Properties of blended cements with thermally activated kaolin

Kaolin, one of the materials of major importance for the ceramic and paper industry, is also used in the construction industry as a raw material for the production of white cement clinker and, in the form of metakaolin, as an artificial pozzolanic additive for concrete. Metakaolin is a vital component of high-performance and architectural concrete; however, its application in regular concrete is very limited due to relatively high production costs. This report evaluates the performance of a low-cost metakaolin-based additive called thermally activated kaolin (TAK), in cement. Due to its pozzolanic properties and the densification of cement matrix, the application of TAK provides a 15% improvement of the compressive strength. It was shown that TAK of optimal quality can be manufactured by the thermal treatment of raw kaolin with 74% of kaolinite at 750 °C without the intermediate beneficiation stage. The application of a developed approach can significantly reduce production expenditures and make the application of such an additive feasible even in regular-grade cement and concrete.     

Application range of thermally activated building systems tabs

This paper presents application range and functionality of thermally activated building systems (tabs). Tabs are increasingly used for energy efficient and economical cooling and heating of commercial buildings. Thereby, the building structure is used as thermal storage allowing the use of renewable energy sources. Based on a simulation study for a typical office building the aspects of thermal comfort, maximum permissible heat gains in the room and the re-cooling of the building mass are analysed. It is shown that depending on the maximum permissible daily room temperature amplitude with tabs typical heat gain profiles with peak loads up to around 50 W/m² floor area can be managed. However, the transitional (mid-season) periods with already high solar gains and still restricted comfort range, in most cases will be decisive for the dimensioning of tabs, thus limiting maximum loads to lower values. The results also show that processes on the room side are almost unaffected from the processes on the supply side. In the cooling case, this allows for the re-cooling period of the fabric being extended to 24 h a day with accordingly “high” supply temperatures and peak load reductions of up to 50%. The results given may serve as orientation guide whether a tabs may be applicable in a specific building, and provides relevant parameters for the dimensioning of tabs.     

氟石膏在水泥生产中的应用

氟石膏是化工行业排放的工业废料,开发利用氟石膏代替天然石膏作水泥缓凝剂,既可节约天然石膏资源和降低水泥成本,又可综合利用工业废渣,解决堆放氟石膏造成的生态环境污染问题。江都未来水泥有限责任公司在氟石膏的使用上做了大量的试验,并成功地投入生产,取得了     

碱-矿渣水泥缓凝物质的选择研究

研究了氯化钡、硝酸钡、硫酸铁、铬酸钠、氯化镁、硫酸镁、硫酸铝等无机盐以及酒石酸、草酸等有机酸对碱-矿渣水泥凝结时间的影响.试验结果表明,氯化钡、硝酸钡、氯化镁、硫酸铝、酒石酸有良好的缓凝作用,硫酸铁、铬酸钠、硫酸镁、草酸不产生缓凝作用.通过强度测试发现,氯化钡、硝酸钡、氯化镁、硫酸铝、酒石酸均对碱-矿渣水泥的强度有一定的不良影响.     

中国水泥工业环境负荷分析

本文运用生命周期评价法,采用2004年中国环境年鉴和中国建筑材料工业年鉴统计数据,分析评价了我国现阶段水泥生产工艺过程及与水泥生产相关的原料开采、电力生产和煤炭生产过程的环境负荷状况。     

Energy and comfort performance of thermally activated building systems including occupant behavior

In building simulations it is common practice to use standardized occupant behavior and internal gains. Although this is a valid approach for designing systems, the probabilistic nature of these boundary conditions influences the energy demand and achieved thermal comfort of real systems. This paper analyzes the influence of occupant behavior on the energy performance and thermal comfort of a typical office floor equipped with a thermally activated building system (TABS). A multi-zone TRNSYS model with 10 adjacent zones per orientation for a typical moderate Belgian climate is set up. First, the energy performance and thermal comfort of thermally activated building systems (TABS) are compared with the performance of idealized cooling with standardized user behavior. TABS are able to deliver good thermal comfort but show to have a higher energy demand. Secondly, probabilistic occupant behavior was implemented in the TABS simulations. The influence of the occupancy rate, the shading device use and switching of the lights are analyzed by defining user profiles. It is shown that occupant behavior may have an important influence on the cooling demand and thermal comfort. However, as long as good solar protection is foreseen and operated in a correct way, TABS are able to cope with different user behavior modeled in this paper. In this case, normal daily stochastic processes do not considerably affect the cooling demand and thermal comfort during summer.     

