聚丙烯纤维增强蒸压加气混凝土防治抹灰裂缝研究

蒸压加气混凝土砌块被广泛用作墙体建筑、内部隔断等建筑材料中,但仍存在强度低、吸水率大及体积变形系数大等不足,砌筑成墙体时容易出现裂缝。为改善上述缺陷,在蒸压加气混凝土中添加聚丙烯(PP)纤维,并研究了PP纤维添加量对蒸压加气混凝土砌块力学性能的影响。试验发现,在蒸压加气混凝土砌块中添加PP纤维可以减少蒸压加气混凝土的干燥收缩,提高其抗压强度和劈裂抗拉强度,改善其韧性,有助于改善将其用作填充墙时抹灰裂缝的产生。     

蒸压加气混凝土砌块墙体施工质量控制

蒸压加气混凝土砌块墙体施工是一种新型材料使用方法,其中蒸压加气混凝土砌块是一种较新的墙体建筑材料,与已有的的建筑材料相比,在性能上具有独特优势.施工中主要使用水泥、砂石、石灰、粉煤灰等进行搅拌和蒸压,形成多孔轻质砌块.文章结合工程实例,简要阐述了墙体施工中蒸压加气混凝土砌块材质的特点,提出了蒸压加气混凝土砌块墙体的施工...     

如何防止加气混凝土墙体空鼓开裂的措施探讨

加气混凝土墙体空鼓开裂作为混凝土施工中常见的问题,对其在工程施工中的推广应用有着十分不利的作用和影响,也是混凝土施工研究和关注的重要内容之一。本文在对加气混凝土施工特点分析基础上,针对加气混凝土墙体空鼓开裂原因,对其防止措施进行了研究与分析,以供参考。     

加气混凝土砌块墙面抹灰层空裂原因及解决方法

加气混凝土砌块具有质轻、隔热、保温、防火、可锯、可刨等多种特性。但在加气混凝土砌块墙面上抹灰施工往往会出现裂缝、空鼓甚至大面积脱落等现象。为解决好此类问题,根据多年外墙保温、防裂工程中的经验,对加气混凝土砌块墙面抹灰层空裂原因进行分析探讨,并提出解决方案。1加气混凝土砌块墙面抹灰层空裂产生的主要原因1.1抹灰砂浆自收缩引起开裂抹灰砂浆收缩是引起裂缝最常见的因素之一,主要包括化学减缩、干燥收缩、自收缩、温度收缩及塑性收缩。化学减缩,又称水化收缩,水泥水化会产生水化热,使固相体积增加,但水泥-水体系的绝对体积减…     

粉煤灰加气混凝土建筑过关

由齐齐哈尔建材厂、中国建筑东北设计院和西林吉林业建筑工程公司联合承担的粉煤灰加气混凝土承重建筑——漠河县北极星宾馆,最近通过了技术鉴定。该建筑为五层,建筑面积2200平方米,主体全部采用齐齐哈尔建材厂生产的加气混凝土。实践证明,该建筑采用36公分厚的加气混凝土外墙,完全可以达到87公分厚红砖外墙的保温效果,而且建筑结构安     

蒸压加气混凝土砌体薄砌法工艺分析

薄砌法是一种采用专用黏结剂替代传统砂浆进行蒸压加气混凝土砌块墙体砌筑的施工方法,主要特点是灰缝厚为2～4mm。结合工程实例,阐述了蒸压加气混凝土砌体薄砌法施工工艺、操作要点、质量控制措施等。实践证明,薄砌法工艺相比传统工艺具有提高灰缝饱满度、避免顶砌问题、填充墙与结构连接更可靠、更加节能和环保的优势。     

加气混凝土建筑体系研讨会在鞍山市召开

为总结交流经验,完善加气混凝土建筑技术、合理发展混凝土建筑体系,进一步开拓市场,推动墙体材料改革,促进新型墙体材料的发展,由中国新型建筑材料公司、中国加气混凝土协会、中国建材工业技术经济和管理现代化研究会——新型建材专业委员会联合召开的加气混凝土建筑体系研讨会,于1991年4月18日～21在鞍山市召开。参加会议的有华北、     

