Increasing Immersion Time Research Articles

Physical and Mechanical Properties Evolution of Coal Subjected to Salty Solution and a Damage Constitutive Model under Uniaxial Compression

Many underground reservoirs for storing water have been constructed in China’s western coal mines to protect water resources. Coal pillars which work as dams are subjected to a long-term soaking environment of concentrated salty water. Deterioration of the coal dam under the attack of the salty solution poses challenges for the long-term stability and serviceability of underground reservoirs. The evolution of the physical and mechanical properties of coal subjected to salty solutions are investigated in this paper. Coal from a western China mine is made to standard cylinder samples. The salty solution is prepared according to chemical tests of water in the mine. The coal samples soaked in the salty solution for different periods are tested by scanning electron microscope, nuclear magnetic resonance, and ultrasonic detector techniques. Further, uniaxial compression tests are carried out on the coal specimens. The evolutions of porosity, mass, microstructures of coal, solution pH values, and stress–strain curves are obtained for different soaking times. Moreover, a damage constitutive model for the coal samples is developed by introducing a chemical-stress coupling damage variable. The result shows that the corrosion effect of salty solution on coal samples becomes stronger with increasing immersion time. The degree of deterioration of the longitudinal wave velocity (vp) is positively correlated with the immersion time. With the increase in soaking times, the porosity of coal gradually increases. The relative mass firstly displays an increasing trend and then decreases with time. The peak strength and elastic modulus of coal decreases exponentially with soaking times. The developed damage constitutive model can well describe the stress–strain behavior of coal subjected to salty solution under the uniaxial compression.

Ultralow-temperature fabrication of chromium-free zinc-aluminum coatings based on polysilazane

To avoid the health risks of Cr6+ in traditional Dacromet coatings, developing chromium-free zinc-aluminum coatings attracts increasing attention in recent years. However, the state-of-the-art chromium-free zinc-aluminum coatings always have very high sintering temperatures over 250 °C, causing serious energy consumption. In the present work, for the first time, we report the fabrication of a novel chrome-free zinc-aluminum coating based on polysilazane. The results show that the polysilazane forms crosslinking structure via Si–O–Si backbones and the equilibrium anticorrosion effect can be achieved with a very low curing temperature less than 130 °C, which is much lower than current zinc-aluminum coatings. The zinc/aluminum particles present unique layered structure that are tightly contacted with the substrate, forming a dense structure with good barrier protection. Electrochemical characterization reveals that the coating exhibits capacitive impedance behavior at the initial stage of immersion test, indicating excellent shielding effect. As the immersion time increases, the activation corrosion of metal powder occurred under the action of corrosion medium, which plays a sacrificial anode protection role, and the resulting corrosion products can play certain shielding effect. Owing to above structural merits and electrochemical features, the developed chrome-free zinc-aluminum coating based on polysilazane demonstrates a superior corrosion resistance.

Cochineal Dye Concentration and Treatment Time for Otolith Marking of Japanese Smelt Hypomesus nipponensis Embryos

AbstractThe main purpose of this study was to find the optimal cochineal dye concentration and treatment time for marking Japanese smelt (also known as Wakasagi) Hypomesus nipponensis, more specifically their eggs, by understanding the mechanisms that determine survival rates and mark quality. Eggs were immersed in a range of cochineal dye concentrations (40–100 g/L) at varying intervals (6–72 h). Following that, mark quality was evaluated according to fluorescence intensity by examining the marked otolith of the larvae. The statistical model selection indicated that the interaction between the cochineal dye concentrations and immersion intervals (g/L × h) had a negative effect on survival such that at low concentrations survival decreased with increasing immersion time but at high concentrations survival was relatively low at all of the immersion times. On the other hand, the results of evaluating the marked otoliths indicated that mark quality improved with increases in concentration and immersion time individually. These results suggest that there is a trade‐off between mark quality and survival of Japanese smelt when using a cochineal dye solution. Combining the results of the survival rate and mark‐quality experiments, the cochineal dye marking conditions with both high survival rates and high fluorescence intensity are 60 g/L for 24 h, 40 g/L for 48 h, and 40 g/L for 36 h.

