高性能环氧树脂透水混凝土的制备及其性能研究

以不同质量分数(0,1%,2%,3%)的水性环氧树脂为改性剂,制备了高性能环氧树脂透水混凝土,研究了环氧树脂掺杂量对透水混凝土力学性能、透水性能、抗冻性能和微观形貌的影响。结果表明,适量的环氧树脂掺入透水混凝土后,可以增加骨料与砂浆之间的粘度,并提高其结合强度,从而提高了改性透水混凝的力学性能、透水性能和抗冻性能;随着环氧树脂掺杂量的增加,改性透水混凝土的抗压强度和抗折强度先增大后减小,透水系数和质量损失率先减小后轻微增大;当环氧树脂的掺杂量为2%(质量分数)时,28 d的抗压强度和抗折强度达到最大值,分别为13.17和1.26 MPa,透水系数和质量损失率(60次冻融循环下)达到了最小值,分别为4.84 mm/s和0.3233%;环氧树脂的掺杂提高了透水混凝土的结构致密性,当环氧树脂的掺杂量为2%(质量分数)时,改性透水混凝土的结构致密性最高,微裂纹较少,抗冻性能最佳。     

地聚物基透水混凝土的制备与性能

透水混凝土因具有透水透气、吸声减噪等功能而被广泛研究和关注。然而,其普遍存在孔隙结构,造成受力不均,使得透水混凝土只能用于低荷载的路面。为了提高透水混凝土的强度和耐久性,本研究将地聚物作为透水混凝土的胶凝材料,并采用正交试验研究了最佳配比,分析了孔隙率、骨料粒径、激固比、矿渣掺量、水玻璃模数对其性能的影响。以抗压强度、劈裂抗拉强度、透水系数、抗冻性为指标,拟合分析了孔隙率与透水系数、透水系数与抗压强度、孔隙率与抗劈裂强度之间的关系。结果表明:目标孔隙率15%、激固比60%、骨料粒径2～5 mm、水玻璃模数1. 4、矿渣掺量20%为最优配比,所得地聚物透水混凝土的28 d抗压强度为33 MPa,抗劈裂强度为2. 4 MPa,透水系数为8. 4 mm/s,抗冻性能达标。     

粘土砖再生骨料开发保水性透水混凝土的强度分析

废弃粘土砖具有良好的吸水、保水能力,用粘土砖开发的透水混凝土具有一定吸水、保水性能。由于粘土砖的抗压强度低,吸水后抗冻融性能亦差,因此,对不同砖骨料掺量下的透水混凝土作对比试验,研究表明,透水混凝土的抗压强度和抗冻融性能随粗骨料掺量增加而减小,在制备透水混凝土时应充分考虑砖骨料对抗压强度和抗冻性的不利影响。     

再生骨料透水混凝土的透水性和抗压强度

为系统掌握再生骨料透水混凝土的制备和性能变化规律,采用实验手段研究了再生骨料透水混凝土的透水性能和抗压强度。参考一般混凝土试验方法,分析在不同骨料粒径组合下原生骨料透水混凝土透水性能和抗压强度的差异。在此基础上,选择透水性能和抗压强度均较优的骨料粒径组合,在其中加入再生骨料,探究不同再生骨科取代率对再生骨料透水混凝土透水性能和抗压强度的影响以及透水系数与抗压强度间的相关性。结果表明:(1)对于采用的粒径组合(10 mm+20 mm),再生骨料透水混凝土的抗压强度较原生骨料透水混凝土高,当取代率不超过50%时,其抗压强度随取代量的增加而增大,但当取代率超过50%时,其抗压强度则有所下降;(2)再生骨料透水混凝土的透水性能较原生骨料透水混凝土好,透水系数随取代量的增加会有30%~195%的增幅;(3)与原生骨料透水混凝土抗压强度随透水系数增加持续下降变化不同,再生骨料透水混凝土的抗压强度随透水系数的增加会呈先上升后下降的变化。     

