共混乳液改性水泥砂浆的氯离子扩散系数

研究了共混乳液组成及其薄膜的力学性能与共混乳液改性水泥砂浆氯离子扩散系数的关系.试验结果发现,少量氯偏乳液与丁苯胶乳共混,可以显著降低改性砂浆的氯离子扩散系数,丙苯乳液与丁苯胶乳共混,当质量比为3∶2～4∶1时,砂浆的氯离子扩散系数较低.聚合物乳液改性砂浆的氯离子扩散性与聚合物本身的拉伸强度和断裂伸长率有关.聚合物本身的拉伸强度越低、断裂伸长率越大,则改性砂浆的氯离子扩散系数越小.当共混乳液薄膜的断裂伸长率从200%～300%增大到800%以上时,相应改性砂浆的氯离子扩散系数由(10～15)×10-12m2/s降低到(3～4)×10-12m2/s.     

聚合物改性自流平水泥砂浆的力学性能

研究了不同掺量的丁苯乳液(SBR)、丙烯酸酯乳液(PAE)和苯丙乳液(SAE)对自流平砂浆不同龄期下的抗压、抗折强度的影响．结果表明,在新拌自流平砂浆流动度相同的条件下,3种聚合物改性砂浆的3d抗折、抗压强度随聚合物掺量的增加均表现出抛物线型变化趋势．SBR掺量为10％～20％(质量分数)的改性砂浆3d抗压、抗折强度分别可达18～20MPa和4～6MPa．同时发现,3种聚合物乳液改性自流平砂浆的7,28d抗压强度均随聚合物掺量的增加而降低,而抗折强度则在一定范围内波动．     

聚合物改性结构修补材料设计及性能研究

利用实验室新开发的聚合物乳液,通过正交试验对比不同水胶比、乳液及乳液掺量对修补砂浆工作、力学性能的影响.并通过空白对照、XRD和SEM试验,分析了乳液对修补砂浆的改性效果及增韧的作用机理.研究结果表明,改性丙烯酸树脂乳液较聚丙烯酸酯乳液及环氧树脂乳液对修补砂浆工作及力学性能更有利.正交试验得到的乳液改性修补砂浆初始流动度达335mm,28min可初凝,4h抗压强度达到43.8MPa、抗折强度达到6.3MPa,后期强度稳定增长,28d抗压强度达到83.5MPa、抗折强度达到23MPa.同时正交试验得到的修补砂浆较不加乳液时抗冲击和耐磨性能分别提高16.5倍和29.3％,且早期收缩更小.XRD和SEM试验分析结果表明,聚合物乳液失水凝聚在砂浆内部形成了区域连续的空间网状结构,这种结构有效分散了砂浆内部的应力集中,增强了砂浆的韧性,提高了砂浆的力学性能.     

聚合物改性砂浆的性能研究

针对铁路隧道渗漏水病害,采用聚合物乳液改性砂浆对其进行封堵。确定了聚合物乳液的最佳掺加工艺并对聚合物乳液改性砂浆的力学性能、防水性能进行了研究,结果表明,聚合物乳液在降低砂浆抗压强度的同时可显著提高砂浆的抗折强度。掺加适量聚合物乳液可以改善砂浆的防水性能,与空白试样相比,当聚合物乳液掺量为20%时,其抗渗压力提高了200%。     

桥面用丁苯乳液改性水泥砂浆的力学性能

用德国标准和规范研究了丁苯乳液D623对桥面用水泥砂浆力学性能的改进效果;丁苯乳液D623对砂浆有良好的减水作用,对提高抗折强度和粘结抗拉强度也有显著作用,并可大幅度降低压折比、提高折弹比,综合抗压强度、抗折强度、抗拉粘结强度和弹性模量等力学性能,桥面用改性砂浆的聚合物D63掺量范围为10.1%～17.5%。     

聚合物改性盾构法同步注浆用水泥砂浆的研究

通过掺加苯丙乳液、纯丙乳液、乳化沥青对超高掺量粉煤灰盾构法同步注浆用水泥砂浆进行改性;并研究了聚合物乳液对砂浆的工作性、力学性能、耐水性能的影响;试验结果表明:聚合物乳液对盾构法同步注浆用水泥砂浆的改性效果显著;丙乳液(SAE)和乳化沥青(RL)对提高砂浆的折压比要优于纯丙乳液(PAE);当聚合物掺量超过10%时,不论是对砂浆和易性、力学性能还是耐水性能的改性效果都减弱.     

