Waterproof Layer Research Articles

Effect of PVA-treated soil on water-salt capillary rise in loess soil: Soil column experiment

In the loess region of northwest China, the accumulation of soluble salt in the soil due to the capillary rise of water often damages earthen buildings. Thus, studies on the cutting off of the capillary-rise path are vital. As a hydrophobicity inducer, polyvinyl alcohol (PVA) solution with water as the solvent has the potential to function as a barrier. This study mainly aims to evaluate the feasibility of using PVA-treated soil as a waterproof layer to prevent water-salt capillary rise through soil column experiments, and the effects of the waterproof layer thickness, waterproof layer position, PVA content, ambient temperature, and type of salt solution on the capillary action. The results indicate that a 1.0% PVA-treated soil with extreme water repellency (i.e. dried at 20 °C) can perfectly prevent the water-salt from migrating to the top of the sample, regardless of the waterproof layer position, waterproof layer thickness, and type of soluble salt. For a 0.5% PVA-treated soil dried at 20 °C, the lower waterproof layer prevents the water-salt capillary rise, while the middle and upper layers exhibit less effectiveness. However, the PVA-treated soil that loses its hydrophobicity after a treatment at 100 °C cannot prevent the water-salt capillary rise, confirming that the prevention of capillary rise is due to the soil hydrophobicity. The waterproof layer thickness and type of soluble salt are less significant than the waterproof layer position, PVA content, and ambient temperature. This study proposes a modified Green-Ampt model to describe the capillary rise, and the hydraulic conductivity and pore size are obtained using the modified model. These parameters and the interface effect are used to explain the experimental results. Finally, the application of PVA-treated soil as a waterproof layer to inhibit water-salt capillary rise is illustrated.

Analysis of Behaviors of the Railway Subgrade with a New Waterproof Seal Layer.

This study proposes a new waterproof sealing layer to reduce the impact of water on subgrade beds. The proposed waterproof sealing layer is composed of a polyurethane adhesive (PA) mixture, which aims to control interlaminar deformation and prevent seepage. A variety of laboratory tests were first performed to analyze the attenuation characteristics and mechanical properties of various polyurethane polymer (PP)-improved gravel mixtures under thermohydraulic coupling effects. In addition, a waterproof performance model test of the PP-improved gravel layer was conducted to investigate its waterproof and drainage performance and hydraulic damage mechanism. Finally, the feasibility and effectiveness of the surface structure of the waterproof drainage subgrade bed containing the PA mixture was tested in combination with the treatment project of the Ciyaowan station of the Baoshen heavy-haul railway. According to the experimental and model results, (1) the waterproof layer containing the polyurethane mixture exhibited satisfactory stiffness, elasticity and flexibility. The waterproof layer containing the polyurethane mixture also controlled the deformation between layers, and its mechanical properties remained stable. (2) The waterproof layer with the dense polyurethane mixture performed well in terms of the waterproof aspect, and no infiltration occurred under cyclic load (3). Long-term field monitoring revealed that the effect of the implementation of a PP-improved gravel layer to treat mud pumping was remarkable. The settlement of the PP-improved gravel layer only reached 13.21 mm, and the settlement remained stable in the later stage.

Evolution evaluation of high-speed railway asphalt concrete waterproofing layer during laboratory freeze–thaw cycles

An in-depth understanding of internal freeze–thaw damage mechanisms in high-speed railway asphalt concrete waterproofing layer is of great importance to achieve its long-term waterproofing and mechanical performance during the prolonged service life. In this work, four types of composite polymerized railway asphalt mixtures with air voids of 2% were custom-designed and treated with a total of 20 modified freeze–thaw cycles. Meanwhile, the volume and mass measurement, X-ray CT, indirect tensile strength test, and Marshall stability test were used to characterize the internal freeze–thaw damage and evaluate the performance deterioration. The results indicated that the internal deterioration resulted from the generation, expansion, and aggregation of voids and micro-cracks. Meanwhile, a “lag effect” of the freeze–thaw damage, that is, a gradual inward erosion process, was verified by dividing the cylindrical specimens into the core layers, intermediate shell layers, and outer shell layers. The efficiency of the “lag effect” was influenced by the air void content in the outer shell layer, which meant the lower the air void content in the outer shell layer, the slower the freeze–thaw damage. In addition, all four types of asphalt mixtures exhibited promising waterproofing performance and freeze–thaw damage resistance. Binder A and AC-10 mixtures exhibited the superiority in terms of high-temperature performance and freeze–thaw damage resistance based on Marshall stability and flow value that were proved to have adequate efficiency on characterizing the freeze–thaw damage in railway asphalt mixtures.

