纳米SiO2改性及纳米SiO2聚氨酯密封胶的制备

为了改善纳米SiO2粒子的分散性,提高纳米SiO2在聚氨酯基体中的相容性,制备性能更佳的密封胶,利用甲苯二异氰酸酯(TDI)与纳米SiO2表面的羟基反应,缩合聚醚,在纳米SiO2粒子表面接枝上长链有机物,并用原位聚合法制得纳米SiO2/聚氨酯密封胶.分散性研究表明,改性后的纳米粒子在有机溶剂中能够很好分散.采用原位聚合法制备的纳米SiO2/聚氨酯密封胶的伸长率、拉伸强度、邵氏硬度有明显提高,能同时达到增强增韧的效果.当纳米SiO2添加量在5%左右时密封胶的综合性能较佳.     

Characteristics of cement mortar with nano-SiO2 particles

The properties of cement mortars with nano-SiO₂ were experimentally studied. The amorphous or glassy silica, which is the major component of a pozzolan, reacts with calcium hydroxide formed from calcium silicate hydration. The rate of the pozzolanic reaction is proportional to the amount of surface area available for reaction. Therefore, it is plausible to add nano-SiO₂ particles in order to make high-performance concrete. The experimental results show that the compressive strengths of mortars with nano-SiO₂ particles were all higher than those of mortars containing silica fume at 7 and 28 days. It is demonstrated that the nano-particles are more valuable in enhancing strength than silica fume. In addition, the continuous hydration progress was monitored by scanning electron micrograph (SEM) observation, by examining the residual quantity of Ca(OH)₂ and the rate of heat evolution. The results of these examinations indicate that nano-scale SiO₂ behaves not only as a filler to improve microstructure, but also as an activator to promote pozzolanic reaction.     

掺纳米SiO2高性能混凝土研究进展

纳米材料的问世及其在诸多工程领域的成功应用,为改善传统混凝土的性能开辟了新途径.纳米SiO2粉体因其特殊的表面与界面效应以及来源广泛、经济性好等特征,成为目前纳米混凝土研究中最常见的纳米改性剂.综述了目前国内外掺纳米SiO2高性能混凝土的制备工艺、工作性能、力学性能和耐久性等相关研究;并结合本研究组的试验成果,分析了纳米SiO2粉体掺量对纳米混凝土强度的影响规律以及纳米材料对混凝土强度的改善机理;概述了纳米SiO2对混凝土自收缩性能、抗氯离子渗透性能、抗冻耐久性的影响,并对掺纳米SiO2高性能混凝土的未来研究方向提出了积极建议.     

纳米TiO2+SiO2改性外墙涂料的耐候性研究

主要研究了利用TiO2对紫外线的吸收散射作用和纳米SiO2对紫外光的强反射作用改性外墙乳胶漆,以提高外墙乳胶漆的耐候性。     

环氧树脂基纳米SiO2复合材料制备研究

研究了纳米SiO2粒子用量对环氧树脂基纳米复合材料性能的影响、纳米粒子分散状况及所得复合材料的物理和化学性能，分析了纳米SiO2对环氧树脂的改性机理。     

改性纳米SiO2对再生沥青胶结料性能的影响

为提高再生沥青的再生效果,文中采用RA-F0110型再生剂作为A型再生剂和OP-900型再生剂作为B型再生剂对旧沥青进行再生;采用硅烷偶联剂KH-550和KH-570对纳米SiO2进行有机化表面改性;对比不同速率、不同搅拌时间、不同静置时间下纳米再生沥青的PG高温分级温度,确定纳米再生沥青的制备方法;对比添加不同种类不同掺量再生剂后再生沥青的PG连续分级确定再生剂的种类和掺量;对比不同纳米SiO2掺量下纳米再生沥青的PG连续分级确定纳米材料的掺量。试验表明：纳米SiO2在表面改性后团聚现象减少。纳米粒子被包覆,所以纳米粒子尺寸增大导致单个粒子的比表面积明显减小,纳米SiO2在沥青中更加稳定,采用KH-550表面改性剂的效果优于KH-570。选用A型再生剂的再生沥青的再生效果优于选用B型再生剂的再生沥青。在相同再生剂掺量下,添加一定比例的纳米SiO2,纳米再生沥青PG连续分级的高低温服务范围更宽广。当纳米材料的掺量为5%,A型再生剂掺量为15%时,纳米再生沥青胶结料的性能指标达到最佳。     

