纤维对磷酸镁水泥性能的影响试验研究

研究了掺入0.5%~2.0%(体积分数,下同)聚丙烯纤维、玻璃纤维、微钢纤维对磷酸镁水泥流动度、凝结时间、抗折强度、抗压强度和耐磨性影响。结果表明:三种纤维均使磷酸镁水泥流动度减小,凝结时间缩短;聚丙烯纤维会使磷酸镁水泥的抗折强度、抗压强度和耐磨性均出现降低;玻璃纤维和微钢纤维可以增强磷酸镁水泥的抗折强度、抗压强度和耐磨性,其中以抗折强度的提高最为明显。三种纤维均不参与水化反应,对磷酸镁水泥性能的影响取决于物理作用。     

短切碳纤维对油井水泥基复合材料性能的影响

为保证油气井固井长期封固的有效性,需要在油井水泥基材料中添加增强增韧材料改善水泥浆性能。针对短切碳纤维对油井水泥基复合材料性能的影响,研究了短切碳纤维加入到油井水泥基材料中的流变性、稠化时间、失水量以及抗压强度、抗折强度和抗冲击强度,最后对碳纤维水泥石微观形貌进行观察。实验结果表明,碳纤维对水泥浆流变性和稠化时间影响较小,对水泥浆施工无不利影响,碳纤维的加入可以有效降低水泥浆的失水量;在0.4%碳纤维加量范围内,水泥石的抗压强度、抗折强度、抗冲击强度随着碳纤维加量增大均有不同程度的增大。养护28 d后,0.4%碳纤维水泥石的抗压强度、抗折强度、抗冲击强度较空白水泥石分别提高19.1%、34.4%、21.1%;短切碳纤维水泥浆凝固形成水泥石后,纤维通过粘结力和机械咬合力限制水泥试件中局部裂缝的扩展,同时也消耗水泥石破坏能量,从而增强力学性能。研究结果为碳纤维在油井水泥基材料中的应用提供借鉴与参考。     

玄武岩纤维水泥基灌浆料力学性能研究

本文通过在硅酸盐水泥基灌浆料中掺入不同长度及掺量的短切玄武岩纤维,研究其对灌浆料力学性能的影响。试验结果表明:短切玄武岩纤维的掺入,灌浆料的流动度从336 mm降至260 mm,但灌浆料各龄期的抗折强度及抗压强度均得到了提升,早期抗折强度提升最为明显。短切玄武岩纤维在水泥基灌浆料中的最佳掺量为0.15%,最佳长度为9mm,抗折强度和抗压强度分别可以达到17.6 MPa和85.4 MPa。     

微粉和水泥用量对刚玉质浇注料性能的影响

主要研究了活性α Al2 O3微粉和水泥加入量对刚玉质浇注料性能的影响。结果表明 :随着微粉用量增加 ,浇注料的流动性和抗渣性改善 ,凝结时间缩短 ,抗热震性降低 ;随着水泥用量增加 ,流动性降低 ,凝结时间缩短 ,高温处理后的常温抗折强度降低 ,抗折强度保持率增加 ,抗渣性恶化。     

短切碳纤维混凝土的力学强度实验与分析

为探究短切碳纤维对混凝土力学强度的影响机制,以C40和C50矿渣水泥混凝土为研究对象,考察了短切碳纤维长度和掺量对混凝土的抗压强度、劈裂抗拉强度和抗折强度的影响规律,特别是与不掺纤维混凝土的强度对比.实验结果表明,碳纤维的加入可使混凝土的力学强度有不同程度的提高,其中以抗折强度的增长最为明显,劈拉强度次之,而抗压强度比的增幅相对最小,在高纤维掺量时抗压强度甚至低于不掺纤维混凝土;纤维长度的增大对混凝土的力学强度增长更为有利,在低强度等级(C40)混凝土中的表现更为明显.力学分析认为,随机分布的短切碳纤维可显著提高混凝土对劈裂或弯折式破坏的抵抗作用,但对受压时所发生的剪切式破坏却难以发挥明显效果.     

