Waterproofing Membrane Research Articles

The influence of unconventional assembly techniques on the comfort indicators of waterproof materials

The present paper aims to highlight the correlations between the comfort indicators of waterproof cotton-based fabrics, and the specific parameters of unconventional assembly technology. The materials considered include layers of Gore-Tex film, serving as substitutes for waterproof materials, intended to manufacture outerwear products such as protective equipment (jackets and overalls), which are breathable waterproof membranes. The comfort indicator values were obtained through standardised methods, and data processing and representation in two-dimensional (2D) and three-dimensional (3D) systems using correlation/graphing methods were carried out in Excel software, and using Jandel Table Curve 3D v2. Although experimental research can be extended to include specific functions related to durability indicators, this study focused theoretically and experimentally on how the variation in temperature of the low-pressure hot air jet can lead to changes in the vaporization coefficient, air permeability index, and thermal conductivity coefficient. The relationship between the comfort indicator values (thermal conductivity coefficient, air permeability index, and vapour permeability coefficient) of the considered materials and the treatment parameters of the installation (pressure, temperature, velocity) is expressed through statistically adequate mathematical models, highlighted by a correlation coefficient R = 0.983, with significance certified by the Fischer test. The study of comfort indicators was conducted under optimized treatment parameters, ensuring durability and presentation value functions in the treatment zone remain unchanged compared to those of the base materials.

Waterproof pavement membrane based on synthetic resins used on concrete and steel bridge deck slabs

Waterproof pavement membrane based on synthetic resins used on concrete and steel bridge deck slabs

Metal–organic framework-based SERS chips enable in situ and sensitive detection of dissolved hydrogen sulfide in natural water: Towards a bring-back-chip mode for field analysis

Hydrogen sulfide (H2S) in natural water plays an important role in carbon and sulfur cycles in biosphere. Current detection protocol is complicated, which need to “bring back water” to lab followed by gas chromatograph analysis. In situ, field detection is still challenging. Herein, a portable, sensitive surface enhanced Raman scattering (SERS) chip was proposed for in situ H2S sampling and SERS signal stabilizing, enabling a “bring back chip” manner for lab analysis. The SERS chip was composed of single core-shell gold nanorod-ZIF-8 framework (Au NR@ZIF-8) nanoparticle. Relying on headspace adsorption, evaporated H2S was enriched in the ZIF-8 shell and then reacted with Au NR, resulting in the weakening of the Au-Br bond Raman peak (175 cm−1) and the appearance of the Au-S bond Raman peak (273 cm−1). The SERS signal reached equilibrium in 10 min. The detection range of H2S was 0.1–2000 μg/L and limit of detection was 0.098 μg/L. SERS signal was not interfered by normal volatile gases. Moreover, SERS signal of a reacted chip was stable at an ambient condition, allowing for in situ sampling and bring-back detection. The applicability of the chip was verified by dynamic H2S monitoring during artificial black-odor water evolution, and in-field quantitative analysis of H2S content in river water and sediment. Finally, the chip was sealed in a waterproof breathable membrane device, which realized the detection of vertical profiles of H2S in the river. This work provided a promising tool for field analysis of H2S in natural environments.

A new tunnel drainage system using double-adhesive spray-applied membrane: key parameters and applicable scope

