Porous anorthite ceramics with ultra-low thermal conductivity

Porous anorthite ceramics with an ultra-low thermal conductivity of 0.018 W/m K have been fabricated by hydrous foam-gelcasting process and pressureless sintering method using γ-alumina, calcium carbonate and silica powders as raw materials. Microstructure and phase composition were analyzed by SEM and XRD respectively. Properties such as porosity, pore size distribution and thermal conductivity were measured. High porosity (69–91%) and low thermal conductivity (0.018–0.13 W/m K) were obtained after sintering samples with different catalyst additions at 1300–1450 °C. Porosity, pore size, pore structure and grain size had obvious effect on heat conduction, resulting in the low thermal conductivity. The experimental thermal conductivity data of porous anorthite ceramics were found to be fit well with the computed values derived from a universal model.     

The use of recycled paper processing residues in making porous brick with reduced thermal conductivity

Production of porous and light-weight bricks with reduced thermal conductivity and acceptable compressive strength is accomplished. Paper processing residues were used as an additive to an earthenware brick to produce the pores. SEM-EDS, XRD, XRF and TG-DTA analysis of the paper waste and brick raw material were performed. Mixtures containing brick raw materials and the paper waste were prepared at different proportions (up to 30 wt%). The granulated powder mixtures were compressed in a hydraulic press, and the green bodies were dried before firing at 1100 °C. Dilatometric behaviours, drying and firing shrinkages were investigated as well as the loss on ignition, bulk density, apparent porosity, water absorption and thermal conductivity values of the fired samples. Their mechanical and microstructural properties were also investigated. The results obtained showed that the use of paper processing residues decreased the fired density of the bricks down to 1.28 g/cm³. Compressive strengths of the brick samples produced in this study were higher than that required by the standards. Thermal conductivity of the porous brick produced in this study (<0.4 W/m K) showed more than 50% reduction compared to local brick of the same composition (0.8 W/m K). Conversion of this product to a perforated brick may reduce its thermal conductivity to very low values. Successful preliminary tests were conducted on an industrial scale.     

Porosity,mechanical and insulating properties of geopolymer foams using vegetable oil as the stabilizing agent

Geopolymer foams, as a new type of potential eco-friendly building material, are increasingly being discussed in the literature. This study reports the synthesis and characterization of geopolymer foams using hydrogen peroxide (H₂O₂) solution as pore-forming agent and oil as the stabilizing agent. The geopolymer foams with low bulk densities (0.37 < ρ_b < 0.74 g/cm³), low thermal conductivities (0.11 < λ < 0.17 W/(m.K)), high porosity (66 < p < 83 vol%), and acceptable compressive strength (0.3 < σ < 11.6 MPa) were successfully fabricated at appropriate conditions. Factors that influence the insulating, mechanical, porous, and microstructural properties were investigated. It was found that the content of the stabilizing agent and the blowing agent had a significant influence on the porous structure and associated foam performance.     

Production of recycled cellulose fibers from waste paper via ultrasonic wave processing

Recycling waste paper can be considered as a means to displace the use of natural cellulose fibers applied in building materials, because it is composed mostly of cellulose. The water absorption and special surface area of cellulose fibers are the key properties for their use in building materials. The objective of this article was to study the production of recycled cellulose fibers from waste paper using ultrasonic wave processing. The physical and chemical properties of recycled cellulose fibers, such as water absorption, specific surface area and pore characteristics, etc., were investigated with various testing methods. The results indicated that the ultrasonic cavitation effect was feasible for the preparation of the secondary fibers. When the ultrasonic treatment time lasted for 10 min, the water absorptions of both newsprint fibers and kraft fibers increased significantly and reached the highest values of 12.5 g/g and 11.2 g/g, respectively, which were nearly two times than that of fibers without ultrasonic treatment. With a pretreatment of 20 min, the average length and fineness of recycled cellulose fibers decreased by 4% and 25%, respectively, and the length‐diameter ratio of the recycled cellulose fibers was 1.28 times than that of the untreated fibers, which greatly increased the special surface area of the recycled cellulose fibers. This work also determined that NaOH was useful to improve the physical properties of the recycled cellulose fibers. Because the recycled cellulose fibers after processing, fulfilled several technical indexes, they can be considered as a filling material for used in cement‐based materials. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 41962.     

