Effect Of Different Environmental Conditions Research Articles

Salt Tolerance in Sugar Beet: From Impact Analysis to Adaptive Mechanisms and Future Research.

The continuous global escalation of soil salinization areas presents severe challenges to the stability and growth of agricultural development across the world. In-depth research on sugar beet (Beta vulgaris L.), an important economic and sugar crop with salt tolerance characteristics, is crucial for to determine its salt-tolerance mechanisms, which has important practical implications for production. This review summarizes the multifaceted effects of salt stress on sugar beet, ranging from individual plant responses to cellular and molecular adaptations. Sugar beet exhibits robust salt-tolerance mechanisms, including osmotic regulation, ion balance management, and the compartmentalization of toxic ions. Omics technologies, including genomics, transcriptomics, proteomics, post-translational modification omics and metabolomics, have played crucial roles in elucidating these mechanisms. Key genes and pathways involved in salt tolerance in sugar beet have been identified, paving the way for targeted breeding strategies and biotechnological advancements. Understanding these mechanisms not only enhances our knowledge of sugar beet's adaptation strategies but also provides insights for improving salt tolerance in other crops. Future studies should focus on analyzing gene expression changes in sugar beet under salt stress to gain insight into the molecular aspects of its salt-tolerance mechanisms. Meanwhile, the effects of different environmental conditions on sugar beet adaptation strategies should also be investigated to improve their growth potential in salinized soils.

Effect of multiple environmental conditions on the formation process and adhesion strength of ice on asphalt binder surface

Road icing caused by freezing rain significantly impacts driving safety. Since asphalt binder plays a pivotal role in pavement infrastructure, understanding the formation process and adhesion strength of ice on asphalt binder surfaces is crucial for assessing road icing risk. This work investigated the effect of different environmental conditions on asphalt-ice interface adhesion strength via a self-designed low-temperature adhesion testing system. In addition, the icing process on asphalt binder surfaces was observed to analyze the asphalt-ice adhesion strength formation mechanism. Results show that the completion time of water-ice phase transition signified the initial development of asphalt-ice adhesion strength. Moreover, as the internal structure of the ice evolved from transparent to needle-like fine lines to dense, the asphalt-ice adhesion strength gradually increased until it reached stability. At asphalt-ice adhesion began forming after 40 min and stabilized after 80 min, whereas at −8°C, adhesion strength started forming after 20 min and stabilized by 60 min. The growth rates of asphalt-ice adhesion strength for temperatures ranging from −2°C to −10°C were approximately 7.92 kPa/°C, 6.56 kPa/°C, 5.14 kPa/°C, 3.29 kPa/°C, and 1.49 kPa/°C, respectively, showing a positive correlation with temperature and a negative correlation with time. According to heterogeneous nucleation theory, the influence mechanism of temperature and water depth on the nucleation icing process and asphalt-ice adhesion strength is analyzed. lower temperatures lead to asphalt-ice adhesion strength increase originating from the larger supercooling, which reduces the critical nucleation energy and thus accelerates the ice nucleation rate. In addition, the increase in water depth promotes the formation of nucleation sites and further enhances the asphalt-ice adhesion strength. Finally, an asphalt-ice adhesion strength prediction model was developed, with PSO-SVM-G achieving over 90 % accuracy. These results provide insights for evaluating ice adhesion behavior on asphalt surfaces and designing anti-icing asphalt materials.

How Lazy Are Pet Cats Really? Using Machine Learning and Accelerometry to Get a Glimpse into the Behaviour of Privately Owned Cats in Different Households.

Surprisingly little is known about how the home environment influences the behaviour of pet cats. This study aimed to determine how factors in the home environment (e.g., with or without outdoor access, urban vs. rural, presence of a child) and the season influences the daily behaviour of cats. Using accelerometer data and a validated machine learning model, behaviours including being active, eating, grooming, littering, lying, scratching, sitting, and standing were quantified for 28 pet cats. Generalized estimating equation models were used to determine the effects of different environmental conditions. Increasing cat age was negatively correlated with time spent active (p < 0.05). Cats with outdoor access (n = 18) were less active in winter than in summer (p < 0.05), but no differences were observed between seasons for indoor-only (n = 10) cats. Cats living in rural areas (n = 7) spent more time eating than cats in urban areas (n = 21; p < 0.05). Cats living in single-cat households (n = 12) spent more time lying but less time sitting than cats living in multi-cat households (n = 16; p < 0.05). Cats in households with at least one child (n = 20) spent more time standing in winter (p < 0.05), and more time lying but less time sitting in summer compared to cats in households with no children (n = 8; p < 0.05). This study clearly shows that the home environment has a major impact on cat behaviour.

