Effects Of Seawater Immersion Research Articles

Experimental Study on Bond Fatigue Between Carbon Fiber-Reinforced Polymer Bars and Seawater–Sea Sand Concrete Under Seawater Immersion and Dry–Wet Cycle Conditions

The durability of carbon fiber-reinforced polymer (CFRP) bars in marine environments is essential for their application in seawater–sea sand concrete (SWSSC), especially under cyclic loading conditions. While previous studies primarily focused on static bonding performance, the effects of seawater immersion and dry–wet cycles on bond fatigue behavior at CFRP–SWSSC interfaces remain underexplored. This study investigated the bond fatigue performance of CFRP bars and SWSSC under seawater immersion and dry–wet cycling conditions. Eighteen CFRP bar-SWSSC bond specimens were divided into three categories and prepared for static and fatigue pull-out tests. The effects of varying stress levels (fatigue upper load/static bond ultimate load) after seawater immersion and dry–wet cycling on fatigue failure modes, bond–slip behavior, and fatigue characteristics were evaluated. The results show that seawater immersion and dry–wet cycling significantly degrade the performance of bonds between CFRP bars and SWSSC, with an average bond strength reduction of 10.31%. These conditions reduce fatigue cycles and stiffness while increasing bond–slip (relative displacement at the bar–concrete interface) and residual–slip (displacement after unloading). Moreover, dry–wet cycling has a greater negative impact on fatigue bond performance than seawater immersion. Higher fatigue stress levels exacerbate damage and crack propagation at the CFRP–SWSSC interface, leading to significant increases in both bond–slip and residual-slip. Under similar conditions, higher stress levels enhance bond stiffness. However, excessively high stresses may lead to bond fatigue failures. Using experimental data and existing fatigue bond–slip constitutive models, a customized model for CFRP bars in SWSSC was developed. These findings highlight that marine environments and fatigue loading severely impair bond performance, thereby emphasizing the importance of careful design for marine applications. The proposed model offers a reliable framework for predicting bond–slip behavior under fatigue conditions, enhancing the understanding of CFRP–SWSSC interactions and supporting the design of durable marine infrastructure.

Concrete Resistance in the Marine Environment: The Effect of Seawater Immersion (Curing) on Compressive Strength

Concrete is the most commonly used type of construction material but is affected by premature damage when exposed to the marine environment. The most common cause of damage is corrosion in the reinforcing steel. The problem that arises during the planning and construction stage of the beach safety building is the impact of seawater on the quality of the concrete we design. The research conducted is an experimental test with research in the laboratory by comparing the compressive strength value of normal concrete soaked in freshwater, saltwater in the laboratory and seawater in situ and the age of the used concrete is only 28 days. concrete that is immersed in seawater will experience a significant decrease in compressive strength value compared to normal concrete immersed in fresh water. For normal concrete soaked with seawater in the laboratory, the compressive strength value decreased from 29.96 MPa to 28.06 MPa. Meanwhile, concrete soaked in situ in seawater experienced a decrease in compressive strength value from 29.96 MPa to 25.55 MPa.

Jute fibre reinforced biocomposite: Seawater immersion effects on tensile properties and its application in a ship hull design by finite-element analysis

Glass Fibre Reinforced Plastics (GFRP) are widely used to manufacture small ship hulls. However, these materials do not use renewable resources, and natural-fibres-reinforced-resins from biological resources could be a more sustainable solution. This work aims to study the mechanical feasibility of a jute-fibre-reinforced-bioepoxy (JFRB) in naval applications. For that purpose, the effects of seawater immersion on the tensile properties of JFRB were evaluated. After seawater immersion, the results showed that Young's modulus and tensile stress decreased by 4% and 1.5%, respectively, and elongation at break increased by 7%, with the density remaining almost constant. Those results make it possible to think of jute as an ecological reinforcement for naval applications. To validate the possibilities of JFRB, a design of a recreational boat hull under ISO 12215-5: 2019 standard was performed. Through a Finite Element methodology, the same safety factor was considered using the GFRP and the JFRB under the simplified load conditions proposed by the standard. The results demonstrated that the solution with the studied JFRB was mechanically feasible by increasing the thickness from 3.5 mm to 4.7 mm, which increased the weight of the biocomposite hull by 11%.

