剑麻纤维沥青混凝土试验研究

剑麻纤维具有价格低廉,性能优良等优点。试验首次将剑麻纤维应用到沥青混凝土中,并针对AC-13目标配合比通过马歇尔试验确定了剑麻纤维的最佳掺量为0.2%。试验结果表明,加入剑麻纤维能显著改善沥青混凝土的高温稳定性、低温抗裂性,对路用性能有较大提高。     

剑麻纤维乳化沥青混凝土路用性能研究

剑麻纤维乳化沥青混凝土是一种新型的乳化沥青混合料,对不同掺量、不同长度的剑麻纤维乳化沥青混凝土进行了路用性能研究,主要包括力学性能、高温性能和水稳定性。通过对比试验,确定剑麻纤维的最佳掺量与最佳长度。     

冻融与腐蚀耦合作用下沥青混凝土性能研究

国内外对冻融循环与硫酸盐腐蚀耦合作用下沥青混凝土的性能鲜有研究。鉴于此,在10%Na2SO4溶液加速劣化条件下采用真空饱水冻融劈裂试验,以冻融腐蚀因子评价沥青混凝土在冻融与腐蚀耦合作用下的性能变化规律。试验结果表明硫酸盐腐蚀加剧了冻融循环对沥青混凝土的破坏作用。SEM微观分析表明硫酸盐溶液较水溶液更易于侵入沥青膜与集料界面及沥青混凝土空隙中,并在冻融条件下发生结冰膨胀导致界面强度降低和裂缝的产生与扩展是沥青混凝土性能衰减的主要原因。水镁石纤维具有优良的稳定效应、界面增强效应和加筋桥接效应,掺加水镁石纤维可以有效提高沥青混凝土抗冻融腐蚀性能。     

剑麻纤维水泥基复合材料弯曲力学性能

通过在水泥基复合材料中掺入不同长度的剑麻纤维,研究剑麻纤维长度对水泥基复合材料抗折强度的影响。试验结果显示,剑麻纤维能有效抑制试件中的细小裂缝,提高试件抗折强度。试件的抗折强度会随掺入剑麻纤维长度的增加而出现先增大后降低的变化规律。剑麻纤维长度超过３ｃｍ时,在水泥基体中会出现较严重的结团、缠绕等现象,试件抗折强度增长率降低。当剑麻纤维长度为３ｃｍ,龄期为２８ｄ时,剑麻纤维水泥基复合材料试件的抗折强度达到最高。     

剑麻纤维增强珊瑚混凝土力学性能试验研究

为研究不同剑麻纤维掺量下珊瑚混凝土力学性能的变化规律,通过对剑麻纤维增强珊瑚混凝土的立方体抗压强度、劈裂抗拉强度、抗折强度及其微观结构进行试验研究,确定剑麻纤维的最佳添加量,为进一步研究剑麻纤维增强珊瑚混凝土其它性能及应用提供参考.试验结果表明,剑麻纤维的掺入对珊瑚混凝土立方体抗压强度的影响很小,掺量3~4.5 kg/m3的剑麻纤维可以显著提高珊瑚混凝土的抗折强度及劈裂抗拉强度,剑麻纤维的掺入可以改善珊瑚混凝土的脆性,使其破坏时表现出良好的延性.     

剑麻纤维对高模量沥青混合料低温性能的改善

采用弯拉应变作为剑麻纤维高模量沥青混合料低温性能的评价指标,考察了剑麻纤维长度及其掺量对高模量沥青混合料低温性能的影响. 同时,对剑麻纤维高模量沥青混合料的高温性能和水稳定性进行了验证. 结果表明,在剑麻纤维掺量为0. 3%条件下,纤维长度能够明显影响弯拉应变值;其中6 mm长的剑麻纤维对高模量沥青混合料的弯拉应变值比不掺加剑麻纤维的高模量沥青混合料增幅高达123%. 在剑麻纤维长度为6 mm的条件下,弯拉应变值随着剑麻纤维掺量的增大呈现出先增大后减小的变化趋势;其中0.3%掺量的剑麻纤维对高模量沥青混合料低温性能改善效果最为突出. 此外,剑麻纤维的添加对高模量沥青混合料的高温和水稳定性能均有一定程度提升.     

剑麻纤维对沥青路面抗滑性能的影响

为提高沥青路面表层抗滑性能,对路面抗滑的机理进行了分析,并对沥青混合料中的纤维添加剂进行了比选,通过往沥青混合料中掺加不同长度、不同掺量的剑麻纤维进行若干组对比试验,确定了沥青混合料中剑麻纤维的最佳长度及最佳掺量。结果表明:剑麻纤维是很适合提高路面表层抗滑性能的沥青混合料添加剂。     

剑麻纤维/砂土复合材料三轴剪切强度特性

为改善砂土的抗剪强度特性,针对剑麻纤维加筋砂土复合材料,通过一系列不固结不排水三轴试验,对不同纤维掺量、纤维长度和砂土干密度条件下剑麻纤维/砂土复合材料的剪切强度特性进行深入研究,并对剑麻纤维加筋机制进行分析。试验结果表明：复合材料中纤维相对含量改变时,初始刚度变化不大;适量的纤维掺量和纤维长度可以在砂体内形成三维网状结构,对比未加筋试样黏聚力显著提高,表明纤维加筋可有效提高砂土的抗剪强度;由于密度增加使得剪切过程中纤维与砂颗粒间的咬合和滑动摩擦力增加使复合材料抗剪强度显著提高;围压增加纤维与砂土界面有效接触面积导致砂土抗剪强度与峰值偏应力明显增强。采用剑麻纤维加筋砂土可增强砂土间界面作用力,明显改善砂土抗剪强度特性。     

