Experimental studies of gypsum plasterboards and composite panels under fire conditions

Gypsum plasterboards are commonly used to protect the light gauge steel‐framed walls in buildings from fires. Single or multiple plasterboards can be used for this purpose, whereas recent research has proposed a composite panel with a layer of external insulation between two plasterboards. However, a good understanding of the thermal behaviour of these plasterboard panels under fire conditions is not known. Therefore, 15 small‐scale fire tests were conducted on plasterboard panels made of 13 and 16 mm plasterboards and four different types of insulations with varying thickness and density subject to standard fire conditions in AS 1530.4. Fire performance of single and multiple layers of gypsum plasterboards was assessed including the effects of interfaces between adjacent plasterboards. Effects of using external insulations such as glass fibre, rockwool and cellulose fibre were also determined. The thermal performance of composite panels developed from different insulating materials of varying densities and thicknesses was examined and compared. This paper presents the details of the fire tests conducted in this study and their valuable time–temperature data for the tested plasterboard panels. These data can be used for the purpose of developing and validating accurate thermal numerical models of these panels. Copyright © 2012 John Wiley & Sons, Ltd.     

Calculation of thermal conductivity of gypsum plasterboards at ambient and elevated temperature

Plasterboard often protects steel structures of buildings because it conducts heat slowly and absorbs the heat of the fire by its volumetric enthalpy. The most important property governing the heat transfer is the thermal diffusion. This property depends on the density, specific heat and thermal conductivity. The first two can be calculated based on the mass composition of the board. The thermal conductivity is more difficult to derive since it is a directional property. This paper will focus on the calculation of the thermal conductivity at ambient and elevated temperatures. It is shown that the thermal conductivity of gypsum plasterboard (i.e. a porous medium) can be assumed to be a three‐phase system. Plasterboard consists of a solid phase and a water/air mix in the voids. The differences between different theoretical equations for both dry and moistured plasterboards are presented. The equation proposed by Zehner and Schlunder (Chem. Ing.‐Tech. 1972; 44 (23):1303–1308) with shape‐factor C of 5 gave good agreement with experimental data of the different boards. Furthermore, the influence of the composition of the boards on the thermal conductivity is investigated. This has an influence, especially since the composition is also related to its moisture content. Regression analysis points out that the moisture content depends only on the gypsum content. A value of 2.8% absorbed water on the mass of gypsum is found, and this water plays an important role in the thermal conductivity of plasterboard at ambient temperature. Finally, the thermal conductivity of board at elevated temperature is computed. A close fit between computed and experimental values derived from literature is found. Copyright © 2009 John Wiley & Sons, Ltd.     

Fire behaviour of sisal short fibers reinforced gypsum

The fire behaviour of sisal short fibers reinforeed gypsum in laboratory tests is described Specially designed testing equipment that is easily available has been implemented in this work to analyze the fibers under load and their composite fire performance.     

Fire behavior of regular and latent heat storage gypsum boards

This paper investigates the fire behavior of a regular and an energy storage gypsum board with latent heat storage characteristics when exposed to fire temperatures. Gypsum board samples, with and without a microencapsulated paraffin mixture phase change material, are studied at material and board level. At the material level, measurements of the physical properties, that is, mass and effective thermal conductivity, as a function of temperature, as well as differential scanning calorimetry experiments, in inert and oxidized environments, are performed. At the board level, specimens are inserted into a preheated oven, and the temperature evolution at preselected board locations is recorded. Both experimental procedures reveal significant information concerning the evolution of the various thermochemical processes taking place inside the gypsum boards during their heating. Results indicated the different fire behavior of the samples at different temperature ranges. At temperatures up to 300°C, the materials act as a fire retardant because of the dehydration of the free and chemically bound water contained in the gypsum boards. On the other hand, at temperatures higher than 300°C, the temperature rise within the samples is enhanced and accelerated because of the oxidation of the phase change material and their external finishing. Copyright © 2014 John Wiley & Sons, Ltd.     

Fire performance of fire-retardant wood fiberboard ceiling tile

Wood fiberboard-based, cellulose ceiling tiles have been used for many years. While various fire-retardant technologies have been developed to reduce the surface flammability of these products to acceptable levels, questions of their suitability for use due to their intrinsic fuel value and the impact of attachment methods used on fire performance have been raised from time to time. This paper reviews the history of these products from a fire-performance perspective and presents materials property data on surface flamespread, thermal conductivity and ignition phenomena. In addition, large-scale room fire test results are presented including compartment tests conducted on a variety of assemblies (including those installed with mastic construction adhesives) according to ASTM E 603—Standard Guide for Room Fire Experiments.     

