Energy-saving Building Materials Research Articles

Tri-phase flame retardant system towards advanced energy-saving building materials with highly efficient fire and smoke toxicity reductions

The extensive usage of rigid polyurethane foam (RPUF) as an energy-saving building materials in construction has raised concerns about fire risks and toxic hazards. To address these challenges, a melamine-derived polyol (MADP) was synthesized using the Mannich reaction, resulting in inherently flame-retardant RPUF materials with the introduction of flame-retardant functional groups. Furthermore, a novel MoS2-Cu2O nanohybrid was prepared and employed to enhance flame retardancy and suppress smoke toxicity in RPUF through a cooperative effect with expandable graphite (EG). The resulting M-RPUF/EG/MoS2-Cu2O nanocomposite exhibited remarkable fire safety, as evidenced by significant reductions in peak heat release rate (PHRR), total heat release (THR), total smoke production (TSP), and peak carbon monoxide (CO) release, amounting to 76.9 %, 64 %, 82 %, and 99 % respectively, compared to pristine RPUF. Furthermore, the nanocomposite effectively addressed interfacial defects and significantly enhanced the mechanical property and thermal stability. The significant improvement in fire safety is mainly ascribed to the catalytic charring effect of MADP and EG, as well as the catalytic oxidation of MoS2-Cu2O nanohybrids, resulting in the formation of a thermally stable protective layer in the condensed phase. Based on these results, the integration of the tri-phase flame retardant system holds great potential for advancing the development of fire-safe polyurethane materials.

Influence of Ca(OH)2 modification on the pore structure and properties of porous glass-ceramics stepwise sintered from granite sludge

The utilization of granite sludge offers significant economic and environmental advantages. This study focuses on preparing porous glass-ceramics from Ca(OH)2-modified granite sludge through a two-step sintering process comprising dense sintering and high-temperature foaming, with the addition of 1 % SiC powder as a foaming agent. The impact of foaming temperature and Ca(OH)2 addition on the structure, compressive strength, specific strength, and thermal conductivity of the porous glass-ceramics is examined. Incorporating the Ca(OH)2 modifier reduces the glass's viscosity and effectively eliminates micropores on the pore walls. The former promotes foaming and increases porosity, while the latter increases the specific strength of porous glass-ceramics. Increasing both the foaming temperature and the Ca(OH)2 concentration reduces glass viscosity and promotes mineral dissolution, facilitating the foaming process. However, the specific strength of the porous glass-ceramics initially increases before decreasing due to pore coalescence and excessive mineral dissolution. Theoretical evaluations of compressive strength and thermal conductivity indicate that porous glass-ceramics possess a closed-cell pore structure. Porous glass-ceramic made from granite powder containing 3.5 % Ca(OH)2 and foamed at 1240 °C exhibits an apparent density and porosity of 0.73 g/cm3 and 67.1 %, respectively. The compressive strength and thermal conductivity are 14.2 MPa and 0.422 W/(m·K) respectively, with a peak specific strength of 19.4 kN·m/kg. This innovative process enables the scalable recycling of granite sludge into energy-saving building materials.

Antileakage performance of Schiff base-reinforced thermal energy storage wood for indoor temperature control

Thermal energy storage wood has been rapidly developed as a green and renewable energy-saving building material. In this study, bio-based Schiff bases (VF) were prepared from vanillin and furfurylamine via aldehyde–amine condensation and used as a small molecule fixative. Subsequently, VF and dodecylamine were mixed uniformly and impregnated into rubberwood under pressure, affording thermal energy storage wood (TESW-x%VF). The results revealed that TESW-x%VF exhibited adjustable enthalpy (41.67–88.23 J g−1) and room-temperature phase transition (25°C–27°C). Moreover, the addition of VF improved the antileakage performance of TESW. According to density functional theory calculations, this is because the adsorption energy between VF and dodecylamine molecules has increased by 3–8 times compared to dodecylamine molecules. The above results provide a solution for the leakage issue associated with organic phase-change materials and aid in the future development of energy-saving wood building materials, which also improves the high-value utilization of chemical components in agricultural and forestry crops.