Efficacy and mechanism of graphene oxide modified silane emulsions on waterproof performance of foamed concrete

As a lightweight construction material, foamed concrete has garnered considerable attention due to a variety of advantages. However, the high-water absorption increases the burden on the structure and accelerates freeze-thaw damage, and thus reduce the durability of foamed concrete. Herein, two kinds of waterproofing materials based on isobutyl triethoxysilane (IBTS) emulsion and graphene oxide/silane (GO/IBTS) composite emulsion were synthesized and used for foamed concrete by facile coating and soaking method. The results show that the soaked specimens exhibit excellent waterproof performance and the water absorption is almost 0%. By contrast, an internal waterproof layer is occurred in the coated specimens, and the water absorption rates of foamed concrete coated with IBTS emulsion and GO/IBTS emulsion are reduced by 75% and 82%, respectively. The waterproofing mechanism of the silane emulsion were analyzed by scanning electron microscope (SEM), energy dispersive spectrometer (EDS), flourier transform infrared (FT-IR), x-ray fluorescence analysis (XRF) and x-ray diffraction (XRD). The results demonstrate that the foamed concrete shows a rough surface topography and low surface energy after IBTS treatment, which resulted in a superhydrophobic surface. While the surface of foamed concrete became rougher with the admixture of GO, which further enhanced the waterproof performance of foamed concrete.

Preparation and experimental research on the properties of neodymium iron boron magnetic powder modified asphalt

Waterproof adhesive layer is an important part of the asphalt pavement system for steel bridge decks. To improve the strength and durability of the paving structure, it is necessary to focus on the high-temperature performance and bonding properties of the waterproof adhesive layer. In this paper, Neodymium iron boron magnetic powder (NP) mixed with SBS modified asphalt was used to prepare NP-SBS composite modified asphalt (NSA) for the waterproof adhesive layer material of the steel bridge deck pavement structure. The excellent mechanical and magnetic properties of NP are used to enhance the related properties of the waterproof adhesive layer. The dynamic shear rheometer (DSR) test, the bending beam rheometer (BBR) test, the direct-tensile-loading test, and the direct-shear-loading test with 6 NP contents (0%, 2%, 4%, 6%, 8%, 10%) were conducted to evaluate the high-temperature performance, the low-temperature performance, the tensile strength and the shear strength of the unmagnetized and magnetized NSA. Through these tests, the variation of rheological properties and bonding properties of NSA could be analyzed. The research results showed that the addition of NP improved the high-temperature performance of NSA, but the effect of the powder mortar had an adverse effect on the low-temperature performance. The tensile strength and shear strength of the NSA increased with the increase of the amount of NP, and the amount of 1.0 L/m2 and the NP content of 6% can achieve better bonding properties. After magnetization, the high-temperature performance and bonding properties of NSA will be further improved, but the low-temperature performance will also be further decreased. It reflects the effect of NP on powder modification, magnetic bonding, and magnetic hardening of NSA. The research results show that NSA has excellent high-temperature performance and bonding properties, which can provide a reference for the subsequent research and application of NSA.

