Geotextile fibres retention properties to prevent surface water nonpoint contamination by pesticides in agricultural areas

In order to investigate the possible use of geotextiles for the retention of pesticides in agricultural watersheds, batch studies of the adsorption and desorption of three widely used pesticides onto/from commercially available geotextiles were performed. The three pesticides considered were diuron, isoproturon and azoxystrobin. Natural and polymeric fibres of jute, hemp, linen, polyamide, polyester and polypropylene were studied. The three most promising fibres appear to be polyamide, jute, and hemp, with adsorption percentages ranging from 35% to 80% at equilibrium. The adsorption kinetics obtained were rather fast. The observed adsorption data are discussed in the light of the physico-chemical characteristics of the different fibres. For jute, hemp and polyamide, desorption at equilibrium does not exceed 50% of the initially sorbed pesticide amount, with rather fast kinetics. Adsorption data are compared with those previously obtained for natural substrates (dead leaves and sediments) typical of agricultural watersheds. Adsorption on geotextile fibres was larger than for sediments, but was lower than for dead leaves.     

Development and performance evaluation of natural thermal-insulation materials composed of renewable resources

Because energy efficiency in buildings will be evaluated not only based upon heating demand, but also according to the primary energy demand, the ecological properties of the building materials for the whole assessment has become essential. The demand for green building materials is rising sharply, especially insulating materials from renewable resources. The application of natural materials has become increasingly important as a consequence of the increasing need to conserve energy, use natural materials, incorporate architecture and construction into sustainable development processes, and the recently promulgated discussions on appropriate disposal of used insulation materials such as polystyrene (EPS).Due to the fact that natural materials are more sensitive to moisture, decomposition factors such as temperature, material moisture content, attacks by microorganisms, and possible decomposition of the material or shorter durability, it is necessary to evaluate the degradation rate of built-in materials and also determine their real in situ hygrothermal properties according to their moisture content, and volume changes.This paper describes the results of a research project carried out at the Vienna University of Technology and Brno University of Technology. The objective is to use jute, flax, and hemp to develop a new insulating material from renewable resources with comparable building physics and mechanical properties to commonly used insulations materials. All input components are varied in the tests. The impact of moisture content changes in relation to the rate of change of other properties was the focus of the investigation. The tests results show that the correct combination of natural materials is absolutely comparable with convectional materials.     

保温材料热阻蜕变对墙体传热系数的影响

外保温结构中保温材料的有效热阻随温度、湿度和使用年限的增加而下降,造成墙体传热系数大于设计值。为此,本文以耦合传热传湿模型为基础,结合保温材料的有效导热系数模型,以分别采用发泡聚苯乙烯,挤塑聚苯乙烯和聚氨酯泡沫作为保温材料的外墙保温结构为例,数值预测了长期实际气候下外墙保温结构的传热系数。计算结果表明,采用上述三种保温材料的墙体传热系数在20年后因保温材料热阻蜕变有不同程度的增加,这意味着需要增加保温层设计厚度才能保证墙体热损失达到设计值。     

A multi-scale homogenization approach for the effective thermal conductivity of dry lime–hemp concrete

Lime–hemp concrete is an environmentally friendly material that is used more and more in building construction. This study develops a multi-scale homogenization approach to model the effective thermal conductivity of this bio-based material. The developed model dedicated to non-compacted and compacted hemp concrete takes into account the shape and the orientations of pores of hemp particles as well as imperfect particle-binding interfaces. Unknown properties of the solid phase of hemp particles and binding, and that of the particle-binding interface are calibrated by inverse analysis using available experimental data. The model is then used to carry out a sensitivity analysis to study the effect of the porosities of hemp particles and binding, the volume fraction of hemp particles, density and temperature on the overall thermal conductivity of hemp concrete. Analytical solution proposed can be used for a fast estimation and optimization of the thermal conductivity of hemp concrete, which is very useful for the building design.     

Water vapor properties of two hemp wools manufactured with different treatments

Hemp wools are environmentally friendly materials that are used for thermal insulation of building. These fibrous materials are the places of moisture transfer and storage that impact on thermal performances of the material. In this work, two kinds of hemp wool are studied: hemp wool with an organic binder (called HW1) and hemp-cotton wool with a polyester binder (called HW2). The investigations are based on water vapor sorption and on water vapor permeability measurements. The two kinds of hemp wool show similar sorption isotherm with quite high values of water content. The water vapor permeability is quite high too.     

Experimental analysis of Deccan hemp oil as a new energy feedstock for compression ignition engine

This study investigates the biodiesel from Deccan hemp oil and its blends for the purpose of fuelling diesel engine. The performance and emission characteristics of Deccan hemp biodiesel are estimated and compared with diesel fuel. The experimental investigations are carried out with different blends of Deccan hemp biodiesel. Results show that brake thermal efficiency is improved significantly by 4.15% with 50 BDH when compared with diesel fuel. The Deccan hemp biodiesel reduces NO_x, HC and CO emission along with a marginal increase in CO₂ and smoke emissions with an increase in the biodiesel proportion in the diesel fuel. The improvement in heat release rates shows an increase in the combustion rate with different percentage blends of Deccan hemp biodiesel. From the engine test results, it has been established that 30–50 BDH of Deccan hemp biodiesel can be substituted for diesel.     