Preparation and Properties of Soft-/Hard-Switchable Transparent Wood with 0 °C as a Boundary

Transparent wood has excellent optical and thermal properties and has great potential utilization value in energy-saving building materials, optoelectronic devices, and decorative materials. In this work, transparent wood with soft-/hard-switchable and shape recovery capabilities was prepared by introducing an epoxy-based polymer with a glass transition temperature of about 0 °C into the delignified wood template. The epoxy resin was well filled in the pore structure of the delignified wood, and the as-prepared wood exhibited excellent transparency; the optical transmittance and haze of the transparent wood with a thickness of 2.0 mm were approximately 70% and 95%, respectively. Because the glass transition temperature of the epoxy-based polymer was about 0 °C, the prepared transparent wood was rigid below 0 °C and flexible above °C; meanwhile, the transparent wood exhibited shape change and shape recovery properties. Incorporating optical transparency and soft-/hard-switchable ability into the transparent wood opens a new avenue for developing advanced functional wood-based materials.

Preparation and mechanical characterization of multi-functional high-ductility engineered magnesium oxysulfate cement-based composites

Aiming at the integrated requirements of building energy saving and thermal insulation reinforcement in reinforcement engineering, the technology of preparing multi-functional high-ductility engineered magnesium oxysulfate cement-based composites (MOSC-ECC) by magnesium oxysulfate cement (MOSC) was proposed; the mechanism of industrial waste fly ash (FA) to improve the ductility of MOSC-ECC was explored; the effects of FA on the density, thermal conductivity and water resistance of MOSC-ECC were studied; the phase composition and microstructure of the hydration products of MOSC-ECC were analyzed. The results show that the incorporation of FA instead of light-burned magnesium oxide (LB-MgO) powder of equal mass can effectively reduce the cracking strength, fracture toughness, density and thermal conductivity of the matrix, and improve the ductility and multiple cracking ability of MOSC-ECC. The incorporation of hydrophobic agent made MOSC-ECC have excellent water resistance. The findings of this study provide useful knowledge for realizing the integrated design of thermal insulation and reinforcement of structures, which is of great significance for promoting the engineering application of ECC and the promotion of energy-saving green building materials.

Shape-Stabilized PEGylated Silica Aerogel-Composite as an Energy Saving Building Material.

Balancing thermal and visual comfort in buildings necessitates effective insulation to counteract heat loss and gain, especially with temperature variances. One promising approach is to combine phase change materials, such as poly(ethylene glycol) (PEG), with high-performance insulators like silica aerogel (Siag). To bolster opto-thermal performance in building envelopes, we introduce a smart insulation composite material through PEG integration, i.e., PEGalyation with Siag. Central to this thermal behavior is the PEG's phase change properties, which foster a shape-stabilized framework with Siag through their porous confinement. Preliminary observations indicate notable capabilities of obstructing near-infrared light while preserving satisfactory visible transparency. An optimized Siag@PEG composite with 5% loading of PEG has the visible range transmission of ∼92%, a decrease of ∼72% in thermal conductivity which is lower than pure glass and PEG, leading to a temperature dependent switchable hydrophobic to hydrophilic wettability characteristics. As a prototype window, the thermal performance evaluation of the synthesized composite, through experimental and computational studies, shows a decrease in indoor temperature of ∼20% with a higher temperature difference of ∼20 °C between outdoor and indoor weather conditions. This lightweight composite can act as sponge media to fill inside the double-paned window and for retrofitting existing glazing to boost the energy efficiency of buildings with facile manufacturing and scalability.