Degradation characteristics of the pineapple leaf fibre reinforced green composite developed by injection moulding under different environmental conditions

The present study examines the mechanical and morphological characteristics of a green composite reinforced with pineapple leaf fiber (PLF) under different environmental conditions. PLF underwent chemical treatment at optimal conditions, using a 1% w/v sodium carbonate solution for 6 hours, to produce an environmentally friendly pineapple leaf fiber (PLF)/polylactic acid (PLA)-based composite via injection molding. The optimal injection settings of 165℃ (melting temperature), 50 mm/sec (injection speed), and 110 bars (injection pressure) to produce the PLF/PLA composite. The PLF/PLA composite was developed with a fiber loading of 20% and a length of 3 mm. The produced PLF/PLA composites were then exposed to a variety of environmental conditions, including water, soil, refrigeration, and room temperature. The impact of these diverse conditions on the mechanical properties (tensile, flexural, compression, and shear) was scientifically observed for four-week. Additionally, the morphology of the fractured specimens was assessed using a scanning electron microscope (SEM). The contact angle measurement was conducted to assess the hydrophilic characteristics of the PLF/PLA green composite. There has been a lack of comprehensive research on the effects of different environmental conditions on the mechanical, wettability, and morphological properties of green composites derived from PLF/PLA. Thus, in this study, emphasis is given for investigating the effect of various environmental conditions on the mechanical properties of PLF/PLA injection-molded green composite. The composite material demonstrated the highest water absorption and swelling thickness at 6.45% and 5.51%, respectively, in comparison to the dry PLF/PLA samples. The green composite of PLF/PLA demonstrated excellent mechanical performance under ambient conditions compared to other environmental conditions. The PLF/PLA composite displayed a peak contact angle of 83.26° when subjected to soil burial conditions. On the contrary, the initial samples of the PLF/PLA composite displayed the minimum contact angle of 56.72°.

Study on effect of thermal, oxidative and ultraviolet coupled aging on rheological properties of asphalt binder and their contribution rates

ABSTRACT This paper aims to investigate the effect of different environmental conditions on the aging properties of virgin asphalt binder and evaluate the magnitude of aging on asphalt binder under different environmental conditions. The effect of thermal, oxidative and ultraviolet aging on the rutting resistance, fatigue resistance and cracking resistance of virgin asphalt binder was characterised based on rheological parameters. The contribution rate of different environmental factors to the aging of asphalt binder was quantitatively analysed. Results showed that high temperature repaired cracks in the asphalt binder caused by ultraviolet aging. The single aging factor of heat, oxygen and light had little effect on the rheological properties of asphalt binder. High temperature and oxygen would accelerate the aging effect of the asphalt binder aging process. Thermal–oxidative–UV-coupled aging had a more pronounced effect on the aging of asphalt binder than thermal–oxidative aging. The fatigue resistance of asphalt binder is more sensitive to the response of aging. The contribution rates of thermal–UV aging, UV–oxidative aging and thermal–oxidative aging were all greater than the sum of the contribution rates of the two corresponding single factors. The aging of asphalt binder was mainly due to thermal–oxidative aging when the aging temperature exceeded 80°C.

Bond degradation at environmentally exposed FRP-strengthened steel elements: State of the art

Due to several advantages that Fiber Reinforced Polymer (FRP) composites offer in comparison with other strengthening techniques for steel structures, they have attracted considerable interest over the past three decades. However, the efficiency of FRP-strengthening for structures was found to be highly dependent on the quality and durability of the adhesive bonding between FRP and steel surface. This paper presents a state-of-the art review on the bond degradation in FRP-steel joints under different environmental conditions. Topics reviewed in this paper comprise the effect of different environmental conditions and their combination on bond durability, synergic effect of combining environmental condition with mechanical load, and the recent developments in the numerical simulation of aged bond. The paper concludes with the research gaps and uncertainties for further investigations.