减水剂及加料顺序对乳液改性砂浆性能的影响

分析了萘系减水剂及苯丙乳液的加料顺序对乳液改性砂浆性能的影响.结果表明:未掺减水剂和等水灰比条件下,乳液改性砂浆的抗折、抗压强度均低于未掺乳液的对比砂浆;在等流动度条件下,掺减水剂的乳液改性砂浆除同掺法7 d外,3 d后各龄期抗折强度均高于未掺乳液的对比试样;无论是否掺加减水剂,同掺法乳液改性砂浆7 d抗折、抗压强度均较后掺法低,而其28 d抗折、抗压强度则较高;后掺法的掺减水剂乳液改性砂浆黏结强度小于同掺法;而对于未掺减水剂的情况,两种掺加方式下乳液改性砂浆28 d黏结强度基本没有差别.总而言之,同掺法工艺更简单,且所得砂浆的28 d力学性能更好.     

道路用聚合物改性水泥砂浆修补材料的研制

研制一种道路修补砂浆。通过比较硅酸盐水泥和铝酸盐水泥不同配比时的凝结时间和砂浆力学性能,初步确定了具有较高早期强度的复配水泥砂浆的配比。在复配水泥砂浆中掺加丁苯聚合物乳液进一步改性。结果表明:改性砂浆早期抗压和抗折强度较低,后期强度有较大持续的增长;聚合物乳液能提高改性砂浆的抗折强度和粘接强度,降低压折比;随着聚合物乳液掺量的增加,耐磨度先下降,后提高。综合考虑,在铝酸盐水泥中掺加20%的硅酸盐水泥,聚合物乳液掺量为5%～10%,水灰比0.26～0.30,砂灰比2.0～3.0时,可得到一种较为理想的道路修补材料。     

丁苯乳液改性水泥砂浆的力学性能与体积密度

在固定水灰比为0．4且改变养护条件下,研究了丁苯乳液掺量对改性水泥砂浆体积密度和力学性能的影响,并对改性水泥砂浆力学性能与体积密度间的相互关系进行分析．结果表明：当丁苯乳液掺量在0～20％（质量分数,下同）之间变化时,改性水泥砂浆体积密度在8％丁苯乳液掺量时最低;改性水泥砂浆的抗压强度和抗折强度在0～8％丁苯乳液掺量之间随丁苯乳液掺量的增加而下降;在丁苯乳液掺量小于10％时,改性水泥砂浆的动弹性模量随着丁苯乳液掺量的增加而减小;当丁苯乳液掺量小于10％时,改性水泥砂浆抗压强度、动弹性模量均与体积密度之间存在着较好的线性对应关系,而抗折强度与其相关性则不明显．     

桥面用丁苯乳液改性水泥砂浆物理性能的研究

通过测定新拌砂浆保水性、含气率,硬化砂浆孔隙率、孔径分布、断面形貌以研究丁苯乳液D623对砂浆物理性能的改性效果,丁苯乳液D623对砂浆有良好的保水和引气作用,可使砂浆体积密度降低,孔径分布改变;聚合物成膜后形成网状结构,与水泥水化产物相互穿透;硬化砂浆的孔隙率与新拌砂浆的含气率没有对应关系,与新拌砂浆的体积密度反倒有一定的关系;砂浆抗压强度、抗折强度和弹性模量均与孔隙率、体积密度有对应关系,而粘结抗拉强度与它们的关系则不明确。     

PVC／ABS／CPE共混体系的相容性与性能研究

聚氯乙烯（PVC）／丙烯晴－丁二烯－苯乙烯共聚物（ABS）共混体系为不相容体系。如入增容剂氯化聚乙烯（CPE）后,相容性明显提高,为部分相容;通过改变ABS用量可调节PVC／ABS／CPE共混体系的韧性;就不同ABS含量对PVC／ABS／CPE共混体系的相容性、拉伸强度、弯典强度、冲击强度、硬度、耐热性能以及耐水性能的影响进行了研究,结果表明,随着ABS含量的增加,PVC／ABS／CPE共混体系的拉伸强度、耐热性、吸水性略有增加,冲击强度有较大提高,而弯曲强度略有下降;当ABS含量超过30％（质量分数）后,共混体系的冲击强度基本上与ABS的相当;ABS含量低于70％（质量分数）的共混体系的表面硬度高于ABS的硬度,基本上与硬质PVC的接近。     

