剑麻-耐碱玻璃纤维混凝土基本强度研究

为研究剑麻-耐碱玻璃纤维混凝土基本强度,设计了30组不同纤维掺量的混凝土试件,测试并分析其抗压强度、劈裂抗拉强度和抗折强度。试验结果表明:剑麻纤维和耐碱玻璃纤维单掺和双掺均能大幅提高普通混凝土基本强度,试验中纤维体积掺量为1.5 kg/m³时,单掺剑麻纤维,混凝土基本强度提升5.65%~15.74%;单掺耐碱玻璃纤维,混凝土基本强度提升3.03%~9.14%;混掺剑麻纤维和耐碱玻璃纤维,混凝土基本强度提升8.33%~21.31%,且试件强度提升效果表现出劈裂抗拉强度>抗压强度>抗折强度。研究成果对剑麻-耐碱玻璃纤维混凝土的制备以及植物纤维在混凝土中的应用提供了参考。     

耐碱玻璃纤维ECC复合材料受压应力–应变关系

为研究耐碱玻璃纤维工程用水泥基复合材料（耐碱玻璃纤维ECC）的抗压性能及应力-应变关系，对33组高性能水泥基材料试件进行了轴压性能试验，分析了纤维掺量、纤维长度及水灰比对耐碱玻璃纤维ECC的受压性能及应力-应变关系的影响，提出了耐碱玻璃纤维ECC受压应力-应变关系计算模型。结果表明，掺入耐碱玻璃纤维可以明显改善水泥基材料在单轴受压状态下的抗裂、受力和变形性能；耐碱玻璃纤维ECC试件抗压强度和变形能力的提升程度与纤维掺量、纤维长度及水灰比有关；随着纤维掺量和长度增加，耐碱玻璃纤维ECC试件的抗压强度和变形能力大致呈递增趋势，但掺量过多会因“团聚”现象明显导致试件抗压强度降低；水灰比主要影响试件的抗压强度，水灰比越大，抗压强度越小；当纤维质量掺量为6.5%、纤维长度为18mm及水灰比为0.32时，碱玻璃纤维ECC的综合力学性能相对较优，其抗压强度和变形能力分别可提升25.6%和88%；提出的应力-应变关系模型的计算值与试验值吻合较好，可用于描述耐碱玻璃纤维ECC的受压破坏全过程。     

Influences of polypropylene fiber and SBR polymer latex on abrasion resistance of cement mortar

Influences of polypropylene (PP) fiber and styrene-butadiene rubber (SBR) polymer latex on the strength performance, abrasion resistance of cement mortar were studied. The experimental results show that the flexural strength, brittleness index (σ_F/σ_C) and abrasion resistance can be improved significantly by the addition of PP fiber and SBR polymer latex. The relationship between the flexural strength and abrasion resistance was analyzed, showing a good linear relationship between them. The reinforced mechanism of PP fiber and SBR polymer latex on cement mortar was analyzed by some microscopic tests. The test results show that the addition of SBR polymer latex has no significant influence on the cement hydration after 7 d curing. Adding SBR polymer latex into cement mortar can form a polymer transition layer in the interfaces of PP fiber and cement hydrates, which improves the bonding properties between the PP fiber and cement mortar matrix effectively.     

钢纤维对聚合物水泥砂浆力学性能的影响

为了研究不同钢纤维掺加率对聚合物水泥砂浆力学性能的影响,制作了不同钢纤维掺加率的钢纤维聚合物水泥砂浆试件,在标准养护条件下分别养护至7d及28d,测定其抗折及抗压强度,得出在钢纤维掺量是砂子用量的4%范围内对砂浆抗压强度显著提高有帮助的结论。     

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．     

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。     

超缓凝剂对硅酸盐水泥砂浆性能的影响

目的为配制一种新型有机复合超缓凝剂，研究不同掺量及养护条件下其缓凝效果和硬化机理．使之可有效地应用于大体积混凝土及缓黏接预应力混凝土工程中．方法利用XRD和SEM等微观手段，对掺入超缓凝剂水泥砂浆的缓凝性能进行了测试和表征．结果超缓凝剂在不同养护条件下，可使水泥水化“休眠”20～40d，“休眠”结束后能迅速水化而结构不发生变化．XRD图谱表明并未发现异常水化物产生；SEM图像表明，掺超缓凝剂的水泥硬化结构更加致密．结论在标准养护条件下，掺量0．035％的超缓凝剂可使水泥水化“休眠”34d，“休眠”结束后59d可达空白试件28d强度．随养护温度增加和超缓凝剂掺量的降低，水化“休眠”期降低．超缓凝剂并未使水化产物发生本质变化，其耐久性应是可靠的．     