THE EFFECT OF SEAWATER SOAKING ON THE STABILITY OF AC-WC MIXTURES USING KOYA AGGREGATE, JAYAPURA CITY

Roads are the basic infrastructure in driving the regional economy, so a good pavement structure is needed. One of the factors of road damage is standing water, for roads around the coast are likely to be inundated by sea water. Asphalt Concrete Wearing Course (AC-WC) is one of the concrete asphalt layer which is able to provide good carrying capacity and waterproof layer for road structures. Some areas in kota Jayapura such as Koya have a large number of local aggregates. This study used oil asphalt as a binder, local aggregate for hot asphalt mixture, and saw the effect of sea water immersion in the asphalt mixture. The purpose of this study is to determine the volumetric value and Marshall value of the Laston AC-WC mixture against sea water immersion and without immersion. The material used is oil asphalt from PT. Pertamina and local aggregates from the Koya area. The research carried out is an experimental test in the laboratory, where the resulting asphalt concrete mixture (AC-WC) will be treated with sea water immersion, then Marshall characteristics testing will be carried out to determine its durability value. Based on the tests carried out, the results showed that the volumetric value and the marshall value of the samples treated with immersion did not provide a significant difference in values compared to normal samples. The results of the marshall value, namely the stability of all asphalt levels meet the specifications, while for flow only the asphalt content of 5.5% and 6% both by soaking and without soaking.

Property quality of Lombok dried squid treated with different water types and soaking time

To date, fishermen from the southern coast of Lombok have been drying fresh squid in direct sunlight for insufficient time, resulting in low quality. It is known that seawater contains salt that have function as an antimicrobial. Therefore, this study sought to examine the effect of immersion in seawater on the quality (physiochemical and sensory) of dried squid. Different types of water (seawater and freshwater) and soaking time (30, 60, and 90 mins) were carried out. Seawater was chosen as a brine solution to follow a common practice conducted in the area of study. The yield, moisture, and ash content as well as the surface dried meat squid colour were determined. The research was statistically analysed in a Completely Randomized Design with three replications. In general, the results showed that soaking the squid using seawater resulted in a higher yield than that when freshwater was used. No significant difference (P<0.05) was obtained for moisture and ash content as well as dried squid colour (oHue). The results also indicated that fresh squid soaked using seawater for 90 mins was the best treatment with the yield, moisture content, ash content, and colour value of 15.63%, 23.99%, 9.44%, and oHue 53.09 respectively. Dried squid sensory characteristics showed that the texture of the meat squid was relatively soft and has a unique aroma and taste.

Effects of Seawater Immersion on Lethal Triad and Organ Function in Healthy and Hemorrhagic Shock Rats

IntroductionMarine casualties are increasing, and mortality from trauma associated with immersion in seawater is high. However, the associated pathophysiological characteristics remain unclear, limiting research into the early emergency treatment strategy. MethodsHealthy and 50% hemorrhagic shock rats were soaked in 15°C and 21°C seawater for 2 h, 4 h and 6 h, respectively, and the effects on vital signs, internal environment, tissue metabolism, lethal triad, vital organ functions and survival were observed. ResultsImmersion in seawater can cause death in healthy rats. Rats with hemorrhagic shock in 15°C seawater showed a lower survival rate than the corresponding groups in 21°C seawater. Moreover, compared with 21°C seawater, 15°C seawater played a more remarkable role in decreasing mean arterial pressure, heart rate, and respiration rate, increasing water content and decreasing Na+/K+-ATPase activity in the brain and lung; increase in plasma osmolality, Na+, K+, Cl−, and the occurrence of the lethal triad manifested by a decrease in core body temperature, pH, lactate, and an increase in coagulation parameters, as well as damage to cardiac, intestinal, hepatic, and renal functions in rats with hemorrhagic shock. ConclusionsImmersion in seawater at low temperatures could be lethal to healthy rats, causing the occurrence of a lethal triad and damage to vital organs. Furthermore, 15°C-seawater had a more significant effect than 21°C-seawater on aggravating the imbalance of internal environment and tissue metabolism, resulting in a higher incidence of the lethal triad and thus aggravating the dysfunctions of vital organs, which eventually resulted in higher mortality in rats with hemorrhagic shock.