浅谈在水泥企业实施清洁生产

本文主要探讨在水泥企业实施清洁生产的途径,以及通过清洁生产能给水泥企业带来哪些益处,倡导通过实施清洁生产,最大限度地提高自然资源综合利用率,减少环境污染,实现少排放甚至零排放。     

掺热活化煤矸石水泥胶砂试验研究

借助于X射线衍射分析、激光粒度分析、宏观力学性能测试等手段,对陕西铜川煤矸石进行了系统的热力活化研究.研究结果表明:掺700℃煅烧后的煤矸石的水泥胶砂试块强度值最高,说明这个温度是本试验所采用煤矸石的最佳煅烧温度.通过XRD分析表明:采用热力活化,煤矸石中活性来源矿物高岭石转变为偏高岭石的温度明显低于纯商岭石的转变温度.水泥胶砂强度随活化煤矸石掺量的增加在早期呈下降趋势,但随水化时间的增加,强度有大的提高,甚至超过纯硅酸盐水泥砂浆强度,其中综合效果以掺量30%为最佳.当掺量超过35%后,强度大幅度下降.     

Physico-chemical characteristics of chemically activated cement containing boron

The use of colemanite ore waste (CW) containing boron as a cement replacement material increases the long-term strength of the concrete. Despite this benefit, the use of CW is limited due to the low-early strength of the CW concrete. The study reported below intended to eliminate this problem. The experimental part comprises two stages: in the first stage the possibility of using CW instead of natural gypsum has been investigated through several tests. In the second stage, a number of chemical activators, namely, sulphonated melamine formaldehyde (SMF) condensates, sulphonated naphthalene formaldehyde (SNF) condensates, _Na2SO4${\mathrm{Na}}_2{\mathrm{SO}}_4$, and calcium chloride were used. The results showed that replacement of natural gypsum by CW results in an acceptable initial and final setting time of cement and increases the compressive strength of the mortar at long term. The addition of chemical activators into the system accelerated pozzolanic reaction and considerably increased early strength of the mortars. The results also indicate that chemical activators not only alter the rate of cement paste hydration, but the microstructure of mortar as well.     

Use of diatomite as partial replacement for Portland cement in cement mortars

The aim of the present study is to investigate the use of diatomite as a partial replacement for cement in the production of cement mortar. Diatomite was used at 0%, 5%, 10% and 15% replacement by weight for cement while sand and water quantities were kept constant. Compressive and flexural strength, freeze–thaw resistance, sulfate resistance, water absorption and dry unit weight of the mortars were determined. The compressive and flexural strength decreased with increasing diatomite content for all curing periods. However the compressive strength of the cement mortar which was produced with 5% diatomite content complied with the minimum specified value of given in the standards. Diatomite replacement generally increased the compressive strength of the cement mortar after 25 freezing and thawing cycles. Water absorption of the mortars decreased with the increase of diatomite content except the mortar containing of 15% diatomite. Dry unit weight of the cement mortar was lower than the control mortar because of high porosity of diatomite. The expansion of the cement mortar bars immersed in 5% sodium sulfate solution decreased with increasing diatomite content and generally the sulfate resistance of the mortars was higher than that of the control mortar.     

活化煤矸石水泥混凝土性能的研究

比较了徐州煤矸石在500～900℃5种不同的温度下活化后的水泥胶砂强度,综合评价后,确定600℃为徐州煤矸石实验室的合理活化温度。以此温度下活化的煤矸石作水泥的混合材,在孔结构分析的基础上,对比研究了活化煤矸石对混凝土抗氯离子渗透性能的影响。研究结果表明,在相同条件下活化煤矸石水泥混凝土的抗渗性能略优于普通水泥混凝土。     

天然植物纤维增强水泥复合物综述

纤维增强水泥复合材料是用途广泛的建筑材料。2000年11月在巴西的Joao Pessoa举行了“进入下个世纪的经久建筑——与环境相容的有创新的水泥基材料”的国际会议,参与者们对天然纤维增强水泥复合材料的课题进行了热烈的讨论。有两篇文章报导了澳大利亚和巴西应用天然植物纤维增强水泥的经验及应用实例。     

谈谈水泥企业的清洁生产审计工作

我国第一部以污染预防为主要内容的专门法律《中华人民共和国清洁生产促进法》已经九届全国人大常委会第28次会议通过,于2003年1月1日起实施。对现有生产装置而言就要通过清洁生产审计,找出污染产生的“地点”和“原因”,并提出可行的解决方法,这次特发表李湘洲先生的文章介绍水泥企业的清洁生产审计工作。     

