Strength of copolymer grouting material based on orthogonal experiment

Using the orthogonal experimental design method involving three factors and three levels, the flexural strength and the compressive strength of copolymer grouting material were studied with different compositions of water-cement ratio (mass fraction of water to cement), epoxy resin content, and waterborne epoxy curing agent content. By orthogonal range and variance analysis, the orders of three factors to influence the strength, the significance levels of different factors, and the optimized compound ratio scheme of copolymer grouting material mixture at different curing ages were determined. An empirical relationship among the strength of copolymer grouting material, the water-cement ratio, the epoxy resin content, and the waterborne epoxy curing agent content was established by multivariate regression analysis. The results indicate that water-cement ratio is the most principal and significant influencing factor on the strength. Epoxy resin content and waterborne epoxy curing agent content also have a significant influence on the strength. But epoxy resin content has a greater influence on the 7-day and 28-day flexural strength, and waterborne epoxy curing agent content has a greater influence on the 3-day flexural strength and the compressive strength. The copolymer grouting material with water-cement ratio of 0.4, epoxy resin content of 8% (mass fraction) and waterborne epoxy curing agent content of 2% (mass fraction) is the best one for repairing of cement concrete pavement. The flexural strength and the compressive strength have good correlation, and the ratio of compressive strength to flexural strength is between 1.0 and 3.3. Foundation item: Projects(40728003, 40772180, 40802064) supported by the National Natural Science Foundation of China; Project (07JJ4012) supported by the Hunan Provincial Natural Science Foundation of China; Project(20080430680) supported by China Postdoctoral Science Foundation; Project(B308) supported by Shanghai Leading Academic Discipline Project     

冻融环境对聚合物水泥砂浆粘结强度的影响

为了分析冻融环境对外墙外保温系统中聚合物水泥砂浆粘结强度的影响,根据寒冷地区温度变化情况,设计了聚合物水泥砂浆的配合比,在冻融环境条件下进行了不同冻融循环次数时聚合物水泥砂浆的粘结强度试验.探讨了冻融循环和胶粉掺量对聚合物水泥砂浆粘结强度的影响,得到了冻融环境条件下粘结强度的变化规律,分析了冻融环境对聚合物水泥砂浆粘结强度的影响机理.结果表明,随着冻融循环次数的增加,聚合物水泥砂浆的粘结强度逐步降低;随着胶粉含量的增加,聚合物水泥砂浆的粘结强度逐步增大.     

塑料砂浆的性能研究

采用废旧PET塑料瓶作胶结料来制备塑料砂浆。研究了不同的PET与砂的比例、养生时间以及少量沥青的添加对塑料砂浆的物理和力学性质的影响。试验结果表明,塑料砂浆具备吸水率低,强度增长迅速的特性。随着塑料砂浆中含砂量的增加,其抗压强度与抗折强度增大。在室温条件下,塑料砂浆养生3h即可达到最终强度的90％以上;养生24h可达到最终强度。在塑料砂浆中加入少量的沥青,能够有效提高塑料砂浆的抗弯拉性能。     

PB-g-PS胶乳改性水泥砂浆的性能研究

PB-g-PS胶乳常用于改性水泥砂浆,聚丁二烯对苯乙烯的重量比的范围从70/30,50/50到30/70.保持水灰比为0.5的常数,在20°、相对湿度为90%的空气中养护24 h,接下来在20°的水中养护27 d.这项研究考察了聚丁二烯与苯乙烯的重量比和聚灰比对PB-g-PS胶乳改性水泥砂浆的流动度,抗压、抗折强度及吸...     

聚合物水泥混凝土(PCC)发展现状

聚合物水泥混凝土具有抗折抗拉强度增加、压折比降低、抗渗、抗冻融、耐化学腐蚀性能显著提高等优点.本文综述了用于混凝土改性的聚合物种类,阐明了聚合物改性混凝土的机理,并介绍了国内外聚合物水泥混凝土的发展现状.     