Degradation properties of magnesium oxychloride bone cement composite modified by hydroxypropyl methylcellulose and KH2PO4

In this study, we report the effects of hydroxypropyl methylcellulose (HPMC) and KH2PO4 on the water resistance of magnesium oxychloride cement (MOC), a novel bone cement composite. Different MOC samples were soaked in simulated body fluid (SBF). After soaking for 7–56 d, the surfaces of the experimental group (1 wt.% HPMC/2 wt.% KH2PO4-MOC) and control group (2 wt.% KH2PO4-MOC) appeared pores, which grew with increasing immersion time. Compared with the control group, the experimental group had smaller pore sizes and a denser surface. Furthermore, the compressive strength in the experimental group increased from 35.1 ± 1.9 MPa to 41.8 ± 2.3 MPa, and the softening coefficient increased from 0.34 to 0.45. Thus, HPMC could improve the water erosion resistance of the MOC. The implantation study of the femoral defects in rats showed that the sample modified by 1 wt.% HPMC/2 wt.% KH2PO4 had good biocompatibility and biodegradability. The results indicate that the modification of MOC with HPMC and KH2PO4 is a promising technique to form biodegradable bone repair materials and has good application prospects in the field of biomedical materials.

Evaluation of Corrosion Inhibition Efficiency of Aluminum Alloy 2024 by Diaminostilbene and Azobenzene Schiff Bases in 1 M Hydrochloric Acid

The Schiff base compounds N,N ′ -bis(salicylidine)-4,4 ′ –diaminostilbene(SDS) and N,N ′ -bis(salicylidine)-4,4 ′ -diamino azobenzene(SDA) were synthesized, and their molecular structure was determined by FT-IR and 1H NMR. The corrosion inhibitions of Schiff base compounds on aluminum alloy 2024 in 1 M hydrochloric acid were evaluated by potentiodynamic polarization, impedance techniques, weight loss method, and scanning electron microscopic technique. The potentiodynamic polarization (PDP) studies revealed that SDS and SDA compounds acted predominantly as cathodic inhibitors. The electrochemical impedance spectroscopic (EIS) parameters confirmed the adsorption of SDS and SDA molecules over the surface of aluminum alloy 2024 alloy by forming an inhibitive layer. The weight loss studies showed that the inhibition efficiency of these compounds increases directly with concentration and decreases with an increase in solution temperature and immersion time. The thermodynamic parameters were calculated to investigate the mechanism of corrosion inhibition. The SDA was found to be more effective than SDS and followed the Langmuir adsorption isotherm model. The scanning electron microscopy (SEM) results revealed that the deterioration of the alloy surface is minimal in the presence of an inhibitor. Both Schiff base molecules exhibited superior corrosion inhibition for aluminum alloy 2024 alloy in HCl medium.

Migration and formation of an iron rich layer during acidic corrosion of concrete with no steel reinforcement

The present study aimed to study the formation, enrichment, and relocation of iron-rich regions in the corroded area of concrete blocks, made without rebar, subjected to severely corrosive highly acidic conditions. In this work, three different concrete mix designs (a proprietary ready-mixed concrete, and laboratory made mortar and concrete) were corroded under induced accelerated conditions in sulfuric acid solutions at pH 1 for a duration of one to six months, in the absence of reinforcement (i.e. rebar) or iron-oxidizing bacteria. A variety of physicochemical and mechanical techniques were applied to monitor and assess the corrosion progress, and physical and chemical changes in the corroded samples. Results indicated a pronounced presence of iron rich layer (iron oxide/hydroxide) at the border of the corrosion front and the transition zone in all mix designs in the form of a ring. While existing papers in the literature describe the iron coming from the rebar, the only source of mobile iron in this experiment was from the iron oxide (Fe2O3) already in the cement. This zone (in a form of a ring) had an average iron content of 2.0 wt% and moved away from the surface to the center of the samples submerged in a sulfuric acid bath with the increase of immersion time, and it was accompanied by hairline cracks. The movement of this zone was in the same direction as sulfate (from acidic media) ingress and the opposite direction of calcium ion leaching, (Ca leaching). The rate of corrosion, the hardness and the compressive strength of concrete are mostly affected by the concrete mix design, the iron-ring enrichment and relocation had no significant impact on them. Detection of the iron-rich zone is an indication of the depth of corrosion at advanced stages in concrete products.