To address water leakage in tunnels with high water pressure, a new waterproof drainage system was proposed. The system uses a spray-applied material with double-adhesive properties as a waterproof layer, significantly reducing leakages, and incorporates a unique bottom drainage system to reduce water pressure. In order to check the effectiveness of the new drainage system and to analyze the effects of various structural measures on pressure reduction, a numerical seepage analysis was carried out under the conditions of a water head of 160 m and a surrounding rock permeability of 1 × 10−6 m/s. The results show that the maximum water pressure on the secondary lining is 0.6 MPa, which is about 60% reduction compared to a fully enclosed waterproof system and shows a significant pressure reduction. The spacing of the circumferential drainage pipe and the width of the drainage sheet significantly affect the drainage performance, while the arrangement of the drainage system and the size of the bottom drainage pipe have minimal impact. With full consideration of pressure reduction, cost efficiency and construction feasibility, it is recommended to use the following drainage scheme for iterative calculations during the design stage: “1” shaped arrangement, blind pipe diameter of 10 cm, width of drainage sheets of 0.8 m, and drainage spacing of 6 m. By combining the experimentally determined hydrostatic peel-off strength of 1.4 MPa for spray-applied membrane, the applicable scope of the new drainage system was acquired. The research results can provide valuable insights into the application of spray-applied waterproofing membrane in drainage tunnels with high water pressure.

Fluorine-free biomimetic membranes with leaf vein-like and lotus leaf dual structure for high-performance waterproof and breathable textiles

Intelligent microporous membranes with excellent water resistance and moisture permeability have a huge market demand owing to their wide applications in personal protection, outdoor equipment and wearable electronics. However, the construction of such high-performance waterproof and moisture-permeable membranes (WBMs) based on a simple preparation process without post-coating treatment presents significant challenges. Herein, we present a simple strategy for constructing a fluorine-free polyethylene terephthalate (PET)-based WBM with a novel composite structure by combining a leaf vein-like nanofibrous substrate membrane and lotus leaf-inspired biomimetic nanofibrous skin using multi-needle electrospinning and heat treatment techniques. Surface hydrophobicity, along with the stable crosslinked structure of PET-based membranes, was achieved by in-suit doping of fluorine-free two-component reactive silicone rubber (PDMS). In addition, the small pore size and high porosity of the composite membranes were regulated by co-assembling PET/PDMS fibers and microspheres with different morphologies and structures. The resulting composite membranes based on substrate membrane-1:3 (BNFM-1:3) achieved excellent waterproof performance of 90.3 kPa, good moisture permeability of 5116 g m−2 d−1, and air permeability of 1.82 mm s−1. The WBMs based on novel composite structures are expected to be applied in various fields because of their ideal comprehensive performance.

Ionic Hydrogel-Based Moisture Electric Generators for Underwater Electronics.

Ubiquitous moisture is of particular interest for sustainable power generation and self-powered electronics. However, current moisture electric generators (MEGs) can only harvest moisture energy in the air, which tremendously limits the energy harvesting efficiency and practical application scenarios. Herein, the operationality of MEG from air to underwater environment, through a sandwiched engineered-hydrogel device with an additional waterproof breathable membrane layer allowing water vapor exchange while preventing liquid water penetration, is expanded. Underwater environment, the device can spontaneously deliver a voltage of 0.55V and a current density of 130µAcm-2 due to the efficient ion separation assisted by negative ions confinement in hydrogel networks. The output can be maintained even under harsh underwater environment with 10% salt concentration, 1ms-1 disturbing flow, as well as >40kPa hydraulic pressure. The engineered hydrogel used for MEG also exhibits excellent self-healing ability, flexibility, and biocompatibility. As the first demonstration of practical applications in self-powered underwater electronics, the MEG device is successfully powering a wireless emitter for remote communication in water. This new type of MEG offers an innovative route for harvesting moisture energy underwater and holds promise in the creation of a new range of innovative electronic devices for marine Internet-of-Things.

Strains in sprayed concrete tunnel linings at Heathrow Terminal 4 and back-calculation of stress

This paper describes the installation and interpretation of strain gauges embedded in the sprayed concrete lining of the concourse tunnel at Heathrow Terminal 4 station, with readings taken over nearly 20 years. The rate of flow method was used to back-calculate stresses from the measured strains, which were then compared to stresses obtained from pressure cells at the same locations. The interpretation of the pressure cell data is described in Jones & Clayton (2021) and the pressure cell results were presented in Jones et al. (2023). The resulting 20-year history of stress and strain gives precious insights into the short- and long-term behaviour of a sprayed concrete lining. An increase of compressive strain up to 3 years followed by a slight decrease over the subsequent 15-16 years has been revealed. It is hypothesised that this is due to radial groundwater flow through the primary lining followed by the gradual application of hydrostatic water pressure to the waterproof membrane and secondary lining. The sprayed concrete primary lining was not designed for permanent loads but nevertheless appears to be supporting all of the effective stress, whereas the secondary lining is not supporting any ground loads but may be loaded by groundwater pressure.