废旧轮胎胶粉对水泥砂浆力学性能的影响

研究了废旧轮胎胶粉的细度、掺量对水泥砂浆抗压强度的影响．利用不同的硅烷偶联剂对废轮胎胶粉进行了改性试验，并测定了改性胶粉对水泥砂浆力学性能的影响．研究结果表明：掺胶粉水泥砂浆28d抗压强度有明显下降，但掺量小于10％时，对水泥砂浆的早期强度几乎没有影响；在等掺量条件下，胶粉越细，砂浆强度越高；胶粉经改性后能明显改善掺胶粉水泥砂浆的力学性能．     

灌注式半刚性路面橡胶粉水泥砂浆物理力学性能试验研究

通过对灌注式半刚性路面橡胶粉水泥砂浆进行物理力学性能试验,研究表明:将不同掺量的橡胶粉代替同体积的砂掺入水泥砂浆所制得的橡胶粉水泥砂浆含气量有所提高,而且具有良好的流动性、较小的干缩率,凝结时间也有所增长;在力学性能方面,抗压强度会随着橡胶粉掺量的增加而降低,而抗折强度则会随着橡胶粉掺量的增加,呈现出先增后减的趋势;在耐磨性能方面,橡胶粉水泥砂浆的耐磨性也是随着橡胶粉掺量的增加,出现先提高后降低的变化趋势;这些都为后续所开展的橡胶粉水泥砂浆最佳配比研究以及灌注式半刚性路面面层复合材料路用性能的研究提供了依据.     

聚合物乳液改性水泥砂浆基本性能研究

为开发高性能的表面修补材料,选用2种聚合物乳液对水泥砂浆进行改性,并对聚合物乳液改性水泥砂浆进行了室内抗压强度、抗折强度、黏结抗折强度、吸水率和孔结构分析等试验.结果表明,聚合物乳液的使用明显提高了砂浆与原混凝土的黏结抗折强度、降低了砂浆的吸水率,改善了砂浆的孔结构分布形态.     

粉煤灰对砂浆强度影响的实验研究

探讨了高烧失量粉煤灰对砂浆强度的影响。用不同掺量的粉煤灰做了两组实验，测试结果表明：粉煤灰砂浆的用水量随着粉煤灰掺量的增加而增加；在蒸养后，粉煤灰砂浆试块的抗压和抗折强度比无粉煤灰试块有较大的提高；当粉煤灰掺量占水泥量的３０％时，其抗压和抗折强度最高；在标差２８ｄ后，粉煤灰掺量大于３０％的砂浆试块抗压和抗折强度比无粉煤灰试块有所降低。     

水泥混凝土地坪"起砂露石"的薄层修复砂浆研究

通过对多种配方修补砂浆的抗压强度、抗折强度、抗拉强度、粘结强度、折压比、拉压比、干缩变形性能、弹性模量、耐磨性能的对比研究，发现了施工性能、力学性能、变形性能、耐久性能完全能满足“起砂露石”的混凝土地坪修补要求的砂浆，避免了采用板块拆除重浇、环氧砂浆罩面等修补方式所造成的费工耗时、色差严重、变形不同步或老化而导致粘结失效等问题。     

水泥掺量对纤维改性聚合物树脂混凝土力学性能的影响

利用抗压试验、抗折试验、扫描电镜等方法,探讨了水泥掺量对聚合物砂浆性能的影响.试验结果表明：当水泥掺量为115%时与水泥掺量0%时相比,聚合物砂浆的抗折强度提高95%,抗压强度提高74%,折压比也相应有所提高.但加入量高于115%时,导致水泥比表面积过大,抗折强度和抗压强度均有所下降.     

