水泥基材料无机/有机复合内养护剂的研究进展

无机/有机复合吸水材料具有一定的亲水基团和三维网络结构,吸水性、保水性和释水性优异,是水泥基材料重要的内养护剂之一。通过在水泥基材料中引入无机/有机复合吸水材料,利用其吸-释水特性可自动调节水泥基材料内部相对湿度,促进水化反应,减少水泥基材料自收缩和早期开裂等现象,提高力学性能和耐久性。概述了无机/有机复合内养护剂(CICA)的制备方法、结构特征以及吸-释水行为;综述了CICA对水泥基材料水化进程、微观结构、宏观性能和耐久性的影响;展望了CICA在混凝土应用的发展前景,为CICA在水泥基内养护中的应用提供一定理论指导和技术参考。     

低温等离子体技术在粉体表面处理中的应用

低温等离子体技术用于粉体表面处理具有工艺简单、无需溶剂、节能高效等特点.等离子体处理粉体表面利用的放电形式从真空放电到空气压力下的气体放电;范围从无机粉体的表面处理到纳米粉体、有机粉体的表面处理都有涉及.评述了国内外利用等离子体对无机粉体、有机粉体低温等离子体表面处理技术的进展.     

我国地下工程刚性防水材料产品专利综述

刚性防水总类繁多。是包括混凝土结构自防水，混凝土结构表面涂渗防水材料以及对结点和缺陷注浆技术等多种防水技术的总称。刚性防水因为其自身持久的耐久性以及与主体结构寿命的同步性，从而有着有巨大的市场需求。刚性防水材料具有既能又能称重，具有抗冻性和抗老化性，具有耐久性，原材料充足，经济小一号，通常为无机材料，无毒、无异味等特点。     

迁移型阻锈剂在钢筋混凝土中的研究进展

钢筋锈蚀导致混凝土耐久性的降低问题一直受到全世界的广泛关注,迁移型有机阻锈剂可以有效提升混凝土的耐久性,并与混凝土结构有着很好的相容性,且在经济上优于普通掺入型无机阻锈剂。从混凝土工程钢筋锈蚀原因、迁移型阻锈剂的阻锈机理进行分析,进而介绍迁移型阻锈剂的国内外研究情况以及迁移型阻锈剂的性能试验和评价方法,最后就迁移型阻锈剂相关应用的问题进行总结。     

牙科复合树脂中无机填料的研究进展

牙科复合树脂是一类由有机树脂基质和经过表面处理的无机填料及引发系统组合而成的牙科修复材料。无机填料作为复合树脂的分散相,在牙科复合树脂中具有重要作用,对复合树脂的力学性能、物理性能、化学性能都有着重要的影响。介绍了无机填料的种类、形态、含量、粒径大小及其表面处理,并结合许多学者对复合树脂中无机填料的研究,探讨无机填料对复合树脂性能的影响,最后展望了复合树脂应提高的性能和无机填料努力的方向。     

水工泄水建筑物抗冲磨材料发展现状

冲磨破坏对水工泄水建筑物的安全运行是一种严重的威胁。抗冲磨材料防护是解决水工泄水建筑物冲磨破坏的有效途径之一,其研究一直以来都是抗冲磨领域研究的重点。结合工程应用阐述了主要无机和有机抗冲磨材料的研究现状和优缺点。在此基础上提出无机抗冲磨材料的研究发展重点是开发高性能抗冲磨混凝土,有机抗冲磨材料研究发展的方向是提高其在复杂服役环境中的耐久性和降低应用成本。     

迁移型阻锈剂对混凝土钢筋的保护作用

氯离子诱发的钢筋锈蚀是影响混凝土结构耐久性的主要因素之一。利用电化学和表面分析技术研究了有机类表面迁移型阻锈剂在混凝土腐蚀模拟液中对混凝土块及其中钢筋的保护作用。结果表明:新型阻锈剂的缓蚀效率超过80%;加入新型阻锈剂后,钢筋表面平整;涂刷在混凝土表面的复合阻锈剂,能够迁移到混凝土内部,通过物理、化学吸附,在钢筋表面形成一层吸附膜,阻碍了氯离子与钢筋表面的接触,使腐蚀反应速率降低,从而起到了保护钢筋的作用。     