Increased Temperature and Discharge Influence Overwinter Growth and Survival of Juvenile Salmonids in a Hydropeaking River: Simulating Effects of Climate Change Using Individual-Based Modelling

Climate change causes warming of rivers and may increase discharge, particularly during winter. Downstream of hydropower plants, fluctuating water temperature and flow create dynamic overwintering conditions for juvenile salmonids. We used inSTREAM 7.2-SD to simulate the effects of increased temperature (+2 °C) and discharge (+10%) on the overwinter growth and mortality of one-summer- and two-summer-old Atlantic salmon and brown trout in a river with a hydropeaking flow regime in a 2 × 2 design with replicated simulations. Water temperature had a major positive relationship with growth for both species and year classes, whereas increased flow alone had no major general effect on overwinter growth. For one-summer-old trout experiencing the high temperature regime, however, increased flow resulted in reduced growth. There were no major effects from temperature and flow on the survival rate of the two-summer-old fishes. On the other hand, there were significant interaction effects for the one-summer-olds, indicating that the effect of flow depended on temperature. For one-summer-old salmon, high flow resulted in increased survival in the low temperature regime, whereas it resulted in reduced survival in high temperature. In contrast, for one-summer-old trout, high flow resulted in reduced survival in the low temperature regime and increased survival in the high temperature. Different hydropower operation alternatives may interact with warming, affecting the relative competitive abilities of stream salmonids. Ecological models that predict the effects of different environmental conditions, such as temperature and flow regimes, may offer insight into such effects when in situ experiments are not feasible.

Response of Soursop (Annona muricata L.) to Clonal Multiplication through Budding and Rootstock Compatibility

A research trial was carried out at the College of Horticulture, Mysuru, University of Horticultural Sciences, Bagalkot, Karnataka, India during January–June 2021 to study the effect of different environmental conditions and rootstocks on success and survival of soursop budlings. There were 6 treatment combinations consisting of different rootstocks of Annona sp. (Annona muricata and Annona squamosa) along with growing conditions (polyhouse, 50% shade net and open condition) were replicated thrice in factorial completely randomized design. The results of the study indicated that soursop scion budded on its own rootstock (A. muricata) and placed under polyhouse condition had significantly affected on days taken to bud sprout (34.96 days), success (91.60%), survival percentage (85.30%) and growth parameters like number of leaves (3.81, 6.56 and 13.67), length of sprouted shoot (3.58 cm, 8.19 cm and 15.42 cm), girth of sprouted shoot (1.35 mm, 1.86 mm and 2.08 mm), number of nodes (3.52 , 6.11 and 11.67) and length of internode (1.20 cm, 1.47 cm and 1.73 cm) at 60, 90 and 120 days after budding whereas A. muricata scion budded on A. squamosa rootstock kept under open condition recorded more number of days for sprouting (37.86), least success (37.86%), survival percentage (85%) and growth parameters like number of leaves (2.33, 4.44 and 11.11), shoot length (2.78 cm, 5.51 cm and 11.13 cm), diameter of shoot (0.70 mm, 1.01 mm and 1.24 mm), number of nodes (2.11, 4.33 and 10.22) and node length (0.84 cm, 1.01 cm and 1.42 cm).

Drying Process of Waterborne Paint Film on Bamboo Laminated Lumber for Furniture

In this study, bamboo laminated lumber for furniture was coated with waterborne acrylic paints. The effects of different environmental conditions (including temperature, humidity and wind speed) on the drying rate and performance of the waterborne paint film were investigated. Then, the drying process was optimized using the response surface methodology, and the curve model of drying rate was established, which can provide a theoretical basis for the drying process of the waterborne paint film for furniture. The results showed that the drying rate of the paint film changed with the drying condition. With an increase in temperature, the drying rate increased, and the surface and solid drying time of the film decreased. Meanwhile, with an increase in humidity, the drying rate decreased and the surface and solid drying time increased. Moreover, the wind speed can influence the drying rate, but the wind speed does not significantly affect the surface and solid drying time. The adhesion and hardness of the paint film were unaffected by the environmental conditions, but the wear resistance of the paint film was affected by the environmental conditions. Based on the response surface optimisation, the fastest drying rate was realised at a temperature of 55 °C, humidity of 25% and wind speed of 1 m/s, and the optimal wear resistance was realised at a temperature of 47 °C, humidity of 38% and wind speed of 1 m/s. The paint film drying rate reached the maximum value in 2 min and tended to remain constant after the film was completely dried.