抗冻性聚合物砂浆的研制

目前在中国寒冷地区使用的外墙饰面砖砂浆,普遍存在着抗冻性差、粘结强度低、耐久性差等缺点,致使外墙饰面砖脱落,破坏了应用 有的装饰效果和保护作用。本研究,利用改性高分林聚合物乳液,制成聚合物水泥砂浆,该砂浆具有抗冻性好、粘结强度高、抗渗性好、耐久性好等特点。抗冻性：冻融循环100次合格;粘结强度达到2．0MPa,是一种理想的抗冻性外墙饰面砖专用砂浆。     

Preparation and properties of a new composite of epoxy emulsion (EEM) modified cement

High performance cement based composite materials was prepared by adding epoxy emulsion. The epoxy emulsion was synthesized with epoxy phosphoric acid ester and poly-glycol in laboratory. This epoxy emulsion has advantages over other emulsion, such as dehydrated slightly, and, well film formation abilities. The mechanical properties corruptness resistance and structure of epoxy emulsion modified cement mortars were studied. Experimental results show that the mechanical properties of modified cement mortars are slightly increased with increasing epoxy emulsion content, especially the flexure strength. The corruptness resistance of all modified mortars is better than the unmodified mortar. The polymer film forms the bridge phases between the matrix and the aggregate regions, and forms a three-dimension structure in the cement hydration system, which improves the mechanical properties of modified mortars.     

再生纤维素纤维增强水泥砂浆的早期抗裂和自收缩行为

早期收缩开裂是导致混凝土劣化的重要因素之一,纤维的加入可以延缓甚至减少裂缝的延伸及扩展。使用具有吸水特性的再生纤维素纤维,与UF500纤维素纤维和无吸水的聚丙烯短纤维对比,研究再生纤维素纤维对水泥砂浆早期抗裂和自收缩行为的影响规律。将掺量为水泥质量1%或2%的各类纤维掺入水泥砂浆,密封养护,分析水泥砂浆强度、折压比及自收缩应变。研究结果表明：水灰比0.3时,添加再生纤维素纤维不能增强砂浆的抗裂性能和自收缩性能;水灰比大于0.35时,添加1%的再生纤维素纤维虽然降低了砂浆的抗折强度和抗压强度,但提高了该样品的折压比,增强了砂浆的抗裂性能和减缩效应。     

Research on the Anticorrosion Coating Under the Paved Layer for Highway Steel Box Bridge Deck

The corrosion of the anticorrosion coating and the defects of the asphalt concrete paved layer have been investigated on long-span steel box bridge decks. The anticorrosion coating lies in the midclle of two entirely different materials： a highway steel box bridge deck and a paved layer, which is used as anticorrosion and waterproof coating for the steel bridge deck. For our study, electrochemical corrosion and pull strength experiments have been selected for the investigation of the corrosion properties of inorganic zinc rich coating, epoxy zinc rich coating and arc sprayed zinc coating. The adhesive strength between the coatings and the panel, and the effect of the coating corrosion on the shear properties of the paved layers including cast asphalt, thermal asphalt mortar, epoxy asphalt and modified asphalt con- crete have been investigated. The results show that the adhesive strength between the coatings and the bridge panel is controlled by the method of pre-processing rust removal. Coating by sandblasting has stronger adhesive strength than coating by shot peening. The results also reveal that shear strength of the paved layer is affected by the corrosion product of zinc coating. The arc sprayed zinc coating has stronger shear strength than zinc rich coatings.     

Effect of Sand Content on Strength and Pore Structure of Cement Mortar

The effects of four sand contents on the compressive, flexural and splitting-tensile strength of cement mortars were evaluated. Moreover, we experimentally investigated the pore structure of cement mortar brought about by changing the sand content and water/cement ratio. The changes in the pore structure were quantified by measuring the porosity and pore size distribution obtained by using mercury intrusion porosimetry(MIP) technique. The test results show that the strengths of cement mortar increase with increasing sand content. It is also suggested that the traditional water/cement ratio law can be applied to cement mortar with different sand contents, provided that a slight modification is introduced. Sand content is an important parameter influencing the pore structure of cement mortar. Moreover, there is a good relationship between the pore structure and strength of cement mortar.     

