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In the lining of water conveyance tunnels, the expansion joint is susceptible to leakage issues, significantly impacting the long-term safety of tunnel operations. Polyurea is a type of protective coating commonly used on concrete surfaces, offering multiple advantages such as resistance to seepage, erosion, and wear. Polyurea coatings are applied by spraying them onto the surfaces of concrete linings in water conveyance tunnels to seal the expansion joint. These coatings endure prolonged exposure to environmental elements such as water flow erosion, internal and external water pressure, and temperature variations. However, the mechanism of polyurea coating's long-term leakage prevention failure in tunnel operations remains unclear. This study is a field investigation to assess the anti-seepage performance of polyurea coating in a water conveyance tunnel project located in Henan Province, China. The testing apparatus can replicate the anti-seepage conditions experienced in water conveyance tunnels. An indoor accelerated aging test plan was formulated to investigate the degradation regular pattern of the cohesive strength between polyurea coating and concrete substrates. This study specifically examines the combined impacts of temperature, water flow, and water pressure on the performance of cohesive strength. The cohesive strength serves as the metric for predicting the service lifetime based on laboratory aging test data. This analysis aims to evaluate the polyurea coating's cohesive strength on the tunnel lining surface after five years of operation. [ABSTRACT FROM AUTHOR]

The growing interest in modern polymer materials has targeted research on complex plastic coatings and the possibilities of modifying their features and properties during manufacturing. Today's modern coatings, including polyurea and polyurethane, are among the most modern developed resins. Compared to other polymer coatings, they are distinguished by their versatility, strength, and durability. They undoubtedly represent the next step in the evolution of coatings. Advances in coating technology have also led to the development of spray, injection, and roto-cast application equipment, improving polyurea-based elastomers' performance. For many years, there has been much interest in increasing the flame resistance of polymers. This is dictated by safety considerations and the increasing requirements for the flammability of plastics, the area of application of which is growing every year. This text attempts to provide an overview of current research on flame retardant composites. Particular attention was paid to polyurea (PU) and polyurea-based hybrids and the application areas of polyurea coatings. The paper defines flame retardants, discusses how they work, and presents the types of flame retardants and the current trends of their usage in the production of plastics. [ABSTRACT FROM AUTHOR]

Polyurea coatings are well recognized for their remarkable protective properties, making them highly appropriate for practical use in the field of concrete building. The use of polyurea coatings in the concrete building business is currently constrained, despite its prevalent application in industrialized nations. The limited use may be ascribed to ambiguities about the determinants of effective implementation in this particular setting, as well as the dearth of extensive study in the realm of new building materials. The primary objective of this research is to assess and conceptualize the key determinants linked to the use of polyurea coatings in concrete building endeavors. Utilizing a quantitative research approach, a comprehensive literature analysis was conducted to identify a total of 21 probable success variables. The reliability of the questionnaire was established by the administration of a pilot survey, and afterwards, an exploratory factor analysis (EFA) was performed to enhance the clarity and precision of the underlying components. The researchers used structural modeling (SEM) approaches to develop a robust model using the primary data obtained from the questionnaire survey. The EFA revealed the presence of five unique constructs that have an impact on the effectiveness of polyurea coatings in concrete building projects. These constructions comprise several characteristics, including environmental considerations, functional requirements, protective properties, execution processes, and creative elements. The significance and relevance of this research are shown by the validation of the study's results using SEM. The study makes a valuable contribution towards the progression of polyurea coating use within the concrete building sector.

In the lining of water conveyance tunnels, the expansion joint is susceptible to leakage issues, significantly impacting the long-term safety of tunnel operations. Polyurea is a type of protective coating commonly used on concrete surfaces, offering multiple advantages such as resistance to seepage, erosion, and wear. Polyurea coatings are applied by spraying them onto the surfaces of concrete linings in water conveyance tunnels to seal the expansion joint. These coatings endure prolonged exposure to environmental elements such as water flow erosion, internal and external water pressure, and temperature variations. However, the mechanism of polyurea coating’s long-term leakage prevention failure in tunnel operations remains unclear. This study is a field investigation to assess the anti-seepage performance of polyurea coating in a water conveyance tunnel project located in Henan Province, China. The testing apparatus can replicate the anti-seepage conditions experienced in water conveyance tunnels. An indoor accelerated aging test plan was formulated to investigate the degradation regular pattern of the cohesive strength between polyurea coating and concrete substrates. This study specifically examines the combined impacts of temperature, water flow, and water pressure on the performance of cohesive strength. The cohesive strength serves as the metric for predicting the service lifetime based on laboratory aging test data. This analysis aims to evaluate the polyurea coating’s cohesive strength on the tunnel lining surface after five years of operation.