Effect of different environmental conditions on quality of DNA extracted from human teeth for gender determination

Use of morphological characteristics in human identification maybe difficult in conditions where human remains are grossly fragmented, decomposed and/or mutilated, or when only a tooth is available. The study aims to ascertain and compare the quantity of DNA from teeth exposed to different environmental conditions using organic and silica column DNA extraction methods and determine their gender using amelogenin gene primer. Human teeth were used and divided into four major groups based on different exposure types (buried in soil, storage in Lagoon water, normal environmental condition by placing them on the floor at the botanical garden, and exposure to temperature of 210oC for 15mins). The powdered dentin-cementum complex was used for DNA extraction, quantification and purity assessments. Amplification was done using amelogenin gene primers. Mean DNA concentration and purity were 187.59±26.25ng/μl and 0.97±0.07 respectively for silica column method, and, 138.98±35.71ng/μl and 0.91±0.11 respectively for organic extraction. With organic extraction, the least and highest mean DNA concentration are from teeth immersed in Lagoon water (74.86±61.19ng/μl) and teeth exposed to temperature of 210oC for 15mins (385.14±106.39ng/μl). In the Silica column method, teeth heated at 210oC for 15mins showed the lowest mean DNA concentration (165.57±33.82ng/μl) while teeth exposed to "normal environmental conditions", gave the highest DNA concentration (218.46±45.03ng/μl). Positive and negative male identification were 30.8% and 69.2% respectively, while female identification was 100% positive irrespective of the environmental exposure. The dentine-cementum is a valuable DNA source for forensic investigations. Male identification using amelogenin gene, should still be investigated in the Nigerian context.

Effect of aging, testing temperature and relative humidity on adhesion between asphalt binder and mineral aggregate

The adhesion between asphalt binder and mineral aggregate directly determines the performance of asphalt pavement, which could be effected significantly affected by light, oxygen, water and other natural conditions. In order to investigate the effect of different environmental conditions on the adhesion between asphalt binder and mineral aggregate, virgin asphalt binder with 70 (0.1 mm) penetration and SBS modified asphalt before and after aging were used as test samples in this study. The effect of aging, testing temperature and relative humidity on adhesion between asphalt binder and mineral aggregate was quantitatively analyzed by using the surface energy theory. The results show that aging reduced the content of resin, increase the content of asphaltene, which resulted in the deterioration of adhesion performance of asphalt binder. The anti-aging performance of SBS modified asphalt was better than virgin asphalt binder in terms of adhesion. The work of adhesion between asphalt binder and mineral aggregate increased when the testing temperature of asphalt binder increased from 0 °C to 80 °C. The work of adhesion between virgin asphalt binder and material aggregate increased much higher than SBS modified asphalt. Asphalt binder was not sensitive to the change of relative humidity, but the total amount of surface energy parameters of the mineral aggregate decreases linearly with the relative humidity increasing. The work of adhesion between asphalt binder and granite aggregate was more likely to be affected by external gaseous water molecules. In order to simulate the real hydrodynamic pressure, the pull-off test was improved by adding ultrasonic wave. The ultrasonic tests' results show that the water invaded the interface between asphalt binder and material aggregate, accelerated the adhesion failure. A strong linear correlation exists between the work of adhesion and the ultrasonic pull-off strength.

Highly efficient removal of Se(IV) using reduced graphene oxide-supported nanoscale zero-valent iron (nZVI/rGO): selenium removal mechanism.

