Smart Building Materials Research Articles

Trap-induced self-recoverable photochromism of rare-earth doped sodium niobate translucent ceramics

Most photochromic ceramics can back up post-irradiation to achieve color state transition. Unfortunately, color recovery usually requires exposure of material to external physical fields (such as light and heat), which severely limits the application as a convenient energy building material such as smart windows. Here, we report a kind of sodium niobate translucent ceramics whose photochromic effect can be completely self-recoverable without any external physical field stimulation. Based on the analysis of time-response transmittance, up-conversion emission spectra and thermoluminescence spectra, the behavior of carrier migration and trap capture/release in the process of self-recovery photochromic reaction has been proposed. It is believed that the emergence of intermediate trap level is an important factor to produce this spontaneous behavior. Moreover, by controlling the amount of rare earth doping and designing two types of materials with different carrier behaviors, Sm/Er-codoped NaNbO3 ceramics are regarded as an appropriate candidate for tracing the time of light irradiation and intelligent regulation of smart building materials. This work can promote the fundamental understanding and practical applications of self-recoverable photochromic bulk materials.

Quasi-monodispersed nanocapsules with form stability at high temperature and under shear force for thermal energy storage

Nanoencapsulated phase change materials (NPCMs) have attracted much attentions during the past decades due to their large potential application in the sectors of solar energy harvesting, waste heat recovery, and smart buildings and fibers. However, it is still a big challenge to obtain form-stable NPCMs without leakage at high temperature (e.g. 180 ℃) and under external shear force. Form-stability investigations of almost of the reported NPCMs focus on the temperature range up to 100 ℃, which cannot satisfy the thermal processing requirements (140–200 ℃ under shear force) of commonly available thermoplastics like poly(vinyl chloride) and poly(lactic acid). We herein for the first time demonstrate a facile method to prepare a series of novel room temperature NPCMs with the latent heat up to 116.1 J g−1 and fabulous form-stability even if the surrounding temperature approximates 180 ℃ under an external shear force of 101.9 kN m−2. To this aim, quasi-monodispersed NPCMs with the average size less than 120 nm were prepared, wherein dodecanol and in-situ cross-linked acrylate copolymers were used as the heat storage core and the supramolecular lock shell layer of the NPCMs, respectively. Storage reliability, morphology, phase change behaviors, and form-stability at different conditions of the resulting NPCMs were extensively evaluated. The fabricated NPCMs exhibit outstanding monodispersity and form-stability at high temperature and under shear force, and probably opens a new avenue to develop functional thermoplastic and/or thermosetting composites for the next generation of smart building, furniture, and decoration materials with a promising heat energy storage and release ability.

Remediation of noxious pollutants using nano-titania-based photocatalytic construction materials: a review.

Nano-titania (n-TiO2), due to its unique photocatalytic and hydrophobic properties, can be used to prepare self-cleaning cement-based smart building materials. The n-TiO2 degrades organic and inorganic pollutants through its photocatalytic action and convert them into non-toxic byproducts, i.e., improves the air quality. In this review, aspects such as methodologies of n-TiO2 synthesis, approaches for n-TiO2 loading on cementitious materials, photocatalytic properties, self-cleaning mechanism, and application of n-TiO2 in cement-based materials have been overviewed. Further, the n-TiO2 can be used either as coatings or admixtures in pavement blocks, mortars/concrete at zebra crossings, road dividers and linings, and high rise buildings. Moreover, the implications and economic aspects of n-TiO2 usage in cement-based materials revealed that n-TiO2 increases the material cost by ~ 27%, (101 to 128.1$) in comparison to conventional building materials. Furthermore, the low-cost carbonized materials such as biochars have been suggested to be used as support of n-TiO2 to lower the cost and improve the remediation efficiency of photocatalytic concrete.

Recent Developments in Nanocellulose-Based Aerogels in Thermal Applications: A Review.