浅谈高层民用建筑防火设计

高层建筑投资规模大,建筑使用功能复杂,使得对设计的要求越来越高,特别是防火安全的设计。我国社会经济还不发达,因此,我们在设计当中既要考虑到控火及灭火的安全性,又要考虑到投资的合理性。本文结合当前实际工程,并以规范为指导,对高层民用建筑消防设施的配置进行探讨。     

High performance UV-cured coatings for wood protection

UV-curable systems based on the copolymerisation of a typical acrylic resin with a low amount of a fluorinated monomer (<1%, w/w) were used for the protection of wood panels. In the presence of the additives, the bulk properties and the adhesion of the acrylic films were unchanged, while a strong modification of the surface was obtained. The quality aspects and the chemical resistance of the coatings applied to the wood panels were also enhanced.     

Fire performance of wood (Pinus radiata) treated with fire retardants and a wood preservative

In this work, we co‐formulated an oil‐borne copper naphthenate/permethrin wood preservative system with synthetic polymer‐based fire‐retardant additives prior to the impregnation of Pinus radiata sapwood. We evaluated what effect, if any, the preservative had upon the fire performance properties of the fire retardants and whether the fire retardants impacted on the fungicidal and termiticidal efficacy of the preservative. The fire retardants included halogenated and phosphorus‐based systems. A mass loss calorimeter, in conjunction with a thermopile, was used to measure the time to ignition and the peak heat release rate (PHRR) from which the fire performance index (FPI) was determined. The preservative properties were evaluated using termite and soil‐block decay bioassays. In summary, we found that the rate of fire growth was reduced when the fire retardants were used in combination with the wood preservative. We also found that the PHRR was a better determinant of fire performance than the FPI. The performance of the wood preservative was enhanced against fungal decay and termite attack when used in combination with the fire retardants. The fire retardants also demonstrated some wood preservative properties of their own. Copyright © 2008 John Wiley & Sons, Ltd.     

脱硫石膏对水泥性能的影响及其品质差异分析

对不同产地脱硫石膏作缓凝剂对水泥物理性能影响进行了研究比较,并分析探讨了脱硫石膏的品质差异及其对水泥性能影响机制。试验结果表明,与天然石膏相比,脱硫石膏对水泥早期和后期强度均有不同程度提高,但水泥凝结时间有不同程度延长。不同产地脱硫石膏对水泥与外加剂相容性、保水性、流变性和干缩率等性能的影响均存在较大差异。研究还发现,亚硫酸钙含量及钙硫比低的脱硫石膏,其水泥凝结时间、干缩性、保水性和砂浆流变性等物理性能均优于或与掺天然石膏的接近;同时,脱硫石膏的结晶程度、晶体形态和石膏溶解速率对水泥凝结时间、与外加剂相容性等也均有较大影响。     

Differential comminution of gypsum in cements ground in different mills

Identical mixes containing fixed amounts of ordinary Portland cement clinker and gypsum were ground in two types of industrial cement mills—viz. ball mill (BM) and vertical roller mill (VRM)—to identical Blaine fineness to examine the effect of any possible differential comminution of gypsum on cement setting times. The present investigation demonstrates that during comminution of cements, the degree of crystallinity of gypsum, as determined by X-ray diffraction (XRD), changes with used grinding mills and this causes changes in setting times of similar cements even when ground to identical Blaine fineness.     

石膏品种对硅酸盐--硫铝酸盐复合体系水泥性能的影响

在试验研究不同石膏品种对硅酸盐-硫铝酸盐复合体系水泥凝结时间、标准稠度需水量、强度等性能影响的基础上,探讨了石膏品种对硅酸盐-硫铝酸盐复合体系水泥性能的影响机理。结果表明：二水石膏对该种复合体系水泥的缓凝作用比硬石膏明显,硬石膏易引起复合体系水泥急凝和需水量增大。石膏品种对硅酸盐一硫铝酸盐复合体系水泥强度的影响较复杂,与水泥体系中含铝矿物及其水化溶液中SO4^2-离子浓度有关;在蒸馏水和饱和石灰水中,二水石膏的溶解速度比硬石膏快,溶解度比硬石膏低。推导证实,石膏的溶解速度和溶解度是决定硅酸盐-硫铝酸盐复合体系水泥性能的主要因素。     

掺有不同石膏的水泥对混凝土性能的影响

把不同的石膏加入同种熟料中,在不同的粉磨设备中磨制成表面积不同的水泥,再在不同温度下将水泥配制成同等级泵送混凝土,测定其初始,1h,2h的坍落度和扩展度,以及3d,7d和28d抗压强度,以此来探讨不同水泥对流动混凝土性能的影响。     

