophilic confinement acts as a water reservoir, which increases the water absorption at low activity. The Nafion membrane with dual chemistry confinement in general has higher water absorption with smaller dimensional instability, which makes it suitable to operate in a high-temperature, low-humidity environment.

Study on the Influence of Formation Temperature on the Water Absorption and Weathering of Swelling Rock in Marine Coal Mines

To study the mechanisms and potential control measures for coal mine engineering safety hazards caused by swelling rock, water absorption experiments were performed under different temperature by using an independently developed rock water absorption test system. The swelling pressure, expansion amount and water absorption amount of specimens were monitored in real time. Nuclear magnetic resonance and uniaxial compression experiments were performed. The water absorption rate of the swelling rock specimens increases significantly with increasing water absorption time. The water absorption capacity of the specimens differs considerably under different temperatures. The water absorption curve can be divided into three stages: the severe stage, deceleration stage and equilibrium stage. The water absorption amount and water absorption rate are linearly related to temperature. The curve of the swelling pressure depicts a double peak shape. The expansion curve can also be divided into three stages. With increasing temperature, the expansion rate increases, and the time needed to achieve expansion stability is prolonged. There is a negative linear correlation between the uniaxial compressive strength and the moisture content. The higher the temperature is, the higher the moisture content. The increase in the rock porosity after water absorption is one of the important factors driving the strength attenuation.

Physiological potential of chickpea seeds

The chickpea crop is grown predominantly in the arid and semi-arid regions of the world. India is the largest producing country, in Brazil production is scarce, leading the country to import almost all of what is consumed. Grains are a good source of carbohydrates, proteins and even essential amino acids. One of the first steps towards profitable production is knowledge about the availability of high-quality seeds. The germination test, evaluates the formation of normal seedlings in ideal conditions, so it must be associated with vigor tests, rapid and uniform germination of the seeds, simulating adversities in the field. Among the tests used, accelerated aging and electrical conductivity are common, as well as the study of the water absorption curve by the seeds. Accelerated aging is based on high temperature and humidity, real stress conditions in the field or in storage. For chickpeas, it is recommended to use saturated saline solution, 24 h exposure, at 41 ºC and evaluation at the first count. The electrical conductivity is determined by the amount of leachate, the higher the values, the less vigor. The most suitable methodology is the use of 75 seeds, volume of 100 mL of water, during 30 h of soaking. The process of water imbibition by the seeds occurs according to a three-phase pattern. In studies with the species, there was no clear definition between the three phases. However, the Peleg model adjusted to the imbibition data of the analyzed cultivars. There are other efficient ways, not yet described, for evaluating the physiological potential in this species, among them the tetrazolium test, images from scanners and radiographs, or even magnetic resonance of seeds. Although these tools require expensive equipment, they can streamline and increase the accuracy of seed analysis.

Effect of hydrothermal nanosilica on the performances of cement concrete

A new technological method for producing a nano-modifier for cement concretes from renewable source of hydrothermal solution using the processes of polycondensation of orthosilicic acid and ultrafiltration membrane concentration is proposed. According to the data of dynamic light scattering, tunneling electron microscopy, and low-temperature nitrogen adsorption, it is shown that in sol samples the average diameters of amorphous SiO2 nanoparticles can be varied in the range 10–100 nm, the specific surface area of ​​SBET is 50–500 m2 / g, the density of chemically active surface silanol Si-OH groups up to σ = 4.9 nm−2. Increasing the compressive strength of concrete specimens modified with SiO2 sol (0.5–3.0 wt%) and polycarboxylate superplasticizer (0.2–3.98 wt%), liquid-binder ratio L/B = 0.5–0.7, with normal hardening and with accelerated hardening with heat-moisture treatment, it reached 128% at the age of 1 day, and up to 40% at the age of 28 days. According to the kinetic curves of water absorption, a significant decrease in the volume, average pore diameter and an increase in the uniformity of the distribution of pores along the diameter of the modified concrete were established, which led to an increase in its water impermeability. The kinetics of the pozzolanic reaction with the formation of crystalline calcium hydrosilicates has been studied by the methods of X-ray diffraction analysis, energy-dispersive spectroscopy, scanning electron microscopy, and thermogravimetry. The chemo-sorption capacity of hydrothermal SiO2 nanoparticles for binding Ca(OH)2 in CaO solution and cement matrice was determined, which, due to the high SBET and σ values ​​for the first 24 h of the reaction, is many times higher than that of silica fume. In modified Portland cement matrice at the age of 1 day, the δCaO value was 750 [mg CaO / g SiO2], which corresponded to a response of 60–70% of the introduced nano-SiO2 and an increase in the rate of alite hydration by 20–30%, and rised at the age 100 days to 1200 [mg CaO / g SiO2]. Hydrothermal sols and SiO2 nanopowders have prospects for the creation of cement composites.