纳米二氧化硅在混凝土中的应用研究进展

纳米材料在诸多领域得到了成功运用,为改善混凝土的性能提供了新思路。纳米Si O2因其极强的火山灰活性、晶核作用和微集料填充效应可以显著改善混凝土性能,成为目前纳米材料在水泥混凝土领域的关注热点。综述了掺纳米Si O2混凝土的应用研究现状,概述了纳米Si O2对混凝土力学性能、工作性以及耐久性能的影响,并就其作用机理进行了分析,还对目前纳米Si O2在实际应用中存在的问题和研究方向提出了合理建议。     

纳米SiO2改性再生砂浆性能研究

采用水泥净浆、纳米SiO2、水泥净浆和纳米SiO2三种强化工艺对再生骨料进行处理,并对比分析。结果表明,纳米SiO2强化后的再生骨料吸水率为2.4%,压碎指标为4%。当再生骨料替代率为40%时,纳米SiO2强化后的再生砂浆7d抗折强度达到26.72MPa,28d抗折强度达到34.04MPa;7d抗压强度达到57.55MPa,28d抗压强度达到68.46MPa;冻融循环50次时质量损失率下降,相对动弹性模量提高,抗冻性能明显改善。     

矿粉对沥青胶浆的性质影响及作用机理

利用常规分析方法及流变测试技术,对普通石油沥青胶浆与SBS改性沥青胶浆进行性能评价和机理探讨.试验发现,沥青胶浆的力学强度和黏弹性变化源于其组成之间的相互作用,2种沥青胶浆在黏弹性组成上有差异,并导致不同的应力响应特点;在高温高频状态下,沥青胶浆内部损耗行为随着粉胶比的增加而提高,胶浆体系更容易被破坏;从沥青胶浆的结构稳定性和损耗特性入手,如相位角的变化,可以更好地研究矿粉对沥青胶浆的影响机制;可利用多应力重复蠕变回复试验中的不可回复柔量差,进行沥青胶浆的最大粉胶比判断.     

纳米SiO2对水泥饰面砂浆性能的影响

研究了纳米SiO2改性水泥饰面砂浆的性能,同时利用环境扫描电镜对砂浆的微观结构进行分析.结果表明,纳米SiO2掺量为1.5%～2.5%时,砂浆的抗压、抗折强度和拉伸粘结强度最大增幅均超过60%;纳米SiO2掺量为0.5%～1.5%时,毛细孔吸水率可降低约40%;纳米SiO2掺量为1.0%～3.0%时,抗泛碱性明显改善;纳米SiO2掺量为0.5%～3.0%时,砂浆耐沾污性优于基准砂浆.纳米SiO2能细化砂浆的孔结构和水化产物Ca(OH)2晶体尺寸,使砂浆更致密.     

纳米SiO2复合环氧树脂/改性胺密封胶的研制

以环氧树脂、改性胺、活性稀释剂、邻苯二甲酸二异辛酯、液体丁腈橡胶及纳米SiO2为原料制备密封胶。讨论原料配比、配合剂用量对密封胶性能的影响。结果表明,环氧树脂与改性胺等摩尔配比,DIOP为环氧树脂和改性胺总质量的4%、活性稀释剂为6%、液体丁腈橡胶为5%、纳米SiO2为6%时,研制的密封胶性能最优。     

Influence of nano-SiO2 addition on properties of hardened cement paste as compared with silica fume

The influence of nano-SiO₂ (NS) addition on properties of hardened cement paste (hcp) as compared with silica fume (SF) has been studied through measurement of compressive and bond strengths of hcp, and by XRD and SEM analysis. Results indicated that the influence of NS and SF on consistency and setting time of fresh cement paste showed different. NS made cement paste thicker and NS accelerated the cement hydration process. Compressive strengths of hcp and bond strengths of paste–aggregate interface incorporating NS were obviously higher than those incorporating SF, especially at early ages. And with increasing the NS content, the rate of bond strength increase was more than that of their compressive strength increase. With 3% NS added, NS digested calcium hydroxide (CH) crystals, decreased the orientation of CH crystals, reduced the crystal size of CH gathered at the interface and improved the interface more effectively than SF. The results suggest that with a small amount of added NS, the CH crystals at the interface between hcp and aggregate at early ages may be effectively absorbed in high performance concrete (HPC).     