Se(IV) removal using nanoscale zero-valent iron (nZVI) has been extensively studied. Still, the synergistic removal of Se(IV) by reduced graphene oxide-supported nanoscale zero-valent iron (nZVI/rGO) has not been reported. In this study, nZVI/rGO was successfully synthesized for Se(IV) removal from wastewater. The effects of different environmental conditions (load ratio, dosage, initial pH) on Se(IV) removal by nZVI/rGO were investigated. When the load ratio is 10%, the dosage is 0.3g/L, the initial pH is 3, and the removal rate is 99%. The adsorption isotherm and kinetics accorded with the Langmuir isotherm and first-order kinetics models (R2 > 0.99). The fitted maximum adsorption capacity reached up to 173.53mg/g. NZVI/rGo and Se(IV) is a spontaneous endothermic reaction (△G < 0, △H > 0) and is characterized by EDS, XRD, and XPS before and after the reaction, to further clarify the reaction mechanism. The XPS narrow spectrum analysis suggested that Se(IV) was reduced to elemental selenium (Se(0)), while the intermediate Fe(II) was oxidized to form hydroxide precipitation. Therefore, nZVI/rGO was favored for Se-contaminated wastewater remediation.

Bio-mimetic Approaches to Kinetic Facades: A Design Proposal for a Light-Responsive Facade Module.

Facades are important for controlling light entering a building and ensuring optimal conditions for occupants. But light can also cause discomfort, such as glare and overheating. Natural light changes with the time of day, the weather, and the season. Creating a responsive structure can enhance the visual quality and energy efficiency. Because of their properties, kinetic facades can react to various stimuli, such as heat and sunlight. In this paper, we discuss bio-mimetic approaches to kinetic facades and how they can be used to develop a design proposal for the light-responsive facade module. Motors drive most kinetic facades, which adds to the maintenance costs, thus,shape memory alloys (SMAs) are investigated as actuators. Facades should be visually appealing and reflect the bio-mimetic concept of the project while allowing natural light to pass through. The results show that the suggested solutions are both feasible and aesthetically pleasing, thus comparable to traditional kinetic facade workflows. In conclusion, if bio-mimicry is to be used in large-scale construction, it is imperative that it is examined for the effects of different environmental conditions on bio-mimetic patterns.

Effect of different environmental conditions on the growth and development of Black Soldier Fly Larvae and its utilization in solid waste management and pollution mitigation

The current waste treatment techniques in developing countries do not meet the standards of appropriate waste management systems. Poor waste management leads to serious environmental issues at the local and global levels, for which an effective and sustainable waste disposal system is in urgent need. Due to its proven waste degradation and biotransformation capabilities, the Black Soldier Fly (BSF) provides a potential and economical alternative to recycling biological waste. The current study investigated the interactions between municipal and organic waste with the help of Black Soldier Fly Larvae (BSFL) as a growing medium for substrate culture by comparing the physicochemical parameters of waste before and after BSFL treatment of municipal and organic waste. The study results revealed that BSFL can improve the quality of the final product and promote the degradation of organic waste, although BSFL cannot effectively directly degrade municipal solid waste, it can reduce municipal solid waste by efficiently degrading organic waste. The optimal environmental conditions for BSFL breeding and growth was summarized in this study, and the environmental conditions of four seasons of four representative cities in different location of Pakistan were collected and analyzed. The most suitable cities for the development of the BSFL waste treatment system were first inferred, which makes basic research for developing an economical and feasible waste treatment system in Pakistan. A comprehensive legal framework regarding integrated MSW management systems should be introduced and implemented in Pakistan, including that local municipal authorities should collect the waste collection fee. • Interactions between municipal and organic waste by Black Soldier Fly Larvae. • Exploitation of BSFL in sustainable management of solid waste in Pakistan. • Increasing or decreasing temperature affects the different stages of BSF. • Summer season is ideal for the growth and development of BSFL. • Organic waste treatment with BSFL works best between 75 and 85% relative humidity. • Environmental conditions evaluation on the BSF growth and waste management efficiency.

Seasonal Change in Activity Rhythms and Time Budgets of Tibetan Macaques.

