Experimental Assessment of the Effects of Building Materials on Wi-Fi Signal 2.4 GHz and 5 GHz

We are all witnesses to the widespread use of wireless LANs (WLAN) and their easy implementation in indoor environments. Wi-Fi is the most popular technology for the WLAN. However, interference caused by building materials is a common, yet often overlooked, contributor to poor Wi-Fi performance. This interference occurs due to the nature of radio wave propagation and the characteristics of the wireless communication system. Therefore, during the implementation of these networks, one must consider the quasi-static nature of the Wi-Fi signal and its dependence on the influence of various building materials on the propagation of these waves. This paper presents the effects of building materials and structures on indoor environments for Wi-Fi 2.4 GHz and 5 GHz. To establish the interdependencies between factors influencing electric field levels, measurements were conducted in an experimental Wi-Fi network at different distances from the access point (AP). The results obtained show that the electric field strength of the Wi-Fi signal decreases depending on the distance, the building materials, and the transmitted frequency. Concrete material had the most significant impact on the strength of the electric field in Wi-Fi, while glass had a relatively minor effect on reducing it. Wi-Fi operates within the radio frequency spectrum, typically utilizing frequencies in the 2.4 GHz and 5 GHz bands. Additionally, measurements revealed that Wi-Fi signal penetration is more pronounced at lower frequencies (2.4 GHz) as opposed to the Wi-Fi signal 5 GHz. The findings can be used to address the impact of building materials and structures on indoor radio wave propagation, ultimately ensuring seamless Wi-Fi signal coverage within buildings.

Numerical Modelling of Coupled Heat and Mass Transfer in Porous Materials: Application to Cinder Block Bricks

In this work, we present numerical modelling of coupled heat and mass transfer within porous materials. Our study focuses on cinder block bricks generally used in building construction. The material is assumed to be placed in air. Moisture content and temperature have been chosen as the main transfer drivers and the equations governing these transfer drivers are based on the Luikov model. These equations are solved by an implicit finite difference scheme. A Fortran code associated with the Thomas algorithm was used to solve the equations. The results show that heat and mass transfer depend on the temperature of the air in contact with the material. As this air temperature rises, the temperature within the material increases, and more rapidly at the material surface. Also, thermal conductivity plays a very important role in the thermal conduction of building materials and influences heat and mass transfer in these materials. Materials with higher thermal conductivity diffuse more heat.

Enhanced Thermal Performance of Roofing Materials by Integrating Phase Change Materials to Reduce Energy Consumption in Buildings

This work focused on characterizing and improving the thermal behavior of metal sheet roofing.To decrease the heat transfer from the roof into a building,we investigated the efficiency of four types of phase change materials,with different melting points:PCMІ,PCM II,PCM III and PCM IV,when used in conjunction with a sheet metal roof.The exterior metal roofing surface temperature was held constant at 50℃,60℃,70℃and 80℃,using a thermal source(halogen lights)for 360 min to investigate and compare the thermal performance of the metal sheet roofing with and without phase change materials for each condition.The thermal behaviors of the phase change materials were analyzed by differential scanning calorimeter(DSC).The results showed the melting points of PCMІ,PCM II,PCM III and PCM IV were around 45℃,50℃,55℃and 59℃,respectively.The integration of PCM IV into the metal roofing sheet increased the thermal performance by reducing the room temperature up to 2.8%,1.4%,1.0%and 0.7%when compared with the normal metal roof sheet,at the controlled temperatures of 50℃,60℃,70℃and 80℃,respectively.The thermal absorption of the phase change materials also caused a time delay in the model room reaching a steady temperature.The integration of phase change materials with metal roofing sheets resulted in better thermal performance and conservation of electrical energy by reducing the demand for cooling.