Moisture sorption and mechanical properties of polymer-cement waterproofing membranes investigated by LF NMR

This study investigates the impacts of environmental humidity on moisture absorption and mechanical properties of polymer-based waterproofing membranes. Membranes of polymer-CaCO3, polymer-white cement composites and pure polymer were used for measurements after treated in different relative humidities (RHs). Results indicate that the humidity treatment greatly changes the mechanical properties of the membranes and increasing RH from 0 % to 100 % leads to reduction of tensile strength by 60–80 %, which is believed to originate from the plasticizing effect of the absorbed moisture. LF NMR (Low field NMR) enables quantification of moisture distribution in the polymer-filler composites and three types of water, i.e. the water stored inside polymer matrix (O/O water), the water located in interfacial regions between polymer phase and fillers (I/O water), and the free water in air voids are detected with increasing T2 values. The absorbed moisture majorly accumulates in the O/O interfacial region during the humidity treatments with RH of 0∼80 %, which is because of the larger O/O interfacial area compared with the I/O interface. A large amount of free water appears only at RH of 100 %. A core-shell structure of the polymer domains with dry core and moisturized shell, is interestingly found during the moisture absorption process of the membranes, based on the LF NMR measurements using MSE sequence. It is surprisingly found that the drop of tensile strength of the membranes upon moisture absorption is majorly related to the growing shell thickness of the polymer domains whereas the moisture accumulated in the I/O interfacial region plays a minor role.

Water Resistance and Pore Characteristics of Organic Silane Waterproof Membrane in Roadbed

Abstract In this paper, the inhibiting effect of organic silane waterproofing membrane on the capillary water rise height (CRH) of roadbed soil has been investigated, and the pore characteristics of the waterproof membrane have been studied. Different tests were performed to validate the resulting performance, such as CRH, contact angle (CA), and mercury intrusion porosimetry (MIP). The results showed that at 92 % compaction degree, the consumption of organic silane per unit area (OSA) of 8 g/m2 to 15 g/m2 could effectively inhibit the CRH. The CA of the waterproof membrane increased with OSA consumption and compaction degree. When the compaction degree and OSA consumption increased, the large pores were divided into small pores, resulting in a decrease in the most probable pore size of the waterproof membrane and an increase in the cumulative mesopore volume. Additionally, the specific surface area of the pores and the roughness of the pore surface of the waterproof membrane increased, the pore structure became more complex, and the fractal dimension was closer to 3.

The influence of radon penetration through joints on the overall radon barrier properties of waterproof membranes

Waterproofing membranes with a proven ability to prevent radon penetration are commonly used to provide basic protection of buildings against radon from the subsoil. The goal of our research was to find out which types of joints of the pre-applied membranes are radon-tight and which, on the other hand, are radon permeable. Another goal was to find out how significant radon penetration through the joints can be, and how it can affect the ability of the whole radon-proof course to prevent radon penetration into the house. Six types of joints were investigated by determining the radon diffusion coefficient. Four of these types had a radon diffusion coefficient up to three orders of magnitude greater than the membranes themselves. A procedure was proposed for taking into consideration the high radon diffusion coefficient of joints in the calculation of the radon resistance of the whole radon-proof course. It has been proven that leaks in the joints can reduce the radon resistance of the whole radon-proof course by two to three orders of magnitude. For this reason, the course may not meet the minimum radon resistance requirements. Numerical simulation revealed that the leaks were due to the use of unsuitable sealing materials and technologies. A correct sealing technology for problematic joints was designed and subsequently verified.