Naturally derived nanocellulose (NC) is a renewable, biodegradable nanomaterial with high strength, low density, high surface area, and tunable surface chemistry, which allows its interaction with other polymers and nanomaterials in a controlled manner. In recent years, NC aerogel has gathered a lot of attention due to environmental concerns. This review presents recent developments of NC-based aerogels and their controlled interactions with other polymers and nanomaterials for thermal applications that include electronic devices, the apparel industry, superinsulating materials, and flame-retardant smart building materials. After going through the distinctive properties of NC aerogels, they are orderly categorized and discussed as thermally insulated, thermally conductive, and flame-retardant materials.

Multifunctional Lightweight Mortars for Indoor Applications to Improve Comfort and Health of Occupants: Thermal Properties and Photocatalytic Efficiency

A new generation of smart building materials, able to passively improve the indoor environment and the comfort of occupants owing to their interaction with the surrounding environment, can be addressed. This paper investigates the use of three highly porous aggregates to manufacture hydraulic lime-based multifunctional mortars to be used as indoor finishes. The same water/binder ratio was used for each mortar mix, and conventional calcareous sand was totally replaced by volume with zeolite, silica gel and activated carbon. Nanosized titanium dioxide was added to award a photocatalytic behaviour under UV-radiation to the mortars. Results show that, as expected, when highly porous aggregates are used, mortars absorb more water by capillary suction. However, even though the mortars manufactured with lightweight aggregates have a lower density, the mechanical behaviour of zeolite and activated carbon mortars are comparable or even higher than those of sand mortars thanks to an optimum ITZ between the binder paste and the aggregate. The photocatalytic activity, in terms of photocatalytic NOx degradation efficiency and selectivity of unwanted produced NO2, results to be optimal when silica gel-based mortar is tested. Additionally, the thermal insulation properties are enhanced up to 40% by using all the unconventional aggregates.

Using Intelligence Green Building Materials to Evaluate Color Change Performance

Environmental protection is an important issue in modern society. Most construction demolition wastes cannot be easily decomposed, thus occupying a lot of space in landfill. Reducing the demand for new resources is an efficient approach to decrease the environmental burden. Most green buildings are made from reused and recycled materials. Although there are a variety of green building materials available on the market, there is no material, as yet, with thermochromic functionality. This study used a form of face bricks, and six recovered materials, including wood chips, iron powder, fallen leaves, concrete, newspaper, and silt, to make smart green building materials. The modules were made in accordance with Taiwan’s green building material regulations. The discoloration efficiency of indoor and outdoor green building materials was tested, and the RGB (red, green, blue) values of the face bricks were measured by a color analyzer to observe the discoloration effect. The findings show that among the A, B, C, and D groups, Group D exhibited the optimal rate of change in color, and the rates of change in the six recycled waste materials of indoor Group D were wood chips > newspaper > fallen leaves > concrete > iron powder > silt, while the rates of change in the outdoor group were newspaper > wood chips > fallen leaves. This study successfully reused waste materials to reduce the environmental burden, achieve sustainable environmental protection, and ensure both the aesthetics and quality of the building materials. The results of this study can offer an alternative choice to architects or space designers when selecting green building materials.

Biocompatible and Smart Composites from Cellulose, Wool, and Phase-Change Materials Encapsulated in Natural Sporopollenin Microcapsules