Additive manufacturing and direct synthesis of sphene ceramic scaffolds from a silicone resin and reactive fillers

Sphene (CaTiSiO5, i.e. CaO·TiO2·SiO2) ceramics were successfully developed via the polymer derived ceramics route, starting from a commercial silicone containing specific oxide fillers. The approach allowed the combination of synthesis, in conditions of high phase purity, and advanced manufacturing. In particular, the adopted starting materials enabled an easy preparation of pastes, to be used for direct ink writing (DIW) of three-dimensional reticulated scaffolds. Sphene scaffolds, after firing at 1300 °C, were always regular and crack-free, despite changes in the line spacing, resulting in variable porosity (from ≈ 59 to 74 %), and exhibited a compressive strength from 3.9 to 12.7 MPa. The porosity was actually hierarchical, considering the formation of ‘spongy’ struts. In vitro tests, with increasing immersion time in SBF solution, confirmed the bioactivity, combined with a quite slow ion release, useful to maintain the pH value at nearly physiological values. Additional biological tests, consisting of the seeding of scaffold with normal human adult dermal fibroblasts, showed adequate cell viability and no toxicity effect.

The Durability of the AC-BC Mixture Using Stone of Baba Mount, Tana Toraja Regency

Several factors that can affect road damage are excessive traffic load, temperature (weather), water, and pavement construction that does not meet the technical requirements. The durability of an asphalt mixture is the resistance of the mixture to the effects of water, water vapor, and temperature. A mixture with a high durability value provides a good mix quality and long-term use. The purpose of this study was to determine the durability of the AC-BC mixture using Mount Baba stone. The general specifications of Bina Marga in 2018 are the reference in this study. By using the standard Marshall test method, the results obtained through the Marshall AC-BC mixture immersion test with a duration of immersion time of 0.5 hours, 12 hours, 24 hours, 36 hours, 48 hours, 60 hours with a durability value of 95.49% - 86.99%. The increase in immersion time causes a decrease in the durability of the mixture.

Bond durability and degradation mechanism of GFRP bars in seawater sea-sand concrete under the coupling effect of seawater immersion and sustained load

In this paper, the bond durability of glass fiber-reinforced polymer (GFRP) bars in seawater sea-sand concrete (SWSSC) under the coupling effect of seawater immersion and sustained load was experimentally investigated. The test parameters included bar diameter (12 and 16 mm), immersion time (90, 180, and 270 days), and sustained load condition (loaded and unloaded). Test results showed that for the specimens with a small bar diameter, the bond strength had a slight growth at the initial stage of exposure mainly due to the water swelling of the bar, and then decreased due to the bond degradation. For the specimens with a large bar diameter, the bond strength increased with the increase of immersion time, which was determined by the increasing compressive strength of SWSSC. The sustained load reduced the bond strength of the specimens with a small bar diameter due to its acceleration of bond degradation, but had little effect on the bond strength of the specimens with a large bar diameter. The degradation mechanism was the rib deterioration of the bars caused by seawater immersion. Moreover, the sustained load could accelerate the degradation. The predicted bond strength retention of the specimen with a bar diameter of 12 mm under the coupling effect of the marine environment (moisture saturated and the mean annual temperature of 25–35 °C) and sustained load is 52% after 50 years of service.

Durability of components of FRP-concrete bonded reinforcement systems exposed to chloride environments

Using fibre-reinforced polymer (FRP) composites as externally bonded reinforcements to retrofit concrete structures has been considered a promising strengthening technique. For the safe and economic use of externally bonded FRP reinforcement in coastal areas, the effects of long-term exposure to environmental chloride on the properties of FRP-concrete bonded systems need to be properly understood. This study aims to investigate the durability of components of FRP-concrete bonded systems immersed in chloride solution. Two types of FRP (carbon FRP or CFRP and basalt FRP or BFRP) specimens, two types of epoxy resin/adhesive (with epoxy values of 0.40 and 0.53) specimens, and conventional concrete cylinders were prepared and then immersed in a laboratory-accelerated chloride solution with a chloride ion concentration of 5% at 40 °C. The effect of immersion time (90, 180, 270, and 360 days) on the residual mechanical properties of the components was examined. In addition, a modified model was presented and used to predict the tensile strength retention of the FRPs. The results show that with increasing immersion time, the tensile strength of CFRP first increased and then decreased, while that of BFRP almost monotonically decreased. CFRP exhibited significantly better chloride resistance than BFRP, and the strength retention of CFRP was approximately 160% higher than that of BFRP after 360 days of exposure. The epoxy resin with a lower epoxy value had better corrosion resistance, although it had a lower tensile strength in the ambient environment, than the epoxy resin with a higher epoxy value. The predictions of the presented model agree reasonably well with the test results from existing studies.