Mechanical properties and microstructure of glass fiber and polypropylene fiber reinforced concrete: An experimental study

This paper presents the results of a comprehensive experimental work investigating the effect of glass fiber (GF) and polypropylene fiber (PPF) on the mechanical and microstructural properties of concrete as a function of the water/binder ratio and fiber content. Different water/binder ratios (0.30 and 0.35), GF and PPF contents (0.45, 0.90, and 1.35% by volume fractions), and curing times (7 and 28 d) were used during the experiment to prepare the concrete specimens. The compressive, four-point flexural, and splitting tensile strengths and the full curves of water absorption of the glass-fiber-reinforced concrete (GFRC) and polypropylene-fiber-reinforced concrete (PPFRC) were obtained. The strength differences and water absorption properties of GFRC/PPFRC were analyzed in depth. Scanning electron microscope observation was undertaken to analyze the mechanism of the water/binder ratio and fiber effects. The results showed that the water/binder ratio can affect the optimal fiber content. When discussing the effect of fibers on the improvement of concrete mechanical or microstructural properties, the influence of the water/binder ratio should be considered. The improvement effect of GF on water absorption was significantly superior to that of PPF. When the water/binder ratio was 0.30, the water absorption of GFRC and PPFRC tended to be stable as the test proceeded, while when the water/binder ratio increased to 0.35, the water absorption of the GFRC and PPFRC with the highest fiber dosage still increased with the prolongation of testing time.

Physical and physiological changes of Crambe abyssinica Hochst seed during maturation

Determination of seed-maturation indicators enables the identification of the ideal moment for harvest to achieve the best production and conservation potential. Our objective here was to evaluate some physical and physiological changes of crambe (Crambe abyssinica Hochst) seeds as possible indicators of seed maturation. Crambe flowering was monitored in Dourados, Mato Grosso do Sul, Brazil. Plants were tagged, and 13, 22, 26, and 28 days after the initiation of flowering, the seeds were collected and following physical attributes evaluated: length, diameter, total mass, dry matter and water content. Physiological quality of the seeds was assessed using the germination test, by registering the percentage of normal seedlings and dormant seeds, immediately after each harvest, and again after six months of storage. The water-absorption curves were characterized as a function the seed-development stages. All physical attributes were observed to increase because of the accumulation of reserve substances during seed development, except for water content, which gradually decreased from 72.2% at the start of development to 29.5% at maturity. At 28 days after anthesis the germination percentage of crambe seeds at physiological maturity was only 17%, indicating that they became dormant while maturing. However, seed germination rate was 89% after six months of storage, indicating that dormancy was almost fully overcome after this period.

Methodology for germination test accomplishment in chia seeds

As sementes de chia são conhecidas por seus elevados teores nutricionais e por ser uma excelente fonte de energia. A chia ganhou notoriedade a partir da década de 90 com a crescente demanda por alimentos funcionais e saudáveis. Com o aumento expressivo da demanda por este produto, a produção de sementes de alta qualidade é imprescindível para alcançar elevados índices de produtividade. Além disso, existem poucos estudos sobre metodologias para análise de sementes dessa espécie, tornando este estudo relevante. Dessa forma, objetivou-se determinar a metodologia quanto à temperatura, substrato e fotoperíodo para o teste de germinação em sementes de chia. O experimento foi instalado em delineamento inteiramente casualizado, com tratamentos em esquema fatorial triplo 7 x 3 x 2 (temperaturas x substratos x fotoperíodo), com quatro repetições. Foram realizados os testes de massa de 1000 sementes, teor de água e teste de germinação com variações de temperaturas de 10, 15, 20, 25, 30, 35 e 40 ºC, nos substratos sobre papel, entre papel e entre areia, com presença ou ausência de luz. Os resultados foram expressos em porcentagem de germinação, índice de velocidade, tempo médio e velocidade média de germinação. Também foi obtida a curva de absorção de água em três temperaturas (20, 25 e 30 ºC). Nas condições testadas, concluiu-se que sementes de chia podem ser germinadas em substratos de papel e areia, com presença ou ausência de luz, nas temperaturas de 15 a 35 ºC, conseguindo assim, obter elevadas taxas de porcentagem de germinação.

Water Absorption Curves versus Gamma-Ray Attenuation Profiles: A Comparative Analysis of Hygric Permeance Results

The knowledge of moisture transfer in multi-layered building materials and components using numerical simulations is fundamental to predict the behaviour of that building materials and components when in contact with moisture and to avoid some possible future pathology guarantying a correct performance.This paper describes a comparative analysis of experimental values of Hygric Permeance (HP) obtained by water absorption curves and gamma-ray attenuation profiles, for perfect contact interface. ARTICLE REVISED ON 25.03.2022