石膏-粉煤灰基复合材料性能研究

本文研究了膨胀珍珠岩、短切维尼纶纤维、水泥熟料对石膏-粉煤灰基胶凝材料抗折、抗压、软化系数和表观密度的影响.结果表明, 半水石膏-粉煤灰胶结材硬化体的强度随着粉煤灰掺量的增加而降低;添加水泥熟料作为粉煤灰的激发剂,可使石膏-粉煤灰复合材料的耐水性能提高;以珍珠岩作为轻骨料的复合材料,随着珍珠岩质量分数的增加,对复合材料的力学性能影响不是很大,复合材料的密度大大减小;短切维尼纶纤维对复合材料的对抗压强度贡献不大,只可以增强制品的抗折强度.     

PET纤维格栅/钢纤维增强水泥基复合材料混杂效应研究

将连续PET纤维格栅与短切钢纤维混掺制备混杂纤维增强水泥基复合材料,其抗压强度高达147.7MPa、抗折强度高达52.6MPa。研究各纤维掺量对混凝土抗压性能及抗折性能影响,表征基体材料与纤维界面微观结构,并分析PET纤维格栅及钢纤维混杂效应。结果表明:钢纤维与PET纤维格栅对水泥基复合材料抗折性能都有增强作用,但钢纤维在抗折性能上发挥了主要作用,导致抗折性能混杂效应并不明显;对于抗压性能,PET纤维格栅对其强度增长有弊,但钢纤维的增强效应弥补了PET纤维格栅的负作用。     

一种环保型混凝土路面修补材料的试验研究

利用正交试验方法,研究了矿渣细度、水泥熟料掺量、水泥熟料细度和水玻璃掺量各因素对凝结时间、砂浆强度的影响规律,确定出环保型混凝土修补材料的初步配方.通过调整水玻璃的模数和水灰比对配方进行优化,研制出一种凝结时间短、抗折强度高、干缩小、粘结强度高的性能优良的环保型混凝土修补材料.     

矿物掺合料对硝基β磷石膏的改性研究

研究了粉煤灰、水泥、粉煤灰-石灰、水泥-石灰四种矿物掺合料对硝基β磷石膏的标稠、凝结时间、强度、吸水率和软化系数的影响。结果表明,不同矿物掺合料对硝基β磷石膏物理性能影响不同,粉煤灰的加入使得凝结时间延长,水泥的加入使得凝结时间变短;矿物掺合料会降低硝基β磷石膏强度,仅当粉煤灰-石灰掺入量分别为15%、5%时,抗折抗压强度保持不变;粉煤灰的掺入增大硝基β磷石膏软化系数,水泥可以降低吸水率。     

偏高岭土、矿渣和赤泥对高性能混合水泥性能影响的研究

通过用硅酸盐水泥、偏高岭土等混合材、膨胀剂及减水剂等制备混合水泥的研究发现：偏高岭土和赤泥的加入使水泥的凝结时间缩短,矿渣的加入延长了水泥的凝结时间;偏高岭土和矿渣对水泥的胶砂流动性影响较小,赤泥的加入使得水泥胶砂流动性显著降低;适量偏高岭土的加入对水泥的3d和28d强度均有增强作用,适量矿渣的加入使水泥抗折强度降低,抗压强度增大;少量的赤泥对水泥强度特别是早期强度有一定的增强作用,但掺量超过20％后水泥强度迅速降低;偏高岭土对水泥微膨胀的产生有促进作用,矿渣和赤泥对水泥微膨胀有抑制作用。用80％～90％的硅酸盐水泥、10％～20％的偏高岭土以及少量的膨胀剂和减水剂能够制备出具有较优流动性、较高的强度以及微膨胀的高性能混合水泥。     

一种高性能环氧树脂固化体系的研究

通过凝胶化测试和示差扫描量热分析（DSC）,研究了CYD128／DMP-30体系固化反应性,20℃凝胶化时间为70min;测试了浇铸体力学性能和耐热性,其中拉伸强度为50．2MPa,拉伸模量为3．5GPa,弯曲强度为156．7MPa,冲击强度为15．0（kJ·m^-2,玻璃化温度（Tg）为96℃。研究了连续纤维增强CYD128／DMP-30体系复合材料的性能,其中连续玻璃纤维增强复合材料弯曲强度为954．8MPa,连续碳纤维增强复合材料弯曲强度为1057．4MPa。     