透水沥青混凝土单轴冲击压缩特性研究

为研究透水沥青混凝土的动态力学特性,采用74 mm钢质分离式霍普金森压杆装置对不掺纤维和掺0.3%聚酯纤维的透水沥青混凝土进行了不同应变率的单轴冲击压缩试验。研究表明,透水沥青混凝土具有明显的应变率效应,试件压缩率随着应变率的增大而提高,掺聚酯纤维透水沥青混凝土的压缩率是不掺纤维的1.2倍左右;透水沥青混凝土的动态应力-应变曲线可分为弹性变形阶段、塑性变形阶段和破坏阶段。从试件的破坏形态可以看出,集料的断裂是透水沥青混凝土破坏的主要原因。在透水沥青混凝土中掺加聚酯纤维能够延缓裂缝的出现和开展,提高材料的冲击抗压强度,增幅最大为45.1%。     

苯丙乳液与聚丙烯酸酯乳液对透水混凝土性能影响的试验研究

聚合物乳液可改善浆体新拌状态，提高透水混凝土强度，本工作采用苯丙乳液(SAE)、聚丙烯酸酯乳液(PAE)对透水混凝土进行改性，研究两者对透水混凝土浆体流变性能、力学性能和透水性能的影响。结果表明，掺入SAE会降低浆体塑性黏度，对新拌浆体流动度影响不显著，透水混凝土抗压强度随着其掺量的增加先提高后降低，聚灰比为1.5%时，浆体的28 d抗压强度相比于对照组R-0提高了8.2%,透水混凝土28 d抗压强度最高为35.5 MPa,相比对照组高了4.1%;掺入PAE会提高浆体的塑性黏度，新拌浆体流动度逐渐减小，透水混凝土抗压强度先提高后降低，透水系数降低，PAE聚灰比为6%时，浆体28 d抗压强度相比于对照组R-0提高了9.6%,透水混凝土28 d强度达到36.8 MPa,相比于对照组R-0提高了7.9%,透水系数达到2.47 mm/s。     

纤维素等若干因素对仿钢纤维增强透水混凝土性能的影响

本实验研究了不同仿钢纤维掺量(0%、0.2%、0.4%、0.6%)对透水混凝土抗压强度和透水系数的影响,并分析了骨料粒径、细骨料、纤维素等因素对仿钢纤维增强透水混凝土抗压强度和透水性能的影响。研究表明:仿钢纤维能够在一定程度上提高透水混凝土的早期强度;随仿钢纤维掺量的增加,透水混凝土28 d的抗压强度呈先上升后下降趋势,即存在最优掺量;当仿钢纤维掺量增加时,透水混凝土的透水能力先下降后上升;透水混凝土的抗压强度随骨料粒径的增大而降低,透水系数随骨料粒径的增大而明显增大;细骨料会使透水混凝土的早期抗压强度降低,但会提高透水混凝土28 d的抗压强度;随着细骨料取代量的增加,透水混凝土的透水系数先增大后减小;透水混凝土的抗压强度随纤维素掺量的增加而降低,透水系数随纤维素掺量的增加而增大。本研究可为实际透水混凝土施工过程中外掺料的选择提供参考。     

再生骨料掺配比对再生透水混凝土性能的影响

为研究再生骨料在透水混凝土（RPC）中的应用,选用废弃路面素混凝土块为再生骨料来源,设计2种系列,研究再生骨料透水混凝土中再生骨料掺配问题,即分别以粒径9.5~19.0 mm,再生骨料按0%、25%、50%、75%和100%（基准）质量替代同粒径天然骨料碎石（系列1）和以4.75~9.5 mm、9.5~19.0 mm两种粒径,再生骨料按0∶1、1∶1、1∶2、2∶1、2∶3和3∶2掺比（系列2）制备RPC,并分析其物理、力学、透水性能及其相互关系,得到了合理的再生骨料替代率和双粒级掺比,在1∶1和2∶1掺配下能够得到较好的强度及透水性能。通过切割试块的图像化处理,分析其孔隙分布特征和趋势,并将平面孔隙率、等效孔径和透水系数联系起来。结果表明,再生透水混凝土的透水能力主要取决于截面孔隙个数和面积。     

废弃纤维再生混凝土框架中柱节点抗震性能试验研究

完成了再生骨料取代率为50%,废弃纤维长度分别为12 mm、19 mm、30 mm以及废弃纤维体积掺量分别为0.08%、0.12%、0.16%的5个废弃纤维再生混凝土框架中柱节点在低周反复荷载作用下的抗震性能试验研究。主要对不同废弃纤维长度、不同废弃纤维体积掺量下梁柱节点的破坏形态、滞回特性、延性性能、耗能特性等问题进行了对比分析。结果表明:废弃纤维再生混凝土框架节点的破坏均经历了初裂、通裂、极限、破坏四个特征阶段,当纤维长度为19mm,废弃纤维体积掺量为0.12%时,废弃纤维再生混凝土梁柱节点构件的滞回性能、延性性能及耗能性能较好;废弃纤维的体积掺量比废弃纤维长度对梁柱节点抗震性能的影响大。提出了废弃纺织纤维再生混凝土的抗剪承载力计算公式,计算结果与试验结果吻合较好。     