The growing interest in modern polymer materials has targeted research on complex plastic coatings and the possibilities of modifying their features and properties during manufacturing. Today’s modern coatings, including polyurea and polyurethane, are among the most modern developed resins. Compared to other polymer coatings, they are distinguished by their versatility, strength, and durability. They undoubtedly represent the next step in the evolution of coatings. Advances in coating technology have also led to the development of spray, injection, and roto-cast application equipment, improving polyurea-based elastomers’ performance. For many years, there has been much interest in increasing the flame resistance of polymers. This is dictated by safety considerations and the increasing requirements for the flammability of plastics, the area of application of which is growing every year. This text attempts to provide an overview of current research on flame retardant composites. Particular attention was paid to polyurea (PU) and polyurea-based hybrids and the application areas of polyurea coatings. The paper defines flame retardants, discusses how they work, and presents the types of flame retardants and the current trends of their usage in the production of plastics.

Nowadays, the mitigation of damage to a ship caused by the underwater explosion attracts more and more attention from the modern ship designers. In this study, two kinds of scale tests were conducted to investigate the effects of polyurea coatings on the blast resistance of hulls subjected to underwater explosion. Firstly, small-scale model tests with different polyurea coatings were carried out. Results indicate that polyurea has a better blast resistance performance when coated on the front face, which can effectively reduce the maximum deflection of the steel plate by more than 20% and reduce the deformation energy by 35.7%–45.4%. Next, a full-scale ship (approximately 50 m × 9 m) under loadings produced by the detonation of 33 kg of spherical TNT charges was tested, where a part of the ship was coated with polyurea on the front face (8 mm + 24 mm) and not on the contrast area. Damage characteristics on the bottom were statistically analyzed based on a 3D scanning technology, indicating that polyurea contributes to enhancing the blast protection of the ship. However, damage results of this test were different from those of the small-scale tests. Moreover, the deformation area of the bottom with polyurea was greatly increased by 40.1% to disperse explosion energy, a conclusion that cannot be drown from the small-scale tests.

Polyurea is widely used in marine anti-corrosion engineering because it has the physical advantages of high tensile strength, strong adhesion, excellent waterproof and anti-corrosion performance as well as mature construction technology. In this paper, the origin, characteristics and development direction of polyurea coating technology were first introduced, and then the applications of polyurea coating in the fields of concrete protection and metal protection in marine atmospheric environment and seawater environment in recent years were summarized, respectively. Aiming at the problems of coating performance degradation and failure caused by complex environmental factors such as temperature, corrosive medium erosion and collision during service, the research progress of new polyurea coatings was discussed, including the research on improving the performance of coatings such as corrosion resistance, wetting and hardness with organic and inorganic nanoparticles as fillers, and the research on new polyurea microcapsule coatings that could respond intelligently and repair microcracks independently, and the research on the processing and preparation technology of new self-healing materials such as electrospinning. Finally, the shortcomings and challenges of the current research on polyurea coating were pointed out, and the future research trend of polyurea coating in marine environment was prospected.

Polyurea coatings are well recognized for their remarkable protective properties, making them highly appropriate for practical use in the field of concrete building. The use of polyurea coatings in the concrete building business is currently constrained, despite its prevalent application in industrialized nations. The limited use may be ascribed to ambiguities about the determinants of effective implementation in this particular setting, as well as the dearth of extensive study in the realm of new building materials. The primary objective of this research is to assess and conceptualize the key determinants linked to the use of polyurea coatings in concrete building endeavors. Utilizing a quantitative research approach, a comprehensive literature analysis was conducted to identify a total of 21 probable success variables. The reliability of the questionnaire was established by the administration of a pilot survey, and afterwards, an exploratory factor analysis (EFA) was performed to enhance the clarity and precision of the underlying components. The researchers used structural modeling (SEM) approaches to develop a robust model using the primary data obtained from the questionnaire survey. The EFA revealed the presence of five unique constructs that have an impact on the effectiveness of polyurea coatings in concrete building projects. These constructions comprise several characteristics, including environmental considerations, functional requirements, protective properties, execution processes, and creative elements. The significance and relevance of this research are shown by the validation of the study's results using SEM. The study makes a valuable contribution towards the progression of polyurea coating use within the concrete building sector., Competing Interests: The authors declare that they do not have any conflict of interest., (© 2024 Published by Elsevier Ltd.)

