钢渣粉在水泥基材料中应用研究综述

目前,钢渣废弃物堆存造成了严重的环境污染和资源浪费,钢渣资源化利用迫在眉睫。将钢渣粉应用于水泥基材料中,不仅可以提高固废资源利用率,还可以减少天然资源的消耗,替代水泥降低CO₂的排放。本文介绍了钢渣的物理化学特性、胶凝性能和活性激发方式,综述了钢渣粉在混凝土复合胶凝材料、全固废胶凝材料、充填胶结材料、干混砂浆四个领域的资源化利用现状。从凝结时间、和易性、力学性能、耐久性和体积稳定性等方面分析了钢渣粉对水泥基材料性能的影响。掺入适量的钢渣粉,可有效改善水泥基材料的性能,特别是在调控拌合物和易性与提升耐久性方面有显著优势。最后,提出了将钢渣粉应用在水泥基材料中存在的问题和未来的研究发展方向。     

碳化养护对钢渣混凝土强度和体积稳定性的影响

当前国内外对钢渣的利用率不高,急需拓展经济、高效的钢渣利用途径。以钢渣粉为主要胶凝材料组分,用钢渣砂、钢渣石为集料配制混凝土,采用CO_2进行养护,研究碳化养护对钢渣混凝土强度和体积稳定性能的影响。结果表明:经碳化养护后,混凝土抗压强度显著提高,碳化14 d强度提高3.2~5.3倍,最高可达65.3 MPa,且碳化时间越长,试件碳化深度越大、pH值越低、碳化程度越高,混凝土强度也越高。碳化过程中生成碳化产物方解石Ca CO_3(碳酸钙镁Ca_xMg_(1–x)CO_3),使混凝土结构更加致密,吸水率降低。钢渣砂和钢渣石作集料也可被碳化,碳化后钢渣砂、钢渣石混凝土强度高于天然砂、天然石混凝土强度,混凝土体积稳定性得到明显改善。     

碳酸化预处理对钢渣-水泥复合胶凝材料体积安定性及水化活性的影响

钢渣水化活性差，体积安定性不良限制了其作为辅助性胶凝材料的应用，但钢渣具有很好的碳酸化活性。本文在对钢渣进行预处理的过程中通过调整CO₂浓度及碳酸化时间，调控钢渣的碳酸化程度，分析了碳酸化对钢渣微观结构及固碳效果的影响，同时评价了碳酸化钢渣作为辅助性胶凝材料的可行性。结果表明：含30%(质量分数)钢渣的水泥砂浆试块3、28 d抗压强度较未掺钢渣水泥砂浆分别降低了43.2%和30.0%,净浆试块经压蒸试验后由于膨胀过大而溃散；CO₂浓度对钢渣的固碳量有显著的影响，高浓度(体积分数为99.9%)CO₂进行碳化养护3 min时钢渣固碳量就达到了3.67%。钢渣的体积安定性与碳酸化程度呈正相关，而过度碳酸化处理会降低其水化活性，掺加30%(质量分数)碳酸化预处理3、10 min钢渣的砂浆3 d抗压强度较掺加30%原始钢渣的砂浆分别提高了28.3%和15.8%。     

微生物提升钢渣胶凝材料安定性和强度的作用及机理

目前钢渣排放量、库存量大,但利用率不高,关键是安定性未能解决.本文研究提出了通过微生物矿化技术提升安定性和强度,研究了不同掺量微生物对钢渣中主要矿物相碳化反应速率的影响,测试了微生物掺量和钢渣粉比表面积对试件压蒸线性膨胀率和强度的影响,通过MIP和SEM分析试件孔隙率和微观形貌,并对微生物改性钢渣胶凝材料机理进行分析.结果 表明,微生物能提高钢渣中游离氧化物和硅酸盐矿物相碳化反应速率,提高矿化产物的强度.要使试样压蒸线性膨胀率降低至0.5‰以下,采用微生物添加剂后,试验所用钢渣粉比表面积可由565 m2/kg降低至360m2/kg.钢渣中掺入微生物可促进碳化过程中矿物相离子溶出和碳酸盐矿物生成,降低试件孔隙率,密实基体结构,从而提高钢渣胶凝材料试件的强度.微生物-钢渣胶凝材料制品强度可达40 MPa以上,其他物理性能均符合国家标准,在实际道路铺装工程应用中体积稳定性好,无泛碱现象,且利润优势显著,应用前景广阔.     

