Heat Insulation Layer Research Articles

Static solid cooling (SSC) method for directional solidification and single crystal production: A CAFE Simulation Approach

This article presents a novel directional solidification (DS) technique called static solid cooling (SSC), which has been characterized and compared to the conventional high rate solidification (HRS) method using finite element simulation and a coupled three-dimensional (3D) cellular automaton finite element (CAFE) method. The SSC technique uses alternative heat conductor and insulation layers to provide DS conditions. Simulation results show that the SSC method provides a higher cooling rate, temperature gradient, and velocity of the solidification front compared to the HRS method. Moreover, due to its higher heat dissipation ability, the SSC method produces a convex shape in the solidification front, which is crucial for the production of defect-free single crystal blades. According to the simulation model, the HRS method can produce a defect-free single crystal structure up to a withdrawal rate of 3 mm/min, whereas, the SSC method can maintain a single crystal structure without any stray grain defects up to a withdrawal rate of 6 mm/min. These findings demonstrate the effectiveness of the novel SSC technique over the conventional HRS method in producing high-quality single crystal structures. The proposed method could have significant implications for industries such as aerospace and energy that require high-performance materials with superior mechanical properties at elevated temperatures.

Justification of the Efficiency of Application of Plaster for Fire Protection of Concrete Structures

The problem of using concrete for building structures is to ensure their stability and durability during operation within wide limits. Therefore, the object of research was the change in the properties of concrete during a fire and its protection when applying a heat-insulating layer of plaster, which is able to inhibit the temperature when the flame affects the coating. It has been proven that in the process of thermal action on fire-resistant plaster, the process of thermal insulation of concrete consists in the application of materials with low thermal conductivity as part of the plaster on the surface of the material. Similarly, under the influence of the burner flame, a temperature was created on the surface of the sample under the influence of the burner flame with a temperature of more than 800°С for 1800 s, the temperature on the surface of the concrete under the plaster coating did not exceed 120°С, which indicates the formation of a curtain for temperature. In this regard, experimental studies were conducted and it was established that the presence of aluminosilicate microspheres in the plaster leads to the formation of a thermally protective layer on the surface of concrete resistant to mechanical vibrations. According to experimental data, the coefficient of thermal conductivity and thermal conductivity of the plaster was calculated, which is 6.22·10–7 m2/s and 0.142 W/(m∙K), respectively, due to the addition of aluminosilicate microspheres. Thus, there are reasons to assert the possibility of targeted regulation of concrete fire protection processes by using fire-resistant plaster capable of forming a protective layer on the surface of the material, which slows down the rate of heat transfer.

Cooling effect and parameter analysis of applying heat insulation layer to tunnel regionalization in construction period based on geothermal level

The construction of high geothermal tunnels presents significant difficulties due to the abnormal rock temperature gradients, including designing a reasonable and cost-effective insulation layer as well as effective cooling measures. In this study, the rock temperature distribution, environmental temperature, and lining surface temperature of the tunnel during the construction period were analyzed through field surveys. A numerical simulation model considering ventilation and heat transfer dynamics was established based on the geothermal measurements and construction characteristics of this tunnel. After validating the 3D numerical model, the effects of installing heat insulation layers according to geothermal levels on the tunnel temperature field control were investigated. Additionally, the impacts of different insulation layer thermal conductivities (λi), ventilation air volume (Wa), and duct thermal conductivities (λd) were analyzed. The results indicate: (1) The comparison of temperature fields in tunnels with insulation layers, which is applied in the range of the rock temperature above 50 °C and without insulation layers was made. The temperature near the excavation face (TAm-1) decreases by up to 0.3% (0.5 °C), tunnel environment temperature with insulation layer applied (TAm-2) decreases by up to 4.2% (2.1 °C), the secondary lining temperature (TSec-lining) decreases by up to 10.5% (4.6 °C), and the wind temperature of air duct outlet (TAir-duct) decreases by up to 0.7% (0.5 °C). (2) The length of the insulation layer increases to the full length of the tunnel, TAm-1 continues to decline by only 0.4°C, TAm-2 by 0.5 °C, TSec-lining by 0.9 °C, and TAir-duct by 0.1 °C, which shows that it is the most economical and reasonable to apply the insulation layer only in the tunnel area where the rock temperature is higher than 50 °C. (3) As λi increases, both the tunnel environment and secondary lining temperatures exhibit linear increases, while increasing Wa and λi cause quadratic decreases and increases in tunnel temperature field parameters, respectively. (4) Range analysis of orthogonal experiments reveals that for tunnel temperature field impact level. For TAm-1, the significance order is Wa >λd >λi. And for TAm-2 and TSec-lining, the significance order is Wa >λi >λd, which can provide the more economical scheme for the insulation layer design and cooling schemes in the high ground temperature tunnel.