Overview: Application of Resin Waterproof Adhesive Materials in Bridge Deck Pavement in China

To further promote the research and application of resin type waterproof adhesive layer materials, the types, relevant specifications, and research trends of resin type waterproof adhesive layer in China are comprehensively investigated. The performance evaluation indicators, performance requirement, and requirements in different specifications are systematically analyzed, and the key performance evaluation indicators are recommended. The basic properties of common resin type waterproof adhesive layer materials are studied, and the bonding properties of different resin waterproof adhesive layers were compared and evaluated. The results showed that pull‐out strength, shear strength, tensile strength, elongation at break, low temperature flexibility, and impermeability are the key performance evaluation indicators of resin waterproof adhesive layer. The tensile property, corrosion resistance, and water impermeability of resin type waterproof adhesive layer material are good, the flexibility of epoxy resin type waterproof adhesive layer material is poor, and the flexibility of methyl methacrylate (MMA) waterproof adhesive layer material is good. The bonding performance of the epoxy resin waterproof adhesive layer is better than that of the MMA. As the temperature rises, the bonding performance of the two waterproof adhesive layers is significantly reduced. At 60°C, the average pull‐out strengths of the epoxy resin and MMA waterproof adhesive layer were 1.83 MPa and 1.47 MPa, respectively.

Нұр-Cұлтан қаласы Алматы ауданы топырағының геогельминттермен ластану жағдайы

The work on determining the main sources of soil pollution in the city, the species composition, the number of pollutants, and assessing their impact on the environment and public health is one of the problems that have not yet been solved in our country. The increase in anthropogenic load on the soil of the city, the accumulation of particularly dangerous untreated substances, the coating of the soil surface with a waterproof layer provoke a violation of the structure and composition of the soils of the city. The article presents an overview of scientific papers on the course and relevance of the study of helminths living on urban soils in general, their species composition, conditions and features of distribution, life cycle. It is proved that soil pollution, which is the main factor in the spread of infectious invasive diseases among animals and humans, has a negative impact on the quality of feed, food products, indicators of underground and surface water reserves, atmospheric air. Examples are given on the state of chemical, biological, and microbiological pollution of the city's soils, sources of pollution, and the relevance of scientific research on the impact of contaminated soils on the environment. This scientific direction describes the course of research in the world, the country. The article also analyzes the results of studies conducted on the state of soil pollution by helminths of the Almaty district of Nur-Sultan. During the study, there were taken soil samples from five points for four seasons of the year (Romanenko's mixed-method), which have various possibilities of infection with helminths in the Almaty district of Nur-Sultan. As a result of the study, there were determined the species composition and abundance (42) of helminth eggs (acute worm - Enterobius vermicularis), giardia duodenalis, and ascarids - Ascarididae). The degree of danger to the environment was assessed by the frequency of occurrence of helminth eggs found in the soil.

Optimization of Energy in Sustainable Architecture and Green Roofs in Construction: A Review of Challenges and Advantages

Sustainability has been one of architecture’s most significant trends over the last twenty years. The environmental consciousness of professionals has put sustainability at the heart of the architectural profession and has contributed to adopting and implementing sustainable designs on the scale of urban landscapes. A green roof or living roof, which is a sustainable solution in architecture, is a roof on the surface of which plants are grown. The roof is covered by plants, covering the waterproof layer beneath the vegetation. However, various types of plants can be used in this scheme. Understanding the influencing factors in choosing the right plant species and the impact that utilizing green roofs has on the overall energy consumption of the building can tremendously help scientists and clarify the possible future research topics in this field. Hence, this article investigates energy optimization in the construction process of a green roof in sustainable architecture and its advantages and challenges. The results of this study show that budget limitations, managerial and organizational policies, legal issues, technical and scientific infrastructure, and cultural and geographical aspects are all affecting the widespread use of green roofs currently and need to be considered in future studies.