Comparative Study of Two Materials Combining a Standard Building Material with a PCM

Phase change materials(PCMs)have the ability to store thermal energy and make it available at a later stage to keep indoor temperature within a specific range and achieve better thermal comfort in buildings.This study focuses on the performances of materials obtained by combining a standard building material with a PCM.In particular,two different materials mixed with the same PCM are considered under the same climatic conditions.The related thermal behavior is assessed in the framework of numerical simulations conducted with ANSYS Fluent assuming parameters representative of a city located in Europe.The results show that the addition of PCM to concrete and bricks can improve the thermal inertia of the resulting material.

Analysis of the Performances of a New Type of Alumina Nanocomposite Structural Material Designed for the Thermal Insulation of High-Rise Buildings

The sol-gel method is used to prepare a new nano-alumina aerogel structure and the thermal properties of this nanomaterial are investigated comprehensively using electron microscope scanning,thermal analysis,X-ray and infrared spectrometer analysis methods.It is found that the composite aerogel alumina material has a multi-level porous nano-network structure.When employed for the thermal insulation of high-rise buildings,the alumina nanocomposite aerogel material can lead to effective energy savings in winter.However,it has almost no energy-saving effect on buildings where energy is consumed for cooling in summer.

Summary of Research on Use of Sediment in Building Materials

Based on the recent research at home and abroad,this paper summarizes the preparation of cement clinker,baking-free brick,subgrade filler and ceramsite from sediment,and puts forward relevant suggestions and prospects for the future research direction of sediment.

Material Analysis of Traditional Folk Dwellings and Its Modern Inheritance:A Case Study of Traditional Folk Dwellings in Hunan Province

Traditional folk dwellings contain rich cultural connotations and plain architectural techniques.In architecture,material is the most fundamental thing,different materials can demonstrate different architectural forms,and reflect local characteristics and change of the time.Therefore,it is of great significance to explore the material selection of traditional Chinese folk dwellings.The paper took traditional folk dwellings in Hunan for example to analyze the regional materials and construction of these dwellings,discussed the application of traditional materials in modern architecture,used some cases to explore the innovative application of traditional materials,so as to figure out the new direction of applying traditional materials,and provide references for the construction of modern architecture.

Synthesis and Characterization of Local Bio-Sourced Geopolymer Binder:Application to Compressed Earth

The construction industry continues to rely on conventional materials like cement,which often can come with a high cost and significant environmental impact,particularly in terms of greenhouse gas emissions.To tackle the challenges of sustainable development,there is growing interest in using local available materials with low environmental impact.This study primarily focuses on synthesizing and characterizing a geopolymer binder made from local materials found in Benin to stabilize CEB(compressed earth brick).The synthesis involves combining amorphous aluminosilicate powder with a highly concentrated alkaline solution.Local calcined kaolinite clay(metakaolin)and corn cob ash obtained after calcination at 600°C were used with a 12 M sodium hydroxide(NaOH)solution.Different mixtures of geopolymer were formulated substituting metakaolin by corn cob ash at rates of 0%,5%,10%,and 15%of the dry weight of the mixture.Thereafter physical and mechanical characterization tests were conducted on each formulation.Results showed that geopolymer binders containing 85%metakaolin and 15%corn cob ash exhibited the best physical and mechanical performance(e.g.12.08 MPa for compression strength).Subsequently,this geopolymer formulation was used to stabilize CEB.Characterization revealed that CEBs stabilized with 10%geopolymer exhibit good mechanical properties(6.93 MPa),comparable to those of CEBs stabilized with 10%cement(7.40 MPa),justifying their use as load-bearing walls in construction.

Basic Characteristics of an Appropriate Waste Fillers for Solvent Free and Water-Borne Industrial Polymer Floors and Their Utilization

Recently the manufacture of epoxy coating and flooring materials begun to be under strong pressure to use more environmentally friendly raw materials in its composition.First tendency to reduce of solvents and diluents contained in the materials appeared at the end of 90´s.This situation was supported by the Council of Europe in 2004 to reduce VOC emissions to zero till 2020.Solvent materials were thus largely replaced by solvent free materials from which the volatile substances are not released into the air.But pressure continued to increase,and over the past decade began to take centre stage water-based epoxy.On the Czech market solvent based material is still occasionally used,but predominant are solvent free materials.There are no commonly used materials containing wastes as fillers in new water-borne and solvent-free epoxy materials.Characteristics identification of the waste material as a potential filler is a set of properties that determine the limits of secondary raw materials or waste as a filler.This paper describes the basic characteristics which must be selected to meet the requirements,to affect negatively the workability,sedimentation,properties and behavior of the final floor system.Some materials must comply with special requirements,such as resistance to chemicals,etc.Next part of paper talks about utilization of polymer floors and their mechanical properties.