REFINING THE EMPIRICAL MODEL OF THE HEAT TRANSFER BOUNDARY CONDITIONS OF THE PISTON OF A HIGH-SPEED DIESEL ENGINE

The level of temperature of ICE pistons is a factor that greatly affects their reliability. Therefore, the need to simulate the temperature state of pistons with sufficient accuracy and minimal allocation of resources and time exists in research and during design. Primary approaches for determining the boundary conditions of the problem of thermal conduction of the piston on the basis of criterion equations, high-level mathematical models, and empirical models are considered. The latter ones have become widespread by virtue of simplicity and ease of use in practice; their usability is limited to a certain set of operating modes of one engine or a few ones of a similar design. On the basis of data from four series of experimental tests for a well-studied diesel engine 4ChN12/14 the existing empirical models of boundary conditions, suitable for identifying the temperature state of the piston only within the respective separate series separately, are refined in the paper. Processing of the data set on the measured temperatures in the control zones of the piston was performed, and linear function approximations were found that satisfactorily describe the effect of diesel power on the specified temperatures. The model of boundary conditions for a set of eighteen separate regions on the surfaces of the piston was proposed, which takes into account the dependence of the piston temperature state on the brake power of the ICE, the crank angle of the start of fuel injection, and the conditions of cooling the piston with oil. The influence of the heat insulation layer on the piston crown surface on the heat transfer was accounted for by introducing an additional thermal resistance term into the boundary condition equations. The model made obtaining the temperature field of the piston possible in simulation that is consistent with the results of all series of experiments in the control zones of the piston periphery, the edge of the combustion chamber, the vicinity of the groove of the first piston ring, the cooled surface opposite to the combustion chamber, and the piston skirt. The importance of a gradual change in the temperature of the oil and coolant during the transition of the internal combustion engine from one mode of operation to another regarding the temperature state of the piston is demonstrated. Taking the temperatures of oil from previous modes of operation into account is recommended during the analysis of engine transient processes.

Revealing patterns in reducing the fire-hazardous properties of insulation made from plant raw materials

An issue related to the use of hemp bundle insulation for building structures is to ensure their fire resistance under the action of a low-calorie ignition source. Therefore, the object of research was the change in the properties of the insulation during fire protection with its compositions capable of forming a layer of pinocoke under the influence of high temperature. On the basis of experimental data, it was established that at fire protection of insulation with a fire retardant agent, hydrolytic stable ethers containing phosphorus and nitrogen atoms are formed on the surface of the fibers. According to the temperature values and the shape of peaks on the DTA curve, it was established that at fire protection, the height of the peaks decreases and the width increases, which characterize the flow of exothermic transformations and the destruction of hemp fibers. At the same time, it was established that the formed residue has 13.3 % for impregnation and 26.6 % for coating. It has been proven that in the process of thermal action on the fire-resistant coating, the heat insulation process of the insulation consists in the formation of soot-like products on the surface of the material. So, it was determined that the sample did not catch fire, it was charred in the place of the radiation panel, and the burning was not recorded. On the other hand, for a sample of insulation treated with a coating during thermal action, the formation of a heat-insulating layer of foam coke occurred, which inhibits the penetration of heat, the temperature of flue gases did not exceed 100 °C, and the flammability index was 0. The practical significance is that the results were taken into account when designing buildings and structures. So, there are reasons to assert the possibility of targeted regulation of fire protection processes of insulation by applying coatings that form a protective layer on the surface of the material