超细CaCO3和纳米SiO2对水泥饰面砂浆性能的影响

研究了超细CaCO3和纳米SiO2对水泥饰面砂浆的标准稠度、凝结时间、强度、化学结合水、孔隙体积和干缩性能的影响。发现纳米SiO2可以提高抗压强度和结合水量,降低了孔隙体积,但是使凝结过快,增加了标准用水量和干缩;当再引入超细CaCO3明显改善了干缩和凝结性能,并使强度和密实度进一步提高。     

纳米SiO2低温稻壳灰用于混凝土的研究

采用SEM/TEM技术,发现了稻壳灰(RHA)中含有纳米SiO2粒子,并揭示了低温稻壳灰(L-RHA)的显微结构。稻壳灰由纳米SiO2(～50nm)粒子疏松地粘聚而成。稻壳灰结构中除了以往报道的微米尺度的蜂窝孔(～10μm)外,还含有大量由SiO2粒子非紧密粘聚而形成的纳米尺度孔隙(<50nm)。纳米尺度的SiO2粒子及大量孔隙使稻壳灰对混凝土具有较强的增强改性作用。当低温稻壳灰替代10%～20%水泥时,可提高高强混凝土抗压强度10MPa以上。     

Applications of sewage sludge ash and nano-SiO2 to manufacture tile as construction material

In this study, various portions of potter’s clay and porcelain clay were replaced with incinerated sewage sludge ash (ISSA) to manufacture sludge ash tile specimens. We used these tiles to investigate the effect of introducing nano-SiO₂ particles as strengthening additives in the clay–ISSA materials. Percentages of ISSA in the porcelain or potter’s clay-based materials ranged from 0% to 50%, and fractions of nano-SiO₂ additives range from 0% to 3%. Tile specimens were manufactured from the different clay–ISSA–additive mixtures and sintered at kiln temperatures of 1000 °C and 1100 °C. Mechanical tests were performed to measure shrinkage, water absorption, abrasion, and bending strength. The sample microstructure was investigated using scanning electron microscopy (SEM). Chemical compositions of the tile specimens were characterized with X-ray diffraction. Results indicate that water absorption of porcelain and potter’s clay-based tiles was reduced when samples were fired at the higher kiln temperature, dropping to less than 12% in porcelain tiles at a kiln temperature of 1100 °C. Kiln temperature appeared to have less influence on the tiles made from potter’s clay. With the addition of nano-SiO₂ additive, the bending strengths of both types of tiles were increased, with the strengthening effect more pronounced in potter’s clay tiles when compared to porcelain clay tiles.     

利用干湿交替法对大掺量矿渣硅酸盐水泥砂浆抗硫酸盐性能的研究

采用干湿交替的试验方法对大掺量矿渣硅酸盐水泥砂浆的抗硫酸盐侵蚀性能进行了研究。对侵蚀过程中砂浆的体积膨胀率、质量变化以及强度变化进行了测试,并对侵蚀后的砂浆试件进行了微观分析。对比不同侵蚀溶液(分别为Na2SO4溶液和MgSO4溶液)中受侵蚀的砂浆试件发现在短时间浸泡、长时间烘干的循环制度下,在镁盐中受侵蚀的砂浆试件具有较低的膨胀率和质量变化率,强度下降也较小。电镜结果显示在镁盐中受侵蚀的砂浆试件形成了大量无胶凝性的物质,而在Na2SO4溶液中受侵蚀的试件表面孔隙中形成了大量膨胀性的针棒状晶体。     

Toxicity bioassays with periphyton communities: design of experimental streams

A method for conducting toxicity or enrichment bioassays using periphyton communities is described. Communities consisting of 35–55 species of diatoms are grown in plastic laboratory streams which may be operated as flowthrough or recirculating systems. Replication of community biomass, species composition and diversity in these streams is excellent, and the communities are easily sampled. The effects of nutrients, heavy metals, or other soluble toxins may be assayed in experiments lasting 3–5 weeks.     

干粉砂浆的研制及机理

讨论了干粉砂浆研究和开发应用的重大意义。对掺加石粉、纤维素和引气剂后砂浆的性能进行了对比，并通过试验研制出各项性能均符合标准要求的不同强度等级的干粉砌筑砂浆和干粉抹灰砂浆。还对所选用的外加剂和填充料的作用机理进行了解释。     

用正交设计法配制高性能泵送混凝土的试验研究

本文利用正交设计试验配比高性能混凝土，试验次数少，周期短，科学合理地分析试验结果，优化施工配比。     

Factorial experimental design of winery wastewaters treatment by heterogeneous photo-Fenton process

Winery wastewaters are difficult to treat by conventional biological processes because they are seasonal and experience a substantial flow variations. Photocatalytic advanced oxidation is a promising technology for wastewaters containing high amounts of organic matter. In this work, the photo-Fenton process in heterogeneous phase is presented as an alternative methodology for the treatment of winery wastewaters. As a consequence of the great number of existing variables, an experimental design methodology has been used in order to study the influence and interaction of various variables and to obtain a reduced empirical model which describes the organic matter degradation process. Applying photo-Fenton treatment in heterogeneous phase under energetic conditions for synthetic samples simulating winery wastewaters results in purification levels of up to 50% (measured as total organic carbon). Different reduced models are obtained and their utilization depends mainly on the degree of degradation of organic matter required.