Industrial TiO2 based nacreous pigments as functional building materials:Photocatalytic removal of NO

In this paper,the photocatalytic activity of industrial titanium dioxide(TiO2)based nacreous pigments was researched as functional building materials for photocatalytic NO remove.Three industrial TiO2 based nacreous pigments were selected to estimate the photocatalytic activity for NO remove.This study is a good proof that pearlescent pigments can eliminate NO,and its performance is positively correlated with its titanium dioxide content.And this research will widen the application of nacreous pigments in functional building materials,and provide a new way to eliminate in door nitric oxide pollution.

Degradation of Formaldehyde and Benzene by TiO2 Photocatalytic Cement Based Materials

A novel photocatalytic cement based material was prepared. The distribution of TiO2 on the surface of cement was characterized by scanning electron microscope（SEM） and X-ray diffraction（XRD）, which showed the relationship of photocatalysis and presence of TiO2. TiO2 also had an impact on cement hydration, which was studied by thermal analysis. With 300 W UV illuminations, formaldehyde and benzene were degraded efficiently by the prepared photocatalytic cement based materials. 15wt% TiO2/cement showed the highest degradation efficiency and capability. The results show that formaldehyde and benzene can be degraded within 4 and 9 hours, respectively. Besides, inorganic ions can induce TiO2 agglomeration. As a result, the presence of inorganic ions in cement is unfavorable for degradation. The photocatalytic cement based materials were fabricated and the degradation efficiency of formaldehyde was measured on building roof under sunlight illumination. Formaldehyde in glass chamber can be degraded thoroughly within 10 days.

Efficiency of Structural Materials in Sustainable Design

The main aim of this paper is to investigate energy consumptions, CO2 emissions and costs during the production and life cycle of structural materials. The virgin and recycled metals as well as waste minerals such as fly ash, slag in concrete save energy consumption, CO2 emissions and costs. The importance and effectiveness of recycled materials will be statistically evaluated via energy consumption, carbon footprint, ultimate strength and their ratios. Embodied energy to ultimate strength or embodied carbon to ultimate strength ratios may emphasize the effectiveness of a sustainable material. The analyses in this study indicate the utilization of the recycled steel and C50 concrete with 50% fly ash or slag is the most efficient way of using sustainable materials.

Exploration on the Recycling of Waste Building Materials in Comprehensive Land Consolidation from the Perspective of Ecological Civilization

The necessity and difficulties of waste building material utilization in comprehensive land consolidation are put forward by analyzing the source,quantity and harm of waste building materials.Combined with the practice of Shanghai,the mechanism and pattern of waste building materials recycling are explored,in order to provide the reference for recycling of waste building materials and efficient promotion of land consolidation.

Training Strategies of Practical Ability of Building Materials Professionals in Higher Vocational Colleges Under the Guidance of“Three Education Reform”Concept

The main purpose of the implementation of the three-education reform concept is to improve the teaching quality and talent training level of higher vocational colleges.Through the reform,one can promote the optimization of teaching methods,provide more space for student’s self-development,and improve the quality of talent training.Building materials in higher vocational colleges are a high requirement for practical ability,which emphasizes the cultivation of students’practical ability.Under the three-education reform concept,the traditional teaching mode should be replaced to provide more practical opportunities for students,in return give more attention to the development of students’practical ability.This paper mainly explores the current situation and training strategies in building material professionals in higher vocational colleges under the reform of the three education systems for a reference.