Experimental study on snow melting and deicing of carbon fiber heating roads considering thermal insulation conditions

The electrothermal method for snow melting and deicing in road engineering provides efficient deicing. To improve the ice melting efficiency of carbon fiber heating cables, employing extruded polystyrene foam board (XPS)、polyethylene foam cotton (PEF) as insulation materials under the carbon fiber heating wire could reduce heat transfer to the lower layers of the road structure. Road model tests were conducted under various conditions to analyze how different heat insulation conditions、environmental temperatures affect road snow melting and ice melting. The results indicate that the placement of the heat insulation layer significantly affects the temperature fluctuation range between its upper and lower layers.The ice melting rate increases by 25∼50 % compared to pavement structures with no heat insulation layer. When heat insulation material is incorporated into the road structure layer, under preheated conditions, snow with a thickness of 0.2 cm on the surface of the plate heat insulation model can completely melt within 2.5 h, reducing the effective ice-melting time by 40∼51.7 %. A comparison of the thermal performance of the two insulation materials under various conditions reveals that the XPS plate is more suitable as an insulation layer compared to other materials.

Construction of TiO2/WO3/TiO2 double heterojunction films for excellent electrochromic performance

Electrochromic devices are applied extensively to camouflages, smart windows, heat insulation layers, and automobile rearview mirrors, etc. The amorphous WO3 is a very attractive electrochromic material, whereas it suffers from degradation of optical modulation and reversibility on ion exchange owing to those deep trapped ions with irreversible reaction behavior. Herein, we designed and, by using magnetron sputtering, prepared a composite film with TiO2/WO3/TiO2 double heterojunctions, which is capable of eliminating the deep trapped ions by itself under ultraviolet light (UV) assistance. The electrochromic device based on this composite film, after being recovery by short-time UV irradiation, can maintain a high transmission modulation of 94.72% after 7000 cycles of the voltammetry measurement. This feature allows the device to maintain its initial electrochromic performance after prolonged use. Moreover, the double heterojunction structure can reduce colouring time and enormously improve the colouration efficiency (CE) of electrochromic devices. Experimental research shows that when the thickness of the bottom and upper TiO2 layer of the WO3 film was 145.5 nm and 97.0 nm, respectively, the CE of electrochromic devices reached a perfectly high value (479.3 cm2/C), being much higher than that of WO3 devices (69.5 cm2/C). Functions of the TiO2/WO3/TiO2 double heterojunction in electrochromic device were investigated by combining theoretical analysis and experiment validation, and these results provide a general framework for developing and designing superior electrochromic materials and devices.

РАДИАЦИОННО-ЗАЩИТНЫЙ КОМПОЗИЦИОННЫЙ МАТЕРИАЛ НА ОСНОВЕ ОТХОДОВ РУДНЫХ МИНЕРАЛОВ И КАМНЕПЕРЕРАБОТКИ

Abstract. The relevance of the research topic lies in the fact that currently there is a steady tendency to increase the amount of electromagnetic radiation (EMR) occurring in the human environment, which negatively affects the healthy indoor environment and determines the focus of experimental research on protecting humans from factors hazardous to health. This article is devoted to the possibility of creating radioprotective building materials from man-made waste from various deposits of Armenia. Research is aimed at creating a comfortable living area inside buildings through the development of radioprotective sandwich-type materials that reduce the impact of EMR on human health. Work was carried out in the direction of developing samples of radio-absorbing structures and selecting radio-absorbing fillers. The laboratory obtained samples from stone processing waste and waste from the extraction of ore minerals with a density from -1500 to 2000 kg/m3, as well as samples based on expanded perlite and a mineral binder with a density of 250-300 kg/m3 as an internal heat-insulating layer and transferred to the National Scientific Laboratory named after A.I.Alikhanyan (Yerevan Institute of Physics) for proton irradiation. In this work, the samples were subjected to proton irradiation, since it is a component of cosmic radiation, as well as EMR and is capable of penetrating through layers of matter depending on its composition and properties. Some physical and mechanical properties of the resulting materials, such as compressive strength and water absorption, were also studied. In addition, the article contains a review of foreign experience in obtaining radioprotective materials with various types of radiation. At this stage, only proton irradiation has been studied, but work in this direction continues. 
 Subject of study: development of radioprotective materials of the “sandwich” type.
 Materials and methods: waste of aluminosilicate rocks (tuffs) and waste from the extraction of ore minerals were used. The method of proton irradiation of the obtained materials was used.
 Results: radioprotective materials have been developed that reduce EMR.
 Conclusions: The possibility of obtaining radioprotective materials by introducing ore mineral mining waste into the composition of the composite material has been confirmed.