不同石膏掺量对新型贝利特水泥性能的影响

０引言出于节能和利用废渣的目的,我们利用粉煤灰和铜尾矿等工业废渣研制了以β-Ｃ２Ｓ、无水硫铝酸钙Ｃ４Ａ３Ｓ为主要矿物的新型贝利特水泥〔１〕。研究过程中发现外掺石膏量对水泥性能有较大的影响。随石膏掺量不同,水泥凝结时间和强度都有较大的变化,当石膏量适宜时,Ｃ４Ａ３Ｓ水化生成较多的钙矾石而不膨胀,此时水泥石的强度最高,凝结时间也可调节到通用水泥的要求。１熟料的化学成分与矿物组成所烧制的新型贝利特水泥熟料β-Ｃ２Ｓ含量为６０%～６８%,Ｃ４Ａ３Ｓ２０%～３０%,其化学成分与计算矿物组成如表１所示表１熟料的化学成分及…     

脱硫石膏代替天然石膏作水泥缓凝剂

脱硫石膏是火力发电厂烟气脱硫时由SO2和CaCO3反应生成的一种工业副产石膏,主要成分为CaSO4·2H2O,还含有一些杂质.脱硫石膏如不加以利用,不但需要资金和土地建造堆场,而且还污染环境.使用脱硫石膏作水泥缓凝剂是非常有效的将废物资源化的途径,可以创造良好的经济、社会和环境效益.本文对此进行了研究.     

A new innovative stabilization method for the protection of natural wood

The UV-light exposure of natural wood leads initially to a fast color change, and in the further stages to large chemical modifications and mechanical breakdown of the wood surface layer. Even in diffuse light exposure, prevailing in indoor conditions, the discoloration of wood is a serious esthetical drawback, for example, for furniture and parquetry.

Progress has been made with the development of new stabilizers, which offer a significant benefit compared to the currently used benzotriazole UV-absorbers. Using these new stabilizers the wood photo-protection against discoloration and the durability of clear and transparent pigmented coating systems can be significantly improved.     

Characterization of liquefied wood residues from different liquefaction conditions

The amount of wood residue is used as a measurement of the extent of wood liquefaction. Characterization of the residue from wood liquefaction provides a new approach to understand some fundamental aspects of the liquefaction reaction. Residues were characterized by wet chemical analyses, Fourier transform infrared (FTIR) spectroscopy, X‐ray diffraction (XRD), and scanning electron microscopy (SEM). The Klason lignin content of the residues decreased, while the holocellulose and α‐cellulose contents increased as the phenol to wood ratio (P/W) increased. A peak at 1735 cm^?1, which was attributed to the ester carbonyl group in xylan, disappeared in the FTIR spectra of the residues from liquefied wood under a sealed reaction system, indicating significantly different effects of atmospheric versus sealed liquefaction. The crystallinity index of the residues was higher than that of the untreated wood particles and slightly increased with an increase in the P/W ratio. The SEM images of the residues showed that the fiber bundles were reduced to small‐sized bundles or even single fibers as the P/W ratio increased from 1/1 to 3/1, which indicated that the lignin in the middle lamella had been dissolved prior to the cellulose during liquefaction. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2007     

脱硫石膏完全代替天然石膏作水泥缓凝剂的应用经验

<正>我公司是年生产能力20万t的水泥粉磨站,有2条由MB2275管磨机和NHX600高效转子式选粉机组成的闭路水泥生产线。2008年3月份开始,我公司     

Synthesis of large plate-like gypsum dihydrate from waste gypsum board

This paper reports the synthesis of large plate-like gypsum (calcium sulfate) dihydrate generated from waste gypsum board via a wet process. Gypsum hemihydrate was formed by dehydrating waste gypsum board in a sodium sulfate solution at 100 °C for 1 h to form needle-like crystals. The large gypsum dihydrate was formed by lowering the temperature of the gypsum hemihydrate suspension below 80 °C. The large plate-like gypsum dihydrate was obtained by adding seed crystals to a suspension cooled at 80 °C. When 40 μm seed crystals were added at 0.5 mass%, the large plate-like gypsum dihydrate crystals obtained from waste gypsum board had average dimensions of 250 μm length × 100 μm width × 35 μm thickness.     

脱硫石膏制备半水石膏晶须的研究

脱硫石膏是电厂湿法烟气脱硫的固体废弃物,不仅造成资源浪费,还会对环境产生污染。为提高脱硫石膏的附加值,以脱硫石膏为原料,采用盐溶液法制备半水石膏晶须,研究了氯化钠浓度、温度、液固比、pH对转化率的影响,并研究了柠檬酸的含量对形貌的影响。采用傅立叶变换红外光谱仪（FTIR）、X射线衍射仪（XRD）、扫描电子显微镜（SEM）等对制备的半水石膏晶须做了表征,并研究了柠檬酸对形貌影响的机理。研究表明：当氯化钠质量分数为20%、反应温度为100 ℃、液固比为5∶1、反应时间为2 h、柠檬酸的质量分数为0.25% 时,可制备出长度为50～100 μm、长径比为（30～50）∶1的半水石膏晶须。