几种纤维在增强混凝土中的应用

介绍了聚丙烯纤维、碳纤维、钢纤维和玻璃纤雏增强混凝土的基本性能,其中聚丙烯纤维有较好的技术经济性能,已在混凝土工程中广泛应用;由于碳纤维等后3种纤维有高强、高模和韧性,可用于次结构甚至主结构的增强或加固用。同时简介了国内外研究情况以及一些实际应用案例,指出今后有待研究的问题和研究的重点及方向。     

Geopolymer reinforced with E‐glass leno weaves

This study explores the viability of fiberglass‐geopolymer composites as an intermediate temperature structural ceramic composite. E‐glass fibers are cheap, readily available, resistant to heat, electricity and chemical attack. Geopolymers are refractory and can be processed at room temperature. However, pure geopolymers have low tensile strength and fracture toughness, as is typical of ceramics. In this work, tensile and flexure properties of metakaolin‐based sodium and potassium geopolymers reinforced with E‐glass leno weaves were measured and the data was analyzed by Weibull statistics. The average tensile and flexural strengths for sodium geopolymer reinforced with E‐glass leno weaves were 39.3 ± 7.2 MPa and 25.6 ± 4.8 MPa, respectively. For potassium geopolymer reinforced with E‐glass leno weaves, the average tensile and flexural strengths were 40.7 ± 9.9 MPa and 15.9 ± 4.0 MPa, respectively. The composites were heat treated for one hour at two temperatures, 300°C and 550°C and their flexure properties were studied at room temperatures. The average flexural strengths for sodium geopolymer reinforced with E‐glass leno weaves were reduced to 6.6 ± 1.0 MPa after heat treatment at 300°C, and 1.2 ± 0.3 MPa after heat treatment at 550°C, respectively. For potassium geopolymer reinforced with E‐glass leno weaves, the average flexural strengths were 6.1 ± 1.5 MPa and 1.3 ± 0.3 MPa after heat treatment at 300°C and 550°C, respectively. SEM and EDS were performed to observe the fiber‐matrix interface. XRD was done to check if the geopolymer was amorphous as expected.     

不饱和聚酯片状模塑料力学性能的研究

研究了玻纤布、短切玻纤及碳酸钙对不饱和聚酯片状模塑料力学性能的影响,实验发现:玻纤布增强不饱和聚酯片状模塑料的力学性能比短切玻纤好,随着玻纤含量的增加,不饱和聚酯片状模塑料的拉伸强度先增加,达到一极大值之后减少。碳酸钙填充不饱和聚酯片状模塑料,随着碳酸钙含量的增加,不饱和聚酯片状模塑料的拉伸强度明显降低,弯曲强度增加。     

Mechanical properties of hybrid fiber-reinforced concrete at low fiber volume fraction

Concretes containing different types of hybrid fibers at the same volume fraction (0.5%) were compared in terms of compressive, splitting tensile, and flexural properties. Three types of hybrid composites were constructed using fiber combinations of polypropylene (PP) and carbon, carbon and steel, and steel and PP fibers. Test results showed that the fibers, when used in a hybrid form, could result in superior composite performance compared to their individual fiber-reinforced concretes. Among the three types of hybrids, the carbon-steel combination gave concrete of the highest strength and flexural toughness because of the similar modulus and the synergistic interaction between the two reinforcing fibers.     

PBO纤维和碳纤维混杂增强混凝土抗弯曲性能研究

采用PBO纤维与碳纤维混杂复合材料片材增强加固混凝土,设计了3种混杂比的复合材料片材对混凝土进行增强实验,采用3点抗弯曲试验测试纤维片材对混凝土抗弯曲性能增强效果。结果表明,掺有纤维片材的混凝土抗弯曲强度比素混凝土明显提高,两种纤维层间混杂增强后抗弯曲强度呈现出正的混杂效应,破坏形式由素混凝土的脆性断裂转变纤维混凝土的层间韧性断裂。     