Development of correction coefficients for cable cross-sections selection in polymeric cable channel

Relevance. The need to develop correction coefficients for selecting cable sections when laying in the polymeric cable channel in the Russian Federation. Currently, there are no recommendations fixed by the state standards for laying cable power lines in polymer pipes. Aim. To develop correction factors for laying cable power lines in the polymer cable channel. Objects. Cable transmission lines laid underground in polymer pipes. Methods. Numerical simulation of combined frequency-stationary method; determination of correction factors based on interpolation of model results; evaluation and analysis of comparison of cables in corrugated and smooth polymer pipes. Results. Calculations of the long-term current load for cables laid in the polymeric cable channel showed the effectiveness of this method of laying cable lines. The use of pipes with smooth walls makes it much more efficient to remove heat from cables into the environment (compared to a corrugated pipe), which allows you to increase the capacity of the same cable by about 25%, depending on the number of pipes laid nearby. Based on the results of the simulation of the thermal mode of corrugated and smooth polymer pipes, it can be concluded that corrugated pipe significantly complicates heat removal from the cable system to the environment (soil). This is due to the presence of air gaps in the ribbed structure of the corrugated pipe. The gaps filled with air act as a heat-insulating layer, unlike a smooth pipe in which this gap is absent. The developed coefficients will take into account the influence of the location of cables on their allowable current already at the design stage, which will reduce the cost of power transmission losses due to the wrong cable cross-section and high temperature.

THE INFLUENCE OF THE MATERIAL AND THE THICKNESS OF THE INSULATION LAYER ON THE HEAT FLOW THROUGH A MULTI-LAYER EXTERNAL WALL PANEL OF A RESIDENTIAL BUILDING

Solved the actual problem of heat flow research through a multi-layer external wall panel of a residential building, depending on the material and thickness of the heat-insulating layer.

Preparation and performance study of SiO2 aerogel thermal insulation coating with nanoporous structure for wind turbine blade surface

To prepare a base layer of thermal insulation for the surface of wind turbine blades, we utilized SiO2 aerogel material with a nanoporous structure as the thermal insulation layer of an inorganic composite photothermal de-icing coating. We further investigated the influence of raw material ratio and process on the thermal insulation layer’s performance. By adjusting the process parameters, the microstructure and characteristics of the SiO2 aerogel thermal insulation coating were controlled. Microstructure scanning and EDS analysis were employed to assess the results. The results of the experiment suggest that, as opposed to brush coating, atomized spraying is a better technique for creating SiO2 aerogel thermal insulation coating. The coating possesses excellent mechanical stability and applicability, maintaining a coating wear rate within 5% after 20 wear cycles under a load of 1734 N/m2, and the coating achieves the highest class 0 surface adhesion to the substrate surface. The coating exhibits exceptional heat insulation performance, reaching a temperature of 32.7 °C after five spraying cycles, which is 20.0 ∼ 29.4 °C higher than the surface without producing a complete heat insulation layer. The SiO2 aerogel aqueous slurry has a viscosity of 31.3 ∼ 36.9 mPa∙s, which is capable of forming a uniform membrane surface when sprayed at a 60° angle at 0.95 MPa pressure. Consequently, this paper’s design of photothermal thermal insulation offers strong anti-abrasion and excellent thermal insulation, presenting a new avenue for scientific investigation into coating photothermal de-icing.

