粉煤灰混凝土强度与抗渗性的研究

我国粉煤灰年排放量已超过亿吨，居世界第二。粉煤灰的综合利用符合“保护耕地”，“保护环境”的基本国策。论文利用正交试验的方法，对原状粉煤灰混凝土的抗渗性、强度与时间的关系做了一些研究，并利用极差分析的方法确定了影响粉煤灰混凝土强度与抗渗性各因素的主次顺序，从而找出利用当地粉煤灰配制普通粉煤灰混凝土的最佳配比，以使粉煤灰混凝土的强度、抗渗性、经济性均达到最佳状态。     

原材料对耐久性混凝土电通量指标的影响

耐久性是评价高性能混凝土的重要指标,而混凝土的抗氯离子渗透能力即电通量最能直接反应混凝土的耐久性.影响混凝土电通量的因素很多,对混凝土的抗氯离子渗透能力的影响因素做了试验研究.     

影响钢筋混凝土耐久性的主要因素及提高耐久性的措施

目前钢筋混凝土耐久性问题已经引起了各国的广泛重视。主要介绍了影响钢筋混凝土耐久性的主要因素,并提出了提高钢筋混凝土耐久性的一些途径,包括预防与控制混凝土的碳化、碱—骨料反应、钢筋的锈蚀与防治以及提高混凝土的抗渗性与抗冻性等。     

煤矸石混凝土抗硫酸盐侵蚀试验研究

针对煤矸石混凝土结构耐久性问题,制作煤矸石混凝土立方体试件,进行抗硫酸盐侵蚀试验,研究了粉煤灰掺量、水胶比和干湿循环次数对煤矸石混凝土耐久性的影响.结果表明:煤矸石混凝土抗压强度随干湿循环次数增加呈先升高后降低的趋势;干湿循环15次时,煤矸石混凝土抗压强度耐蚀系数与粉煤灰掺量呈负相关,与水胶比关系不大;干湿循环大于30次时,煤矸石混凝土抗压强度耐蚀系数与粉煤灰掺量呈正相关,与水胶比呈负相关,相关显著性强弱表现为干湿循环90次＞干湿循环60次＞干湿循环30次.煤矸石混凝土抗硫酸盐侵蚀能力能满足一般建筑物要求,这为煤矸石混凝土应用提供了试验依据.     

三峡库区抗滑桩施工中一个值得重视的技术问题

阐述了在地质灾害治理施工中，必须对抗滑桩混凝土耐久性引起高度重视，扼要地列举了提高温凝土耐久性的途径，针对三峡库区技滑桩大体积混凝土水化热控制的技术问题，提出了采用粉煤灰混凝土控制混凝土水化热、防止混凝土收缩开裂的若干措施，达到提高抗滑桩混凝土耐久性的目的。     

钢纤维粉煤灰混凝土的研究现状及展望

钢纤维掺入到混凝土中能显著改善其抗拉、抗弯、抗冲击、抗疲劳性能,具有良好的阻裂限缩能力,并能大幅度提高混凝土的韧性;粉煤灰掺入到混凝土中能够减轻结构自重、增强抗震性、抗裂性、耐久性、耐火性,且粉煤灰的利用对保护环境有积极的影响,技术经济效益也有所提高。文中介绍了钢纤维粉煤灰混凝土的研究现状和应用情况,并对该新型复合材料的发展方向作了分析。     

硫酸盐侵蚀粉煤灰混凝土的耐久性试验研究

针对盐渍土地区隧道衬砌混凝土耐久性问题,在不同质量分数硫酸盐溶液的侵蚀下,改变干湿循环次数,对粉煤灰混凝土抗硫酸盐侵蚀的耐久性进行了深入研究。结果表明:干湿循环作用下,硫酸盐溶液侵蚀粉煤灰混凝土试件,试件强度先小幅度增长,然后逐渐衰减。其中,质量分数为10%的溶液侵蚀的试件,强度增长最为明显,可达到57.5 MPa;而动弹性模量则与干湿循环次数成反比,表现出循环次数越多,相对动弹性模量越低的特征。其中,质量分数为10%的溶液侵蚀的试件,动弹性模量下降的速率最快,试件动弹性模量从339 MPa下降到235 MPa。粉煤灰混凝土的抗硫酸盐耐久性在一般盐渍土地区都可以较好的保持其强度。     

矿渣、粉煤灰对碱骨料反应的抑制效果

通过对掺细磨矿渣、粉煤灰试验证明，细磨矿渣、粉煤灰都对碱骨料反应有抑制效果，在混凝土中掺加适量矿渣或粉煤灰，是增强混凝土建筑物耐久性的有效手段。     

荷载与环境复合因素作用下混凝土结构耐久性研究现状

综合评述了目前荷载与环境因素共同作用下混凝土耐久性的研究进展情况,着重介绍了荷载(应力)对混凝土抗碳化、抗氯盐和硫酸盐侵蚀,抗冻融性能方面的研究成果.得出一致结论:随着拉应力水平的提高,混凝土耐久性降低;随着压应力水平的提高,混凝土耐久性提高,但当压应力超出临界应力范围,混凝土耐久性反而降低.因此,荷载是耐久性研究中不可忽视的因素之一.     

