聚合物改性砂浆综述

介绍了聚合物改性砂浆在国内外的使用现状和应用前景、分类和性质、国内外研究现状以及研究趋势等,同时也探讨了聚合物改性砂浆的作用机理,并详细介绍了目前本领域所存在的几个问题,展望了聚合物改性砂浆未来的应用.     

橡胶微粉对无机聚合物胶凝材料力学性能的影响

主要研究了橡胶微粉对无机聚合物砂浆和水泥砂浆力学性能的影响.实验结果表明,随着橡胶微粉掺量的增加,无机聚合物砂浆和水泥砂浆的抗压强度、抗折强度均有所下降,其中无机聚合物砂浆弹性模量降低、变形能力增强、弯曲韧性系数稍有降低;水泥砂浆弹性模量升高、变形能力下降、弯曲韧性系数下降.分析材料微观破坏形貌后发现,与水泥砂浆相比,橡胶微粉与无机聚合物砂浆界面粘结较好,粘结强度高,从而造成无机聚合物砂浆和水泥砂浆这两种材料体系在橡胶微粉掺杂后力学性能的差异.     

聚合物改性砂浆界面粘接特性的研究

根据聚合物改性砂浆不同的界面破坏形式,提出了表征界面粘接特性的内聚强度和界面结合强度概念,并通过二者的总体宏现效应-粘接强度试验探讨了乙烯-醋酸乙酸共聚物、双级配填料和水泥对砂浆内聚强度和界面结合强度的影响.试验表明,在本试验务件下乙烯-醋酸乙酸共聚物的最佳掺量范围为1.5%～3.5%.当聚合物掺量低于3.5%时,随着聚合物掺量的增加,聚合物改性砂浆的粘接强度增大,破坏形式为内聚破坏;当聚合物掺量高于3.5%时,聚合物改性砂浆界面的结合强度降低,导致粘接强度降低,破坏形式为界面破坏.具有合适配比的双级配填料可增强砂浆粘接强度,但大粒径填料的增加会降低砂浆与基材界面的结合强度,导致砂浆的粘接强度降低,在本试验条件下填料A/填料B的比例取1:2为宜.聚合物改性砂浆的粘接强度随水泥掺量的增加而增大,并在掺量为30%时出现拐点,故在本试验条件下水泥掺量取30%较佳.     

碳纳米管/聚合物基复合材料的研究现状和发展动态

介绍了碳纳米管/聚合物基复合材料在国内外的研究现状及应用.重点介绍了共轭发光聚合物修饰碳纳米管形成的聚合物基复合材料具有很强的发光性能,有望用于光电器件;而且,通过连结氨基聚合物,可使多壁碳纳米管溶解和功能化,从而将碳纳米管引入生物学系统中.因此,碳纳米管/聚合物基复合物有许多潜在的应用,有待进一步发展.     

聚合物改性砂浆的强度性能研究

通过正交试验研究了胶粉、硅灰、纤维素醚、石膏、减水荆、消泡荆对干粉砂浆性能的影响.结果表明,聚合物改性后砂浆的1d抗压强度达38.4MPa,抗折强度达6.4MPa.该早强修补砂浆特别适用于紧急抢修工程,具有一定的经济和社会效益.     

丁苯乳液改性水泥砂浆的物理性能

本文研究了丁苯乳液SD622S改性水泥砂浆的物理性能,包括新拌砂浆的减水率、保水率、体积密度、凝结时间,硬化砂浆的体积密度、孔隙率、毛细孔吸水率等.实验结果表明:丁苯乳液可提高砂浆的减水率和保水率,使砂浆的凝结时间延长.随着丁苯乳液掺量的增加,硬化砂浆的毛细孔吸水率降低.丁苯乳液使新拌砂浆和硬化砂浆的体积密度减小,但随聚合物掺量的增加有所回升.硬化砂浆的孔隙率随聚合物掺量的变化趋势正好相反.     