Titanium foil-sealed thermoelectric generator for seafloor hydrothermal vent

The seafloor hydrothermal activity observation equipment needs a stable electric power supply; this study explored the thermoelectric generator (TEG) as the in-situ power supply method. The TEG can utilize the considerable temperature difference of the hydrothermal vent to supply electricity for the observation system. We use the titanium foil combined with the O-ring as the sealing component, thus can decrease the cold side thermal resistance and obtain a compact structure. The pressure test result shows the TEG can withstand pressure up to 20 MPa without leakage. Furthermore, a simulation is conducted to evaluate the temperature distribution of the TEG. To reduce heat loss, Polyetheretherketone (PEEK) material is used as the heat insulation layer at the surface of TEG. The simulation shows that adding the heat insulation layer can increase the hot side temperature by 4.9–7 K. The pool power generation results show that the novel structure TEG can realize 22 W output at the hot fluid temperature of 467 K. This study provides a novel sealing method for seafloor equipment with corrosion-resisting and low thermal resistance features.

Mechanical structure design and performance analysis of heat storage working medium for heat insulation layer

In order to solve the problems of low temperature inside the greenhouse caused by continuous haze weather or cloudy, rainy, and snowy weather, as well as the large heat dissipation capacity and insufficient cross time heat storage of existing solar greenhouses, by optimizing the design of the external insulation materials and structure of the heat storage water tank and studying the combination of heat storage working fluids, the greenhouse heat storage device has achieved cross time heat storage and segmented slow release heat release. The experiment shows that the combined heat insulation effect of heat insulation coating + aerogel + rubber and plastic insulation cotton is better, its 24-hour heat dissipation is reduced by 0.367 MJ compared to a single insulation material. The heat preservation material of the tank is 80~120 mm, and the cylinder heat storage tank is 6~10 m3 and 1:1. Which cannot only ensure a low effective heat dissipation rate, but also control engineering. The results show that the composite phase change material can increase the heat storage capacity, optimize the exothermic process, and achieve the gradual release of heat.

Patterns of air temperature changes in air ducts of non-contact air heating or cooling systems

The article is devoted to the study of the patterns of changes in air temperature during its movement in a sheet steel air duct during the operation of non-contact air heating systems, when the temperature of the moving air through the duct is higher than the room air temperature, as well as in the process of non-contact air cooling, when the temperature of the moving air in the duct below the room temperature. Based on the mathematical model of the ongoing physical processes developed in the article, an analytical formula is derived that allows, taking into account the presence of a heat-insulating layer or without it, to determine the patterns of changes in the temperature of moving air through the air duct at a given distance, depending on the thickness of the wall of the air duct and the speed of its movement. A dependence is given that determines the value of the heat transfer coefficient of air moving inside the duct to the inner surface of the duct on the speed, which at a constant flow rate is presented as a dependence of heat transfer on the open cross-sectional area of the duct. An analysis was carried out of the change in temperature of the moving volume of air inside the duct as a result of heat exchange with the surrounding air. A comparative calculation of the change in temperature of air moving in a thermally insulated air duct and in an air duct without thermal insulation was performed. The necessity of carrying out a calculation to determine the patterns of changes in the temperature of moving air inside the air duct when designing air heating systems or air conditioning systems is substantiated. It is concluded that it is necessary to conduct a technical and economic analysis on the feasibility of installing thermal insulation of air ducts made of thin sheet steel.