The Effect of Immersion Corrosion Time on Electrochemical Corrosion Behavior and the Corrosion Mechanism of EH47 Ship Steel in Seawater

In this paper, electrochemical corrosion tests and full immersion corrosion experiments were conducted in seawater at room temperature to investigate the electrochemical corrosion behavior and the corrosion mechanism of high-strength EH47. The polarization curve, EIS (electrochemical impedance spectroscopy), SEM (scanning electron microscope), and EDS analyses were employed to analyze the results of the electrochemical corrosion process. The electrochemical corrosion experiments showed that the open circuit potential of EH47 decreases and then increases with an increase in total immersion time, with the minimum value obtained at 28 days. With an increase in immersion time, the corrosion current density (Icorr) of EH47 steel first decreases and then increases, with the minimum at about 28 days. This 28-day sample also showed the maximum capacitance arc radius, the maximum impedance and the minimum corrosion rate. In the seawater immersion test in the laboratory, the corrosion mechanism of EH47 steel in the initial stage of corrosion is mainly pitting corrosion, accompanied by a small amount of crevice corrosion with increased corrosion time. The corrosion products of EH47 steel after immersion in seawater for 30 days are mainly composed of FeOOH, Fe3O4 and Fe2O3.

Qualitative and quantitative detection of corrosion inhibitors using surface-enhanced Raman scattering coupled with multivariate analysis

In this study, a novel strategy was proposed for the on-site detection and quantitation of corrosion inhibitors by means of surface-enhanced Raman scattering (SERS) detection and partial least squares regression (PLSR) algorithm. Using a SERS tape as the signal amplifier, the Raman signals of 2-mercaptobenzothiazole (MBT) inhibitors adsorbed on aluminium alloy were intensively magnified. The SERS intensities grew monotonously with the increase of inhibitor concentration and immersion time, indicating the continuous accumulation of MBT molecules that facilitated the effective corrosion inhibition performance. Furthermore, PLSR method was adopted to achieve the quantitative analysis of inhibitors on metal surface based on the SERS spectra variations. The regression relationship between the SERS spectra of MBT molecules on the alloy surface and their concentrations showed good predictive ability. Based on the established PLSR model, it has been employed for the quantification of remaining MBT inhibitors during reversible desorption process. SERS analysis combined with PLSR algorithm can be used to sensitively detect, quantify and predict corrosion inhibitors, which is helpful for the in-depth understanding of corrosion inhibition mechanism and will promote the exploitation of new corrosion inhibitors.

Mitigating Corrosion Effects of Ti-48Al-2Cr-2Nb Alloy Fabricated via Electron Beam Melting (EBM) Technique by Regulating the Immersion Conditions

The corrosion behavior of newly fabricated γ-TiAl alloy was studied using electrochemical impedance spectroscopy (EIS) and cyclic potentiodynamic polarization (CPP) techniques. The γ-TiAl alloy was produced from powder with compositions of Ti-48Al-2Cr-2Nb processed using electron beam melting (EBM) technique. The corrosion behavior of the bulk alloy was investigated in 1 M HCl solution for different immersion times and temperatures. The experimental results suggest that the fabricated alloy exhibits good resistance to corrosion in acid solution at room temperature. The results also indicate that with an increase in immersion time and solution temperature, the corrosion potential (Ecorr) shifts to a higher positive value, resulting in an increase in corrosion current (jcorr) and consequently a decrease in the corrosion resistance (Rp) of the alloy.

Effect of structural transitions of n-hexadecane in nanoscale confinement on atomic friction

Atomic-scale friction of graphene supported on silica as a function of immersion time in non-polar n-hexadecane is investigated using atomic force microscope (AFM) and molecular dynamics (MD) simulations. With an increase in immersion time, n-hexadecane molecules diffuse and intercalate at the graphene-silica confinement initially, decreasing friction forces until a transition time, and beyond which the forces increase till the end of the measurement (∼70 h). This non-monotonic change in friction is explained by the structural transformations of the intercalated n-hexadecanes at graphene-silica nanoconfinement. A disorder-to-order transition of n-hexadecane molecules in the intercalated layer is established by measuring the structure of solvation layers formed above the graphene layer and the stick-slip friction loops. The intercalated layer structure affects the flexibility of graphene, determining the quality of the contact between the AFM tip and substrate, which dominates the atomic friction. Our combined experiments and simulations have enabled a fundamental understanding of dissipation mechanisms for supported-graphene in non-polar solvents, critical for employing two-dimensional materials as additives in friction-reducing or rheological oils.