Flexural properties after exposure to elevated temperatures of a ground granulated blast furnace slag concrete incorporating steel fibers and polypropylene fibers

Experiments were carried out to investigate the flexural properties of fiber‐reinforced ground granulated blast furnace slag (GGBFS) concrete after exposure to high temperatures. On the basis of experimental observation, the effect of GGBFS content, the steel fiber dosage, the polypropylene (PP) fiber dosage, and the strength grade on the residual strength of concrete after exposure to elevated temperatures were systematically examined. Test data indicate that exposure to high temperatures causes deterioration in the flexural strength of concrete; inclusion of GGBFS, PP fibers, and steel fibers, all effectively improve the residual flexural strength of concrete after fire. The optimum amounts of GGBFS, PP fibers, and steel fibers are identified respectively for better fire resistance of concrete. The strength losses of concretes characterized by different strength grades are very close to one another. Equations are proposed to predict the residual flexural strength of concrete incorporating GGBFS, PP fibers, and steel fibers after being heated to temperatures up to 800°C. Copyright © 2013 John Wiley & Sons, Ltd.     

Mechanical properties of natural fiber hybrid composites based on renewable thermoset resins derived from soybean oil,for use in technical applications

Natural fiber composites are known to have lower mechanical properties than glass or carbon fiber reinforced composites. The hybrid natural fiber composites prepared in this study have relatively good mechanical properties. Different combinations of woven and non‐woven flax fibers were used. The stacking sequence of the fibers was in different orientations, such as 0°, +45°, and 90°. The composites manufactured had good mechanical properties. A tensile strength of about 119 MPa and Young's modulus of about 14 GPa was achieved, with flexural strength and modulus of about 201 MPa and 24 GPa, respectively. For the purposes of comparison, composites were made with a combination of woven fabrics and glass fibers. One ply of a glass fiber mat was sandwiched in the mid‐plane and this increased the tensile strength considerably to 168 MPa. Dynamic mechanical analysis was performed in order to determine the storage and loss modulus and the glass transition temperature of the composites. Microstructural analysis was done with scanning electron microscopy. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

Concentration effect of γ‐glycidoxypropyltrimethoxysilane on the mechanical properties of glass fiber–epoxy composites

In this study, glass fibers were modified using γ‐glycidoxypropyltrimethoxysilane of different concentrations to improve the interfacial adhesion at interfaces between fibers and matrix. Effects of γ‐glycidoxypropyltrimethoxysilane on mechanical properties and fracture behavior of glass fiber/epoxy composites were investigated experimentally. Mechanical properties of the composites have been investigated by tensile tests, short beam tests, and flexural tests. The short‐beam method was used to measure the interlaminar shear strength (ILSS) of laminates. The tensile and flexural properties of composites were characterized by tensile and three‐point bending tests, respectively. The fracture surfaces of the composites were observed with a scanning electron microscope. On comparing the results obtained for the different concentrations of silane solution, it was found that the 0.5% GPS silane treatment provided the best mechanical properties. The ILSS value of heat‐cleaned glass fiber reinforced composite is enhanced by ∼59% as a result of the glass fiber treatment with 0.5% γ‐GPS. Also, an improvement of about 37% in tensile strength, about 78% in flexural strength of the composite with the 0.5% γ‐GPS treatment of glass fibers was observed. POLYM. COMPOS., 2009. © 2008 Society of Plastics Engineers     

高性能、低成本复合材料用环氧体系的研究

通过凝胶化测试和示差扫描量热分析(DSC)研究了CYD128环氧树脂/部分钝化间苯二甲胺固化体系的反应特性,测试了该体系浇铸体的力学性能和耐热性。设计了一种新型低成本真空辅助传递模塑(VARTM)成型工艺并研究了该成型工艺对复合材料力学性能的影响。结果表明,浇铸体弯曲强度可达131.0 MPa,拉伸强度71.8 MPa,拉伸模量3.1 GPa,冲击强度37.5 kJ/m2,玻璃化温度(Tg)98.1℃。使用新工艺得到的复合材料力学性能优异,其中连续玻璃纤维、连续碳纤维增强复合材料弯曲强度分别达到950.2 MPa、1 097.4 MPa。