THE EFFECT OF SEA WATER IMMERSION ON BUTON ASPHALT (AS-BUTON) MIXTURE

One of the causes of flexible pavement damage is being submerged in water with a high acidity, such as seawater. To overcome this condition, a study on the use of buton asphalt (as-buton) was conducted. The advantages of as-buton are that it has higher adhesion and is more resistant to temperature changes. As-buton modification by mixing Lawele as-buton Southeast Sulawesi with oil asphalt pen 60/70. This study focuses on determining the effect of the addition of as-buton to the modified asphalt mixture and the effect of seawater immersion on as-buton mixture based on the Marshall characteristic test. The percentage by weight of as-buton used is 5%, 7.5%, and 10%. The immersion was carried out in freshwater and seawater immersion for up to 24 hours at a temperature of 30°C. The result of this study show that the addition of as-buton increase the value of stability, void in mixture, Marshall quotient (MQ), and void in mineral aggregate, but reduce the flow, void filled with asphalt, and density. The increase of stability and MQ value in seawater-immersion due to the addition of as-buton was higher than that in freshwater. The stability value of the 10% modified as-buton mixture in freshwater-immersion increased by 169.338 kg (14.61%) and in seawater-immersion increased by 1261.669 kg (55.65%). The flow value in freshwater-immersion decreased by 1.9 mm (25.33%) while in seawater-immersion decreased by 1 mm (14.08%). For further research, variations in the addition of as-buton will be carried out to produces a modified asphalt mixture.

Effects of seawater immersion on a glass fibre reinforced bioepoxy mechanical properties and its application in the ship hull finite-element analysis

Currently, there is a grown tendency to manufacture environmentally more sustainable composite structures. In this work, a glass fibre reinforced bioepoxy composite was manufactured and submerged in seawater between T = 17[Formula: see text]C and T = 24[Formula: see text]C for a bioactivity period of 6 months. Tensile and flexural tests were performed in order to characterize the new composite before and after seawater immersion. A drop of 20% in Young’s modulus and 9% in tensile strength were observed after immersion. The same trend was analysed in both the flexural modulus and flexural strength, with a fall of 18% and 6%, respectively. It is also remarkable a higher ductility of the specimen after seawater immersion due to a plasticization process by moisture absorption. Those results were confirmed by scanning electron microscopy. Given the mechanical behaviour of the new composite, an L = 6.26 m in length ship hull was designed. Structural analysis was conducted on the suitability and reliability of the composite by using ANSYS software. The simulations revealed the optimal structural performance of the new design even in the extreme sagging situation. To sum up, SuperSap® bioepoxy resin is a suitable matrix to manufacture small glass fibre ship-hulls.

Effect of Seawater Immersion on Impact Strength of Composites Reinforced Ramie Fiber

Effect of Seawater Immersion on Impact Strength of Composites Reinforced Ramie Fiber

Investigation on Seawater Ageing of PET-Epoxy Composites: An Ecological and Sustainable Approach for Marine Applications

The effect of sea water immersion on the durability and performance of the PET fibre reinforced epoxy composites were experimentally investigated. The reinforcing fibres and their respective composite samples were immersed in artificial seawater over a period of 120 days. The extent of degradation post immersion was studied using thermal gravimetric analysis. Water uptake behaviour of the composites and the losses in their mechanical properties were studied by testing them under tensile, flexural and impact loads before and after immersion. Effect of degradation in interfacial region and the fracture morphology in the failed samples were analysed through SEM micrographs. The outcome of these results was compared with the glass fibre reinforced epoxy counterparts, which are often used in today’s marine structures. It was found that the glass–epoxy composites experienced about 8% decrease in their overall mechanical properties while polyester-epoxy composites remain unaffected to seawater ageing. Therefore, PET-epoxy material combinations can be approached to cater the long term structural requirements of maritime applications and further open up new gateways for utilization of recycled hazardous plastics.