Properties of composite laminated material produced with layers of beech and paperboard made from waste paper

One of the basic principles for sustainable development is to prevent wasting resources, preserve natural resources, and recycle the products obtained from resources. For this study, paperboard obtained from waste paper was laminated with natural wooden layers in accordance with the order of beech‐paperboard‐beech‐paperboard‐beech and an alternate material was produced. In this context, experiments were made for determining the specific gravity, compression, shearing, bending strength, elasticity module, and the resistance to direct withdrawal of screws and nails on a radial section surface with the objective of determining the usability of this material as a building material. When the findings obtained at the end of the experiments are studied carefully in a comparative manner, it was observed that paperboard laminated materials could be used with different objectives in interiors to protect against humidity. It was determined that it could be used in place of solid poplar materials for places of use where resistance to compression, elasticity module, and resistance to direct withdrawal of screws and nails on a radial section surface are important and in places where resistance to bending and shearing is required after taking the necessary measures. In the end, a contribution to the literature was provided by researching possibilities for different use of a material regained from waste and to provide sustainability. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 101: 1943–1952, 2006     

Characteristics of heat insulating clay bricks made from zeolite,waste steel slag and expanded perlite

In order to lessen the energy loss of buildings during the operation phase, and also considering the importance of sustainable construction, producing bricks having more desirable thermal characteristics has become essential. In this study, insulation bricks composed of expanded perlite (EP), natural zeolite, ground granulated blast furnace slag (GGBFS) and clay were fabricated. The effect of replacing clay with GGBFS, zeolite and EP in amounts up to 15%, 15%, and 50% respectively on the bricks' properties was investigated. Mix proportion parameters of bricks were analyzed using the Taguchi method. Various properties of bricks including density, weight loss, shrinkage, apparent porosity, water absorption, resistance to freezing and thawing, compressive strength, thermal conductivity, and microstructural analysis of fired bricks were examined and compared against standard requirements for bricks. Overall, the results showed that while satisfying the standard requirements, bricks containing the aforementioned additives had lower thermal conductivity compared to normal bricks, and therefore, they could be utilized as heat insulation materials.     

Preparation and thermal shock resistance of anorthite solar thermal energy storage ceramics from magnesium slag

Anorthite solar thermal energy storage ceramics were fabricated from magnesium slag solid waste by pressureless sintering. The effects of CaO/SiO₂ ratio and sintering temperature on the physical, chemical, and thermophysical properties of ceramics were explored. X-ray diffraction results demonstrated that thermal shock process contributed to the formation of anorthite, and increasing CaO/SiO₂ ratio promoted the transformation of anorthite (CAS₂) into melilite (C₂AS). Some micro-cracks were found according to SEM analysis, forming by the mismatch of thermal expansion coefficients among phases. The combined effects of the low thermal expansion coefficient of anorthite and micro-crack toughing endowed the ceramic with good thermal shock resistance. Optimum comprehensive performances were observed in the sample with a CaO/SiO₂ ratio of 0.58 sintered at 1160°C, of which the specific thermal storage capacity was 0.63 J·g^-1·°C^-1(room temperature). The bending strength increased by 0.22% after 30 thermal shock times (room temperature-800°C, wind cooling). Therefore, the anorthite ceramics exhibited great potential for solar thermal energy storage.     

Synthesis and characterization of calcium silicate insulating material using avian eggshell waste

This work focuses on the synthesis of calcium silicate insulating material via solid state reaction using avian eggshell waste as alternative calcium source. The calcium silicate formulations were mixed in a molar ratio SiO₂:CaO (1:1) and fired at 1100 °C for 24 h. The calcium silicate formulations were characterized by XRD, TG-DTA, dilatometry, SEM/EDS, and thermophysical properties (thermal diffusivity, heat capacity per unit volume, and thermal conductivity). The synthesized calcium silicate materials are composed mainly of wollastonite with minor amounts of larnite and rankinite. It was found that a processing of the avian eggshell waste (raw eggshell waste and calcined eggshell waste) had an influence on the thermophysical properties. Calcium silicate pieces were prepared by uniaxial pressing at 82 MPa, curing, and then testing to determine their use as thermal insulating material. The microstructure was evaluated by SEM. The results showed that both raw and calcined avian eggshell wastes could be used as an alternative calcium source in the calcium silicate formulation. It was found that the calcium silicate pieces reached low thermal conductivity values (0.252–0.293 W/mK). Thus, the developed calcium silicate materials using avian eggshell waste act as a good thermal insulation ceramic material.     