Geotechnical conditions of in-field road design in northern territories of Yamalo-Nenets Autonomous Okrug (Tomsk)

The Yamal-Nenets Autonomous District is the largest hydrocarbon resource base, supplying up to 300–330 billion m3/year of gas and up to 10–15 million t/year of liquid hydrocarbons. Mineral extraction is accompanied by the development of engineering infrastructure, namely: cluster pads, oil storage tanks, pumping stations and automobile roads that link both within and between sites. The area is unique in terms of complexity of geotechnical conditions due to permafrost soils in particular in the upper open-cast. The assessment of geotechnical conditions of the field development as well as adverse processes, hazards, risks and impacts on designed, constructed and operating roads to the cluster pads is undoubtedly relevant.Purpose: The evaluation of geotechnical conditions of design, construction and operation of in-field roads in the Severo-Komsomolsk field.Methodology/approach: The analysis and generalisation of materials of geotechnical surveys for design and construction documentation of the cluster pad 11 in the Severo-Komsomolsk oilfield, performed by AO "TomskNIPIneft". Determination of composition and physical properties of undisturbed soils taken when equipping observation posts, performed in the Laboratory of Ground Science and Soil Engineering, TSUAB.Research findings: Natural and geotechnical conditions of the Yamal-Nenets Autonomous District includes areas with hard frozen soil and areas with complete or partial absence of permafrost soils. In the first case, the subgrade design envisages that the upper permafrost horizon is not lower than the embankment bottom and remains at this level during the entire period of the road operation. In the second case, the design implies preliminary thawing of frozen soil lenses and road drainage prior to the subgrade construction. In the first case, the position of perennially frozen soils is evaluated by the appropriate embankment height, when non-cemented road-building materials are used, and by arranging heat-insulating layers (peat, polystyrene foam, hard frozen soil) with their thermotechnical calculation. The first principle implies the subgrade construction only in winter. To prevent deformation of embankment slopes, it is recommended to build peat benches fixed with a geosynthetic material. Land reclamation in the road construction zone should be avoided to prevent erosion of the soil cover.

Fire Performance of Cotton Fabrics Coated with 10-(2,5-Dihydroxyphenyl)-9,10-dihydro-9-xa-10-phosphaphenanthrene-10-oxide (DOPO-HQ) Zr-Based Metal-Organic Frameworks.

We investigated the performance of cotton fabrics coated with DOPO-HQ and Zr-based Metal-organic Frameworks when exposed to fire. The chemical structure of the cotton fabrics before and after the coating was characterized using FTIR spectroscopy, and the surface morphology of cotton and their combustion residues was probed via scanning electron microscopy. In our experiments, we used flammability tests and thermogravimetric methods to understand the burning behavior of the coated fibers, as well as their thermal stability. The cotton fabrics coated with DOPO-HQ and Zr MOFs exhibited shorter combustion times, had better thermal degradation properties, promoted the creation of heat-insulating layers, and exhibited improved smoke suppression behavior.

Determining thermal and physical characteristics of wood polymer material for pipeline thermal insulation

One of the methods for ensuring the efficiency of pipelines for transporting heat-carriers during operation is their thermal insulation, which inhibits heat transfer processes and does not affect environmental indicators. Therefore, the object of research was wood, a polymer material made by polymerization of wood sawdust and dry mixtures of synthetic resins for thermal insulation of pipelines. It has been proven that in the process of thermal action on the heat insulating layer of wood polymer material, the process of heat inhibition involves the formation of pores. This is due to the fact that the thermal conductivity of the material depends on the volumetric mass, the decrease of which for a wood polymer product leads to a decrease in thermal conductivity. In this regard, the simulation of the process of heat transfer through a cylindrical heat-insulating layer made of wood of polymer material was carried out and the dependences derived, which allow obtaining a change in the dynamics of heat transfer and determining thermophysical properties. According to the experimental data and the established dependences, it was found that the thermal conductivity of the wood of the polymer material was within 2.4÷2.9·10-8 m2/s, the thermal conductivity of the sample did not exceed 0.030 W/(m∙K). In addition, the heat capacity of the product corresponds to a value of more than 1034÷1145 kJ/(kg·K) depending on the thickness, which accordingly categorizes it as a heat-insulating material. At the same time, data on thermal insulation properties for polyurethane foam show that when it is used with a density of 100 kg/m3, the thermal conductivity is 0.029 W/(m∙K), which is approximately the same as the value of the proposed wood polymer material. The practical value is the fact that the results of determining the heat-insulating properties of a wood polymer material make it possible to establish the scope and conditions of its application