高强钢绞线与聚合物砂浆加固施工

当建筑物或构筑物的结构体系已不能满足使用要求时,就要进行结构改造与加固。采用高强钢绞线与聚合物砂浆加固施工,具有强度高,施工速度快,工期短等优点。高强钢绞线强度高,其标准强度约为普通钢材的5倍,加固后对结构自重增加小;聚合物砂浆的收缩性小,减少裂缝的产生,有效的防止二氧化碳,可以预防砼碳化,冻融及耐久性好,它的力学性质与砼相近,具有渗透性,提高了长期粘结性能,耐火、耐腐蚀、耐老化性能好。钢绞线网片---聚合物砂浆加固复合面层技术是将被加固构件进行界面处理后,将钢绞线网敷设于被加固构件的受拉区,再在其表面涂抹聚合物砂浆。主要是在结构加固的过程中不影响建筑的正常使用。     

聚合物乳液固化方法与性能间关系的研究

聚合物乳液是一种性能优良的环境友好型材料,具有无毒、不易燃烧、不污染环境等优点,已被广泛的应用于涂料、胶粘剂、皮革、纺织等工业生产中.聚合物乳液的固化速率一直制约其应用,笔者介绍了聚合物乳液在应用中的固化方法与原理,深入分析了目前各种固化方法与性能之间的关系,指出了各种固化方法中存在的问题,并对聚合物乳液固化的发展进行...     

爆炸作用下高强钢绞线网片-聚合物砂浆加固钢筋混凝土板的数值模拟

为了探究高强钢绞线-聚合物砂浆加固技术对钢筋混凝土板的抗爆性能的影响,应用有限元分析软件ANSYS/LS-DYNA对其进行了在爆炸荷载作用下的数值模拟。在验证有限元模型合理性的基础上,对比分析了爆炸荷载作用下砂浆层厚度、砂浆强度和钢绞线直径等不同加固参数对钢筋混凝土板的破坏形态与板底位移的影响。结果表明:采用高强钢绞线-聚合物砂浆加固后钢筋混凝土板的抗爆性能显著提高;在砂浆加固层厚度、砂浆强度、钢绞线直径3种加固影响参数中,砂浆加固层厚度对钢筋混凝土板的加固效果影响显著,而砂浆强度和钢绞线直径对板的加固效果不明显。如果运用该技术提高钢筋混凝土板的抗爆性能,优先考虑增大加固层厚度。     

EPS板薄抹灰外墙外保温系统施工质量控制要点

EPS板板薄抹灰外墙外保温系统具体做法是在建筑物墙体外侧采用聚合物砂浆直接粘贴EPS板,并采用塑料锚栓加以辅助固定,然后在面层上涂抹铺有耐碱玻璃纤维网格布的聚合物砂浆抗裂抹面层,再做饰面层。本文介绍了EPS板薄抹灰外墙外保温系统施工质量控制要点     

新型聚合物水泥胶浆界面剂粘结性能及作用机理研究

采用新型聚合物水泥胶浆作为界面剂以提高新旧混凝土之间的粘结性能,通过拉拔粘结强度与劈裂抗拉粘结强度实验对5种不同类型的聚合物水泥胶浆界面剂的粘结性能进行了测试,并利用扫描电镜(SEM)分析研究了丁苯聚合物水泥胶浆的界面增强机理。实验结果表明,5种聚合物乳液中,丁苯聚合物水泥胶浆具有较好的拉拔粘结性能,当优选m(水泥)∶m(DB-1乳液)=3∶2时,其7d、28d拉拔粘结强度分别达到1.83MPa、2.41MPa,相比水泥净浆空白样分别提高了144%、96%;在劈裂抗拉粘结强度方面,水平方向浇筑时劈裂抗拉粘结强度相对较高,当聚合物水泥胶浆的优选m(水泥)∶m(DB-1乳液)=3∶2,水平浇筑时其28d劈拉粘结强度达到2.96MPa,明显高于不掺界面剂的试样以及掺加其它配比界面剂的混凝土试样;经过微观测试分析,丁苯DB-1聚合物水泥砂浆内部界面过渡区(ITZ)相比空白样明显致密,表明丁苯聚合物的加入有效填充了水泥基材料内部的宏观与微观缺陷,提高了界面过渡区的密实程度。     