Elaboration and characterization of porous granules based on waste glass

The evolutions of the world today and the population increase have resulted in pollution and human wastes, which contaminate the environment and adversely affect the human's quality of life.All forms of food and drink packages, made of paper, plastic foam, aluminum and glass, are designed for the consumers' convenience. After being used, these packages are discarded as garbage and have today become a social problem.It is in this context that our work for obtaining a building material (foam glass granules) that is much lighter is registered with the properties of heat insulation and acoustic improved based on cullet in order to recycle it and for improving the present laws about the waste products in closed circuit (finished products → waste products → finished products).Investigations have shown that grinding waste glass to particle size less than 0.1 mm and adding 1% of Ca CO₃ content provide the production of material with the following properties: particle density of 0.5 g/cm³, strength of 17.50 MPa and water adsorption of 95%, with the temperature for foaming ranges determined at 850 °C. The microstructures are homogenous, with pore sizes of up to 2 mm. The foam glass is counted among the new glass products meeting certain requirements on comfort, in particular in the building industry (thermal and acoustic insulation). The product obtained presents excellent thermal (λ = 0,031 W/m°C) and acoustic (R = 15 dB) properties.     

Effect of polymer cement modifiers on mechanical and physical properties of polymer-modified mortar using recycled artificial marble waste fine aggregate

Various polymer-modified mortars using recycled artificial marble waste fine aggregate (AMWFA) were prepared and investigated for the purpose of feasibility of recycling. Styrene–butadiene rubber (SBR) latex and polyacrylic ester (PAE) emulsion were employed as polymer modifier, and compared each other. The replacement ratio of AMWFA was also changed to investigate the effect of it on physical properties. Adding polymer cement modifier into mortar reduced water–cement ratio, and PAE was the more effective polymer cement modifier to reduce water–cement ratio than SBR. PAE emulsion-modified mortar increased the air content entrained as the proportion of PAE was increased. There was little difference in water absorption between SBR latex and PAE emulsion. The compressive strength decreased in the presence of polymer cement modifiers compared to that of no polymer cement modifiers, but the compressive strength of 20% of polymer–cement ratio was higher than that of 10%. After the hot water resistance test, both compressive strength and flexural strength were decreased.     

Reuse of mineral wool waste and recycled glass in ceramic foams

Novel ceramic foams have been prepared by high temperature sintering of waste mineral wool and waste glass using SiC as a foaming agent. The aim of the research was to understand the effects of composition and sintering conditions on the properties and microstructure and produce commercially exploitable ceramic foams. Optimum ceramic foams were formed from 40 wt% mineral wool waste and 2 wt% SiC, sintered at 1170 °C using a heating rate of 20 °C/min with a 20 min hold at peak temperature. The ceramic foams produced had a bulk density of 0.71 g/cm³ and a uniform pore size distribution. The research shows that ceramic foams can be formed from waste mineral wool and these can be used for thermal insulation with associated economic and environmental benefits.     

The relationship between electric processing condition and microstructure in the solidification of multicomponent oxides

Systematic characterization for the relationship between the electropulse processing conditions and microstructure has been carried out in the present work. It is found that electropulse can refine porosity and alter grain morphology considerably. A processing with optimum electropulsing parameters can reduce over 75% volume fraction of porosity and more than 70% average pore diameter in comparison with that of reference sample without electric treatment. Electric current treatment promotes the growth of dendrites with smaller thickness of primary arms dendrite and prevents the liquid entrapping between the growing solid grains. The former is caused by the effect of electricity-enhanced kinetic mobility on the radius of curvature at the tip of dendrite. The latter is attributed to the effects of electric thermodynamics on the microstructural formation such as the enhanced connectivity of conductive phase. The microstructures obtained by electropulsing treatment are favourable for heat conduction, structural strength and crack prohibition. However, the excess pulse frequency and pulse width can generate unwanted heat to counteract electric effect. The research reveals the relationship between electric processing conditions and microstructure in a perfectly controversial solidification condition in oxide materials to that of the metals and alloys. The results confirm from the opposite side the validity of the pulsated solidification.     