Temperature under a house with variable insulation

A calculation method of high accuracy is presented for the two-dimensional steady-state ground temperature under a long house. The thermal insulation thickness is arbitrarily variable along the ground surface. Explicit, iterative formulas with rapid convergency are given. The heat loss from the house and the ground surface temperature are given for three types of insulations. The method is available as a PC-program.     

典型汽车内饰材料的燃烧特性研究

采用锥形量热仪实验对涤纶面料丙纶玻璃纤维板、涤纶面料丙纶麻纤维板和 PVC 革丙纶麻纤维板 3 种典型汽车内饰材料在 25、35、50 kW/m2 热辐射强度下的点燃时间、质量损失率、热释放速率等燃烧特性参数进行研究,并选取点燃预测模型计算材料的临界热辐射强度,使用轰燃倾向指数和热释放总量评价其潜在火灾危险性。结果表明,在实验热辐射强度下,涤纶面料丙纶麻纤维板质量损失百分率最大,结构完整性最差;涤纶面料丙纶玻璃纤维板平均点燃时间最短,临界热辐射强度最小,最容易被引燃;PVC 革丙纶麻纤维板热释放速率峰值最大,火灾性能指数最小,发生轰燃的可能性最大。     

Experimental study of parameters influencing mechanical properties of hemp concretes

Hemp concrete is a multifunctional ecological material used in buildings. Due to its high porosity (about 80% in volume), it presents an “atypical” mechanical behavior and its thermal and acoustic properties are particularly interesting. It is today possible to design this material according to the required use. This paper focuses on the mechanical properties of hemp concrete. It is shown that extreme curing conditions (30%, 75% and 98% RH) are prejudicial to the mechanical setting of the hydraulic binders whereas only high relative humidity disrupts the one of the air lime-based binder. It is also established that the binder content hugely influences the setting and hardening of the material. Finally, according to the hemp particle size, it appears that small particles (about 3 mm in length) lead to reduce the porosity and consequently the setting process of hemp concrete as compared to concrete manufactured with large particles (about 9 mm).     

Influence of hysteresis on the transient hygrothermal response of a hemp concrete wall

Building envelopes with bio-materials like hemp concrete are currently undergoing an increasing development due to their low environmental impact and their interesting hygrothermal properties. This kind of hygroscopic material is characterized by a hysteretic behaviour. In this paper, the influence of such behaviour on the hygrothermal response of a building wall is discussed. An experimental facility is designed to measure temperature and relative humidity within a hemp concrete wall submitted to climatic variations. This facility provides a set of experimental data suited for benchmarking. Numerical simulations are performed with a hysteresis model implemented in a heat and moisture transfer model. Comparisons between numerical and experimental results show that hysteresis modelling is relevant to simulate the hygrothermal response of the wall. The discussion is extended to the influence of the initial moisture content.     

Temperature analysis of heavily-insulated steel structures exposed to fire

An exact analytical one-dimensional solution of the temperature response of insulated steel structures is derived and a closed form solution is given for a structure exposed to the ISO 834 standard curve.

Alternative approximate solutions are also given where all the heat capacity is assumed lumped in the steel core; only one third of the insulation heat capacity is then considered. It is also shown that approximate solution schemes given elsewhere strongly underestimate the temperature rise in structures protected with heavy insulations system. In addition the theoretical background of a proposed NORDTEST test method on how to obtain the thermal properties of an insulation system is outlined. Finally a numerical calculation scheme is recommeded.     

Concrete for Tunnel Linings Exposed to Severe Fire Exposure

The fire resistance with respect to temperature response and spalling have been experimentally determined for several different concrete qualities. The results show that some qualities perform relatively well even without any type of passive fire protection. Tests have also been made using protection in form of addition of polypropylene fibres as well as thermal barriers. Concrete with addition of polypropylene fibres perform very well. Although, there is still a question regarding the long term durability such as frost resistance and chloride penetration when polypropylene fibres are used. The tests made on concrete with thermal barriers were unsatisfactory since the products used in the tests had documentation on the performance but failed during these tests. A reason for this may be that the previous tests did not catch eventual problems with adhesion between the thermal barrier and the concrete. In the present study three different systems were tested and all failed. Although, when using mechanical bonding and reinforcement net two of the products (spray-on systems) worked well.     