专利信息

摘要一种氢氧化铝阻燃剂的制备方法。涉及用作阻燃剂的一种氢氧化铝粉体的表面包覆改性处理方法。其特征在于将铝酸钠溶液进行净化后，加入选自碳酸钙、硅酸盐、磷酸盐的无机添加剂进行包覆处理；再加入2％～12％的含磷基硅烷或钛酸脂表面改性剂，进行有机化改性处理。本发明方法制备的氢氧化铝粉体表面经多层包覆改性及无机一有机多层包覆改性处理，其热稳定性大大提高。分析结果表面经无机．有机包霜后初始脱水温温度245℃。     

有机/无机共混聚丙烯纤维中无机粉体表面处理效果评价

用钛酸酯偶联剂对TiO2 、ZnO等无机粉体表面处理 ,增加其与聚丙烯基体之间的相容性作用 ,并利用沉降体积这一参数对处理效果进行表征 ,讨论了偶联剂用量对处理效果的影响 ,并通过透射电镜观察、评价了无机填料在有机基体中的分散性。     

无机—有机纳米杂化材料的分子设计与构筑的研究

着重介绍用分子设计制备无机—有机纳米杂化材料的新方法及其结构、性能演变规律和功能化的工作。特别介绍关于纳米晶—聚合物杂化材料、纳米二氧化硅—聚合物纳米复合材料及其有机—无机聚合物表面结构与性能关系规律。如通过对纳米无机材料功能化修饰,使其含有与聚合物共聚的官能团,实现了与聚氨酯、硅橡胶、环氧树脂的分子组装,形成了无机—有机的互穿网络式嵌断共聚物,大大提高了聚氨酯、硅橡胶和环氧树脂的力学性能和热稳定性能。该聚氨酯杂化材料的拉伸强度和伸长率比未改性前均提高了2倍以上。通过原位聚合、聚合物刷、从表面接枝技术制备出高性能材料。探讨用催化链转移聚合等聚合方法实现新颖有机—无机纳米杂化材料的制备及其表面构筑。通过无机材料的表面设计和表面处理控制无机/聚合物复合材料的界面结构和行为,得到了多种性能优良的多元多尺度复合材料。提高纳米杂化复合高分子材料的加工性能,探索其特异的光电等特异性能。     

Effects of inorganic surface treatment on water permeability of cement-based materials

The permeability of the cement-based materials can be used as an important indicator of their durability. Surface treatment is a simple way to reduce permeability and improve durability of cement-based materials. This paper studied the effects of fluosilicate and sodium silicate surface treatments on the permeability of cement-based materials using the Autoclam water permeability and water absorption testing method. The experimental results showed that both fluosilicate and sodium silicate surface treatments could effectively reduce the permeability of cement-based materials. However, fluosilicate worked within the first 28days after treatment, while sodium silicate showed more obvious effect at later ages. Autoclam water permeability index exhibited an exponential relationship with the water absorption of the cement-based materials. In addition, mercury intrusion porosimetry result suggested that these inorganic surface treatment agents could reduce the porosity of surface layer of cement-based materials.     

不同表面处理剂对道面混凝土性能的改善作用

为研究硅酸盐渗透剂、纳米二氧化硅和硅酸乙酯三种表面处理物对混凝土性能的改善,对经处理后混凝土表面的摩擦性能、吸水率、耐磨性、抗氯离子渗透性和抗冻性进行测试分析。结果表明,硅酸乙酯是一种理想的表面处理材料,相对于未经处理的混凝土而言,处理后混凝土的7 d吸水量降低75%,耐磨度增大31.8%,且不会影响混凝土的表面摩擦性能;经硅酸乙酯处理后的混凝土在经历28次单面冻融循环后剥落物总量只有251 g/m²。硅酸盐渗透剂也能降低混凝土的渗透性,但需注意用量,避免在混凝土表面形成薄膜。纳米二氧化硅的增强作用相对有限,不适用于机场道面混凝土。     