Natural pollen grains were cleaned to remove all external and internal cytoplastic materials to produce sporopollenin exine capsules (SECs). SECs are empty microcapsules with extensive networks of holes that are ∼200 nm in diameter, which remain intact. Various substances including phase-change materials (PCMs) such as n-octadecane (C18), n-eicosane (C20, EIS), n-docosane (C22), or a mixture of them (C18 + C22) can be encapsulated into the cavity of SECs. [EIS (or PCMs)@SEC] was obtained with an encapsulation efficiency of at least 76 wt %. SECs are robust and very stable. They protect encapsulated EIS during phase transitions, so they retain their phase change property and guard them against corrosive environments and elevated temperatures. [EIS@SEC] can therefore be incorporated into cellulose (CEL) and keratin (KER, from wool) composites using butylmethylimmidazolium chloride [BMIM+Cl–], a simple ionic liquid, as a sole solvent to synthesize [CEL + KER + EIS@SEC] composites. EIS in the [CEL + KER + EIS@SEC] composites behaves similarly to EIS alone. It will melt when heated and crystallize when cooled. Energy resulting from these phase transitions allows [CEL + KER + EIS@SEC] composites, like other PCMs, to warm their surroundings by releasing energy and, conversely, to cool their surroundings as they heat up by absorbing energy. The latent heat storage and release efficiency of the [CEL + KER + EIS@SEC] composites is estimated to be about 80%. After going through the heating–melting cycle 200 times, the DSC curves of the [CEL + KER + EIS@SEC] composites remained the same. This indicates that SECs are in fact fully and effectively retaining the encapsulated EIS and protecting it from leaking out. The [CEL + KER + EIS@SEC] composites are robust, have strong mechanical properties, and possess antibacterial activity. This makes them superior to other microencapsulated PCMs that are currently available. Furthermore, the composites are sustainable and biocompatible as they are synthesized from naturally abundant materials (cellulose, wool, natural pollen grains, and wax) using a green and recyclable synthesis. More importantly, the fact is that not only individual PCM such as EIS but also a mixture of two different PCMs such as a mixture of (C22 + C18) can be simultaneously encapsulated into the SEC. These features enable the [CEL + KER + EIS@SEC] composites to be uniquely suited as high-performance materials for such uses as dressings to treat infected burn wounds, smart textiles for clothing, smart building materials, and energy storage at any given temperature.

Fracture Toughness Analysis of Epoxy-Recycled Rubber-Based Composite Reinforced with Graphene Nanoplatelets for Structural Applications in Automotive and Aeronautics.

This study proposes a new design of lightweight and cost-efficient composite materials for the aeronautic industry utilizing recycled fresh scrap rubber, epoxy resin, and graphene nanoplatelets (GnPs). After manufacturing the composites, their bending strength and fracture characteristics were investigated by three-point bending (3PB) tests. Halpin–Tsai homogenization adapted to composites containing GnPs was used to estimate the moduli of the composites, and satisfactory agreement with the 3PB test results was observed. In addition, 3PB tests were simulated by finite element method incorporating the Halpin–Tsai homogenization, and the resulting stress–strain curves were compared with the experimental results. Mechanical test results showed that the reinforcement with GnPs generally increased the modulus of elasticity as well as the fracture toughness of these novel composites. Toughening mechanisms were evaluated by SEM fractography. The typical toughening mechanisms observed were crack deflection and cavity formation. Considering the advantageous effects of GnPs on these novel composites and cost efficiency gained by the use of recycled rubber, these composites have the potential to be used to manufacture various components in the automotive and aeronautic industries as well as smart building materials in civil engineering applications.

Natural Sporopollenin Microcapsules Facilitated Encapsulation of Phase Change Material into Cellulose Composites for Smart and Biocompatible Materials.

Sporopollenin exine capsules (SECs) are empty microcapsules that are 25 μm in diameter and have extensive networks of ∼200 nm diameter holes obtained by chemically removing all external and internal cytoplastic materials from the natural pollen grains. We have demonstrated that a phase change material (PCM) such as n-eicosane (EIS), a natural paraffin wax, can be successfully encapsulated in the SECs to produce [EIS@SEC]. The high stability and robust nature of SECs retain EIS in the microcavity even during phase transitions, enabling EIS to fully maintain its phase change property while also protecting the EIS from elevated temperatures and corrosive environments. [EIS@SEC] can, therefore, be incorporated into cellulose (CEL) composites with a synthetic process that uses the simple ionic liquid butylmethylimmidazolium chloride to produce [CEL+EIS@SEC] composites. Similar to EIS alone, EIS in the [CEL+EIS@SEC] composites melts when heated and crystallizes when cooled. The energies associated with the crystallization and melting processes enable the [CEL+EIS@SEC] composites to fully exhibit the properties expected of PCMs, i.e., heating the surroundings when they cool and absorbing energy from the surroundings when they warm. The efficiency of latent heat storage and release of [CEL+EIS@SEC] composites was estimated to be around 57% relative to pure EIS. The fact that the DSC curves of the [CEL+EIS@SEC] composites remain the same after going through the heating-melting cycle 220 times clearly indicates that SEC effectively retains EIS in its cavity and protects it from leaking and that the [CEL+EIS@SEC] composites are highly stable and reliable as a phase change material. The [CEL+EIS@SEC] composites are superior to any other available materials based on encapsulated PCM because they are not only robust, reliable, and stable and have strong mechanical properties. They are also are sustainable and biocompatible because as they are synthesized from all naturally abundant materials using a green and recyclable synthesis. These features enable the [CEL+EIS@SEC] composites to be uniquely suited as high performance materials for such uses as dressings to treat burnt wounds, smart textiles for clothing, smart building materials, and energy storage.