玄武岩/聚丙烯纤维水泥砂浆的力学性能与抗裂性

研究了玄武岩纤维、聚丙烯纤维单独和混杂掺加对水泥砂浆工作性、力学性能和抗裂性的影响.结果表明,在掺率为0.075%～0.20%(体积分数)的范围内,单独掺加玄武岩纤维和聚丙烯纤维均可以不同程度地提高水泥砂浆的抗折强度和早期抗压强度,而对28d抗压强度均有不利影响;在体积掺率相同的情况下,掺加玄武岩纤维的砂浆比掺加聚丙烯纤维的砂浆具有更好的力学性能;玄武岩纤维与聚丙烯纤维以适当比例混杂掺加时,可以得到较掺加单一种类纤维更好的效果;混杂纤维可以有效地改善水泥砂浆的韧性,提高水泥砂浆的抗裂性能.     

Damage performance of particles filled quasi-isotropic glass–fibre reinforced polyester resin composites

The purpose of this work was to determine the toughening mechanisms in interlayered quasi-isotropic glass–fibre reinforced polyester resin (GFRP) composites. Particles of polyethylene and aluminium tri-hydrate, Al(OH)3, were mixed with the polyester resin prior to laminating with woven E-glass-fibre cloth. Mode-I, mode-II, and impact tests were performed to determine critical strain energy-release rates (GIc and GIIc), absorbed energy and residual compressive strength for the laminates with and without particulate additions. Mode-I and mode-II delamination toughness were characterized using double cantilever beam (DCB) and end-notched flexure (ENF) specimens, respectively, and the delaminated surfaces of specimens were examined using scanning electron microscopy (SEM) to investigate the interlaminar morphology after fracture. The results indicate that the interlaminar toughness (GIc and GIIc), absorbed energy and residual compressive strength values of the GFRP composite increases with increase of particle content. The improved behaviour of particle containing GFRP is linked to stress-concentration induced plastic deformation and crack bridging. Polyethylene particles increase the toughness of the matrix material, which results in composites with higher values of mode-I, mode-II and impact than the composites with aluminium tri-hydrate particles. © 1998 Chapman & Hall     

A novel water permeable geopolymer with high strength and high permeability coefficient derived from fly ash,slag and metakaolin

In this work, a new water permeable geopolymer with high strength and high water permeability coefficient based on fly ash-slag-metakaolin was proposed. The experimental results show that fresh geopolymer composite exhibits dry characteristic and porous structure. The void ratio is 27.6% and the permeability coefficient reaches 1.70 cm/s. The compressive strength and flexural strength reach about 30 MPa and 6.2 MPa, respectively at 1 day and reach as high as 49 MPa and 11.3 MPa at 28 days of curing, respectively. After 100 freeze-thaw cycles, the terminal remaining mass is still larger than 80% along with internal damages and deteriorations on geopolymer paste coating. The dense microstructure of geopolymer matrix and interfacial transition zone indicates the high compressive strength, flexural strength and high freeze-thaw resistance of water permeable geopolymer.     

国产CCF300碳纤维单向织物液体成型工艺性及其复合材料力学性能

选取国产碳纤维CCF300所制备的2种单向织物,单向无纬织物U3160及单向无屈曲织物KUC160,分别对其预成型体进行压缩特性和渗透特性测试,以研究2种单向织物的液体成型工艺性,并采用树脂传递模塑(RTM)工艺制备2种单向织物/双马来酰亚胺树脂基复合材料,测试并对比其面内力学性能。结果表明:预成型体压缩试验中,嵌套效应受压力及织物层数影响较大,压力越高、层数越多,嵌套效应越显著。U3160织物的嵌套效应较KUC160织物更为明显,在较高压力下,KUC160织物预成型体的纤维体积分数较U3160织物的下降了约20%。渗透率测试结果表明:相比U3160织物,KUC160织物0°方向的渗透率较高,而90°方向的渗透率有所降低;这是由于经编线的绑缚作用能促进0°方向的宏观流动,而阻碍90°方向的微观渗透。此外,KUC160织物的经编线与U3160织物的纬向纱线的导流作用也对渗透率有影响。力学性能试验结果表明:相比U3160织物增强复合材料,KUC160织物增强复合材料0°方向的拉伸、弯曲和压缩性能均有所下降,拉伸强度和弯曲模量降幅最大,分别约为11%和21%;而层间剪切强度有小幅提高,增幅约为8%。      