Effect of seepage flow on gas loss during the removal of shale core immersed in a drilling fluid

In the process of shale coring, the drilling fluid and its solid-phase immersion inevitably cause core pollution, thereby increasing the flow resistance of the gas inside the core and leading to inaccurate calculations of the loss of shale gas. To study the changes in the seepage resistance and the amount of gas lost while the shale is immersed in the drilling fluid, an experimental study on the effects of immersion pressure on the permeability of fractured shale and matrix shale was carried out. The changes in the permeability due to reservoir fluid changes and the swelling deformation due to soaking in the drilling fluid significantly affected the shale gas loss. In this study, the shale samples were analyzed by varying the immersion time (12, 24, 48, 72, 96 and 120 h) and pressure (4, 8, 12, and 16 MPa). For each saturation cycle, the permeability of the shale samples was measured using the transient method under various injection pressures (1–6 MPa). The results showed that the permeability of the shale samples decreased significantly after immersing in the drilling fluid, and the decrease rate increased with the increase in the immersion time. Compared with the matrix shale samples, the fractured shale samples exhibited better pore micro-fractures and higher hydrophilicity, so the fractured samples exhibited a greater reduction in the permeability than the matrix shale samples. Shale permeability had a negative exponential relationship with the effective stress, and its stress sensitivity increased with increasing immersion time. Importantly, during the shale coring process, under the actions of the effective stress, drilling fluid, and its solid-phase pollution, the gas escape rate on the core surface even changed by an order of magnitude. In the case of serious drilling fluid pollution, the core desorption rate was close to zero, in which case the shale gas loss may be easily underestimated.

Natural Corrosion Inhibition and Adsorption Characteristics of Tribulus terrestris Plant Extract on Aluminium in Hydrochloric Acid Environment

Corrosion inhibitive and adsorption capabilities of Tribulus terrestris plant extract on aluminum in 1.0 N HCl solution was evaluated by mass loss and electrochemical methods. The inhibition efficiency increased with increasing extract concentration, whereas it decreased with increasing immersion time. The adsorption of the extract on the metal surface was physisorption, supported by ΔGads values( around -20 kJ mol−1) and obeyed by Langmuir, Temkin and Freundlich adsorption isotherms. Electrochemical studies revealed mechanistic aspects of corrosion inhibition like Potentiodynamic polarization measurements indicated the nature of inhibitor is a mixed type and impedance studies supported the formation of a protective layer of inhibitor on a metal surface. SEM micrograms were also applied to study surface morphology. These images confirmed the creation of a protective film over the metal surface.

Thermodynamic and Adsorption Study of the Corrosion Inhibition of Mild Steel by Aframomum chrysanthum Extract in 0.1 M Hydrochloric Acid Solution

The study reports the corrosion inhibition activity of methanol extract of Aframomum chrysanthum on mild steel in 0.1 M HCl, using gravimetry analysis. The weight loss of the mild steels was observed to increase with increasing immersion time. The inhibition efficiency (%IE) was also observed to have increased with increasing concentrations of the inhibitor but decreases with increasing immersion time. The effect of temperature change on the inhibition efficiency was also studied and it was observed that for every increase in temperature there was a corresponding increase in weight loss and decreased in the %IE. The highest values of %IE; 46.66, 56.66, 60.0, 80.0 & 93.33 was observed at temperature 303 K for 0.2, 0.4, 0.6, 0.8 & 1.0 g/L respectively. Activation energy (Ea) values and the enthalpy values reviews that the adsorption process followed a physisorption’s mechanism. Change in enthalpy (ΔH) and entropy change (ΔS) of the reaction was positive indicating the endothermic nature and the spontaneity of the reaction. Three adsorption isotherms were tried on the inhibition process and only the Temkin isotherm gave the best fit with R2 value of 0.903, describing the best adsorption mechanism. The adsorption equilibrium constants K­ads were positive, indicating the feasibility of the adsorption of the inhibitor to the metal surface. Gibb’s Free Energy change of adsorption, ΔGads are negative indicating that the adsorption of the extract of Aframomum chrysanthum on mild steel surface is spontaneous. The values of ΔGads shows physisorption mechanism. All confirming that Aframomumm chrysanthum extract is a good corrosion inhibitor on mild steel in 0.1 M HCl.