Preparation and Properties of GMS/HTSF-Modified Waterborne Polyurethane Fluorine-Free Waterproof and Breathable Film.

Developing a fluorine-free, durable, high-performance waterproof breathable film for fabrics remains a formidable challenge. In this paper, a strategy for the preparation of fluorine-free, durable, and high-efficiency fabric waterproof and breathable membranes using glyceryl monostearate (GMS)/double-ended hydroxy silicone oil (HTSF)-modified waterborne polyurethane was proposed. The orderly orientation of GMS and HTSF gives the fabric excellent water-repellent properties, and the polyurethane macromolecular chain ensures strong adhesion of long-chain alkanes and silicones to the fabric surface. In this paper, the effects of different GMS contents on the stability, chemical structure, particle size, viscosity, water absorption performance, surface morphology, and XPS of a waterborne polyurethane fluorine-free waterproof and breathable membrane (GHWPU) were studied. At the same time, the application properties of GHWPU-treated fabrics, such as waterproof performance, antifouling performance, surface energy, morphology, and air permeability, were discussed. Through the analysis of SEM and XPS, it was found that the folds on the surface of the film were more and more orderly with the increasing content of GMS, and this orderly distribution of water-repellent groups endowed the film with excellent water-repellent ability. When the GMS content was 28 wt %, the finished fabrics had excellent comprehensive properties such as static contact angle of 141.6°, hydrostatic pressure of 96.7 KPa, resistance to more than 30 washes, and air permeability of 119.3 mm/s.

Interlaced Amphiphobic Nanofibers for Smart Waterproof and Breathable Membranes with Instant Waterproofness Monitoring Ability

Interlaced Amphiphobic Nanofibers for Smart Waterproof and Breathable Membranes with Instant Waterproofness Monitoring Ability

Comparison of ePTFE membranes with fluorine-free alternatives considering durability of laminated fabrics using hydrostatic pressure testing

Pleasant wearing comfort is achieved using laminated fabrics containing a waterproof and breathable membrane. The most used membrane type is expanded polytetrafluoroethylene. Due to the negative impact of perfluoroalkyl and polyfluoroalkyl substances on the environment, fluorine-free alternative materials are necessary. In this work, alternative membrane materials, polyurethane and polyethylene terephthalate, were compared with expanded polytetrafluoroethylene. First, the mass per unit area, thickness, tensile properties, water vapor resistance, and hydrostatic pressure of corresponding laminates were determined. Furthermore, their durability, which is an essential aspect of sustainability, was investigated. Therefore, they were hydrolyzed, weathered, washed, and incorrectly treated (e.g. washed with fabric softener) and then investigated for hydrostatic pressure resistance, by scanning electron microscopy, infrared spectroscopy, and digital microscopy. It was shown that polyethylene terephthalate and expanded polytetrafluoroethylene are comparable with respect to breathability, waterproofness (>20 bar), and durability. However, the hydrostatic pressure resistance (approximately 11 bar) and the water vapor resistance values (>23 m2 · Pa · W−1) of microporous polyurethane membranes are poorer, but they still provide suitable alternatives. In addition, a beginning degradation of polyurethane could be proved after hydrolysis and weathering. Furthermore, the deposition of calcium salts on all membranes was observed after washing with tap water, fabric softener, and washing agents.

Superelastic and fluorine-free nanofiber membranes prepared by one-step electrospinning for waterproof and breathable applications

Waterproof and breathable membranes (WBMs) possessing high mechanical properties are widely sought after for a variety of applications. However, their manufacture still presents challenges in terms of environmental protection and process simplification. Herein, we present a facile way of developing fluorine-free and superelastic WBMs. The in-situ integration of poly(methylhydro-siloxane) and poly(styrene-butadiene-styrene) simultaneously satisfies the required mechanical properties, waterproofness, and breathability. The resultant membranes possess excellent tensile properties, exhibiting a breaking strain of 557.7 % and stress of 3.98 MPa. Further investigations reveal the membranes demonstrate excellent breathability (3303.7 g m−2 d−1) and hydrostatic pressure (70.9 kPa) while maintaining their comprehensive performance even under large tensile strains. The innovation of superelastic WBMs with stable properties holds promising application prospects in numerous fields.