Crack behavior of expanded polystyrene foam-ceramsite composite thermal insulation mortar

To compensate for the deficiencies of thermal insulation, fire and crack resistances of traditional thermal insulation mortars, this paper prepares expanded polystyrene foam (EPSF)-ceramsites composite thermal insulation mortar (ECTIM) with ceramsite and EPSF particles as insulation aggregates. The effects of fiber content (i.e., P = 0.3%, 0.6%, 0.9%), fiber length (i.e., l = 3 mm, 6 mm, 9 mm) and fiber types (i.e., polypropylene fiber (PF), steel fiber (SF), alkali resistant glass fiber (ARGF)) on crack resistance of the ECTIM were analyzed. The test results demonstrated that the incorporation of fibers could significantly improve crack resistance and delay the cracking of mortar. With the increase of fiber content P, the water loss rate and cracking index decreased to 43.70% and 79.17% of the specimen without fiber. As the fiber length l increased from 0 mm to 9 mm, the water loss rate and cracking index decreased by 41.50% and 77.08%, respectively. Comparatively, the PF could obviously improve the crack resistance of the ECTIM. Based on the experimental research, the microscopic stress mechanism of mortar cracking, as well as the early and late anti-cracking mechanism of the ECTIM were revealed. In addition, considering the effects of fiber content and fiber length, a comprehensive influence coefficient ϖ was introduced, and a formula for conveniently calculating the maximum crack width Wmax of the ECTIM was proposed. The predicted results agreed well with the test data. The thermal insulation mortar prepared in this study could considerably overcome the deficiencies of traditional organic and inorganic thermal insulation mortars, and had excellent thermal insulation, fire and crack resistances. The resource utilization of iron tailings and the introduction of ceramsite reduced the materials cost. The prepared thermal insulation mortar could be used for wall substrate, geothermal heat insulation layer, external wall, internal wall and roof insulation.

Research on Ventilation and Heat Insulation Layer Design of Split-Type Roof Greening Based on Topological Interlocking Principle

In this paper, the roof ventilation and heat insulation layer modules are combined with the roof greening, and each module is assembled and combined through the principle of topological interlocking. The assembly of these modules does not require any rivets or cement mortar, and the structural stability of the overall assembled roof can be achieved only through the interlocking and limiting of the specific geometric shapes between the modules. Due to the modular design, this kind of green roof has strong applicability and can be applied to roofs of different shapes. Such a roof can not only meet the aesthetic needs, but also beautify the urban environment and reduce carbon emissions.

Evaluation of Curing Effects on Bitumen Emulsion-Based Cold In-Place Recycling Mixture Considering Field-Water Evaporation and Heat-Transfer Conditions

The strength growth of a bitumen emulsion-based cold in-place recycling asphalt mixture (BE-CIR) is time-dependent and time-consuming due to the addition of water. There is a great difference between the curing conditions of specification in the laboratory and the in situ conditions, which often leads to a great discrepancy between the results of lab specimens and the field cores. The main objective of this paper is to evaluate the curing effect on laboratory BE-CIR considering field-water evaporation and heat-transfer conditions. Four different curing methods were designed by using different combinations of waterproof layers, heat insulation layers, and variable temperature modes. The variations in temperature indexes, moisture content, air void, and indirect tensile strength (ITS) with curing time were tested, and the mutual influence of these indicators was analyzed. Furthermore, the results of the laboratory samples were compared with the field cores. Testing results show that the performance of the BE-CIR mixture is significantly different from that with no treatment, which is manifested as higher moisture content and lower air void and ITS under the same curing time. The internal temperature of the mixture is the main factor affecting the variation of moisture content, especially on the first curing day. The air void of the mixture has a strong linear relationship with the moisture content. Moisture content and ITS under different curing methods showed similar trends and could be divided into two stages. Taking the field cores as a benchmark, it can be concluded that the field-water evaporation condition should be considered in the setting of indoor curing methods, while the heat transfer could not.