内嵌碳纤维板条加固混凝土梁抗弯性能试验研究

为研究内嵌碳纤维板条加固钢筋混凝土梁抗弯性能,对5根试验梁进行抗弯静载试验,对CFRP板条加固梁的破坏形态、极限承载力、刚度、荷载-应变、裂缝等进行了分析,与外贴碳纤维板条加固梁相比,内嵌板条加固梁同样可以改善混凝土梁的力学性能,且内嵌加固梁加固效果优于外贴碳纤维板条加固梁;同时对比分析了以不同黏结材料（环氧树脂、环氧砂浆、水泥砂浆）为不同加固情况对加固梁极限承载力的影响。     

不饱和聚酯挡风抑尘板力学性能研究

以玻璃纤维毡为增强骨架,不饱和聚酯树脂为基体材料,制备挡风抑尘板,并对不饱和聚酯树脂与玻璃纤维的配比、玻璃纤维的种类和固化剂、促进剂含量对挡风抑尘板力学性能的影响进行了研究。结果表明,当不饱和聚酯与玻璃纤维毡的质量比达到3∶1时,其拉伸强度和冲击强度都达到最大。高碱、中碱和无碱的玻璃纤维毡增强的挡风抑尘板拉伸强度分别达到55.198,75.249,89.446MPa,冲击强度分别达到30.699,35.367,41.343kJ/m2。而无碱玻璃纤维毡其拉伸强度比高碱提高了62%,比中碱提高了18.8%。冲击强度比高碱提高了34.7%,比中碱提高了16.9%。当促进剂质量分数为0.5%、固化剂质量分数为1%时,挡风抑尘板的拉伸强度最大为89.446MPa,冲击强度最大为41.343kJ/m2。     

Effect of Waste Paper Fiber on Properties of Cementbased Mortar and Relative Mechanism

The aim of this work was to investigate the effect of waste paper fiber on the properties of cement-based mortar and the relative mechanism. The cement-based mortars with various contents and mixing way of waste paper fibers were prepared and the slump flow, setting time and strength developments of all mortars were tested. Besides, Ca(OH)_2 content in hardened pastes at different ages and the microstructures of all mortar at 90 d were observed by scanning electron microscopy. The experimental results showed that in the process of mixing, more superplastizier was consumed to maintain the workability because of the absorption of water and superplastizer on waste paper fiber. With more waste paper fiber being added, longer setting time is available for the pastes with it because of the carbohydrate dissolving and its retarding to the cement hydration. Waste paper fiber is adverse to the early and later strength of cement-based mortar, but it increases the mortar strengths at 7 and 28 d. The strength, Ca(OH)_2 content and microstructure are related to the content and mixing way of waste paper fiber. Waste paper fiber helps produce the Ca(OH)_2 at 7 and 28 d, but this case is reverse at ages of 1 and 3 d. Overall, waste paper fiber leads to the appearance of more pores in the hardened paste. However, it increases the toughness of cement-based mortar.     

耐碱玻璃纤维及其混杂纤维混凝土的弯曲疲劳特性

研究了玻璃纤维、有机纤维及混杂纤维增强混凝土的弯曲疲劳特性。试验结果表明：耐碱玻璃纤维对疲劳性能的改善效果优于聚丙烯纤维;当玻璃纤维掺量为2.7 kg·m^-3时,玻璃纤维混凝土疲劳强度比素混凝土提高24%;玻璃纤维与有机纤维混杂使用后,构件的弯曲疲劳性能有了较为显著的改善,玻璃纤维掺量2.7 kg·m^-3与有机纤维掺量1.3 kg·m^-3混掺时,混杂纤维混凝土疲劳强度比素混凝土提高35.0%,即混杂纤维能充分发挥各种纤维的优势,对改善混凝土的疲劳性能比单掺玻璃纤维和有机纤维的作用都显著。     

碳纳米管增强水泥砂浆在混凝土修补加固中的应用研究

采用8字形新老砂浆抗拉粘结强度的试验方法,研究了不同粘结砂浆粘结材料在不同配比条件下的粘结性能,得到了不同粘结材料抗拉强度的变化规律。试验结果表明,碳纳米管增强水泥砂浆粘结性能良好,适宜作为新老混凝土界面修补材料。     

Ultra high early strength self-compacting mortar based on sulfoaluminate cement and silica fume

The influences of silica fume and aluminum sulfate on hydration process of sulfoaluminate cement were carried out by ring flow, setting time, hydration heat, XRD and DTG analyses. In addition, mortar mixtures with different functional additives have been studied through compressive strength, flexural strength, volume stability at early age and porosity characterization tests. The results show that the addition of silica fume and aluminum sulfate reduces the fluidity and shortens the setting time of sulfoaluminate cement paste, promoting hydration process and increasing hydration products at early age. In the case of appropriate proportion of mortar, the inclusion of hydroxy propyl methyl cellulose, dispersible polypropylene fiber and organic silicon kind of defoamer can control segregation and bleeding, improve mechanical strength and volume stability at early age, and modify the pore distribution of sulfoaluminate cement mortar, respectively. The sulfoaluminate cement mortar can carry out gravitational grouting in the absence of outside force, the compressive strength of 2 hours and 24 hours have reached 26 and 58 MPa respectively, and have good microexpansion and tiny pore distribution characterization.     