Bioinspired fabrication of asymmetric wood materials for directional liquid manipulation and transport

Directional liquid transport, an essential process found in many natural creatures, is of great importance to environment, energy, and even life. Wood plants possess directional water transportation from soil to air, however, wood-based materials have no longer such performance because the pressure difference induced by transpiration is lost. Inspired by the controlled transport of water droplets on cactus pine, here, wettability gradient is constructed along wood channels, fabricating novel asymmetric wood slices. The hierarchically micro-/nano-structures and wettability gradients of the slices guarantee the tunable surface wettability and directional liquid transport property. Besides water, the resultant asymmetric wood can directionally deliver oils and moisture. Moreover, the functional wood displays high resistance against harsh corrosions without changing micro-structures or losing directional liquid transport property. The results demonstrate the asymmetric wood material will be useful in liquid manipulation, water harvest and treatment, self-cleaning, anti-fouling, and smart building materials.

Application of Multipoint Impedence Spectroscopy to Corrosion Monitoring on Shape Memory Alloys in Smart Building Materials.

Impedance spectroscopy has been widely employed in order to monitor the hydration phenomena which reflect the electrical conduction along the porous paths whose ionic features are easily discerned from the electrode polarization. The microstructural changes influence the impedance features composed of resistors, capacitors, and inductors, through their intermixed connections involving series, parallel or, both. Unlike the application of impedance spectroscopy to the bulk phenomena, the three-point impedance spectroscopy can be exploited towards the rational separation of a specific electrode from the remaining system through the multipoint electrode configuration in order to localize the corrosion responses of the electrode under interest. The effects of the electrode configuration are investigated in order to establish the methodology on the corrosion monitoring in reinforcement materials in building materials. The current work chooses Ni/Ti-Based and Fe-Based shape memory alloys as model systems in monitoring the corrosion phenomena encountered in construction applications. The shape memory alloys are mixed with the cement-based materials with the aim to providing self-healing functions in association with the detrimental cracks in smart composite materials. In particular, the Ni-Ti and Fe-Si shape memory alloys are subjected to corrosion environments in everyday and hostile conditions. The conventional potentiostat approaches are performed in parallel, in order to prove the applicability of the multipoint impedance spectroscopy in the electrochemical applications involving nano-materials. The ramifications of multi-point impedance spectroscopy are discussed towards corrosion-specific monitoring in functional shape memory alloys which is recommended as one of powerful next-generation building materials.

Smart Building and Construction Materials

Smart Building and Construction Materials

Optical and dielectric properties of nano-sized tricalcium aluminate hexahydrate (C3AH6) cement

The present study investigates the optical and dielectric properties of nano-sized C3AH6 cement hydrates. A cement product was fabricated via a simple hydration process using a derivative of a C12A7 cement precursor reacting with de-ionized water while raising the reaction temperature to 100 °C. A crystalline phase of the C3AH6 cement product was characterized and confirmed using an XRD technique. Its morphology was also evaluated using TEM and SEM techniques. It was found that nano-sized C3AH6 (in size 10–50 nm) was successfully derived via this process. This cement product was thermodynamically stable over the range of room temperature to 300 °C. The optical direct gap was 4.1 eV and the indirect energy gap was 2.45 eV. Over the range of 20 Hz to 2 MHz, the observed capacitance was 10−10 F–10−11 F and the dielectric constant varied from 20 to 150. The dielectric properties were enhanced over those of general cement compounds. This effect was due to its complex structure in which –O–H bonding appeared in the structure and the formation of nano-sized structures from this process. These results suggested that the nano-C3AH6 hydrated particles were transparent to visible light and exhibited a high frequency electrical response. This implies an important role for these cement-based materials as potential candidates having optical and dielectric properties appropriate for applications such as smart building materials in the form of transparent electrode windows, smart wall capacitors, triboelectric devices and supercapacitors.