Preparation of silica-based hybrid materials coated on polypropylene film

In this study, silica-based organic–inorganic hybrid coating materials were prepared by the sol–gel method. Tertaethoxysilane and polyvinyl alcohol were used as the inorganic and organic compounds, respectively. The substrate polypropylene film surface was modified by corona-plasma treatment to provide appropriate adhesion between the coating material and the polymer base film. A silane.coupling agent of vinyltriethoxysilane was also used to improve the adhesion between the base film and the coated layer. The effects of vinyltriethoxysilane in the hybrid materials were investigated using Fourier transform infrared analyses and X-ray diffraction. The vinyl group of vinyltriethoxysilane increased the hydrophobicity of the hybrid materials. The polypropylene films coated with the hybrid materials were characterized by examining their morphology, optical transparency and oxygen permeability. The results showed that the formation of hydrogen bonds between polyvinyl alcohol and the other compounds affected the microstructure of the coating solution and the final oxygen permeation property. Further, although the presence ofvinyltriethoxysilane in the hybrid coating solution could improve adhesion between the coated layer and the polymer base film, it deteriorates the effectiveness of the barrier to prevent of oxygen permeation through the coated film. However, the coated film maintained visible transparency and even enhanced the transmission of long wavelength visible-light owing to refractive index matching.     

Assessment of the surface permeation properties of recycled aggregate concrete

The water permeability, air permeability and surface permeability of recycled aggregate concrete (RAC) are compared with those of a control concrete made with natural aggregate. The study shows that the permeation properties of RAC depend on mix-design, conditions of curing and drying of samples. Relationships between permeability and other physical characteristics of concrete such as water absorption capacity and diffusivity are discussed. According to the criteria existing for ordinary concrete made with natural aggregate, RAC could be classified as being of moderate quality rather than poor quality. The testing methodology shows that some of the techniques used to measure the permeability of RAC need to be modified in order with the distinctive characteristics of this material.     

Poly(methyl methacrylate) capsules as an alternative to the ‘’proof-of-concept’’ glass capsules used in self-healing concrete

Development of suitable capsules is essential to achieve self-healing by encapsulation. In the context of self-healing concrete, capsules that can be easily mixed into concrete and release the healing agent when cracking occurs are ideally required. The optimization of these properties would allow for a successful implementation at large scale in practical (concrete) applications. In the present work, the suitability of polymeric cylindrical capsules made of poly(methyl methacrylate) (PMMA) to carry healing agent in self-healing concrete has been evaluated. An innovative method to assess more easily the capsules survival during concrete mixing was developed. This method is based on the evaluation of the setting behavior of concrete containing capsules filled with setting accelerator. Capsules with a wall thickness of 0.7 mm were able to resist the concrete mixing process and to rupture at relatively small crack widths (116 μm) after applying a surface treatment to increase the adhesion between the capsules and the cementitious matrix. Next, the self-healing efficiency of the encapsulation materials (glass or PMMA) was evaluated on real-scale concrete beams. The results showed that cracked concrete beams with mixed-in capsules (glass or PMMA) filled with water-repellent agent showed higher resistance against chloride ingress compared to plain cracked concrete beams. PMMA capsules showed a lower self-healing efficiency (in relation to chloride ingress) compared to glass due to a less favorable distribution of the capsules in the concrete. However, concrete containing glass capsules is susceptible towards alkali-silica reaction.Although optimization of the PMMA capsules is still necessary to improve their distribution in concrete and achieve higher self-healing efficiency, the obtained results indicate that these capsules could be a promising solution towards self-healing concrete.     

结构型纤维对混凝土弯曲韧性和裂缝表面形态的影响

为了研究结构型聚丙烯纤维、结构型钢纤维及混杂纤维(包括结构型聚丙烯纤维和结构型钢纤维)对混凝土弯曲韧性及裂缝表面形态的影响,参照RILEM TC 162-TDF[10]标准进行混凝土开口梁的三点弯曲试验。利用激光扫描仪对每个试件裂缝表面形态进行信息采集。基于裂缝表面信息,计算了四种裂缝表面粗糙程度参数(即裂缝粗糙度(R_N)、分形维数(D)、z坐标正态分布的标准差(σ_z)和裂缝曲折度(τ)),并比较分析了裂缝表面粗糙程度参数与弯曲韧性参数之间的相关性。研究表明:随着纤维掺量的增多,混凝土弯曲韧性和裂缝表面粗糙程度均随之增大。与结构型聚丙烯纤维和结构型钢纤维相比,混杂纤维在提高混凝土弯曲韧性和增大混凝土裂缝表面粗糙度方面均展现出正混杂效应。与分形维数D、z坐标正态分布标准差σ_z和裂缝曲折度τ相比,裂缝粗糙度R_N与纤维增强混凝土梁弯曲韧性参数的相关性最为显著,且存在指数函数关系。基于该函数关系,可借助纤维增强混凝土梁的弯曲试验快速估测裂缝表面的粗糙程度。      