碳化MgO-CaO-粉煤灰-水泥四元组分制备砂浆的强度和微观结构

开发新型水泥和其它低碳胶凝材料是水泥工业CO2减排的有效途径。采用CO2养护,加速碳化活性MgO、CaO、粉煤灰和水泥四元组分配制的砂浆,制备低碳胶凝材料,研究碳化对砂浆力学性能和微观结构的影响。结果表明:在浓度为99%、压力为0.55 MPa的CO2气体条件下碳化处理3~9 h后,砂浆抗压强度提高了1.1~4.6倍。提高碳化温度、延长碳化时间均有利于砂浆强度的提高,且温度对砂浆强度的提高影响更为显著。碳化后生成大量碳化产物碳酸钙CaCO3和碳酸钙镁CaxMg1-xCO3,使得砂浆p H值降低、试件更加致密,砂浆试件中大孔数量明显减少,总孔隙率显著降低。     

复合组分调节材料对重构转炉钢渣胶凝性能的影响

采用钢铁企业自身排放的白渣和热闷渣为组分调节材料,在实验室内开展了转炉钢渣的高温重构试验,研究了组分调节材料组成及重构温度对转炉钢渣胶凝性能的影响.试验结果表明,转炉钢渣经高温重构后,胶凝活性得到了显著的提高,可达到甚至超过GB/T 20491-2006中所规定的一级钢渣粉的标准;相较处理温度和掺量,组分调节材料的比例对重构钢渣7d和28d的胶凝活性影响最为显著;综合7d和28d的活性指数,最佳的重构条件是组分调节材料中白渣的质量分数为60％～70％、重构温度为1000℃和复合组分调节材料的掺量为60％～70％.     

纳米SiO2对钢渣水泥基胶凝材料的影响

钢渣和水泥具有相似的矿物组成,可以作为一种潜在的胶凝材料,然而钢渣掺量较高时并不利于混凝土早期性能的发展。以钢渣质量分数为30%的钢渣水泥基胶凝材料为研究对象,探讨纳米SiO₂对其早期性能的影响。主要通过测量流动度、凝结时间和抗压强度评估物理力学性能,并利用微量热分析、X射线衍射(XRD)、差热分析(DSC-TG)等方法对掺有纳米SiO₂的钢渣水泥基胶凝材料的水化过程和水化产物进行分析。结果表明,当纳米SiO₂掺入的质量分数为3%时,纳米SiO₂可充分发挥火山灰活性,消耗大量Ca(OH)₂,同时由于纳米SiO₂颗粒的结晶成核作用和微集料填充作用,促进了钢渣和水泥的水化,水化初期的放热速率有所提高,从而提高钢渣水泥基胶凝材料的力学性能,28 d的抗压强度提高了14.0%。     

CaO和Na2SO4活化高P钢渣微粉—水泥胶凝材料的研究

高P钢渣含P量偏高,掺入高P钢渣微粉的钢渣—水泥胶凝材料凝结时间偏长,且早期强度过低,使其使用受到很大的限制。试验采用Ca O和Na2SO4作为高P钢渣的活化剂,并进行了一系列的试验研究。结果表明:(1)适量的Ca O可以缩短高P钢渣微粉—水泥胶凝材料凝结时间,提高其各龄期强度;(2)Na2SO4对高P钢渣微粉—水泥胶凝材料凝结时间无显著影响,适量Na2SO4可以提高高P钢渣微粉—水泥胶凝材料的1d、3d强度,过量Na2SO4会降低高P钢渣微粉—水泥胶凝材料28d强度;(3)作为高P钢渣的活化剂,Ca O的适宜掺量为4%,Na2SO4的适宜掺量1%。     