Effects of seawater immersion on open traumatic brain injury in rabbit model

We emulated instances of open traumatic brain injuries (TBI) in a maritime disaster. New Zealand rabbit animal models were used to evaluate the pathophysiological changes in open TBI with and without the influence of artificial seawater. New Zealand rabbits were randomly divided into 3 groups. Control group consisted of only normal animals. Animals in TBI and TBI + Seawater groups underwent craniotomy with dura mater incised and brain tissue exposed to free-fall impact. Afterward, only TBI + Seawater group received on-site artificial seawater infusion. Brain water content (BWC) and permeability of blood–brain barrier (BBB) were assessed. Reactive oxygen species levels were measured. Western blotting and immunofluorescence were employed to detect: apoptosis-related factors Caspase-3, Bax and Bcl-2; angiogenesis-related factors CD31 and CD34; astrogliosis-related factor glial fibrillary acidic protein (GFAP); potential neuron injury indicator neuron-specific enolase (NSE). Hematoxylin & eosin, Masson-trichrome and Nissl stainings were performed for pathological observations. Comparing to Control group, TBI group manifested abnormal neuronal morphology; increased BWC; compromised BBB integrity; increased ROS, Bax, CD31, CD34, Caspase-3 and GFAP expressions; decreased Bcl-2 and NSE expression. Seawater immersion caused all changes, except BWC, to become more significant. Seawater immersion worsens the damage inflicted to brain tissue by open TBI. It aggravates hypoxia in brain tissue, upregulates ROS expression, increases neuron sensitivity to apoptosis-inducing factors, and promotes angiogenesis as well as astrogliosis.

Effect of Seawater Immersion on Power Frequency Over Voltage Calculation of AC Three-core Submarine Cable

AC three-core submarine cable is an important carrier to transmit offshore wind power. Limited by the laying conditions, the reactive power compensation is generally carried out at both ends of the submarine cable line. And the armour along the submarine cable is immersed by seawater until the metal sheath, which causes the sheath of the submarine cable line to be grounded everywhere. With the growth of submarine cable lines, power frequency overvoltage becomes more and more serious. In order to effectively limit power frequency overvoltage, it is necessary to study and compare the effect of different reactive power compensation schemes on overvoltage. This paper is based on the research of double loop AC three-core submarine cables. The submergence of seawater is simulated by dividing the submarine cable into sections and grounding the sheath and armour of each section of submarine cable through resistance. On the basis of this model, the changes of line power frequency overvoltage under the conditions of “55” compensation, “28” compensation and three terminal compensation are calculated and compared. Under the scheme of “28” compensation at both ends, the maximum power frequency overvoltage of the line is the lowest. The research results provide a theoretical reference for the reactive power compensation scheme of offshore wind power access system.

The effect of sea water soak on asphalt porous characteristics with and without waste of rubber tire waste as an asphalt addictive

The use of rubber tire scraded in the developement of porous asphalt technology as a part of flexible pavement aims to minimize the adverse effects of transportation facilities. The use of rubber tire scraded as an asphalt modifier in the pavement can provide several benefits, including reducing reflective cracking on overlays, reducing maintenance cost, increaseing resistance to new pavement cracking and rutting, increasing skid resistance an pavement age. This paper presents laboratory investigation on the effect of seawater immersion on porous asphalt performance using rubber tire scraded. Method use in laboratory investigation is based on AAPA 2004 and Bina Marga 2010. The results showed the permeability all types of mixture indicator “moderate drainage”. The results of testing the Marshall characteristics showed a decrease in the value of stability, flow, and MQ in the porous asphalt mixture with Pen 60/70 asphalt and rubber asphalt as the duration of sea water immersion increased. The porous asphalt mixture using Pen 60/70 asphalt and rubber asphalt has Index of Retained Strength values which tend to decrease with increasing sea water immersion duration. Indirect Tensile Stength test results due to seawater submersion indicate a decrease in ITS value in porous asphalt mixtures with Pen 60/70 asphalt and rubber asphalt. The Cantabro test results showed an increase along with the increasing duration of seawater immersion.