Recycling of commingled plastics waste containing polypropylene,polyethylene, and paper

Polymer waste recycling is a major technical problem, because large amounts of synthetic polymers are produced every day and polymeric wastes are gathered from municipal solid wastes. There are a few polyolefins, such as polyethylene (PE) and polypropylene (PP) with huge amounts of paper in the waste materials. In order to recycle the commingled plastics waste that contains paper, hydrolytic treatment is needed prior to conventional processing. In this project, the optimum conditions of hydrolytic treatment of paper and the mechanical properties and morphological state of different compositions of PP high‐density PE (HDPE) blends with paper were studied. Ethylene‐propylene‐diene copolymer (EPDM) was added to improve the mechanical properties of blends. The results show that the hydrolytic treatment of paper improves the mechanical properties, such as the tensile strength and modulus of the PP/HDPE/paper composites relative to the untreated samples, and up to 30% paper can be added to commingled PP and HDPE blends. The EPDM was used as an impact modifier. The plastics waste containing paper can be used in applications such as artificial wood. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 80: 2573–2577, 2001     

The impact of heat treatment on the microstructure of a clay ceramic and its thermal and mechanical properties

This paper presents the results of an experimental study on the microstructure, the thermal and the mechanical properties of a clay-based ceramic used in building applications. The X-ray tomography analysis showed a layered microstructure of clay with 200 µm sheets of porosity after the extrusion process. The gas release from the dehydration, dehydroxylation and decarbonation induced a 7 vol% formation of porosity during the heat treatment of the clay-based ceramic up to 850 °C. The porosity increase and the development of metakaolin led to a 38% decrease in the thermal conductivity. On the other hand, the Young's modulus of the clay-based ceramic was conserved due to the formation of smaller pores than the 200 µm sheets of porosity. The densification and the crystallization of amorphous phases also led to a 110% increase of the Young's modulus from 850 °C to 1050 °C. The Young's modulus of the clay-based ceramic was only decreased by the β→α quartz inversion of the cooling due to sand addition. Hence, this study provided a useful insight into how the microstructure of fired clay bricks can be specifically transformed by the porosity during the heat treatment to control the thermal and mechanical properties.     

Thermal conductivity of MgO-C refractory ceramics: Effects of pyrolytic liquid and pyrolytic carbon black obtained from waste tire

In the present study, thermal conductivity and mechanical properties of MgO-C refractory ceramic bricks were investigated. Pyrolytic liquid and pyrolytic carbon black obtained from pyrolysis of waste tires were used as a resin and carbon source, respectively. The pyrolysis of the tires was conducted in a fixed bed reactor at the temperature of 500?°C with a 15?°C/min heating rate under nitrogen flow (0.5?lt/min). Before using in MgO-C refractory ceramic blends, pyrolytic products were purified with the acidic extraction methods which resulted in 61and 66?wt%. decreases in sulfur and ash contents in pyrolytic carbon, respectively. After this treatment of pyrolytic liquid, the sulfur content was reduced by 24?wt%. Eight different blends of MgO-C refractory ceramics consisting of different pyrolytic product contents were prepared, pressed, and tempered at 250?°C, and then characterized in terms of porosity, thermal conductivity, and density. The mechanical behavior of the samples was tested using a three-point bending test. Archimedes test was employed to determine the porosity and density. Surface properties of the bricks were analyzed by scanning electron microscopy (SEM). The obtained results were compared with a reference consisting of graphite and resin. The results revealed that mechanical and thermal properties of the developed bricks were highly sensitive to the porosity and the carbon source as well as the type of binder.     