矿渣微粉和粉煤灰在水泥生产中的应用

年产100万吨的水泥粉磨站在节约能源、提高产品质量、减轻环境污染等方面具有诸多优势,而且投资成本较低,成为水泥生产的重要生产基地。本文对矿渣微粉和粉煤灰混合材料在年产100万吨水泥粉磨站水泥生产中的应用进行了分析。     

浅谈水泥企业应急管理中存在的问题及对策措施

中国经济发展速度不断加快,作为中国基础产业之一的水泥生产企业,近年来得到了一定的发展,为中国经济的发展起到了推动作业,在发展的同时,存在的安全隐患也逐渐被被国家和社会所重视。为提升水泥企业生产过程的安全性,文章从4个方面探讨应急管理中存在的问题,并根据这些问题提出科学合理的解决措施,避免水泥制造企业生产中安全事故的发生,提升企业生产经营的安全水平和效率。     

Validation and modification of modeling thermally activated building systems (TABS) using EnergyPlus

EnergyPlus (EP) integrates a low temperature radiant system module to evaluate thermal performance of radiant systems such as thermally activated building systems (TABS), but the assumptions in this module neglect thermal resistance of the pipe and thermal resistance between the pipe exterior surface and the pipe level, which may result in the inaccurate evaluation of TABS in terms of surface temperature and surface heat flow. In this paper, in order to validate this module used in EP, steady and transient heat transfer processes of TABS in buildings were studied by analytical solution, two-dimensional numerical simulation and EP simulation. The comparison shows that the assumptions indeed result in a largely overestimated cooling and heating capacity of TABS. In order to improve this radiant module, a simple solution of introducing a no mass material layer with the neglected thermal resistances to both sides of the pipe level was proposed. With this method, the results of mean surface temperature and mean heat flow show good agreement with that from analytical solution as well as numerical simulation. Furthermore, the results of the simulation coupling the modified module with room systems show very small deviation from the results found in the literature. In addition, the application of the modified module in a hollow core concrete deck structure with TABS was investigated.     

Development of a thermally activated ceiling panel with PCM for application in lightweight and retrofitted buildings

This paper describes the development of a thermally activated ceiling panel for incorporation in lightweight and retrofitted buildings. The system allows use of renewable energy sources for the heating and cooling of office and industrial buildings. The design for the new ceiling panel exploits the properties of the phase change material (PCM) paraffin. Its high thermal storage capacity during phase change—up to 300 Wh/(m² day)—enables the overall panel thickness to be limited to a mere 5 cm. Active control of the thermal storage is achieved by means of an integrated water capillary tube system. The research project also included the development of a numerical model for computation of the thermal behavior of wall and ceiling systems incorporating PCMs. Simulation calculations were performed to determine the necessary thermal properties of the ceiling panels and specify requirements for the materials to be used. Laboratory tests were performed to verify the system’s performance and a pilot application is soon to be tried out in practice.     

水泥天然砂卵石混合料地基工程施工技术

结合工程实例,对水泥天然砂卵石混合料地基处理方法的特点、使用范围及其工艺原理进行了介绍,并对施工机具和各施工环节的施工技术进行了详细阐述,最后提出了质量要求及其质量控制措施,以推广该技术。     

Removal of phosphate from aqueous solution by thermally treated natural palygorskite

The potential of activated palygorskite was assessed for sorption of phosphate from aqueous solution. The natural palygorskite used was treated by thermal activation over 100-1000 °C for 2 h. The thermal activation increased the phosphate sorption capacity and the highest phosphate sorption capacity occurred at 700 °C. H700 (palygorskite heated at 700 °C) showed higher sorption rate than natural palygorskite (NPAL), and the removal was favorable in acidic media. The sorption data were described using Freundlich isotherm equation over the concentration range (5-1000 mg/L) (25 °C). Calcium bound phosphorus was the main fraction of the adsorbed phosphorus, about 98.0% in NPAL and 58.2% in H700, but the extractive Ca-P species varied greatly, Ca₂-P was 87.7% in NPAL and 3.0% in H700, Ca₈-P was 10.1% in NPAL and 54.5% in H700, and metal bound phosphorus was less than 2% in NPAL but more than 41.4% in H700, respectively. The dependence of the phosphate sorption capacity in the heating samples on thermal activation appears to be related to major changes in the crystal structure of palygorskite, and more calcium, iron and aluminum were released from the crystal matrix at 700 °C, which promoted phosphorus sorption.