Monotonic and cyclic behavior of polyamide 66/hectorite nanocomposites in marine environment

Product design for safe performance and operation in harsh environments triggers the importance of understanding property degradation due to prolonged exposure of advanced composite materials to such environments. The effect of seawater immersion on monotonic tensile, stress relaxation, and cyclic bending fatigue response of polyamide 66 nanocomposites containing 0%, 1%, and 5% hectorite organoclay were investigated. Seawater equilibrated nanocomposites demonstrated less moisture absorption compared to their pure counterparts. The imbibed seawater significantly increased the ductility, and reduced the tensile modulus and strength of nanocomposites. A nine-parameter Prony series viscoelastic constitutive model was used to estimate the influence of seawater on the viscoelastic behavior based on stress relaxation data. The phenomenological model evaluated a drop of 82% in the instantaneous and the residual elastic moduli indicating a significant plasticizing effect of seawater. However, the amount of increase in the rubbery nature of polyamide is observed from the reduction in stress relaxation time of first Maxwell element by about 40%. Nanocomposites exhibited improved fatigue life with an increase in organoclay content even after equilibration in seawater. The fracture surface observation of seawater equilibrated bending fatigue specimen revealed rubbery behavior indicating the positive difference between cyclic steady-state temperature and material glass transition temperature.

Effect of seawater immersion on the explosive blast response of a carbon fibre-polymer laminate

Explosions are an ever-present risk to laminates used in naval ships, submarines and offshore oil/gas platforms that are immersed in seawater. This study determines whether the absorption of water by a carbon fibre laminate changes its deformation response and damage resistance when impulsive loaded by an explosive blast. The stiffness and strength properties of the laminate were reduced with increasing immersion time in seawater up to and beyond the point of saturation. Explosive blast tests of increasing shock wave impulse were performed on the laminate before immersion and when in the saturated and beyond saturated conditions. Softening and weakening of the laminate caused by absorbed water reduced the resistance against deformation and damage when subjected to an explosive blast. The amount of blast-induced damage to the laminate increased with the immersion time in seawater due to plasticisation of the polymer matrix and weakening of the fibre–matrix interphase region.

Seawater immersion aggravates burn-associated lung injury and inflammatory and oxidative-stress responses

With the increasing frequency of marine development activities and local wars at sea, the incidence of scald burns in marine accidents or wars has been increasing yearly. Various studies have indicated that immersion in seawater has a systemic impact on some organs of animals or humans with burn. Thus, for burn/scald injuries after immersion in seawater, it is desirable to study the effects and mechanisms of action on important organs. In the present study, we aimed to investigate the effect of immersion in seawater on lung injury, inflammatory and oxidative-stress responses in scalded rats. The structural damage to lungs was detected by hematoxylin and eosin staining and the results showed that seawater immersion aggravated structural lung injury in scalded rats. The expression of HMGB1 in lung tissues was detected by immunohistochemical analysis and the results showed that seawater immersion increased HMGB1 expression in lung tissues of scalded rats. Apoptosis in lung tissues was detected by terminal deoxynucleotidyl transfer-mediated dUTP nick end-labeling (TUNEL) staining and the results showed that seawater immersion increased apoptosis rate in lung tissues of scalded rats. In addition, the expression levels of TNF-α, IL-6, IL-8, SOD, and MDA in serum were analyzed by enzyme-linked immunosorbent assays (ELISAs) and the results showed that seawater immersion induced secretion of proinflammatory factors (TNF-α, IL-6, and IL-8), increased MDA protein level, and suppressed SOD activity in the serum of scalded rats. Furthermore, measurement of plasma volume and pH showed that seawater immersion decreased plasma volume and pH value. Overall, the results indicated that all effects induced by immersion in seawater in scalded rats are more pronounced than those induced by freshwater. In conclusion, seawater immersion may aggravate lung injury and enhance inflammatory and oxidative-stress responses after burn.

