Search Results (6)

Epoxy resin-modified concrete (ERMC) demonstrates significant potential for enhancing the durability of concrete structures exposed to harsh environmental conditions. However, the performance of ERMC under the combined effects of salt erosion and freeze–thaw cycles remains inadequately explored. This study systematically evaluates the durability of ERMC through experimental investigations on specimens with epoxy resin-poly ash ratios of 0%, 5%, 10%, 15%, 20%, and 25%. Resistance to salt erosion was assessed using composite salt solutions with concentrations of 0%, 1.99%, 9.95%, and 19.90%, while frost resistance was tested under combined conditions using a 1.99% Na₂SO₄ solution. Key performance metrics were analyzed with microstructural observations to elucidate the underlying damage mechanisms, including the compressive strength corrosion coefficient, dynamic elastic modulus, mass loss rate, and flexural strength loss rate. The results reveal that incorporating epoxy resin enhances concrete’s resistance to salt erosion and freeze–thaw damage by inhibiting crack propagation and reducing pore development. Optimal performance was achieved with an epoxy resin content of 10–15%, which exhibited minimal surface deterioration, a denser microstructure, and superior long-term durability. These findings provide critical insights for optimizing the design of ERMC to improve the resilience of concrete structures in aggressive environments, demonstrating that ERM is a sustainable material, and offering practical implications for infrastructure exposed to extreme climatic and chemical conditions. Full article

This work aims to investigate the synergistic effects of hybrid bio-fillers and compatibilizers on the properties of natural rubber composites. Rice husk silica (RSi) and hydroxyapatite (HA), derived from rice husk ash and seabass fish scales, respectively, were successfully prepared and used as bio-fillers. Poly(acrylic acid-co-acrylamide)-grafted deproteinized natural rubber (gDPNR) was synthesized via emulsion graft copolymerization, achieving a grafting efficiency and grafting percentage of 15.94 and 4.23%, respectively. The gDPNR was utilized as a compatibilizer in the preparation of natural rubber composites. The addition of hybrid bio-fillers at an RSi-to-HA ratio of 25:75 exhibited superior mechanical properties compared to composites containing a single filler. The incorporation of gDPNR improved filler dispersion and interfacial adhesion between the NR matrix and the bio-fillers, further enhancing the mechanical, thermal, and dielectric properties. The composite with hybrid bio-fillers and 10 phr of gDPNR exhibited the highest tensile strength, showing a 2.10-fold and 1.06-fold improvement over neat natural rubber composite and hybrid filler composite without compatibilizer, respectively. The presence of polar functional groups in gDPNR enhanced the dielectric constant of the natural rubber composites. These composites could have potential in sustainable industrial applications, including flexible electronics and eco-friendly devices. Full article

In order to improve the crack repair effect of high-performance segment structure crack repair materials, in this paper, we used the orthogonal test research method of four factors and three levels to analyze changes in the microstructure of crack repair materials under different material compatibility levels, followed by analysis through the performance testing of repair materials. The flow performance, setting time, compressive and flexural strength, and bonding and tensile strength were studied. The results show that (1) excessively thick epoxy polymer film affects the bond strength, an appropriate increase in the polymer–cement ratio can promote the hydration of cement, and an appropriate increase in gel material can enhance the repair function of repair material; (2) the setting time clearly increases with increases in the polymer–cement and water–cement ratios and the decrease range clearly increases with an increase in the water–cement ratio; (3) the adhesive flexural strength of epoxy polymer repair material increased the most in 28 days; and (4) the bonding tensile strength of the repair material increases first and then decreases with increases in epoxy polymer content. An appropriate increase in the polymer–cement ratio can promote cement hydration. Full article