Enhanced thermal conductivity of a superhydrophobic thermal energy storage coating based on artificially cultured diatom frustules

Solid-liquid phase change materials (PCMs) provide an eco-friendly and cost-effective solution for waste heat recovery and thermal management. However, leakage and low thermal conductivity are two long-standing bottlenecks for their large-scale application. Applying a synthesized multi-level porous scaffold to prepare shape-stabilized PCMs (ss-PCMs) is an efficient, but high-cost strategy used to address the above problem. Herein, a strategy for fabricating enhanced thermally conductive ss-PCM coatings has been developed using artificially cultured, hierarchically porous Ag nanoparticle decorated diatom frustules (Ag-DFs) utilizing a facile spray-coating method. The delicate pores and high specific surface area (101.78 m2/g) endow the Ag-DFs to adsorb 55 wt% of paraffin wax (PW) without leakage, thereby exhibiting a melting enthalpy of 114.27 J/g. The corresponding ss-PCM coatings demonstrate a thermal conductivity of 0.87 W/m·K, which is ∼ 2.95-fold higher than pure PW. In addition, the abundant micro/nanoscale texture in the Ag-DFs along with the low-surface-energy of PW synergistically produce superhydrophobicity in the coating, thereby improving its ability to resist external environmental impacts, extending the service life. With high energy storage density, enhanced thermal conductivity, and good scalability, our superhydrophobic ss-PCM coating should find potential use in energy-saving building materials and thermal management of electrical devices, as well as self-cleaning surfaces.

A Simpler Fabrication for Thermal Energy Storage Wood

Using thermal energy storage wood with phase change materials (PCM) as a building material can save thermal energy during heat-induced phase transition, and can reduce the energy consumption of indoor heating. In our work, three thermal energy storage poplars (TESPs: TESP-1, TESP-2 and TESP-3) were prepared by directly infiltrating three PCMs (fatty alcohol/acid materials: lauryl alcohol, decanoic acid and myristic acid myristyl ester), respectively, into the longitudinal-cutting plantation poplar woods and by directly encapsulating the PCMs in the poplar-based materials with SiO2 films. The phase-changing temperature ranges of TESP-1, TESP-2 and TESP-3 were at 19–30 °C, 26–39 °C and 33–54 °C, respectively. The phase-changing temperature peaks were at ~24 °C, ~31 °C and ~42 °C, respectively. After the same heat treatment on TESPs and original poplar (OP), the average temperature of TESPs was higher than that of OP after 35 min, thus proving that TESPs can save more thermal energy than OP. The radial bending strengths of TESP-1, TESP-2 and TESP-3 had increased by 50.85%, 70.16% and 70.31%, respectively, as compared to with that of OP. Additionally, the radial bending elastic modules of TESP-1, TESP-2 and TESP-3 had increased by 47.14%, 67.38% and 74.57%, respectively, as compared to OP. The tangential section hardness of the TESPs also had also increased by 67.09%, 71.80% and 80.77%, respectively. These improved mechanical properties of TESPs are almost close to that of ash wood (ash wood is a common building material), therefore, this proves that our TESPs can be used as thermal energy-saving building materials.

Facile fabrication of multifunctional energy-saving building materials with excellent thermal insulation, robust mechanical property and ultrahigh flame retardancy

Rigid polyurethane foam (RPUF) has received extensive attention as an energy-saving building material. However, it is still a great challenge to easily fabricate multifunctional RPUFs that combine excellent mechanical properties, flame retardancy, and thermal insulation. Herein, ammonium polyphosphate was chemically modified with 2-aminobenzimidazole (APP@Abz) through an ion exchange reaction. It has been found that APP@Abz is well-dispersed in RPUF matrix. FR-RPUF3 containing 10.0 wt% of APP@Abz shows excellent thermal insulation performance with a 5% increase in thermal conductivity compared to virgin RPUF. In addition, FR-RPUF3 exhibits ultrahigh flame retardancy and smoke suppression (total heat release, total smoke production, and smoke factor decreased by 50.61%, 61.90%, and 64.70%, respectively) in comparison to virgin RPUF. More importantly, FR-RPUF3 exhibits improved mechanical properties and hydrophobicity compared to virgin RPUF. This study is of great importance for the development and application of building insulation materials.