Defects systematization of reinforced concrete bridges of ukrainian railways as the result of their inspection

Visual inspection is the important part of the bridges management. Many defectscan be detected that determine the traffic conditions, service life, and operation cost. Thedeterioration of bridges calls for effective methods for condition evaluation and maintenance as wellas suitable methods of their repair and recovery. This article aims defects systematization ofreinforced concrete bridges to define the effective method for recovering of their technical state. Morethan 100 reinforced concrete bridges in Ukrainian railways were inspected from 2017 to 2021.Ultrasonic pulse velocity, penetration resistance, reinforcement corrosion tests, and rebar locatingwere performed on beams, bed block, and piers of reinforced concrete bridges. It is shown that themost probable reasons of defects are natural impacts (freezing-thawing, moisturizing-drying),technogenic factors (train vibration, leakage current), and technological disadvantages(unsatisfactory production or setting). During the inspection, there are three categories of defectswere defined. The first one does not influence the train traffic (for example, deficient protectiveconcrete layer). The second one can limit the train traffic (for instance, crack width more than 0.3mm). The third category endangers the safe railway operation (such as an intense leaching of cementstone at an area more than 2 m2). It is made a proposal to match external signs of damage withreasons their appearance and methods of recovery. Three main types of repairs are used in Ukrainianrailways: torkret process, steel hooping, waterproof layer. However, the relationship between thetype of defect and the method of recovery has not been estimated before. It is important that themethods of repair and protection will be assigned according to their operation state (a disabled staterequires immediate recovery of the structures) as well as the reasons of appearance (destructiveacts). These methods must prevent a future destruction or protect of the structures.

Ensuring safe working conditions during the rehabilitation of operated combined insulated rolled roofs

The recommended option for rehabilitation of operated combined insulated rolled roofs allows to reduce the cost of measures to ensure safe working conditions. The article proposes a construction solution similar to an inverted roof. In the proposed solution, the role of a vapor barrier is played by the repaired layers of the existing waterproofing layer to which the insulation board has been attached.

Study on the Influence and Law of Waterproof System Design Factors on the Typical Stress of Bridge Deck Pavement

To improve the structural design rationality of cement concrete bridge deck pavement systems and reduce diseases such as interlayer displacement and rutting in the early stage of bridge deck use, this paper studies the influence and law of the coupling effect of various factors of the waterproof system on the typical stress of bridge deck pavement and determines the best structure combination for the bridge deck pavement structure. A finite element model was established by using commercial software to simulate the mechanical response of different types of waterproof bonding layer, waterproof leveling layer, and impervious structure layer under different parameters. The simulation results show that when the thickness of the pavement layer was 8 cm, the maximum shear stress of the pavement layer occurred in the middle of the wearing course and the junction between layers. When the pavement layers were continuous, the maximum strain of the waterproof bonding layer with the “rubber asphalt + protective plate” structure in the transverse and longitudinal directions was the largest. When the waterproof leveling layer was cement concrete, the structure bore a large amount of stress and easily produced cracks, resulting in water damage. High-density water-based asphalt concrete with a low permeability coefficient can reduce the interlayer shear stress and effectively ensure the interlayer bonding effect. On this basis, the following bridge deck pavement structure was proposed: waterproof system + multifunctional waterproof layer + load-bearing structure layer + surface functional layer.

Experimental Evaluation of Tensile Performance of Aluminate Cement Composite Reinforced with Weft Knitted Fabrics as a Function of Curing Temperature.

Cement composites (CC) are among the composites most widely used in the construction industry, such as a durable waterproof and fire-resistant concrete layer, slope protection, and application in retaining wall structures. The use of 3D fabric embedded in the cement media can improve the mechanical properties of the composites. The use of calcium aluminate cement (CAC) can accelerate the production process of the CC and further contribute to improving the mechanical properties of the cement media. The purpose of this study is to promote the use of these cementitious composites by deepening the knowledge of their tensile properties and investigating the factors that may affect them. Therefore, 270 specimens (three types of stitch structure, two directions of the fabric, three water temperature values, five curing ages, with three repetitions) were made, and the tensile properties, absorbed energy, and the inversion effects were evaluated. The results showed that the curing conditions of the reinforced cementitious composite in water with temperature values of 7, 23, and 50 °C affect the tensile behavior. The tensile strength of the CCs cured in water with a temperature of 23 °C had the highest tensile strength, while 7 and 50 °C produced a lower tensile strength. The inversion effect has been observed in CC at 23 °C between 7 and 28 days, while this effect has not occurred in other curing temperature values. By examining three commercial types of stitches in fabrics and the performance of the reinforced cementitious composites in the warp direction, it was found that the structure of the “Tuck Stitch” has higher tensile strength and absorbed energy compared to “Knit stitch” and “Miss Stitch”. The tensile strength and fracture energy of the CC reinforced with “Tuck Stitch” fabric in the warp direction, by curing in 23 °C water for 7 days, were found to be 2.81 MPa and 1.65 × 103 KJ/m3, respectively. These results may be helpful in selecting the design and curing parameters for the purposes of maximizing the tensile properties of textile CAC composites.