Smart Building Materials of BIM and RFID in LifeCycle Management of Steel Structure

With the development of economy, steel structure is more and more widely applied in China. With the deepening of sustainable development, the industrialization of construction become more and more hot in construction industry. Steel Structure is expected to be an important building material of industrialization. Obviously steel structure has been a main forms using in China. According to the characteristics of steel structure, smart material of BIM and RFID can be chosen as a new integration. This smart material can be used to solve the key technology of lifecycle management and information is shared, exchange with each other between participants during each stage.

A smart building material for low/zero carbon applications: heat insulation solar glass—characteristic results from laboratory andin situtests

Heat insulation solar glass (HISG) is a recently developed smart building material to minimize energy consumption of building sector. HISG might be presumed to be a conventional photovoltaic glazing product; however, it is completely unique by having some characteristic features such as superior thermal insulation, which is competitive with triple-glazed windows using argon as inert gas, acoustic and thermal comfort, self-cleaning ability owing to TiO2 nano-coating on module surface and extraordinary energy saving potential in both summer and winter. In our previous works, comprehensive experimental and numerical works have been carried out for power generation and thermal insulation performance of HISG under various climatic conditions. Within the scope of this research, optical- and lighting-related performance parameters of this smart building material are evaluated through extensive laboratory and in situ tests. Shading coefficient, visible light intensity, and UV and IR penetration are investigated via the tests conducted in real operating conditions. It is achieved from the results that the shading coefficient of HISG is only 0.136, which yields almost 80% reduction in solar heat gain compared with ordinary glazing. It is also observed from the in situ tests that HISG has a %100 UV and 99% IR blocking rate, which is of vital importance in terms of human health and thermal comfort conditions. Glaring effects are totally resolved via HISG, which is still a challenge for the buildings with conventional glazing products, especially in summer.

BIOMIMETIC ARCHITECTURE AS A NEW APROACH FOR ENERGY EFFICIENT BUILDINGS THROUGH SMART BUILDING MATERIALS

INTRODUCTION As skin wraps our body, building envelopes wraps buildings and therefore acts and performs the functions that the skin performs, especially in thermoregulating the building which results in decreasing the energy consumed. The objective of this paper is to establish a building envelope as a living envelope able to control the heat in buildings the same way that nature does with our skin, without the use of electricity or mechanical elements, and hence decrease energy consumption and its devastating effect on the environment. This objective can be reached by using suitable smart building material and integrating it into the architectural design of the building. The methodology and objectives of this paper are as follows: Review the global warming problem, its consequences, and the role of the building sector in this problem. Study Biomimicry in architecture and its potential to decrease the share of the building sector's role in global warming. Select a smart building material that would allow ...

WO3/TiO2 core–shell nanostructure for high performance energy-saving smart windows

The electrochromic, photodegradation, and photoinduced hydrophilicity properties of the WO3/TiO2 core–shell nanostructure as a smart building material for energy-saving are investigated. The core–shell nanostructure exhibits a highly reduced ion intercalation capacity with good reversible electrochemical cycling of intercalation–deintercalation, and shows a higher coloration efficiency (110.8cm2C−1), faster switching speed (0.7s and 2.9s) and better cycling performance than as-deposited WO3 nanowires (NWs). The TiO2 shell layer greatly enhanced the photocatalytic oxidation activity of WO3 NWs, increasing the photoinduced hydrophilic conversion. The enhanced photocatalytic reaction by the core–shell structure was attributed to the multi-electron reduction in the interlayer, caused by the electrons injected from the conduction band of the WO3 NWs. These results suggest that the WO3/TiO2 core–shell nanostructure enhances the electrochromic, photodegradation, and photoinduced hydrophilicity properties due to the increased density of charge separated electron–hole pairs aided by the TiO2 and WO3 interlayer. The WO3/TiO2 core–shell structure was found to possess superior properties giving it good potential for use in energy-saving smart windows.