Application of energy-saving building’s designing methods in marine cities

From the perspective of the relevant concept of green development, the use of energy-saving building materials in marine cities can not only effectively meet the requirements of green and healthy buildings, as well as environmental protection and low energy that urban people are concerned about, so how to fully use energy-saving building materials in the design of marine city’s buildings has become the focus of research. In view of this, this paper first explains the importance of the application of energy-saving building materials in architectural design, and introducing the significance of using energy-saving architectural design in marine cities, and then uses a swot analysis to examine the benefits and drawbacks of developing energy-saving building materials. Finally, concrete methods for incorporating energy-saving materials and technologies into marine city architecture design are summarized, and deeply analyzes how to apply energy-saving building materials well in marine city architectural design, aiming to better realize the concept of healthy development of building ecology in marine cities, which will help to promote the use of renewable energy in marine city architecture.

Sustainable Thermal Energy Batteries from Fully Bio-Based Transparent Wood.

The sustainable development of functional energy-saving building materials is important for reducing thermal energy consumption and promoting natural indoor lighting. Phase-change materials embedded in wood-based materials are candidates for thermal energy storage. However, the renewable resource content is usually insufficient, the energy storage and mechanical properties are poor, and the sustainability aspect is unexplored. Here a novel fully bio-based transparent wood (TW) biocomposite for thermal energy storage, combining excellent heat storage properties, tunable optical transmittance, and mechanical performance is introduced. A bio-based matrix based on a synthesized limonene acrylate monomer and renewable 1-dodecanol is impregnated and in situ polymerized within mesoporous wood substrates. The TW demonstrates high latent heat (89Jg-1 ) exceeding commercial gypsum panels, combined with thermo-responsive optical transmittance (up to 86%) and mechanical strength up to 86MPa. The life cycle assessment shows that the bio-based TW has a 39% lower environmental impact than transparent polycarbonate panels. The bio-based TW holds great potential as scalable and sustainable transparent heat storage solution.

Phase-Change-Material-Impregnated Wood for Potential Energy-Saving Building Materials

PCMs (phase change materials) are ideal for thermal management solutions in buildings. This is because they release and store thermal energy during melting and freezing. When this material freezes, it releases a lot of energy in the form of latent heat of fusion or crystallization energy. Conversely, when the material melts, it absorbs the same amount of energy from its surroundings as it changes from a solid to a liquid state. In this study, Oriental spruce (Picea orientalis L.) sapwood was impregnated with three different commercial PCMs. The biological properties and the hygroscopic and thermal performance of the PCM-impregnated wood were studied. The morphology of PCM-impregnated wood was characterized through the use of scanning electron microscopy (SEM), Fourier-transform infrared spectroscopy (FT-IR), thermogravimetric analysis (TGA), and differential scanning calorimetry (DSC). PCM-impregnated wood demonstrated low performance in terms of storing and releasing heat during phase change processes, as confirmed by DSC. The results show that PCMs possess excellent thermal stability at working temperatures, and the most satisfying sample is PCM1W, with a phase change enthalpy of 40.34 J/g and a phase change temperature of 21.49 °C. This study revealed that PCMs are resistant to wood-destroying fungi. After the 96 h water absorption test, the water absorption of the wood samples decreased by 28%, and the tangential swelling decreased by 75%. In addition, it has been proven on a laboratory scale that the PCM material used is highly resistant to biological attacks. However, large-scale pilot studies are still needed.

Моделирование физических характеристик теплоаккумулирующих строительных материалов

The article discusses the results of studies of the physical characteristics of heataccumulating building materials. Modern trends in the production and use of materials determine the need to develop new scientific and methodological devices for assessing the physical characteristics of energy-saving building materials, which will significantly improve the properties of materials, reduce their cost and improve the quality and reliability of structures and products. As such a device, the authors propose the use of a mathematical model, the statistical description of experimental data of which is linear regression. The initial substances for the formation of a microcapsulated heat-accumulating material are selected as input parameters of the system, and the output characteristics are dependent variables (specific heat of the phase transition, compressive strength). Based on the results of experimental studies and using the DataFit program.

Preparation and Pore Structure of Energy-Storage Phosphorus Building Gypsum.