Cementitious composites reinforced with continuous carbon fibres for strengthening of concrete structures

“Continuous fibre wrapping technique” is becoming a common repair and strengthening technique for concrete structures. In this method continuous fibre sheets are bonded to the surface of a concrete structure using organic resins. The main disadvantages of this method are: (i) the use of resins (organic compounds) which are hazardous for the manual worker, and (ii) the low permeability of this type of organic materials. These problems could be solved if a cement-based matrix is used instead of epoxy matrix. In the current development stage one of the limiting parameter in a cementitious carbon fibre composite is the bond between the fibres and the cementitious matrix.The main objective of the study presented in this paper was to improve the bond between the carbon fibres and the cementitious matrix. Two possible methods were studied: (i) the design of a complex binder based on Portland cement with polymer and silica fume additions and (ii) surface treatment of the carbon fibres prior to their casting in the cementitious composite.     

Ethyl silicate for surface protection of concrete: Performance in comparison with other inorganic surface treatments

The protection of concrete surface from environmental aggressions is often a basic issue for the enhancement of its durability. Due to the unsatisfactory long-term performance of many organic products and the subsequent need for frequent re-application, growing interest has been recently addressed toward inorganic materials. In the present study, ethyl silicate, widely used for the consolidation of weathered stones in architectural restoration and recently investigated for surface treatment of reinforced concrete structures, is compared with some inorganic products based on sodium silicate and nanosilica, generally used for the protection of concrete floors. Performance and effectiveness of the treatments are investigated in terms of morphology and microstructure; water absorption rate; water contact angle; chloride, carbonation and abrasion resistances. The results obtained highlight ethyl silicate, among the products investigated, as the most effective protection treatment for reinforced concrete structural elements.     

淀粉基食品包装膜材料的研究进展

目的将淀粉应用于绿色包装领域,开发出具有良好生物降解性的淀粉基食品包装膜材料。方法综述淀粉种类、增塑剂、多糖、脂质及类脂物质、蛋白质、交联剂、无机物和活性物质等对淀粉膜性能的影响。结果在淀粉膜的制备中,选用高直链淀粉含量的淀粉,并加入增塑剂和交联剂可以改善淀粉膜的力学性能,降低薄膜的水蒸气渗透性;淀粉与多糖或蛋白质复合后,不同成膜材料优势互补,薄膜性能会得到改善,加入脂质或类脂物质可改善薄膜的阻水性。结论随着研究的深入,淀粉基食品包装膜材料在很多领域都会有广阔的应用前景。     

Mock-up experiments on permeability measurement of concrete and construction joints for air tightness assessment

Concrete permeability is subject to various test conditions, and on-site measurement at in situ structural scale is much preferable. This paper presents an experimental study to measure the permeability of concrete linings and their construction (placing) joints between old and new concretes using a novel in situ permeability testing system. Using the developed system, we performed in situ scale permeability tests of rectangular concrete specimens with dimensions of 500 × 500 × 2800 mm³, within which the construction joints were artificially placed. From this model experiment, we verified an effective applicability of the system to both low permeability concrete matrices and highly permeable construction joints thanks to its selective capability of gas or water permeability test, depending on the air/water tightness of tested materials. The experimental results presented in this paper also showed that the intrinsic permeability of the construction joint could be higher than that of the concrete matrices by orders of magnitude (10¹–10⁴ times), but it could be reduced to as low as those of the concrete matrix by pasting a bonding agent on the interfacing surfaces. As a result of geomechanical monitoring during the experiment, the opening displacement of construction joints with relatively higher stiffness values showed a reversible deformation when the gas injection pressure was unloaded, which is much preferable in a storage performance perspective of underground lined rock caverns.