Styrene–butadiene latex modified calcium aluminate cement mortar

This paper investigates properties of calcium aluminate cement (CAC) mortar modified with the styrene–butadiene-rubber (SBR) latex. This material may be advantageously applied as a rapid repair mortar. Mortar specimens were prepared with constant water-to-cement mass ratio; polymer solid content of latex was varied from 0% to 9%, and Li₂CO₃ was investigated as an accelerator. Specimens were treated at different curing conditions: 1, 7 days and transformation of metastable hydration products at 70 °C. The heat of hydration evolution of mortar specimens was measured by means of a self adopted isoperibol calorimeter.The measurement results indicate that SBR latex improves workability of fresh state mortar and retards nucleation and growth of hydration products. Due to polymer coagulation process and co-matrix formation permeability, stiffness and compressive strength decrease while adhesion strength to old concrete substrate, and flexural strength increase with amount of added latex.     

可再分散乳胶粉对硫铁矿尾砂自流平砂浆性能的影响

探究硫铁尾矿砂在自流平砂浆的资源化利用途径,以硫铁矿尾砂为细集料制备水泥基自流平砂浆,分析了可再分散乳胶粉掺量对砂浆流动度、力学性能及耐磨性的影响。结果表明：乳胶粉掺量可以显著降低20 min、60 min 后的流动度经时损失,乳胶粉掺量为2.0%时,砂浆的拉伸粘结强度为1.9 MPa,并在天然河砂与尾砂复配情况下,尾砂替代率为75%时,磨损量仅有0.09 kg/m2。     

Microstructure and mechanical performance of modified mortar using hemp fibres and carbon nanotubes

Mechanical performance of modified mortar using hemp fibres is studied following various processing conditions. Hemp fibres combined with carbon nanotubes (CNT) are introduced in mortar and their effect is studied as function of curing time. The cement phase is replaced by different percentages of dry or wet hemp fibres ranging from 1.1 wt% up to 3.1 wt% whereas carbon nanotubes are dispersed in the aqueous solution. Our experimental results show that compressive and flexural strengths of wet fibres modified mortar are higher than those for dry hemp-mortar material. The achieved optimal percentage of wet hemp fibres is 2.1 wt% allowing a flexural strength higher than that of reference mortar. The addition of an optimal CNT concentration (0.01 wt%) combined with wet hemp has a reinforcing effect which turns to be related to an improvement of compressive and flexural strengths by 10% and 24%, respectively, in comparison with reference condition.     

The effect of polymer addition on the electrical behavior of ordinary and pulverized fly ash modified cement mortars

The electricla behavior of polymer-modified cement mortars has been evaluated as a function of the polymer and the evaporable water contents. The effects have been correlated to microstructural changes induced by the addition of an acrylic polymer and an epoxy resin purposely formulated for cement-based composites. Moreover, the effect of the addition of pulverized fly ash, which has proved to be beneficial on many of the cement composite properties, has also been studied. Polymer modified cement mortar composites exhibit a tendency towards insulating behavior which is greatly enhanced by water losses: the electrical properties must thus be carefully evaluated when static charge accumulation is not desired. The addition of pulverized fly ash to ordinary Portland mortars slightly influences the electrical behaviour, but strongly enhances the insulating behaviour of polymer modified cement mortars.     

Resistance to biogenic sulphuric acid corrosion of polymer-modified mortars

The use of polymer-modified mortar and concrete (PMM and PMC) is investigated to improve the durability of concrete sewer pipes. The aim of the research is to ameliorate the resistance of concrete to biogenic sulphuric acid attack through polymer modification. Prior to the durability tests, experimental research is carried out to reveal the influence of polymer modification on the physical and mechanical properties of mortar and concrete. The results of this research are presented in this paper. Due to the interaction of the cement hydrates and the polymer particles or film, an interpenetrating network originates in which the aggregates are embedded. The density, porosity and location of the polymer film depend on the type of polymer emulsion and on its minimum film-forming temperature (MFT). If air entrainment is restricted, an increased flexural strength is measured. Scanning electron microscope (SEM) analyses reveal the presence of polymer film and cement hydrates in the mortar. The polymer film causes a retardation of the cement hydration as well as a restriction of crystal growth.     