Synthesis and Characterization of TiO2 Thin Film Based on Iron Sand of Lampung Province - Indonesia

This study aims to make a thin layer of TiO2 based on ilmenite stored in iron sand of Lampung Province, Indonesia. The TiO2 powder, which was used to make the thin layer, was obtained from the extraction of iron sand using the leaching method with a purity of 60,7%. The preparation of TiO2 thin layers was carried out by the Chemical Bath Deposition (CBD) method with immersion time variations of 2, 3, 4, and 5 hours for samples A, B, C, and D respectively. Afterward, the samples were calcined at 500°C for 4 hours. The characterizations involved X-Ray Diffraction (XRD), Scanning Electron Microscope (SEM), X-Ray Fluorescence (XRF), and four-point probe to measure the resistivity of the film. The XRD results in samples A (immersion time 2 hours) and D (immersion time 5 hours) show that the amorphous phase still dominates even though the diffraction peaks indicate that the presence of crystals has started to grow at several angles of scattering. The identification results of the phase presence show that the thin layer of TiO2 at sample D is the brookite phase. The results of characterization using SEM show that the surface of the TiO2 thin layer forms a porous structure. The average thickness of the thin film at sample B based on SEM analysis is 1.9 μm. The electrical resistivity increased with an increasing immersion time.

Surface Modification of Poly(l-lactic acid) through Stereocomplexation with Enantiomeric Poly(d-lactic acid) and Its Copolymer.

Poly(l-lactic acid) with high molecular weight was used to prepare PLLA films by means of the solvent casting technique. Poly(d-lactic acid) (PDLA) and poly(d-lactic acid-co-glucose) copolymer (PDLAG) with a low molecular weight were synthesized from d-lactic acid and glucose through melt polycondensation. PLLA films were immersed in PDLA or PDLAG solution to prepare surface-modified PLLA films. The modified PLLA film presented stereocomplex crystal (SC) on its surface and homogeneous crystals (HC) in its bulk. The HC structure and surface morphology of modified PLLA films were obviously damaged by PDLA or PDLAG solution. With increasing immersion time, the PLLA films modified by PDLA decreased both the HC and SC structure, while the PLLA films modified by PDLAG increased the SC structure and decreased the HC structure. Hydrophilic glucose residues of PDLAG on the surface would improve the hydrophilicity of surface-modified PLLA films. Moreover, the hydrophilicity of glucose residues and the interaction of glucose residues with lactic acid units could retard HC destruction and SC crystallization, so that PLLA films modified by PDLAG possessed lower melting temperatures of HC and SC, the crystallinity of SC and the water contact angle, compared with PDLAG-modified PLLA films. The SC structure could improve the heat resistance of modified PLLA film, but glucose residues could block crystallization to promote the thermal degradation of PLA materials. The surface modification of PLLA films will improve the thermal stability, hydrophilicity and crystallization properties of PLA materials, which is essential in order to obtain PLA-based biomaterials.

Bond durability of BFRP bars embedded in concrete with fly ash in aggressive environments

Fiber-reinforced polymer (FRP) bars are an environmentally friendly alternative to steel and are considered ideal substitutes for steel reinforcement in marine concrete structures due to their excellent resistance to chloride ions and mechanical properties. However, the strong alkaline environment in concrete results in the degradation of FRP bars, and the degradation of FRP bars is detrimental to the long-term performance of these structures due to the decrease in interfacial bonding. This study aims to investigate the bond durability of basalt FRP (BFRP) bar and concrete with or without fly ash in corrosion environments by pull-out tests. The laboratory-accelerated aging environments are an alkaline solution (pH 12.8 ± 0.2) and simulated seawater, and the immersion temperatures are set at room temperature (~26 °C), 40 °C, and 60 °C. Furthermore, the mechanical properties of the BFRP bars are also determined under the same conditions. Results indicate that the mechanical properties of the BFRP bars and the bond strength decrease as the immersion time increases. The addition of fly ash in concrete can improve the interfacial bond strength. For instance, the bond strength of BFRP-ordinary concrete decreases by 69.0% when immersed in a 60 °C alkaline solution for 6 months, and that of BFRP-fly ash concrete decreases by 58.1% in the same immersion environment. The similar experimental phenomenon can also be obtained in seawater, which can be attributed to fly ash refining the concrete pores and inhibiting the reaction of alkaline with silica contained in the basalt fibers. Finally, the retention of bond strength is predicted based on the apparent horizontal shear strength of the BFRP.