混凝土耐久性防护新技术研究

阐述了耐久性防护的必要性及混凝土耐久性常规防护措施的局限性,介绍了新材料技术-喷涂聚脲在混凝土耐久性防护方面的研究工作。早期防护对提高混凝土耐久性十分必要,常规防护方法存在功能较单一、施工性差等问题,喷涂聚脲可显著改善混凝土的抗硅酸盐腐蚀、抗冻融和抗氯离子侵蚀能力,在混凝土耐久性防护与防腐领域具有良好的应用前景。     

Current situation and future trend of China rare earth luminescent material industry

<正>Rare earth luminescent material is one of the most important application sectors of rare earths.China enjoys the exceptional advantage to develop rare earth luminescent material for its abundant rare earth resources.After several decades'endeavor,China's rare earth luminescent material industry,headed by rare earth phosphor for lamp and LED and high efficient rare earth energy-saving light source,has been gradually developed into a scale industry.China has become a major production base of rare earth phosphor for lamps and rare earth     

China rare earth market review

正June 1~10,2014Rare earth market remained weak.Quoted price of rare earth products was similar to that in May.There was no sign of recovery in downstream market.The market of NdFeB magnetic materials and phosphor was depressed.Catalyst,polishing powder and ceramic industries remained inactive.Demand from downstream industry was soft.Consumers purchased on their needs.Suppliers had strong intention to sell.Prices of rare earth products     

Annual Report analysis of Chinese rare earth-related listed companies in 2013

<正>Chinese rare earth-related listed companies have published their 2013 annual reports.It can be understood from their reports that production and operation activities of Chinese rare earth-related companies were still heavily affected by macro economy and industrial policies.They basically followed the steps of national economy.In 2013,world economy recovered slowly but the economy     

Market opportunities and challenges for rare earth polishing powder

正1.Status of rare earth polishing powder Rare earth polishing powder with high content of cerium oxide began to replace iron oxide for glass polishing and became one of the key materials in glass polishing process since 1940.Compared with traditional iron oxide,rare earth polishing powder has many advantages,such as fast polishing rate,high polishing quality and long service life.It can achieve good surface quality and improve operation conditions.For example,in lens polishing,the polishing work that cerium     

Baotou Research Institute of Rare Earths developed a new RE alloy preparation technology

正Pyrometallurgy Laboratory of Baotou Research Institute of Rare Earths had independently developed a new preparation technology of rare earth alloy for NdFeB.The alloy can remarkably enhance the coercivity of NdFeB magnet but also evidently reduce the production cost of the magnet.The new master alloy was prepared in the kA pilot-scale electrolytic cell by the independent technology.The rare earth master alloy can be used as the raw material for NdFeB.Compared     

Market and recycling of NiMH battery

<正>Market status and future trend of NiMH battery1.Global market of small NiMH battery Global market size of small NiMH batteries declined year on year since 2011.The trend will continue to 2018,at the rate of 5%to 10%annually.Demand for small NiMH batteries will be stable gradually.Many electrical apparatuses are powered by the built-in lithium battery today,which is the main reason for the shrunk market of small NiMH batteries.But,for some products,small NiMH     

China rare earth market review

正September 1-10,2014 Affected by the National Day holiday,rare earth transaction was stagnant and the market showed a weak steady state.As there was no good news for downstream market,some products with flat demand would likely rally slightly for some time to     

2014 second batch of rare earth quota released

正~~     

矿用防爆轴流对旋主要通风机叶片ANSYS模态分析及应用

高效节能矿用防爆对旋主要通风机的叶片是主要通风机运行的关键部件,叶片在运行时不断受到气流的作用力,从而使叶片产生振动,当叶片振动的频率与叶片的固有频率接近时,容易产生共振从而导致叶片的断裂。一旦叶片断裂时,对主要通风机的安全运行产生致命的影响,从而导致矿山、化工等企业发生重大事故,将会产生不可估量的损失。基于有限元分析软件ANSYS,对高效节能矿用防爆轴流对旋主要通风机叶片进行模态分析及产生对应的六阶模态频率,对主要通风机叶片的运行频率、固有频率及产生的共振问题进行了原理分析,并且解决了叶片频率共振的问题,从而为主要通风机叶片结构设计提供理论依据,并对主要通风机叶片的安全运行提供保障。     

2013 NdFeB export analysis

<正>China totally exported nearly 24,000 tonsof NdFeB products during 201 3,including 18,825 tons of permanent magnet,valued USD 1.34 billion at an average price of 71.4 USD/kg;3,277 tons of NdFeB magnetic powder,valued USD 1 01 million at an average price of 30.9 USD/kg;1,334 tons of strip casting ribbon,with total export value of USD 74million at an average price of 55.3 USD/kg;and 586