Moisture and mould growth risk of cross-laminated timber basement walls: Laboratory and field investigation

Reinforced concrete is a commonly used material for constructing basements in low-rise buildings or residential houses in Canada, and as the use of cross-laminated timber (CLT) advances, the door to think of an alternative basement material to offset greenhouse gas emissions associated with reinforced concrete is open. However, the evaluation of CLT durability in below-grade environments, specifically concerning moisture and mould development, remains an unexplored field in research. Hence, this paper aims to analyze CLT's moisture response and mould growth risk in below-grade environments using field and laboratory experiments. A laboratory experiment was carried out to test a waterproofing membrane solution selected to compose the wall assembly in the field experiment. A large-scale experimental CLT basement was built at a cohesive soil site in Edmonton, Canada. The field experiment involved monitoring the relative humidity, temperature, and soil volumetric water content of the CLT panels, which measure 3 m by 6 m in plan and 2 m deep. Data was collected for an extended period from June 2022 to July 2023. The VVT model, developed by Hukka and Viitanen (1999) and updated by Viitanen et al., 2011 to estimate the mould growth level, was used to predict the risk of mould growth. The laboratory experiment showed that the waterproofing membrane is suitable for protection against moisture in a still-water setup. Field experiment results suggested that the primary moisture source was below the basement floor when the floor was finished inadequately. The moisture content of CLT walls was significantly increased by floor flooding and decreased by heating the basement interior. The acceptable mould index of three was surpassed during periods of abundant water below the basement floor due to flood events, showing that the CLT panels were at risk of mould growth development.

Bionic lotus‐leaf‐structured fluorine‐free polyurethane by combining electrospinning and electro‐spraying for waterproof and breathable textiles

AbstractDeveloping environmentally friendly and high‐performing viable waterproof and breathable membranes (WBMs) is critical but significantly challenging. Herein, we combine electrospinning and electro‐spraying methods. First, elastic thermoplastic polyurethane (TPU) is used as the polymer, and poly(methylhydrosiloxane) (PMHS) with low surface energy is introduced to prepare TPU/PMHS fiber‐based membranes by electrospinning. Electro‐spraying is performed using a dilute solution of TPU/PMHS/SiO2, with fluorine‐free hydrophobic SiO2 nanoparticles introduced to facilitate the construction of a rough lotus‐leaf‐like surface structure, ultimately obtaining TPU/PMHS/SiO2 WBMs with bead‐on‐string fiber binary structures and a strong water repellency. The results indicate that the TPU/PMHS/SiO2 WBMs comprise a three‐dimensional porous structure formed by randomly arranged fibers and a lotus biomimetic structure consisting of bead‐like fibers, providing the membrane with excellent mechanical properties and waterproof breathability, including a tensile strength of 15.8 MPa, static water pressure of 33 kPa, water vapor transmission rate of 5169 g m−2 d−1, and contact angle of 142°. Additionally, the fiber membrane exhibits an excellent strain recovery after 1000 cycles of cyclic stretching under 100% strain, verifying the excellent elastic properties of the TPU/PMHS/SiO2 WBMs. This simple preparation process and unique composite structure can facilitate the design and preparation of environmentally friendly, waterproof, and breathable materials.