Abstract The response of composite cylinders to near field underwater explosive (UNDEX) loading, including the effects of polyurea coatings, have been studied through experiments with corresponding computational simulations. Experiments were conducted on woven E-glass/epoxy roll wrapped cylinders in three unique configurations: (1) base composite, (2) base composite with a thin (100% composite thickness) coating, and (3) base composite with a thick (200% composite thickness) coating. Each cylinder configuration was subjected to near field underwater explosive loading in a large diameter test tank at charge standoff distances of 2.54 cm and 5.08 cm. The response of the cylinders on the non-loaded side was evaluated through high speed photography coupled with three-dimensional Digital Image Correlation (DIC). Transient deformation and Post-mortem damage comparisons were made to evaluate the effects of the applied coatings. The LS-Dyna finite element code has been utilized to conduct corresponding computational simulations of the experiments to allow for additional evaluations of the cylinder response. The simulations are shown to provide high correlation to the experiments in terms of pressure loading and final damage mechanisms. Results for the internal / kinetic energy levels and the material strains as determined through the simulations are presented. The experimental and numerical results show that the application of a polyurea coating is effective for significantly reducing damage in the cylinders. It is also shown that there is in increase in both material internal energies as well as overall strains with increasing coating thickness. [ABSTRACT FROM AUTHOR]

• The driving power of osmosis under the polyurea coating. • The relationship between the chemical resistance of a material and its flexibility. • The relationship between the thickness of the polyurea coating and its tightness. • Defects in polyurea applications. • The reasons for the loss of polyurea coatings adhesion to the concrete. The article discusses the use of one of coatings protecting and strengthening concrete surfaces. It is polyurea coatings to strengthen waterproofing in tanks for water and other related liquids. Details of polyurea application technologies for specific tank structures and preparatory works that must be performed before the application of spray polyurea coatings have been discussed, as well as essential points related to minor and major cracks, cover reprofiling, type of coating used in chemically aggressive environments, causes and examples of structures where destructive corrosion processes of concrete surfaces and, consequently, the polyurea coatings covering them have been activated. The presented examples of failures in the application of polyurea coatings arise due to insufficient knowledge about the coatings themselves and the substrate on which the coatings are applied, but above all in failing to follow the strict procedure for their application. [ABSTRACT FROM AUTHOR]

An experimental study with corresponding numerical simulations has been conducted to evaluate the response of E-Glass / Epoxy composite plates, including polyurea coating effects, subjected to near field underwater explosion (UNDEX) loading. Experiments are performed in a water filled blast tank in which the including transient plate response during the UNDEX loading is measured utilizing high speed photography coupled with Digital Image Correlation. The experimental results show that the transient response of the plate is improved through the use of a thicker plate or through the application of a polyurea coating, although there is a weight penalty associated with the additional material which should be considered. Corresponding computational models of the experiments have been conducted with the commercial finite element code LS-Dyna. The simulations are shown to have a high level of correlation to the experimental data. [ABSTRACT FROM AUTHOR]

Polyurea is a polymeric material that can be used to provide environmental protection and structural enhancement. In this study, a low modulus polyurea coating, having high elongation, high energy absorption capacities, and a fast gel time, was sprayed under field conditions onto the surfaces of high-performance cementitious composites (). Flexure tests were conducted to measure toughness so that predictions could be made regarding the impact performance of two uncoated and coated matrices, one containing polyvinyl butyral (PVB) as the only aggregate, the other with polyvinyl alcohol (PVA) fibers added for reinforcement. Results from the flexure tests showed that encapsulation by plain polyurea increased the flexural strength of specimens by at least 60%. Results from drop-weight tests showed that the PVA fibers helped to improve impact resistance. A visible reduction in damage was seen when polyurea was applied to one surface, more so by coating the tension side opposite the striker. Coating both surfaces further increased impact resistance. [ABSTRACT FROM AUTHOR]

Polyurea is a polymeric material that can be used to provide environmental protection and structural enhancement. In this study, a low modulus polyurea coating, having high elongation, high energy absorption capacities, and a fast gel time, was sprayed under field conditions onto the surfaces of high-performance cementitious composites (). Flexure tests were conducted to measure toughness so that predictions could be made regarding the impact performance of two uncoated and coated matrices, one containing polyvinyl butyral (PVB) as the only aggregate, the other with polyvinyl alcohol (PVA) fibers added for reinforcement. Results from the flexure tests showed that encapsulation by plain polyurea increased the flexural strength of specimens by at least 60%. Results from drop-weight tests showed that the PVA fibers helped to improve impact resistance. A visible reduction in damage was seen when polyurea was applied to one surface, more so by coating the tension side opposite the striker. Coating both surfaces further increased impact resistance. [ABSTRACT FROM AUTHOR]