Simple SummaryPrimate activity rhythms and time budgets are dictated by food availability, temperature, and social factor; thus, primates must adapt their behaviors to accommodate fluctuations in environmental change. We conducted a year-long field study in the Huangshan region to collect data on Tibetan macaques’ behavior and local weather. We compiled and analyzed these data, explored Tibetan macaques’ behavioral patterns, and analyzed the potential factors that differentiate these behavioral patterns. The results indicate that Tibetan macaques have two foraging peaks and one resting peak in a day. Temperature and food were the main factors affecting the activity time budget of Tibetan macaques. Tibetan macaques’ daily activity time budgets are significantly different in sex and age group.Activity rhythms and time budgets are important to understand behavioral variability and adaptation in primates because animals normally use a behavioral adjustment as a preferential choice in response to environmental changes. Therefore, we observed a group of un-provisioned Tibetan macaques (Macaca thibetana) in Tianhu Mountain County Nature Reserve, Mount Huangshan, Southern Anhui, China. We used the instantaneous scan sampling method to collect behavioral data on their activity rhythms and time budget. The results showed that Tibetan macaques have two foraging peaks (9:00–10:00 and 14:00–15:00) and a resting peak at 12:00–13:00. They spent 31.96% resting, 28.59% foraging, 26.96% moving, 6.90% grooming, and 5.59% other. The total time of foraging and moving per month significantly and positively correlated with fruits and buds and negatively correlated with leaves. Different sexes and age groups demonstrated different activity time budgets, with adult males, adult females, and young macaques spending most of their time resting, grooming, and playing, respectively. We elucidated the effects of different environmental conditions on Tibetan macaques and their behavioral adaptation strategies.

Bacterial Communities Along Environmental Gradients in Tropical Soda Lakes.

Soda lake environments are known to be variable and can have distinct differences according to geographical location. In this study, we investigated the effects of different environmental conditions of six adjacent soda lakes in the Pantanal biome (Mato Grosso do Sul state, Brazil) on bacterial communities and their functioning using a metagenomic approach combined with flow cytometry and chemical analyses. Ordination analysis using flow cytometry and water chemistry data from two sampling periods (wet and dry) clustered soda lakes into three different profiles: eutrophic turbid (ET), oligotrophic turbid (OT), and clear vegetated oligotrophic (CVO). Analysis of bacterial community composition and functioning corroborated this ordination; the exception was one ET lake, which was similar to one OT lake during the wet season, indicating drastic shifts between seasons. Microbial abundance and diversity increased during the dry period, along with a considerable number of limnological variables, all indicative of a strong effect of the precipitation-evaporation balance in these systems. Cyanobacteria were associated with high electric conductivity, pH, and nutrient availability, whereas Actinobacteria, Alphaproteobacteria, and Betaproteobacteria were correlated with landscape morphology variability (surface water, surface perimeter, and lake volume) and with lower salinity and pH levels. Stress response metabolism was enhanced in OT and ET lakes and underrepresented in CVO lakes. The microbiome dataset of this study can serve as a baseline for restoring impacted soda lakes. Altogether, the results of this study demonstrate the sensitivity of tropical soda lakes to climate change, as slight changes in hydrological regimes might produce drastic shifts in community diversity.

Long-Term Behavior of PBO FRCM and Comparison with Other Inorganic-Matrix Composites.

Fabric-reinforced cementitious matrix (FRCM) composites, comprising high-strength fiber textiles embedded within inorganic matrices, represent an effective, cost-efficient, and low-invasive solution for strengthening and retrofitting existing masonry and reinforced concrete structures. Among different textiles employed in FRCM composites, polyparaphenylene benzo-bisoxazole (PBO) textiles are adopted due to their high tensile strength and good adhesion with the matrix. Although several experimental, numerical, and analytical works were performed to investigate the mechanical properties of PBO FRCM composites, limited information is available on their long-term behavior, as well as in the case of exposure to aggressive environments. This paper presents and discusses the results of a wide experimental campaign aimed at investigating the effect of different environmental conditions on the long-term tensile behavior of a PBO FRCM composite. Tests are performed using a clamping-grip tensile test set-up. The effect of various aggressive environments on the composite matrix cracking stress, composite tensile strength, ultimate strain, and fully cracked stage slope is investigated by comparing the results of nominally equal conditioned and unconditioned (control) specimens. These results are also compared with those of other FRCM composites comprising glass and carbon textiles subjected to the same conditionings, collected from the literature. The results show only limited reductions in the tensile properties, even after long exposure to aggressive environments.