Zeolite synthesis from paper sludge ash with addition of diatomite

BACKGROUND: This study aimed to investigate the synthesis of zeolites from paper sludge ash (PSA) with added diatomite to remove both NH₄⁺ and PO₄^3? for water purification. The PSA had low Si and significant Ca contents. Four types of diatomite: white (T‐W) and brown (T‐B) from deposits of marine origin in Takanosu, and white (S‐W) and gray (S‐G) from lacustrine deposits in Shonai, were added to NaOH solution to increase the Si content and thereby synthesize zeolites with high cation exchange capacity (CEC). RESULTS: The order of the amounts of Si extracted from the diatomite to the alkali solution was S‐W > T‐W = T‐B > S‐G, which correlates with the amorphous SiO₂ content of diatomite. The original ash without addition of diatomite yielded hydroxysodalite with CEC of about 1.0 mmol g^?1. For all samples, the addition of diatomite to the solution yielded zeolite‐P with a higher CEC, but the addition of excess Si inhibited the synthesis of zeolite‐P, and the CEC of the product was low. A product with high CEC including zeolite‐P was obtained in a solution with around 500 mmol L^?1 of Si concentration, and had the ability to remove both NH₄⁺ and PO₄^3?. CONCLUSION: Diatomite has the potential for used as an additive for the synthesis of high CEC zeolite from PSA. The product with zeolite‐P exhibited relatively high CEC, capacity for NH₄⁺ uptake, and the ability to remove PO₄^3? by precipitation, which is preferable for water purification applications. Copyright © 2008 Society of Chemical Industry     

Effect of starch addition on microstructure and properties of highly porous alumina ceramics

Porous alumina ceramics with ultra-high porosity were prepared through combining the gel-casting process with the pore-forming agent technique. Porosity and pore size distribution of the sintered bulks were evaluated with and without adding starch, respectively. In particular, the influences of starch addition on the properties, including thermal conductivity and compressive strength were studied. It was found that the incorporation of starch increased the nominal solid loading in the suspension and subsequently promoted the particle packing efficiency. The porosity is raised with increasing starch content from 0 to 30 vol%, which brings the decrease in thermal conductivity, whereas the compressive strength isn't seriously degraded. The further higher starch addition (40 vol%), however, would deteriorate the performance of the alumina porous ceramics. It is believed that the appropriate starch amount (lower than 30 vol%), working as a pore-forming agent, suppresses the driving force of densification without affecting the connections of neighboring grains while excessive starch amount would lead to the collapse of the porous structure.     

废旧聚丙烯/废弃印刷线路板非金属粉复合材料的制备及性能

采用挤出注塑法以废旧聚丙烯（WPP）为基体、废弃线路板非金属粉（WPCBN）为填料制备了复合材料。考察了WPCBN对材料阻燃性能及力学性能的影响。通过红外光谱和扫描电子显微镜分析研究了WPCBN改性前后官能团结构及复合材料冲击断面形貌的差异,以探讨硅烷偶联剂（KH550）、马来酸酐接枝聚丙烯（MAPP）对WPP/WPCBN界面相容性改善及复合材料力学性能提高的作用机理。结果表明,WPCBN超过10 phr后复合材料具有自熄性;经1.5 phr KH550改性后,WPCBN与WPP间的界面黏结力增强,复合材料拉伸、弯曲及冲击强度分别提高6.5%、6.25%和17.9%;m（WPP）：m（WPCBN）：m（MAPP）为100：30：9时,复合材料的拉伸、弯曲强度增幅最大,分别为37.5%和48.8%;WPP/WPCBN与新聚丙烯（NPP）/WPCBN复合材料相比,拉伸、弯曲强度仅降低16.8%、20.4%。     

Fabrication of cordierite foam ceramics using direct foaming and slip casting method with plaster moulds

The cordierite foam ceramics were successfully fabricated using direct foaming and slip casting method with plaster moulds. Kaolin, attapulgite and magnesium oxide were used as starting materials with Arabic gum added as the dispersant. The samples were sintered at 1200°C, and then the microstructure, porosity, bulk density and thermal conductivity were characterised. The results show that the cordierite foam ceramics had a porous structure of open cells and the struts had abundant small pores. The maximum open porosity achieved 87·65% with a bulk density of 329 kg m^??3, and the thermal conductivity was as low as 0·095 W (m K)^??1. Therefore, these cordierite foam ceramics show promise for use as the thermal insulator.