In this study, the pore structure of a hardened phosphorous building gypsum body was optimised by blending an air-entraining agent with the appropriate water–paste ratio. The response surface test was designed according to the test results of the hardened phosphorous building gypsum body treated with an air-entraining agent and an appropriate water–paste ratio. Moreover, the optimal process parameters were selected to prepare a porous phosphorous building gypsum skeleton, which was used as a paraffin carrier to prepare energy-storage phosphorous building gypsum. The results indicate that if the ratio of the air-entraining agent to the water–paste ratio is reasonable, the hardened body of phosphorous building gypsum can form a better pore structure. With the influx of paraffin, its accumulated pore volume and specific surface area decrease, and the pore size distribution is uniform. The paraffin completely occupies the pores, causing the compressive strength of energy-storage phosphorous building gypsum to be better than that of similar gypsum energy-storing materials. The heat energy further captured by energy-storage phosphorous building gypsum in the endothermic and exothermic stages is 28.19 J/g and 28.64 J/g, respectively, which can be used to prepare energy-saving building materials.

Mechanical and light transmittance properties of high-performance translucent concrete

High-Performance Translucent Concrete (HPTC) is an innovative energy-saving building material, as it is a high-quality translucent concrete with high workability, superior mechanical properties, and good light transmittance. This paper investigates the performance of HPTC incorporated with plastic optical fibers (POF), its fresh properties, mechanical properties, and light transmittance performance. The data presented here refer to specimens of 21 mixtures divided into six main groups, the latter group upgraded to be ultra-high performance translucent concrete (UHPTC). Besides fresh concrete tests, bulk density, all-ages compressive strength, splitting tensile strength, flexural strength, bond strength, modulus of elasticity strength, and light transmittance as well as relations between light transmittance and mechanical properties were investigated in the HPTC hardened phase. Although the HPTC mechanical properties increase with increasing POF volume ratios and diameters, the light transmittance significantly increases with increasing POF volume ratios. In this paper, HPTC performs up to 21.35% light transmittance for specimens with a volume ratio of 4% POF and 2 mm POF diameter as well as good mechanical properties such as compressive strength of 54.30 MPa at 91 days. In addition, UHPTC performs up to 154.2 MPa compressive strength, 13.8 MPa tensile strength, 23 MPa flexural strength, 25.7 MPa bond strength, and 49.71 GPa modulus of elasticity, as well as 10.31 % light transmittance.

Properties of Scots pine wood impregnated with capric acid for potential energy saving building material

Abstract Scots pine sapwood (Pinus sylvestris L.) was impregnated with different concentrations of capric acid (CA) (20, 40, 60 and 80%) as phase change material (PCM). The hygroscopic, mechanical properties and thermal energy storage (TES) characteristics of the CA-impregnated wood were studied. The morphology, crystalline properties, phase change properties and thermo-regulative performance of CA-impregnated wood were characterized by scanning electron microscope (SEM), X-ray diffraction (XRD), Fourier transform infrared (FT-IR), thermogravimetry (TGA), differential scanning calorimetry (DSC) and thermal performance analysis. CA-impregnated wood demonstrated an excellent performance of storing and releasing heat during phase change process, confirmed by DSC and FTIR analysis after an accelerated thermal cycling test. In addition, the accelerated thermal cycling test results indicated that CA-impregnated wood showed good thermal reliability and CA did not leach from the wood after the thermal cycling. Wood impregnated with CA solution of 80% concentration reduced the maximum temperature by 4.04 °C at the end of the heating period while it increased the minimum temperature by 2.83 °C at the end of the cooling period. The performance of storing and releasing heat during phase change process of CA impregnated Scots pine proves that it can be used as a thermal regulating building material to reduce energy consumption and cost caused by day and night temperature fluctuations.

Large size translucent wood fiber reinforced PMMA porous composites with excellent thermal, acoustic and energy absorption properties

From the perspective of the comprehensive requirements of building materials, this study introduces a foaming process into wood fiber transparent wood to prepare wood fiber reinforced Polymethyl methacrylate (PMMA) porous composites. The material not only further optimizes the mechanical and thermal properties of transparent fiber wood, but also improves the acoustic properties. It also has a characteristic of translucency. At the same time, the preparation process is simple, which has many advantages to be used as potential energy-saving building materials. According to the experimental results, the thermal conductivity is only about 40% of that of the common transparent wood. The sound absorption coefficient can reach 0.6, which is equivalent to that of polyimide foam. The mechanical compressive strength can reach 9 MPa, and the energy absorption performance is excellent. The yield stress platform is long, and the energy absorption efficiency can reach higher than 90%, which is better than currently available metal foams.