聚合物纤维改性高性能沥青混凝土的研究

在试验研究及系统分析高性能沥青混凝土路用性能的基础上 ,选用玄武岩与国创 PG76 - 2 2改性沥青作为原材料 ,设计并制备 Super12 .5型高性能沥青混凝土 ,并通过在混合料中添加聚合物纤维来改善沥青混凝土的路用性能。试验结果表明 ,在使用纤维作为改性剂后 ,混合料的动稳定度、劈裂强度等指标均有不同程度的提高     

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。     

碱处理对剑麻连续长纤增强聚丙烯复合材料力学性能的影响

以丙纶长纤为经纱,剑麻连续长纤为纬纱,织成剑麻/PP平纹机织物。采用不同浓度的氢氧化钠对织物进行碱处理,将处理后的织物与聚丙烯薄板模压成型,制备出剑麻连续长纤增强聚丙烯复合材料。采用SEM对碱处理前后的剑麻纤维形貌进行分析,讨论不同碱处理浓度对复合材料力学性能的影响。结果表明：碱处理对剑麻连续长纤的表面具有刻蚀作用,以及对剑麻连续长纤增强聚丙烯复合材料的动态热机械性能、拉伸性能、弯曲性能均有一定的影响。     

Fiber-reinforced Mechanism and Mechanical Performance of Composite Fibers Reinforced Concrete

To understand the enhancing effect and fiber-reinforced mechanism of composite fibers reinforced cement concrete, the influences of composite fibers on micro-cracks and the distribution of composite fibers were evaluated by optical electron micrometer(OEM) and scanning electron microscope(SEM). Three kinds of fiber, such as polyacrylonitrile-based carbon fiber, basalt fiber, and glass fiber, were used in the composite fibers reinforced cement concrete. The composite fibers could form a stable structure in concrete after the liquid-phase coupling treatment, gas-liquid double-effect treatment, and inert atmosphere drying. The mechanical properties of composite fibers reinforced concrete(CFRC) were studied by universal test machine(UTM). Moreover, the effect of composite fibers on concrete was analyzed based on the toughness index and residual strength index. The results demonstrated that the composite fibers could improve the mechanical properties of concrete, while the excessive amount of composite fibers had an adverse effect on the mechanical properties of concrete. The composite fibers could significantly improve the toughness index of CFRC, and the increment rate is more than 30%. The composite fibers could form a mesh structure, which could promote the stability of concrete and guarantee the excellent mechanical properties.     

Enhanced flexural performance of epoxy polymer concrete with short natural fibers

Epoxy polymer concrete (EPC) has found various applications in civil engineering. To enhance the flexural performance of EPC, two kinds of short natural fibers with high specific strength (sisal fibers and ramie fibers) have been incorporated into EPC. The results of mechanical tests show that a small loading of natural fibers (0.36 vol%) can significantly increase the flexural strength of EPC by 25.3% (ramie fibers) or 10.4% (sisal fibers). This enhancement is achieved without any sacrifice of compressive strength of EPC. The reinforcing effects of short natural fibers on the flexural properties and compressive properties of EPC decrease with further increase in fiber content, due to the insufficient wetting of fibers by epoxy resin which results in poor interfacial bonding. The reinforcing mechanisms of short natural fibers are explored according to the observation of fracture surfaces and micromechanical modelling. It is found that the parallel model based on the rule of mixture can be a good approximation to describe the improvement in flexural strength of the short natural fiber reinforced EPC at low fiber volume fractions.     

复合材料套箍混凝土轴压柱的试验研究

为解决钢筋或钢管容易发生锈蚀的问题,进行了纤维复合材料套箍混凝土轴压柱的试验。结果表明,玻璃纤维复合材料管的套箍作用很大,抗变形能力很强,受力性能与钢管混凝土类似。碳纤维复合材料箍对混凝土的套箍作用也很明显,随着碳纤维复合材料箍间距的减少,柱极限荷载稳步提高。它与复合材料管混凝土柱比可节省造价;与螺旋筋混凝土柱比可节省模板,方便施工。     

巴西剑麻基本性能研究

为提高剑麻纤维的可纺支数和可纺性,以实验方法检测巴西剑麻在无处理、氯漂处理、碱液煮练下的性能.实验结果表明,剑麻纤维中果胶和木质素的含量较高,纤维刚性大,抱合力差,处理时最好选择碱液煮练为主,可有效去除果胶和木质素.     

The multi-scale flow behaviors of sisal fiber reinforced composites during resin transfer molding process

The flow behaviors of the resin during the resin transfer molding (RTM) process of sisal fiber reinforced composites was studied at different scales with the consideration of the unique hierarchical and lumen structures of sisal fibers compared to those of manmade fibers. The work mainly focused on the development of the multi-scale flow models which include the resin flow inside lumens, intra-bundles and inter-bundles. The models not only quantified the lumen flow based on the Hagen-Poiseuille equation, but also ensured the continuity of the velocity and stress on the boundaries between intra-bundle and inter-bundle regions by applying Brinkman equation. Three dedicated experiments were designed and implemented to validate the effectiveness of the proposed models. The absorbed resin mass over the infiltration time obtained from the single sisal fiber and sisal fiber bundle infiltration experiments showed good agreement with the calculated curves. In terms of the RTM process, the dynamic flow front of the resin was perfectly predicted by the proposed model at macro-scale.