养护温度对凝灰岩基胶凝材料力学性能的影响机理

凝灰岩是经过火山喷出散落在地面,经过压结和水化胶结固化而形成的一种火山灰碎屑岩,具有一定的火山灰活性。本文研究养护温度对凝灰岩基胶凝材料力学性能的影响,并借助FTIR、TG、SEM和MIP等对凝灰岩基胶凝材料水化产物的微观结构进行分析。结果表明,提高养护温度对凝灰岩基胶凝材料的力学性能具有一定的增强作用,提高养护温度不仅能提高早期强度,还可以提高后期强度,凝灰岩基胶凝材料的最佳养护温度为50 ℃。提高养护温度后凝灰岩基胶凝材料中没有生成新的水化产物,AFt和C-S-H等水化产物含量增加,Ca(OH)₂的含量减少。提高养护温度有利于增加凝胶孔和过渡孔占比,细化孔径结构,降低孔隙率,提高基体结构的致密度。     

铝酸盐水泥对石膏基复合胶凝材料的改性研究

研究了铝酸盐水泥对石膏基复合胶凝材料的力学性能、体积稳定性及耐水性能的影响。对复合胶凝材料进行了微观结构分析研究,认为铝酸盐水泥的添加使得复合胶凝材料硬化后结构致密,提高了晶粒接触点的热力学稳定性,减少了与水作用时的融蚀现象。其最佳掺量应在20%左右。     

Sapindaceae,cyanolipids, and bugs

Scentless plant bugs (Heteroptera: Rhopalidae) are so named because adults of the Serinethinae have vestigial metathoracic scent glands. Serinethines are seed predators of Sapindales, especially Sapindaceae that produce toxic cyanolipids. In two serinethine species whose ranges extend into the southern United States,Jadera haematoloma andJ. sanguinolenta, sequestration of host cyanolipids as glucosides renders these gregarious, aposematic insects unpalatable to a variety of predators. The blood glucoside profile and cyanogenesis ofJadera varies depending on the cyanolipid chemistry of hosts, and adults and larvae fed golden rain tree seeds (Koelreuteria paniculata) excrete the volatile lactone, 4-methyl-2(5H)-furanone, to which they are attracted.Jadera fed balloon vine seeds (Cardiospermum spp.) do not excrete the attractive lactone. Loss of the usual heteropteran defensive glands in serinethines may have coevolved with host specificity on toxic plants, and the orientation ofJadera to a volatile excretory product could be an adaptive response to save time.Mention of a commercial product does not consititute an endorsement by the USDA.     

2008～2009年世界塑料工业进展

收集了2008年7月～2009年6月世界塑料工业的相关资料,介绍了2008～2009年国外塑料工业的发展情况,提供了世界塑料产量、消费量及全球各类树脂的需求量及产能情况。按通用热塑性树脂(聚乙烯、聚丙烯、聚苯乙烯、聚氯乙烯、ABS树脂)、工程塑料(尼龙、聚碳酸酯、聚甲醛、热塑性聚酯、聚苯醚)、特种工程塑料(聚苯硫醚、液晶聚合物、聚醚醚酮)、通用热固性树脂(酚醛、聚氨酯、环氧树脂、不饱和聚酯树脂)不同品种的顺序,对树脂的产量、消费量、供需状况及合成工艺、产品应用开发、树脂品种的延伸及应用的进一步扩展等技术作了详细介绍。     

Insect antifeedant properties of anthranoids from the genusVismia

Vismiones and ferruginins, representatives of a new class of lypophilic anthranoids from the genusVismia were found to inhibit feeding in larvae of species ofSpodoptera, Heliothis, and inLocusta migratoria.     

Direct observation of freeze-thaw instability of latex coatings via high pressure freezing and cryogenic SEM

Despite its industrial importance, the subject of freeze-thaw (F/T) stability of latex coatings has not been studied extensively. There is also a lack of fundamental understanding about the process and the mechanisms through which a coating becomes destabilized. High pressure (2100 bar) freezing fixes the state of water-suspended particles of polymer binder and inorganic pigments without the growth of ice crystals during freezing that produce artifacts in direct imaging scanning electron microscopy (SEM) of fracture surfaces of frozen coatings. We show that by incorporating copolymerizable functional monomers, it is possible to achieve F/T stability in polymer latexes and in low-VOC paints, as judged by the microstructures revealed by the cryogenic SEM technique. Particle coalescence as well as pigment segregation in F/T unstable systems are visualized. In order to achieve F/T stability in paints, latex particles must not flocculate and should provide protection to inorganic pigment and extender particles. Because of the unique capabilities of the cryogenic SEM, we are able to separate the effects of freezing and thawing, and study the influence of the rate of freezing and thawing on F/T stability. Destabilization can be caused by either freezing or thawing. A slow freezing process is more detrimental to F/T stability than a fast freezing process; the latter actually preserves suspension stability during freezing. Presented at the 82nd Annual Meeting of the Federation of Societies for Coatings Technology, October 27–29, 2004 in Chicago, IL. Tied for first place in The John A. Gordon Best Paper Competition.     