Effect of curing regime on bonding strength of EVA modified mortar to tile

Ethylene-Vinyl Acetate (EVA) redispersible powder and latex were used to modify mortar. Three kinds of curing regimes: standard curing, high temperature curing and freeze-thaw circle curing were adopted to cure the bonded samples. Bonding strength of EVA modified mortar was tested at 28 days. The development of bonding strengths under all three curing regimes were discussed and compared. The experimental results show that bonding strength increases with the increase of EVA content in mortar. The curing regime used within 28 days is critical according to the bonding strengths values under three curing regimes for different ages. The reasons of that the EVA can improve the bonding strength were analyzed.     

Effects of Specimen Height on the Acoustic Emission Rate Value 'a' for Cement Mortar

In order to study the size effect on the AE rate 'a' value,three kinds of mix ratios were set up by different particle sizes and water cement ratios,45 cement mortar specimens with five different heights were tested under axial compression.And the whole damage processes were monitored by full-digital acoustic emission acquisition system,followed by an analysis of mechanical behavior and AE activity.The experimental results show that the height of the cement specimen has significant effects on the compressive strength and the acoustic emission rate 'a' value,but a slight effect on the accumulated AE hits number,which is analyzed from aspects of failure process of cement mortar specimens.     

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.     

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．     

改性多孔沥青混合料水稳定性与损伤规律

为了提高季冻区多孔沥青路面的使用质量、减轻路面冻融损伤,采用玻璃纤维、硅藻土与沥青路面旧料以改善多孔沥青混合料性能。分析不同材料掺量的多孔沥青混合料在冻融循环下的抗压强度、空隙率及应变变化,并考虑不同材料与不同材料掺量对多孔沥青混合料水稳定性的影响;基于损伤力学理论以抗压强度为指标表示强度率,研究改性多孔沥青混合料的冻融损伤演化规律;基于CT无损检测与数字图像处理技术,分析玻璃纤维多孔沥青混合料冻融前后空隙数量与空隙面积的变化规律。结果表明：混合料抗压强度随冻融循环次数的增加而降低,而空隙率与应变呈上升趋势;具有玻璃纤维掺量0.7%、沥青路面旧料掺量15%、硅藻土掺量25%和掺量15%沥青路面旧料及20%硅藻土的4种多孔沥青混合料水稳定性能最好,其中玻璃纤维的改性效果最佳;掺入玻璃纤维、15%掺量硅藻土与15%掺量沥青路面旧料能减轻多孔沥青混合料的冻融损伤,但硅藻土再生多孔沥青混合料损伤程度均较大,损伤前期强度较高,更适用于短时冻土区;与硅藻土再生多孔沥青混合料相比,玻璃纤维多孔沥青混合料、再生多孔沥青混合料与硅藻土多孔沥青混合料经历了长时间的快速损伤期、短时间的损伤稳定期与损伤发展期;玻璃纤维掺量较低的试样空隙数量增加,平均单个空隙面积减小,而掺量较高的试样表现相反。     

Preparation and Microstructure Analysis of High Strength Cementitious Materials Containing Metakaolin

The preparation and microstructure analysis of high strength cementitious materials containing metakaolin (MK) was studied in this paper. The MK was prepared firstly,and then was mixed with fly ash,ground blast furnace slag,quartz powder and cement with different percentage to produce high strength cementitious materials. After cured under different environment,the compressive strength of such materials was tested. Techniques of X-ray diffraction (XRD) and scanning electron microscopy (SEM) were further employed to identify the composition and microstructure. The results obtained reveal that the compressive strength of such materials mainly effected by component of raw materials,the water binder ratio (W/B) and the curing regime. When the three factors above are optimized,the compressive strength of such materials can get to 156 MPa in maximum. The X-ray diffraction analysis and the scanning electron microscopic images indicated that under optimal curing condition,more raw materials can take chemical reaction and the microstructure is dense to yield good mechanical properties.     

Effect of Curing Regime on Bonding Strength of EVA Modified Mortar to Tile

Ethylene-Vinyl Acetate (EVA) redispersible powder and latex were used to modify mortar. Three kinds of curing regimes: standard curing, high temperature curing and freeze-thaw circle curing were adopted to cure the bonded samples. Bonding strength of EVA modified mortar was tested at 28 days. The development of bonding strengths under all three curing regimes were discussed and compared. The experimental results show that bonding strength increases with the increase of EVA content in mortar. The curing regi...