Comparison between Waterproofing Sheets Membrane and Polyurea Waterproofing Coating Methods

This research aims to compare between Waterproofing Sheets Membrane and Polyurea Waterproofing Coating Methods, and know the waterproofing methods applying time, cost, weight, materials durability, and the waterproofing methods materials fire resistance properties. The research used qualitative analysis techniques to compare the two waterproofing methods objectively, Through lab testing, researchers found that: the polyurea waterproofing coating method usually takes between 1 to 2 working days to apply while the traditional sheet membrane waterproofing method takes between 5 to 7 working days applying time, and the polyurea waterproofing coating method can be more expensive than the traditional waterproofing sheet membranes method. Applying polyurea requires specialized equipment and trained personnel for proper handling and application, Both methods' materials weight are considered relatively light but the polyurea coating method materials are lighter, the polyurea waterproofing coating system lasts up to 30 years. Rather than the traditional system which durability is up to 20 years, the polyurea waterproofing coating system is considered a good fire resistance system rather than traditional sheet membrane system. It is recommended to clean and clear the surface before the commence of the waterproofing process. and the surface needs to be tested for at least 3 full days to confirm that the waterproofing system was applied successfully and without missing any openings.

Investigation of Antiaging Performance and Service Life of OMMT/SBS Modified Bitumen Waterproof Membranes

Investigation of Antiaging Performance and Service Life of OMMT/SBS Modified Bitumen Waterproof Membranes

Effects of fluorosilane addition on polyurethane electrospun membranes with waterproof and breathable performance

Waterproof and breathable fibrous membrane is a new type of polymer functional material widely used in outdoor protection, sports equipment, industrial production, and other fields. To impart waterproof ability and breathability, a common practice is to modify the electrospun membrane with low surface-energy materials, such as fluorosilane. However, when directly added to the electrospinning solution, the effects of fluorosilane on the property of the prepared membrane have been scarcely reported. Herein, we prepared the electrospun polyurethane membrane by adding two types of fluorosilane into the polyurethane solution. The effects of fluorosilane type and concentration on the conductivity and viscosity of the electrospinning solution were investigated. Moreover, the prepared polyurethane/fluorosilane fibrous membranes are analyzed in terms of their surface morphology, structure, water contact angle, breathable performance, and mechanical properties. Results show that the dual effects of fluorosilane content exert an opposing influence on the jet drawing process, which yields a minimum fiber diameter when the fluorosilane content is 20%. Under this condition, the membrane shows the highest water vapor transmission rate (10.4 kg/(m2·d). In addition the membranes have the maximum water contact angle (138°) and breaking strength (12 MPa) when the fluorosilane content is 40%. This study provides insights into fabricating electrospun waterproof and breathable membranes in equipment for outdoor sports and protection.

Facile fabrication of fluorine-free waterproof and breathable nanofiber membranes with UV-resistant and acid-alkali resistant performances

Membranes with good waterproofness and breathability are desired for the preparation of outdoor sports garments. However, current waterproof and breathable membranes use environmentally hazardous fluorine-containing raw materials and suffer from many problems such as complicated preparation processes and single function. Therefore, it is a great challenge to select environmentally friendly raw materials to prepare multi-functional membranes with waterproof-breathable performance by simple preparation method. In this paper, fluorine-free poly(styrene-b-butadiene-b-styrene) (SBS), polyurethane (PU), and 2-hydroxy-4-n-octyloxy benzophenone (UV531) were selected to prepare multi-functional nanofiber membranes by convenient one-step electrospinning. The properties of the environmentally friendly multi-functional SBS/PU/UV531 nanofiber membranes were systematically optimized by adjusting the concentration of UV531 in the nanofiber membranes. The ultimately obtained multi-functional SBS/PU/UV531–2 nanofiber membrane shows excellent waterproofness (hydrostatic pressure: 58.8 kPa), high breathability (WVT rate: 5.2 kg m−2 d−1), good mechanical properties (breaking strength: 7.26 MPa, breaking elongation: 327.9%), excellent UV resistance (UPF: 238.23), and strong acid and alkali resistance properties. This multi-functional nanofiber membrane has broad application prospects in a variety of fields such as outdoor protective clothing, extreme environment materials, and military products.