Sea Water Effects on Surface Morphology and Interfacial Bonding of Sugar Palm Fiber to Sago Matrix

Effects of sea water immersion for palm fiber in relation to surface morphology, roughness and bonding between the fiber and sago matrix were observed. Duration of immersion varied in 1, 2, 3 and 4 weeks, and then dried at room temperature for 3 hours continued by oven at 80 °C for 6 hours. SEM and roughness arithmetic tests were applied to see surface morphology, roughness and bonding between fiber and the matrix. Result shows fiber morphology and roughness varies by the duration of immersion. The surface roughness increases as immersion continues along with fiber - matrix bonding improvement. The maximum duration of 4 weeks fiber immersion resulted in the best interlocking of matrix and fibers, as the slits between them disappear.

Effects of seawater exposure on mode II fatigue delamination growth of a woven E-glass/bismaleimide composite

The effects of seawater exposure on Mode II fatigue delamination growth of a woven E-glass Bismaleimide composite are investigated by end-notched flexure tests in this study. Dynamic mechanical analysis shows a strong plasticization effect of seawater immersion on the matrix material. Static tests of specimens after 2500 h of immersion in 50℃ seawater reveal that the critical strain energy release rate ([Formula: see text] is increased by 15.4%. This is mainly due to seawater effects of plasticization of the matrix, extension of the damage zone and enhancement of the ductility of the material. In fatigue tests, a practical formulation based on the Paris law is proposed to model the stable delamination growth rate for both dry and wet specimens. At a given normalized strain energy release rate, the delamination growth was found to be slower in wet specimens than in dry specimens. The examination on fracture surfaces by scanning electron micrographs also reveals evidence of the plasticization effect of seawater which improves the [Formula: see text] of wet specimens.

Sea Water Ageing of GFRP Composites and the Dissolved salts

This paper houses the effect of sea water immersion on glass fibre reinforced polymer (GFRP) composites. The major sources of interest are study of sea water absorption, penetration of the dissolved salts, details of chemical and physical bonds at the interface, variations of mechanical properties and study of failure mechanisms as revealed through SEM fractographs. Eighteen ply GFRP composites are immersed in sea water for a period of one year in steps of two months durations. It is revealed that the moisture absorption transforms from a Fickian to non-Fickian behavior with lapse of time. The dissolved salt 'K' shows highest depth of penetration after one year of immersion while 'Na' shows a least depth of penetration, as revealed from the EDS spectra. It is also revealed that 'Ca' seems to have a sudden burst in the rate of penetration even surpassing that of 'K'. This trend can be attributed to the combined effect of ionic mobility of the various dissolved salts and the probable interaction between 'K' and the -OH group of epoxy resin. This interaction between dissolved 'K' and the -OH group in the polymer could have arrested the further advancement of 'K' salts in the polymer, resulting in comparatively high rates of 'Ca' penetration. The mechanical properties such as inter laminar shear stress (ILSS), stress and strain at rupture, glass transition temperature (Tg) and elastic modulus show a decreasing trend with the increased duration of immersion. As revealed from the SEM fractographs pot- holing, fiber pull-out, matrix crack etc. are seen to be the major reason for failure of the immersed samples under load.

Effects of Seawater Immersion on Mechanical Properties of CFRP Composites

Water absorption behavior and mechanical properties variation of the carbon fiber reinforced epoxy matrix composites (CFRP) immersed into artificial seawater were investigated by experiments. The rate of water absorption of the composite specimens is gradually reducing as the duality of immersion increasing. Due to the reversible and irreversible changes in the resin matrix and the failure of the fiber/matrix interface, the tensile strength, the flexural strength, and the ILSS of the composite specimens after 70 days immersion decreased 9.3%, 13%, and 17% respectively. And the tensile modulus and the flexural modulus the specimens after desorption were 83% and 70% of the original state, respectively