Hydrophobic Molecule Monolayer Brush-Tethered Zinc Anodes for Aqueous Zinc Batteries.

Aqueous zinc batteries are of great interest as a rechargeable energy storage system, particularly owing to the low cost and high safety of aqueous electrolytes, as well as the high capacity of zinc anodes. Unfortunately, the wide commercialization of aqueous zinc batteries is impeded by the irreversible water reduction and irregular zinc evolution issues on the anode side. Hereby, a hydrophobic and ultrathin polystyrene molecule brush layer is tethered onto the surface of zinc metal anodes to tackle the above limitations. Experimental investigations reveal that the waterproof artificial layer can sustain fast interfacial ionic transportation, minimize hydrogen evolution, and smoothen Zn deposition, thus conferring enhanced electrochemical performance to the as-protected Zn anode in both symmetric Zn//Zn cells and Zn//LiV3O8 full cells.

Перспектива снижения запыленности в очистном забое и увеличения коэффициента извлечения в условиях калийного рудника при камерной системе разработки

When developing potash deposits, an important point is to preserve the continuity of the water-proof layer for ensuring prevention of the groundwater penetration into the mine space. For this purpose, the development of the Verkhnekamskoye field is carried out by a chamber development system with the abandonment of chain poles to preserve the waterproof layer. Ore crushing is carried out with the help of high-performance combine systems, at the same time, the ore extraction process is accompanied by emissions of a large amount of dust into the mine atmosphere. The existing mining system assumes the movement of the outgoing flow of polluted air through the entire mine roadway (chamber), from the face to the mouth. In addition, there is a self-propelled carriage in the cell, driven by a miner who is forced to work in a polluted atmosphere. The most efficient method of reducing the air dustiness involves the use of hygroscopic properties of dust, however, the use of moisture in the bottom to reduce the dustiness of the air in potash mines is highly undesirable, since when sylvinite is contacting with water, an aggressive environment is formed that can disable working equipment. With such a system, mining is about 30–45 %, and the ventilation scheme of a dead-end treatment face does not allow to ensure safe working conditions for the workers of the working face, in particular, the driver of a self-propelled wagon. The dust collection system available in the design of the combine system is very inefficient. In this paper, a system of mining is proposed, which includes regular cutting of the chain poles. A solution is considered that allows to reduce the concentration of dust in the atmosphere of the working face by changing movement of the outgoing air flow, as well as to increase the air volume.