The significance of carbon nanotubes on styrene butadiene rubber (SBR) and SBR modified mortar

A New approach is introduced to incorporate multi-walled carbon nanotubes (MWCNTs) in cementitious materials. The MWCNTs are dispersed in styrene butadiene rubber (SBR) matrix before mixing the matrix with cement. Surfactants have been successfully applied to enhance the dispersion and functionalization of MWCNTs in SBR. The significance of using this MWCNTs–SBR nanocomposite on the mechanical characteristics including compressive and tensile strengths and microstructural features of latex modified mortar (LMM) were examined. Subsequently, the significance of the functionalized MWCNTs on surface chemistry, microstructure and thermal stability of SBR were characterized. MWCNTs were found to be a useful additive for enhancing the mechanical response and thermal stability of SBR. MWCNTs–SBR nanocomposite was observed to be able to bridge micro-cracks in the LMM which helped enhancing its mechanical properties. The ability of MWCNTs to enhance the mechanical response of SBR polymer matrix might be attributed to chemical bond that functionalized MWCNTs can establish with the SBR polymer matrix. The enhanced MWCNTs–SBR nanocomposite gave rise to improved microstructural features of the LMM. Microstructural investigations showed MWCNTs were well dispersed in and bonded to the SBR matrix.     

聚合物水泥砂浆的力学性能

本文采用美国产 MTS试验机 ,分别研究了掺聚醋酸乙烯水泥砂浆的轴拉和轴压应力 -应变关系及抗弯性能。试验结果表明 ,随着聚醋酸乙烯的掺入 ,砂浆的轴压强度和弹性模量显著下降 ,但极限应变却明显增大 ;砂浆的轴拉强度和抗弯强度均略有提高 ,而极限应变、拉压强度比和弯压强度比则显著增加。因此 ,掺入聚醋酸乙烯能有效改善砂浆的变形力学性能。根据 12年龄期的粘结抗弯强度试验结果 ,聚醋酸乙烯砂浆不但具有优良的粘结性能 ,还具有良好的耐久性 ,可广泛用于新老混凝土的粘结、修补及结构加固中的钢板粘贴和表面粉刷等。     

Study of cement mortars modified by emulsifier-free latexes

Cationic copolymer latex of vinyl acetate (VA) with methacryloxyethyl trimethylammonium chloride (MTC) and anionic copolymer latex of VA with sodium acrylate (SA) were prepared via emulsifier-free emulsion copolymerization. Modifications of cement mortars by these copolymer latexes were studied, and the results were compared with mortars modified by homopolymer of VA (PVA) as well as with blank mortars. The experimental results showed that flow of the mortars modified by PVA homopolymer and P(VA–MTC) copolymer latexes were increased compared with the blank, whereas a decrease was observed for that modified by P(VA–SA) anionic copolymer latex; a volume expansion was detected in polymer modified mortars by PVA and P(VA–MTC), while no volume expansion was observed in the anionic P(VA–SA) modified mortars; the flexural strength of mortars modified by P(VA–MTC) increased by 79.5% compared to unmodified mortars after 5 day water curing plus 21 day air curing. This value reached 95% when the curing process was followed by a supplementary 24 h vacuum curing. These polymer modified mortars were then subjected to hydration analysis through X-Ray diffraction (XRD). Mechanisms of the mortar modification are discussed based on the characterization results.     

混杂纤维增强水泥基复合材料的力学性能

研究了化学改性聚丙烯（PP）纤维以及掺加聚丙烯纤维和芳纶纤维混杂比例和混杂效应对水泥基复合材料力学性能的影响,并构建了纤维增强水泥砂浆界面层的物理模型,描述了纤维对水泥砂浆的增强机制。实验表明,聚丙烯纤维经改性后使水泥砂浆前期抗折强度明显提高,聚丙烯纤维和芳纶纤维的混杂使水泥砂浆的后期抗折强度显著提高。改性聚丙烯纤维掺加体积分数为0.56%,芳纶纤维的体积分数为0.24%时,混杂纤维增强水泥砂浆试样较空白试样,3天、28天抗折强度分别提高了18.48%、31.17%,3天、28天抗压强度分别提高了7.16%、5.19%。