A dispersive solid-phase microextraction (DSPME) sorbent consisting of poly(1,6-hexanediol diacrylate)-based polymer microspheres, with embedded graphene microparticles (poly(HDDA)/graphene), was synthesized by microfluidic emulsification/photopolymerization and characterized by optical microscopy and X-ray fluorescence spectrometry. This sorbent was applied for simple, fast, and sensitive vortex-assisted DSPME of rare earth elements (RREs) in coal fly ash (CFA) leachate, prior to their quantification by inductively coupled plasma mass spectrometry (ICP-MS). Among nine DSPME variables, the Plackett–Burman screening design (PBD), followed by the central composite optimization design (CCD) using the Derringer desirability function (D), identified the eluent type as the most influencing DSPME variable. The optimum conditions with maximum D (0.65) for the chelating agent di-(2-ethylhexyl) phosphoric acid (D2EHPA) amount, the sorbent amount, the eluting solvent, the extraction temperature, the centrifuge speed, the vortexing time, the elution time, the centrifugation time, and pH, were set to 60 μL, 30 mg, 2 M HNO₃, 25 °C, 6000 rpm, 1 min, 1 min, 5 min, and 4.2, respectively. Analytical validation of the DSPME method for 16 REEs (Sc, Y, La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu) in CFA leachate samples estimated the detection limits at the low ppt level, the recovery range 43–112%, and relative standard deviation within ± 22%. This method was applied to a water extraction procedure (EP) and acetic acid toxicity characteristic leaching procedure (TCLP) for leachate of CFA, from five different coal-fired thermoelectric power plants. The most abundant REEs in leachate (20 ÷ 1 solid-to-liquid ratio) are Ce, Y, and La, which were found in the range of 22–194 ng/L, 35–105 ng/L, 48–95 ng/L, and 9.6–51 μg/L, 7.3–22 μg/L, 2.4–17 μg/L, for EP and TCLP leachate, respectively. The least present REE in TCLP leachate was Lu (42–125 ng/L), which was not detected in EP leachate. Full article

Solution polymerization synthesized alt-resistant superabsorbent poly (acrylic acid-acrylamide/fly ash) composites. The mass ratio of acrylic acid (AA) to acrylamide (AM), the concentration of crosslinker, the neutralization degree (ND) of AA, and the polymerization temperature were investigated by single-factor method. Optimized conditions for the synthesis of poly (acrylic acid-acrylamide/fly ash) (PAA-AM/FA) are, as following: m (AA)/m (AM) is 1.5, the content of crosslinker N, N-methylenebisacrylamide. (MBA) is 0.7%, neutralization degree of AA is 70%, polymerization temperature is 70 °C, and fly ash (FA) content is 50%. The prepared PAA-AM/FA demonstrated superior water absorption performance. The absorption capacities of PAA-AM/FA for pure water and 0.9% NaCl solution were found to be 976 g·g⁻¹ and 81 g·g⁻¹, respectively. Furthermore, PAA-AM/FA was found to have excellent adsorption capacity (148 mg·g⁻¹) for Rhodamine B in water. Fourier Transform-Infrared Spectroscopy (FT-IR), Thermogravimetric Analysis (TGA), and Scanning Electron Microscopy (SEM) characterized the prepared materials. Results showed that fly ash was incorporated into the macromolecular polymer matrix and played a key role in improving the performance of the polymer composites. Full article

The sensitivity of carbon nanofiber polyurethane cement (CNFPUC) was evaluated to determine whether the cement can act as an intelligent reinforcement material. The percolation thresholds at different polymer-to-cement ratios were determined through experimentation. Taking a specific carbon nanofiber (CNF) content of the percolation zone, several CNFPUC mixtures with different poly-ash ratios and silica fume contents were made. They were then sampled from the mixture and poured into a hexahedron CNFPUC test block; the coefficient of variation of resistance and the piezoresistive characteristics under axial load were examined and the blocks were examined by scanning electron microscope. The sensitivity of the CNFPUC mixture was evaluated via the resistance variation coefficient of a sample hexahedron. For different CNF dosages, the critical value of the variation coefficient was used to assess the sensitivity characteristic by fitting the conic curve. These findings may provide a novel and simple method for determining the sensitivity of CNFPUC mixtures. Full article