A Responsive Evaluation of the Green Roof Policy in Kaohsiung City

<p>以高雄市政府建築物立體綠化及綠屋頂補助計畫為評估對象，依據政策評估指標六面向:效能性、效率性、充分性、公平性、回應性、適當性為架構，深度訪談利害關係人，包含政策執行者、專業顧問、環保團體之政策監督者，以及使用者與受補助者。研究目的為評估政策實施品質，同時檢討政策推動的阻礙因素。研究結果顯示綠屋頂隔熱降溫效益獲得一致肯定，但減緩都市熱島效應之政策目標必須擴增綠化面積與提升植栽養護品質，長期持續實施之後才能正確評估效能。目前申請補助不踴躍，因為經濟誘因不足、宣導層面不廣。阻礙因素在於初期設置成本、後續維護費用負擔，以及人力不足。建議設計規劃階段提供專業技術輔導，包含水資源管理、防水層評估、生態美學教育，以及綠屋頂搭配光電板配置，結合開源節流策略，使綠屋頂能永續經營，有助於達成政策預期目標。</p> <p> </p><p>The present study aimed at conducting performance evaluation and making recommendations on the green roof subsidy policy that the Kaohsiung City Government promotes for existing buildings improvement. Analytical framework is based on the six aspects of policy evaluation indicators: effectiveness, efficiency, adequacy, equity, responsiveness, appropriateness. Stakeholder in-depth interviews on site were used to gather opinions and perceptions from policy implementers, consultant, policy supervisors of environmental protection association, as well as users and recipients. The purpose was to evaluate the quality of policy implementation and to review the impediments to policy promotion. The research results show that the effectiveness of green roof insulation and cooling has been unanimously affirmed. However, the policy goal of mitigating the urban heat island effect requires more greening and better quality of planting and maintenance which have to be implemented continuously for a long term in order to evaluate its effectiveness correctly. At the current stage, the challenges for the promotion of the green roof subsidy policy are passive applicants, insufficient incentives, and the narrow promotion of target users. The barriers of implementing green roofs for existing buildings are substantial upfront cost, maintenance costs and staff shortage. It is suggested that professional technical consultants should involve in the design planning, such as water resources management, the waterproof layer assessment, ecological aesthetics education, and the configuration of green roofs with photovoltaic panels. These integrated strategies of broadening income sources and economizing expenditure help to manage green roofs sustainably and to achieve the policy desired goals.</p> <p> </p>

Preliminary Investigation of an Approach to Improve Water Impermeability in Concrete with Externally Bonded FRP Systems

Good bond and water impermeability in fiber-reinforced polymer (FRP) bonded/coated systems are essential if the durability of FRP-rehabilitated concrete structures is to be ensured. In addition, water impermeability is required in some special FRP applications, such as the strengthening of underground water pipes. So far, there has been no method in the literature guaranteeing water impermeability in FRP strengthening works. This paper studies the feasibility of using a waterproof coating as the initial primer on cementitious materials before applying externally bonded FRP. In this preliminary investigation, by examining the two most important indicators (i.e., pull-off bond tests and water penetration tests), it was found that the use of an initial waterproof layer in the proposed FRP bonding system did not influence the pull-off bond strength but significantly improved the system's water impermeability. It is, therefore, suggested that an initial waterproof layer can be included in method statements for externally bonded FRP systems to upgrade the effectiveness and durability of FRP systems.

IMPORTANCE OF PIPELINE TRANSPORTATION, USE OF CONCRETE WEIGHTING AND INSULATION MEASURES, USED DURING PIPELINE CONSTRUCTION

It was determined that the advantages and importance of pipeline transportation are related to the priority of environmental measures, the fact that costs are within the norm, and the possibility of uninterrupted transportation regardless of the season. Of the transportation methods, special attention was paid to pipe transportation, which is considered to be the most efficient. At the design stage of the pipeline, the organization of repair work during the operation of the pipeline and the capital investment allocated for construction are referred to the criteria of optimality. Although there are many technologies for pipeline aggravation, the most common of these is aggregation with a concrete coating layer. It is known that pipes with a diameter of 530 mm and a wall thickness of 14 mm are used during pipe laying in offshore areas. For concrete treatment of these pipes, it is recommended to use 400-500 grade slag portland or putty cement, especially in the marine environment. Waterproofing is considered suitable for protecting submarine pipes from wear. For the implementation of the waterproofing layer, it is recommended to use either brizol or insulation in construction. An important factor is the provision of special insulation measures in the open part of the pipe after welding, which is explained in the article. Welding must be performed in accordance with the standard and welding materials must be licensed. There are many technologies for welding. Manual arc welding has the widest field of application. Prior to welding, there are important works that can affect the quality of work, including heating the pipe and sawing the pipe ring. The differences between the post-heated welding process of the pipe and the unheated welding process are known from production experience. During operation, the pipeline is affected by climate change and loads (various shock effects; seismic; as well as ripples if submerged; underwater currents, etc.). If the weld is as strong as the base metal, it will continue to do so. This strength can also be achieved by the absence of temperature differences during welding. Keywords: pipe, pump, concrete coating, insulation, welding.