Indoor thermal environment of kindergarten building: A case study in China

Based on the building of a kindergarten in Weinan, Shaanxi Province, this paper explores the influence of different envelope structures and heating modes on the indoor thermal environment for the energy saving and thermal comfort of the existing buildings. Using operating temperature as the evaluation index of thermal comfort, the 15 designed schemes were simulated through Energyplus software and actual measurement to obtain the operating temperature change law and annual heating energy consumption value. The envelope structure optimized by choosing energy-saving building materials such as expansion perlite and foam cement is obviously conducive to the improvement of indoor thermal comfort, and the thickness of the insulation layer increases, and the operating temperature increases accordingly; Although the standard effective temperature in intermittent heating mode is slightly lower than that in continuous heating mode, the standard effective temperature rises significantly with the extension of preheating time, which can meet the requirements of thermal comfort.After energy saving transformation, the total heating energy consumption of the kindergarten building is reduced by up to 3644 GJ, and the energy-saving rate reaches 67%.

FRESH STATE AND MECHANICAL PROPERTIES OF ULTRA-LIGHTWEIGHT FOAMED CONCRETE INCORPORATING ALKALI TREATED BANANA FIBRE

For a Lightweight Foamed Concrete (LFC) to efficiently function as an energy-saving building material, its self-weight (density) should be reduced. However, the problem associated with a reduced density is a decline in strength. To improve the mechanical properties of LFC, this research attempts to integrate banana fibre into LFC composite with a focus on fresh and harden state properties. An Ultra-Lightweight Foamed Concrete (ULFC) with a density of 600 kg/m3 was produced with the inclusion of treated and untreated banana fibres. The volume fractions of banana fibre added into LFC were 0.00% (control specimen), 0.25%, 0.35%, 0.45% and 0.55%. In addition, an optimised batch mix of ULFC reinforced with 0.35% untreated banana fibre was produced. The batches were tested for rheological, physical, and mechanical properties. Findings reveal that the workability of ULFC composites decrease with increase in fibre addition. The compressive, flexural, and tensile strengths of the alkali-treated composites were higher than the untreated banana fibre composite. SEM micrograph reveals that defibrillation of bundle fibrils due to cleaning the surface amorphous hemicellulose, lignin and pectin of the alkali-treated fibre, leads to rough surfaces and increase surface area resulting in better interfacial adhesion of the fibre with cement matrix.

Design and synthesis of microcapsules with cross-linking network supporting core for supercooling degree regulation

A novel microencapsulated composite phase change materials (MCPCMs) with low-supercooling was designed using melamine formaldehyde resin (MF) as the shell via in-situ polymerization. The composite phase change materials (CPCMs) were composed of low cross-linked polyoctadecyl methacrylate (C-PODMA) as solid–solid PCM and n-octadecane (C18) as solid–liquid PCM, respectively. The C-PODMA can be used not only as a support material, but also as an energy storage material. In this work, the effects of C-PODMA with different cross-linking degree, C18/C-PODMA mass ratios and particle size on the performance of cross-linking network supported microcapsules (CS-MCPCMs) were investigated in detail. The results showed that the spherical CS-MCPCMs had been successfully prepared. During the synthesis process, the crystal transformation and heterogeneous nucleation caused by C-PODMA can inhibit the supercooling degree of CS-MCPCMs to some extent, which can decrease by 3.7℃ ∼ 8.3℃ and increase the crystallization temperature by 1.0℃ ∼ 2.6℃. At the same time, the thermal decomposition temperature of CPCMs increased by 11.6℃ ∼ 34.6℃ and the energy storage efficiency of CS-MCPCMs was enhanced to 84.2%. It also has relatively high latent heat and satisfactory 150 thermal cycle stability. CS-MCPCMs has broad application prospects in heat storage textiles, forming processing and energy saving building materials.