Effect of Different Environmental Conditions on Durabilities of Polyester- and Vinylester-Based Glass-Fiber-Reinforced Polymer Pultruded Profiles

This paper presents the results of experimental investigations on the durability of glass-fiber-reinforced polymer (GFRP) pultruded profiles made of unsaturated polyester (UP) and vinylester (VE) resins commonly used in civil engineering. The water absorption, tensile properties, and microstructures of GFRP profiles exposed to several typical accelerated aging environments (e.g., deionized water, salt water, salt fog, and combined hygrothermal cycles) for 12 months were investigated. Moreover, a sustained loading factor was included in the test to reflect the behavior of the GFRP profiles in real structures. A normalization approach based on the controlled specimens was used to assess the effectiveness and relevance of the accelerated exposure. The results indicated that the maximum moisture absorption of both UP and VE GFRP profiles was immersed in deionized water, where the masses increased by 1.03 and 0.53%, respectively, leading to the maximum degradation of tensile strength (24.03%) of UP GFRP profile immersion in deionized water after 360 days of aging. However, the tensile modulus was more sensitive to high temperatures and has the maximum degradation (47.03%) after hygrothermal cycles. Moreover, VE GFRP profiles show superior humidity and temperature endurance. Furthermore, the sustained loading exacerbated the degradation of tensile properties slightly under the same conditions. Finally, by incorporating the cumulative damage caused by the sustained loading and a time-dependent factor into a residual strength model, a revised model was proposed to describe the tensile strength loss of pultruded UP GFRP profiles.

Mechanical Behavior of GFRP Laminates Exposed to Thermal and Moist Environmental Conditions: Experimental and Model Assessment.

This paper presents an experimental and analytical study about the mechanical response at a different temperature on glass fiber-reinforced polymer laminates. The effect of different environmental conditions on compressive, tensile, stiffness, and viscoelastic behavior (storage modulus, loss modulus and damping ratio) of laminates were investigated. Before testing, laminates were preserved in a deep freezer at −80 °C, −20 °C, 0 °C, and room temperature (25 °C) for up to 60 days. Results confirmed that temperatures ranging from −80 to 50 °C, which were below the glass transition temperature of the epoxy resin, did not significantly affect the compressive, tensile, and stiffness performance of all laminates. When the testing temperature increased to 100 °C, the properties were decreased significantly due to the damaging of the fiber/matrix interface. Additionally, results obtained from dynamic mechanical analyses tests showed a drop-in storage modulus, high peaks in loss modulus and high damping factor at the glass transition region of the epoxy resin. The highest storage modulus, two phases of glassy states and highest damping ratio on the −80/G group of laminates were obtained. The accuracy of experimental results was assessed with empirical models on the storage modulus behavior of laminates. The empirical model developed by Gibson et al. provided accurate estimates of the storage modulus as a function of temperature and frequency. The remaining empirical models were less accurate and non-conservative estimations of laminates stiffness.

Durability of a Glass Fabric-Reinforced Cementitious Matrix Composite under Different Environmental Conditions

The use of fabric-reinforced cementitious matrix (FRCM) composites for strengthening and retrofitting of existing masonry structures is nowadays a well-established practice, due to the speed and ease of application, low invasiveness, and high performance-to-cost ratio. Among different FRCMs, those comprising glass fiber textiles (GFRCM) represent an excellent choice due to the good mechanical properties and low cost of the raw material. However, limited information is available on the effect of environmental conditions on the performance of GFRCM composites and on their long-term behavior. This paper investigates the effect of different environmental conditions on the tensile performance of a GFRCM composite comprised of a cement-based matrix reinforced with an open-mesh alkali-resistant glass textile. Namely, the effect of hygrothermal conditioning, saline environment, alkali environment, freeze-thaw cycles, and dry heat conditioning were considered. After conditioning, specimens were tested using a clamping-grip tensile test configuration and the effect of the various exposure was analyzed comparing the composite tensile strength, ultimate strain, and elastic modulus of conditioned and control specimens. The experimental results show a good performance of the tested GFRCM composite with respect to the conditions considered.