A concept of capillary active, dynamic insulation integrated with heating, cooling and ventilation, air conditioning system

When a historic fa?ade needs to be preserved or when the seismic considerations favor use of a concrete wall system and fire considerations limit exterior thermal insulation, one needs to use interior thermal insulation systems. Interior thermal insulation systems are less effective than the exterior systems and will not reduce the effect of thermal bridges. Yet they may be successfully used and, in many instances, are recommended as a complement to the exterior insulation. This paper presents one of these cases. It is focused on the most successful applications of capillary active, dynamic interior thermal insulation. This happens when such insulation is integrated with heating, cooling and ventilation, air conditioning (HVAC) system. Starting with a pioneering work of the Technical University in Dresden in development of capillary active interior insulations, we propose a next generation, namely, a bio-fiber thermal insulation. When completing the review, this paper proposes a concept of a joint research project to be undertaken by partners from the US (where improvement of indoor climate in exposed coastal areas is needed), China (indoor climate in non-air conditioned concrete buildings is an issue), and Germany (where the bio-fiber technology has been developed).     

外墙外保温系统质量问题的分析研究

针对外墙外保温系统的应用现状及存在的问题,从施工企业经营现状、原材料本身质量及质量检测等方面进行了分析,结合现行的标准规范,对实际检测工作中遇到的难点和问题进行了探讨,并提出了一些意见和建议。     

Thermal Performance of Composite Panels Under Fire Conditions Using Numerical Studies: Plasterboards, Rockwool, Glass Fibre and Cellulose Insulations

In recent times, light gauge steel frame (LSF) wall systems are increasingly used in the building industry. They are usually made of cold-formed and thin-walled steel studs that are fire-protected by two layers of plasterboard on both sides. A composite LSF wall panel system was developed recently, where an insulation layer was used externally between the two plasterboards to improve the fire performance of LSF wall panels. In this research, finite element thermal models of the new composite panels were developed using a finite element program, SAFIR, to simulate their thermal performance under both standard and Eurocode design fire curves. Suitable apparent thermal properties of both the gypsum plasterboard and insulation materials were proposed and used in the numerical models. The developed models were then validated by comparing their results with available standard fire test results of composite panels. This paper presents the details of the finite element models of composite panels, the thermal analysis results in the form of time–temperature profiles under standard and Eurocode design fire curves and their comparisons with fire test results. Effects of using rockwool, glass fibre and cellulose fibre insulations with varying thickness and density were also investigated, and the results are presented in this paper. The results show that the use of composite panels in LSF wall systems will improve their fire rating, and that Eurocode design fires are likely to cause severe damage to LSF walls than standard fires.     

热激发煤矸石活性影响因素研究

全面探讨了煤矸石的产出地理条件、地质年代、化学组成、矿物成分、高岭石含量及其结晶程度、热激发工艺制度等因素对热激发煤矸石活性的影响.结果表明:我国北方热激发煤矸石的活性普遍高于南方热激发煤矸石;随着地质年代由老到新,不同地质年代的热激发煤矸石活性呈马鞍状特征变化;煤矸石化学组成与其活性的相关性受地域分布的控制;煤矸石中高岭石的含量与其活性正相关,而高岭石的结晶程度与其活性负相关;在煤矸石的热激发过程中,煅烧温度、恒温时间、冷却方式三者之间存在着最佳的匹配关系.     

改性剑麻改善水泥混凝土性能的试验研究

研究了改性剑麻纤维对水泥混凝土的坍落度、抗压、抗劈拉和抗折强度的影响。采用 NaOH 碱液对天然剑麻表面进行了预处理,且根据特定的分散性拌和工艺制备改性剑麻混凝土。试验结果表明:混凝土中掺入改性剑麻比天然剑麻对新拌混凝土坍落度产生不利影响小;掺入一定量的改性和天然剑麻的混凝土抗压强度均有所减弱;掺量为2kg/m~3的改性剑麻对其抗劈拉和抗折强度分别增强了25%和35%,而天然剑麻的增强作用效果不佳。     

Bautechnisch‐bauphysikalische Beurteilung der Wirksamkeit energetischer Sanierungen am Beispiel städtischer Wohnhausanlagen in Wien

Study on the efficiency of thermal refurbishment of residential buildings in Vienna. In the framework of the Kyoto Protocol Austria has committed to reduce its greenhouse gas emissions until 2008/2012 by 13% on the base of 1990. Therefore the Federal Government as well as the provincial governments have implemented programs for the protection of climate including several measures to reduce the emission of hazardous greenhouse gases mainly CO₂. Regarding the enormous potential reduction activities were mainly focused on residential buildings. The refurbishment of the building envelope reduces the heating costs as well as the carbon dioxide emissions and improves the indoor climate. Several investigations were taken to check the utility of thermal refurbishment under structural and physical conditions. Plenty of data available in the line of several expertises of existing residential buildings were analysed and completed by additional investigations. The economic efficiency of thermal insulations is pointed out as well as the period of repayment or the influence of the thickness of insulation on the heating energy demand or possible CO₂‐reductions.     

镀铝玻璃纤维润滑涂层

本文主要对镀铝玻璃纤维用润滑涂料的配方研制、涂复方法和性能进行了讨论,该润滑涂料是一脂肪酸水乳液,具有良好的润滑效果,并有益于纤维箔条束的切割,涂有该润滑涂料的镀铝纤维束,其分散率可达到80%以上,和未涂无滑涂料的纤维箔条相比,分散率提高了50%左右。