“双掺法”高性能混凝土在提高耐久性方面的应用

以福宁高速公路杨家溪 1#、2 #特大桥为例 ,阐述以“双掺”法 (即掺粉煤灰和高效减水剂 )配制高性能砼在提高跨海湾桥梁防腐抗渗等耐久性方面的应用     

丁苯橡胶改善高铝水泥石

本文研究了丁苯橡胶对高铝水泥石物理力学性能的改善。从凝结时间及初期水化热研究了丁苯橡胶对高铝水泥水化过程的影响。用扫描电镜观察分析了高铝水泥石微观结构形态的改变。     

洋里污水处理厂办公综合楼

通过对洋里污水处理厂办公楼建筑设计恩路的分析,提出了现代建筑三种根本性设计手法。     

乳胶改性的碳纤维增强砂浆

本文介绍了乳胶改性对含有硅灰的碳纤维增强砂浆之性能特征的影响。在国外的研究中使用了两种苯乙烯-丁二烯乳胶。据观测,乳胶改性提高了胶结料与碳纤维的粘结力。乳胶改性的纤维水泥复合物同未改性者相比较,其吸水率和干缩率均降低了,而弯曲延性则提高了。乳胶改性的碳纤维增强砂浆具有较高的抗冻性,而且在耐酸性方面有明显提高。     

Energy conservation in 29 historic school buildings in Palermo

In the rehabilitation programme of 29 old school buildings in Palermo energy conservation measures were included.

By means of simulation models, several options were examined, ranging from solar active systems to properly designed heating systems.

The study showed, because of the characteristics of the buildings, their occupation pattern and the mild climate, that the most cost-effective option was a properly controlled heating system.

Italian energy conservation building regulations were shown to be scarcely suitable to the cases examined, and a certain resistance to technological innovation was found in some designers, especially the older ones.     

天然气代石脑油制煤气的质量控制

用天然气代替石脑油在富气催化工艺下生产城市煤气，由于两种原料性质的不同，用天然气为原料时得到的产品气不能完全符合城市煤气的标准，因此需要对产品气处理调整以符合标准，生产合格的城市煤气。     

溶解度参数分析PVC共混物相容性

介绍了应用三维溶解度参数预测聚氯乙烯与均聚物、共聚物、杂链聚合物的共混物的相容性。     

Characterization and reduction of formaldehyde emissions from a low-VOC latex paint

The patterns of formaldehyde emission from a low volatile organic compound (VOC) latex paint applied to gypsum board were measured and analyzed by small environmental chamber tests. It was found that the formaldehyde emissions resulted in a sharp increase of chamber air formaldehyde concentration to a peak followed by transition to a long-term slow decay. A semi-empirical first-order decay in-series model was developed to interpret the chamber data. The model characterized the formaldehyde emissions from the paint in three stages: an initial "puff" of instant release, a fast decay, and a final stage of slow decay controlled by a solid-phase diffusion process that can last for more than a month. The model was also used to estimate the peak concentration and the amount of formaldehyde emitted during each stage. The formaldehyde sources were investigated by comparing emission patterns and modeling outcomes of different paint formulations. The biocide used to preserve the paint was found to be a major source of the formaldehyde. Chamber test results demonstrated that replacing the preservative with a different biocide for the particular paint tested resulted in an approximate reduction of 55% of formaldehyde emissions. But the reduction affected only the third-stage long-term emissions.     

Lead content in household paints in India

Lead and its compounds are used in paints not only to impart colour but also to make it durable, corrosion resistant and to improve drying. Adverse health impacts of lead especially on children have led countries to restrict or ban its use in paints. While U.S. and other developed countries instituted measures to limit the use of lead in paints, some developing countries including India have failed to regulate their lead content. The present study was undertaken to determine the levels of lead in new latex (water-based) and enamel paints (oil-based) intended for residential use in India. A total of 69 paint samples (38 latex and 31 enamel samples) from six of the most popular brands were analysed for lead concentrations. While all latex paint samples contained low levels of lead, (i.e., well below 600 ppm as regulated by United States' Consumer Products Safety Commission) the enamel paint samples of all but one brand contained significant concentrations of lead, ranging up to 140,000 ppm. In fact 84% of the enamel paints tested exceeded 600 ppm whereas only 38 % of all samples (including latex and enamel types) exceeded this regulatory level.