Many Drugs of Abuse May Be Acutely Transformed to Dopamine,Norepinephrine and Epinephrine In Vivo

It is well established that a wide range of drugs of abuse acutely boost the signaling of the sympathetic nervous system and the hypothalamic–pituitary–adrenal (HPA) axis, where norepinephrine and epinephrine are major output molecules. This stimulatory effect is accompanied by such symptoms as elevated heart rate and blood pressure, more rapid breathing, increased body temperature and sweating, and pupillary dilation, as well as the intoxicating or euphoric subjective properties of the drug. While many drugs of abuse are thought to achieve their intoxicating effects by modulating the monoaminergic neurotransmitter systems (i.e., serotonin, norepinephrine, dopamine) by binding to these receptors or otherwise affecting their synaptic signaling, this paper puts forth the hypothesis that many of these drugs are actually acutely converted to catecholamines (dopamine, norepinephrine, epinephrine) in vivo, in addition to transformation to their known metabolites. In this manner, a range of stimulants, opioids, and psychedelics (as well as alcohol) may partially achieve their intoxicating properties, as well as side effects, due to this putative transformation to catecholamines. If this hypothesis is correct, it would alter our understanding of the basic biosynthetic pathways for generating these important signaling molecules, while also modifying our view of the neural substrates underlying substance abuse and dependence, including psychological stress-induced relapse. Importantly, there is a direct way to test the overarching hypothesis: administer (either centrally or peripherally) stable isotope versions of these drugs to model organisms such as rodents (or even to humans) and then use liquid chromatography-mass spectrometry to determine if the labeled drug is converted to labeled catecholamines in brain, blood plasma, or urine samples.     

Ethanol and (−)-α-Pinene: Attractant Kairomones for Bark and Ambrosia Beetles in the Southeastern US

In 2002–2004, we examined the flight responses of 49 species of native and exotic bark and ambrosia beetles (Coleoptera: Scolytidae and Platypodidae) to traps baited with ethanol and/or (−)-α-pinene in the southeastern US. Eight field trials were conducted in mature pine stands in Alabama, Florida, Georgia, North Carolina, and South Carolina. Funnel traps baited with ethanol lures (release rate, about 0.6 g/day at 25–28°C) were attractive to ten species of ambrosia beetles (Ambrosiodmus tachygraphus, Anisandrus sayi, Dryoxylon onoharaensum, Monarthrum mali, Xyleborinus saxesenii, Xyleborus affinis, Xyleborus ferrugineus, Xylosandrus compactus, Xylosandrus crassiusculus, and Xylosandrus germanus) and two species of bark beetles (Cryptocarenus heveae and Hypothenemus sp.). Traps baited with (−)-α-pinene lures (release rate, 2–6 g/day at 25–28°C) were attractive to five bark beetle species (Dendroctonus terebrans, Hylastes porculus, Hylastes salebrosus, Hylastes tenuis, and Ips grandicollis) and one platypodid ambrosia beetle species (Myoplatypus flavicornis). Ethanol enhanced responses of some species (Xyleborus pubescens, H. porculus, H. salebrosus, H. tenuis, and Pityophthorus cariniceps) to traps baited with (−)-α-pinene in some locations. (−)-α-Pinene interrupted the response of some ambrosia beetle species to traps baited with ethanol, but only the response of D. onoharaensum was interrupted consistently at most locations. Of 23 species of ambrosia beetles captured in our field trials, nine were exotic and accounted for 70–97% of total catches of ambrosia beetles. Our results provide support for the continued use of separate traps baited with ethanol alone and ethanol with (−)-α-pinene to detect and monitor common bark and ambrosia beetles from the southeastern region of the US.