Preparation and Characterization of Sandwich Structured Materials with Interesting Insulation and Fire Resistance

A cellular material in the form of 3-layered sandwich structure material was prepared via sole use of mechanical stirring without any use of a foaming agent,while Tween-80 was employed as a foam stabilizer via a developed in-situ mold casting.The resulting structure displayed a good appearance with no visual defects.The 3-layered composition of the sandwish structure,“nonporous resin layer-porous foam layer-nonporous resin layer”,was examined in terms of the microstructure,density&density distribution,pulverization ratio,mechanical strength,insulation and flame retardant performance.It was indicated from the results that the bonding between the resin layer and foam layer was tight,while the tensile rupture always occurred in the porous layer.Also,the density of the sandwich structure material was symmetrical with“saddle”distribution,and a uniform density for any given layer.The increase in the density at the interface layer provided a good interpretation for the tensile rupture never occurred at the interface.The brittleness resistance of the developed material was significantly improved,and the pulverization ratio was sharply decreased from 9.93%to 0.31%.The material acquired a thermal conductivity and limiting oxygen index(LOI)of 0.0241 W/m⋅K and 29.92%,respectively,indicating potential use of such materials broadly in fields of insulation and flame retardancy.

Modeling Water Adsorption and Retention of Building Materials From Pore Size Distribution

Water adsorption and capillarity are key phenomena involved during heat and moisture transfer in porous building materials.They account for interaction between solid matrix,liquid water and moist air.They are considered through Water Vapor Adsorption Isotherm(WVAI)and Retention Curve(RC)functions which are constitutive laws characterizing water activity within a porous medium.The objective of this paper is to present a water vapor adsorption and retention models built from multimodal Pore Size Distribution Function(PSDF)and to see how its parameters modify moisture storage for hygroscopic and near saturation ranges.The microstructure of the porous medium is represented statistically by a bundle of tortuous parallel pores through its PSDF.Firstly,the influence of contact angle and temperature on storage properties were investigated.Secondly,a parametric study was performed to see the influence of the PSDF shape on storage properties.Three cases were studied considering the number of modalities,the weight of each modality and the dispersion around mean radius.Finally,as a validation,the proposed model for WVAI were compared to existing model from literature showing a good agreement.This study showed that the proposed models are capable to reproduce various shapes of storage functions.It also highlighted the link between microstructure and adsorption-retention phenomena.

A Brief Analysis of Energy Conservation Ways by Building Materials for Ecological Architecture

The development of society and economy in China is bringing growth to all industries. In particular, the development of China’s building industry has attracted much attention. Building materials are an important part of and widely used in the building industry. Energy conservation by building materials has become an inevitable way of sustainable development. Centering on the building industry, this paper mainly discusses in detail the energy conservation ways by ecological architecture and building materials.

Natural Radioactivity Measurements for Some Algerian Building Materials

The objective of this work is to assess the radiation hazards associated gamma rays from building materials. Natural gamma rays activities of natural radionuclide represented mainly by three natural radioactive series ^238U, ^235U and ^232Th, and the primordial ^40K in the samples of building materials which consist of bricks, ceramics, marble and gypsum from different areas of eastern Algeria are measured using gamma ray spectrometry. The values of the activities of these radionuclides do not clearly reflect the radiation hazard associated with these materials. Therefore, the radium equivalent （Raeq） concentration is defined taking into account the effectiveness of these isotopes in creating the radiation hazard. Radium equivalent activities, external and internal hazard indices （Hex and Hin） are calculated from the activities of ^226Ra, ^232Th and ^40K for suitability of the materials.

Running States of China's Iron & Steel,Nonferrous,and Building Materials Industries in 2012

Iron ＆ Steel Industry China＇s outputs of crude steel, steel products, coke and ferrous alloys in 2012 were 716.54 million tons （up 3.1% YOY）, 051.86 million tons （up 7.7% YOY）, 443.23 million tons （up 5.2% YOY） and 31.29 million tons （up 15% YOY）,