巨龙水泥集团粉煤灰加气砼生产工艺及其砌筑

江苏巨龙水泥集团巨龙实业公司粉煤灰加气混凝土厂 ,是市墙改定点厂之一 ,支持百万元上了年产 5万ｍ3加气混凝土砌块厂 ,被徐州誉为“迈向 2 1世纪的新型墙体节能材料” ,受到工业和民用建筑界青睐。1　粉煤灰加气混凝土生产工艺1.1　粉煤灰加气混凝土生产线石灰、石膏粗碎、细     

蒸压条件对固硫灰加气混凝土性能影响研究

蒸压条件对固硫灰加气混凝土的性能可能有一定的影响。本实验在固硫灰加气混凝土最佳钙硅比的基础上,调节蒸压温度和压强,探究蒸压条件对加气混凝土水化产物、干密度、强度和干缩性能的影响,并与粉煤灰加气混凝土进行对比研究。结果显示,在165℃、0.65 MPa的蒸压条件下,固硫灰加气混凝土的干密度和抗压强度最高、干缩程度最小,体积稳定性最高;在175℃、1.00 MPa的蒸压条件下,粉煤灰加气混凝土的干密度和抗压强度最高、干缩程度最小,体积稳定性最高;在165~175℃、0.65~1.00MPa时,固硫灰加气混凝土的性能较优于粉煤灰加气混凝土,且达到相近性能时,固硫灰加气混凝土所需的蒸压温度较低。     

加气混凝土研究现状及发展展望

加气混凝土是一种常用于节能保温建筑用墙体的新型轻质混凝土,其性能取决于原材料的种类、养护制度等多方面因素。本文综述了国内外近年来对加气混凝土在胶凝材料的种类、外加剂的选用、养护方式、加气混凝土的结构、水化产物、物理性能等方面的研究进展,并针对"十二五"期间加气混凝土的发展状况,阐述了加气混凝土今后的发展方向及研究重点。     

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.     

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.     

Methyl 2,4,6-decatrienoates Attract Stink Bugs and Tachinid Parasitoids

Halyomorpha halys (Stål) (Pentatomidae), called the brown marmorated stink bug (BMSB), is a newly invasive species in the eastern USA that is rapidly spreading from the original point of establishment in Allentown, PA. In its native range, the BMSB is reportedly attracted to methyl (E,E,Z)-2,4,6-decatrienoate, the male-produced pheromone of another pentatomid common in eastern Asia, Plautia stali Scott. In North America, Thyanta spp. are the only pentatomids known to produce methyl 2,4,6-decatrienoate [the (E,Z,Z)-isomer] as part of their pheromones. Methyl 2,4,6-decatrienoates were field-tested in Maryland to monitor the spread of the BMSB and to explore the possibility that Thyanta spp. are an alternate host for parasitic tachinid flies that use stink bug pheromones as host-finding kairomones. Here we report the first captures of adult and nymph BMSBs in traps baited with methyl (E,E,Z)-2,4,6-decatrienoate in central Maryland and present data verifying that the tachinid, Euclytia flava (Townsend), exploits methyl (E,Z,Z)-2,4,6-decatrienoate as a kairomone. We also report the unexpected finding that various isomers of methyl 2,4,6-decatrienoate attract Acrosternum hilare (Say), although this bug apparently does not produce methyl decatrienoates. Other stink bugs and tachinids native to North America were also attracted to methyl 2,4,6-decatrienoates. These data indicate there are Heteroptera in North America in addition to Thyanta spp. that probably use methyl 2,4,6-decatrienoates as pheromones. The evidence that some pentatomids exploit the pheromones of other true bugs as kairomones to find food or to congregate as a passive defense against tachinid parasitism is discussed.     

2007～2008年世界塑料工业进展

收集了2007年7月～2008年6月世界塑料工业的相关资料,介绍了2007～2008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、不饱和聚酯树脂、环氧树脂)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.     

2005～2006年国外塑料工业进展

收集了2005年7月～2006年6月国外塑料工业的相关资料,介绍了2005—2006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生产量以及各国塑料制品的进出口情况。作为对比,介绍了中国塑料的生产情况。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（聚酰胺、聚碳酸酯、聚甲醛、热塑性聚酯、聚苯醚）、通用热固性树脂（酚醛、聚氨酯、不饱和树脂、环氧树脂）、特种工程塑料（聚苯硫醚、液晶聚合物、聚醚醚酮）的品种顺序,对树脂的产量、消费量、供需状况及合成工艺、产品开发、树脂品种的延伸及应用的扩展作了详细的介绍。