纳米高岭土颗粒改性水泥基复合材料的性能

研究了纳米高岭土颗粒对不同龄期水泥基材料微观结构（微孔结构、微观结构）及物理力学性能（工作性、抗弯强度、抗压强度、氯离子渗透性）的影响。结果表明,纳米高岭土颗粒的填充效应及其对水泥水化的促进作用改善了水泥基材料的微观孔结构,限制了氯离子在水泥基材料中的渗透扩散。当高岭土为水泥质量的1％时,水泥浆1、3、7、90 d抗弯强度分别提高30．41％、39．04％、36．27％和38．32％;当高岭土为水泥质量的5％时,水泥砂浆氯离子扩散系数降低53．03％;混凝土氯离子扩散系数随高岭土掺量增加呈指数递减;当高岭土为水泥质量的5％时,氯离子扩散系数降低18．87％;抗压强度分别提高28．4％;改性混凝土28 d抗压强度与混凝土氯离子扩散系数呈线性增加关系。     

Effect of rubber particles on cement stabilized gravel system

The primary objective of this paper was to study the mechanical properties and durability of the cement stabilized gravel by different compact method. The influence of rubber particle content on mechanical properties of samples was studied by compaction tests and freezing thawing recycle tests. Pore structure and fractal characteristic of mixture were analyzed quantitatively using mercury intrusion porosimetry （MIP）. X-ray diffraction （XRD） was adopted to identify the composition phases. The morphology analysis in micro scale and elemental analysis of samples were carried out by scanning electron microscope （SEM）. The optimum compressive strengths of rubber cement stabilized gravel （RCSG） with static compaction method and with vibratory compaction method were obtained by controlling compaction degree and vibration time, respectively. From the compaction tests, the vibratory compaction method is preferred compared with the static compaction method as better compressive strength can be improved by about 340%-360%. Besides, test results also reveal that compressive strength of samples with vibratory compaction method or static compaction method will decrease with the rubber particle bulk content increasing. The freezing thawing recycle tests indicate that freezing thawing resistance has been improved （frozen stability coefficient K has been increased from 0.89 to 0.97） by the addition of rubber particles. MIP tests show that the mean pore diameter and porosity of mixture have been increased from 70 to 250 nm and 9% to 24% respectively, with the rubber particles content increasing. Component analysis shows that the calcium silicate hydrate （CSH） is the predominant hydrate product with or without the addition of rubber particles.     

温度对聚丙烯纤维砂浆及测强曲线的影响

目的研究温度对聚丙烯纤维砂浆及测强曲线的影响,为以后工程防火加固选用砂胶比提供依据,从而达到降低成本的目的．方法通过测试不同胶砂质量比的聚丙烯纤维砂浆的初始流动度、终凝时间、抗压强度和抗折强度,研究不同温度下不同碳纤维掺量的聚丙烯纤维砂浆的耐高温性能．结果当碳纤维体积分数为0．3％、胶砂质量比为1．5时,聚丙烯纤维砂浆流动度大于320mm,终凝时间60min左右,28d抗压强度大于80MPa,1000℃高温燃烧后,残余50％以上强度,各龄期的测强曲线与实测强度有较好的拟合关系．结论采用普通硅酸盐水泥、铝酸盐水泥、石膏三元体系,通过添加碳纤维、偏高岭土掺合料及多种化学添加剂,可满足工程实际需要,并且具有良好的经济性．     

聚酯纤维掺量对聚合物树脂混凝土力学性能的影响

利用抗压试验、抗折试验及扫描电镜等方法,探讨了聚酯纤维对聚合物砂浆性能的影响.试验结果表明:当聚酯纤维掺量为0.8%与聚酯纤维掺量0%相比,聚合物砂浆的抗折强度提高17%,抗压强度提高5%,折压比也相应有所提高.但加入量高于0.8%时,抗折强度和抗压强度均有所下降.