Use of Flexible Engineered Cementitious Composite in Buildings

This article describes the applications and benefits of a recently developed smart building material namely Engineered cementitious composite (ECC), also known as flexible or bendable concrete. Conventional concretes have a strain capacity of only 0.1 percent and are highly brittle and rigid. This lack of bendability is a major cause of failure under strain and has been a pushing factor in the development of an elegant material which is capable to exhibit an enhanced flexibility. An ECC has a strain capacity of more than 3 percent and thus acts more like a ductile metal rather than like a brittle glass. The aim of this paper is to highlight a probable success of ECC in terms of industrial and commercial use in Pakistan. With the introduction of flexible concrete in building technology, it is likely to have safer and more durable construction. The material is expected to display reduced detrimental impacts on the natural environment. A bendable concrete is composed of all the ingredients of a traditional concrete minus coarse aggregates or crushed stones and is reinforced with micromechanically designed polymer fibers. The mechanism of action of the micro-polymeric fibers in concrete has also been emphasized. The principles of mix designs of the mortar incorporating fibers to make an ECC have also been explained. It has also been mentioned in detail as how this technology can be used to enhance the flexibility of some modern concrete types like flowing concrete, self-compacting concrete, and lightweight concrete. ECC is a green construction material. The possible benefits like environment friendliness, cost effectiveness, and durability have been also been elucidated in the paper.

Phase distribution and microstructural changes of self-compacting cement paste at elevated temperature

Self-compacting concrete, as a new smart building material with various advanced properties, has been used for a wide range of structures and infrastructures. However little investigation have been reported on the properties of Self-compacting when it is exposed to elevated temperatures. Previous experiments on fire test have shown the differences between high performance concrete and traditional concrete at elevated temperature. This difference is largely depending on the microstructural properties of concrete matrix, i.e. the cement paste, especially on the porosity, pore size distribution and the connectivity of pores in cement pastes. In this contribution, the investigations are focused on the cement paste. The phase distribution and microstructural changes of self-compacting cement paste at elevated temperatures are examined by mercury intrusion porosimetry and scanning electron microscopy. The chemical decomposition of self-compacting cement paste at different temperatures is determined by thermogravimetric analysis. The experimental results of self-compacting cement paste are compared with those of high performance cement paste and traditional cement paste. It was found that self-compacting cement paste shows a higher change of the total porosity in comparison with high performance cement paste. When the temperature is higher than 700 °C, a dramatic loss of mass was observed in the self-compacting cement paste samples with addition of limestone filler. This implies that the SCC made by this type of self-compacting cement paste will probably show larger damage once exposed to fire. Investigation has shown that 0.5 kg/m 3 of Polypropylene fibers in the self-compacting cement paste can avoid the damage efficiently.

Smart Building Materials which Prevent Damage or Repair Themselves

ABSTRACTWe developed designs in which hollow porous fibers filled with chemicals release them into a matrix over time. A coating covering the fibers is degraded by chemicals, pH change, or broken by structural loading, thus, releasing the chemicals. These stimuli for release are the very agents of environmental attack.The design to alleviate cracking consists of hollow porous fiberglass fibers containing crack-closing chemicals. The chemicals are released from the fibers when the outer sheath cracks or the fibers flex due to loading. This is the ideal situation in which the agent of environmental degradation, namely loading, is the stimulus to release the repair chemical.The design to prevent corrosion consists of an anticorrosion chemical in hollow porous polypropylene fibers. Change in chloride ion concentration dissolves the polyol coating and allows the chemical to be released from the fiber wall. The cause of deterioration, change in chloride level which causes corrosion, is the sensor (coating deterioration) and also the activator for the remedial or preventive action (release of anticorrosion chemical).These are distributed systems responding to environmental stimuli for sensing and repairing when and where they are needed. The control of the amount of chemical released is being researched mainly as a function of coating design and also fiber type.