An Experimental Study on a Composite Bonding Structure for Steel Bridge Deck Pavements

As one of the major contributors to the early failures of steel bridge deck pavements, the bonding between steel and asphalt overlay has long been a troublesome issue. In this paper, a novel composite bonding structure was introduced consisting of epoxy resin micaceous iron oxide (EMIO) primer, solvent-free epoxy resin waterproof layer, and ethylene-vinyl acetate (EVA) hot melt pellets. A series of strength tests were performed to study its mechanical properties, including pull-off strength tests, dumbbell tensile tests, lap shear tests, direct tension tests, and 45°-inclined shear tests. The results suggested that the bonding structure exhibited fair bonding strength, tensile strength, and shear strength. Anisotropic behaviour was also observed at high temperatures. For epoxy resin waterproof layer, the loss of bonding strength, tensile strength, and shear strength at 60°C was 70%, 35%, and 39%, respectively. Subsequent pavement performance-oriented tests included five-point bending tests and accelerated wheel tracking tests. The impacts of bonding on fatigue resistance and rutting propagation were studied. It was found that the proposed bonding structure could provide a durable and well-bonded interface and was thus beneficial to prolong the fatigue lives of asphalt overlay. The choice of bonding materials was found irrelevant to the ultimate rutting depth of pavements. But the bonding combination of epoxy resin waterproof and EVA pellets could delay the early-stage rutting propagation.

The waterproofing effect and mechanism of graphene oxide/silane composite emulsion on cement-based materials under compressive stress

The influence of the water-to-binder ratio and compressive stress on the waterproofing effect of graphene oxide/isobutyltriethoxysilane (GS) composite emulsion on cement-based materials was investigated. The results show that GS combines with calcium silicate hydrate to form a hydrophobic film, which prevents the intrusion of external water and carbon dioxide. In addition, after undergoing self-condensation, silanol reacts with calcium hydroxide to generate calcium silicate hydrate gel, which improves the microstructure of cement-based materials. Furthermore, the increase in the water-to-binder ratio and stress ratio leads to the expansion and connection of the pore structure of cement-based materials, resulting in an increase in the capillary water absorption coefficient. Meanwhile, the higher porosity is conducive to the penetration of the emulsion in cement-based materials and the formation of a waterproof layer. Thus, the waterproofing effect of GS composite emulsion on the specimen was improved.

Temperature features of the asphalt concrete waterproofing layer on high-speed railway in cold regions

The asphalt concrete waterproofing layer (ACWL) has been used as a potential waterproofing structure for the subgrade in Chinese high-speed railway in cold regions. The waterproofing behavior and dynamic response of ACWL have been evaluated in the previously published studies. However, the research on the temperature and thermal stress distribution in ACWL track structure has not yet been studied. This research aims at investigating the strain distribution of ACWL under the temperature influence in winter. The field test was conducted to monitor the strain changes on the ACWL surface under ambient temperature. A 3D numerical model of track structure with ACWL was also developed based on the thermo-mechanical coupled method. The field test results indicated that the longitudinal strain on the ACWL surface changed periodically with the air temperature while the tensile strain increased with the decrease in temperature. The temperature analysis showed that the temperature change inside the track structure caused by the daily temperature change was mainly focused on the depth range from the track slab to the base plate. The maximum negative temperature gradient inside the track slab was reported to occur at 4:00 a.m in winter. The geotextile was further introduced to weaken the bond between the base plate and the ACWL. The calculations proved that the geotextile could effectively reduce the peak tensile strain on the ACWL surface at the joints of the base plates. 1 m − 2 m geotextile was recommended to be placed at both sides of the joint of the base plates.