氧化石墨烯对玄武岩织物/酚醛树脂复合材料性能的影响

将偶联剂改性的氧化石墨烯(GO)添加到酚醛树脂中,制备了GO改性的玄武岩织物/酚醛树脂复合材料板材。采用三点弯曲、短梁剪切和落锤冲击试验方法,研究了GO的含量对复合材料弯曲性能、层间剪切强度(ILSS)和冲击性能的影响。结果表明,GO的加入显著提高了玄武岩织物/酚醛树脂复合材料的力学性能,随着GO含量的增加,复合材料的力学性能先增大后减小;相对于空白样,当GO的含量为2wt%时,弯曲强度和弯曲模量分别提高了39%和25%;ILSS提高了43%;当GO的含量为1wt%时,冲击破坏载荷增加40%,破坏吸收能量增加60%。     

Mechanical properties of high strength concrete reinforced with metallic and non-metallic fibres

This paper focuses on the experimental investigation carried out on high strength concrete reinforced with hybrid fibres (combination of hooked steel and a non-metallic fibre) up to a volume fraction of 0.5%. The mechanical properties, namely, compressive strength, split tensile strength, flexural strength and flexural toughness were studied for concrete prepared using different hybrid fibre combinations – steel–polypropylene, steel–polyester and steel–glass. The flexural properties were studied using four point bending tests on beam specimens as per Japanese Concrete Institute (JCI) recommendations. Fibre addition was seen to enhance the pre-peak as well as post-peak region of the load–deflection curve, causing an increase in flexural strength and toughness, respectively. Addition of steel fibres generally contributed towards the energy absorbing mechanism (bridging action) whereas, the non-metallic fibres resulted in delaying the formation of micro-cracks. Compared to other hybrid fibre reinforced concretes, the flexural toughness of steel–polypropylene hybrid fibre concretes was comparable to steel fibre concrete. Increased fibre availability in the hybrid fibre systems (due to the lower densities of non-metallic fibres), in addition to the ability of non-metallic fibres to bridge smaller micro cracks, are suggested as the reasons for the enhancement in mechanical properties.     

复合材料带筋壁板预成型体压缩性与渗透性对树脂流动的影响

以航空碳纤维增强树脂基复合材料典型结构件带筋壁板为研究对象,通过对U3160单向织物的组织结构进行分析,根据纤维束的受压变形状态对其压缩响应进行理论建模,然后以纤维束压缩模型为基础,预测了U3160单向织物按0°/45°/90°/-45°铺层时预成型体在压缩应力作用下厚度变化的响应行为。建立了压缩应力作用下纤维预成型体的渗透率解析模型:在织物压缩模型的基础上,建立了纤维束等效渗透率模型;根据张量理论,分别建立了0°、±45°和90°铺层织物等效渗透率模型;运用渗透介质串并联关系,建立了带筋壁板各特征区域渗透率综合表征模型。基于PAM-RTM流动模拟软件,进行分区渗透率定义,在充模过程中对树脂在带筋壁板预成型体中的流动行为进行模拟,优化工艺参数,确定出最终充模方案,并制作带筋壁板实验缩比件进行成型实验,验证了充模方案的合理性。研究结果为制件的成功制作提供理论依据,从而指导生产实践。      

混杂纤维增强应变硬化水泥基复合材料的压缩本构关系

混杂纤维增强应变硬化水泥基复合材料(HyF/SHCC)的力学性能是近年来的研究热点问题之一，但是目前依然欠缺HyF/SHCC压缩本构关系的深入探讨。本文研究了钢纤维(SF)-聚乙烯醇(PVA)纤维增强SHCC (SF-PVA/SHCC)的压缩应力-应变全曲线，分析了纤维对HyF/SHCC抗压强度、压缩应变以及压缩韧性的影响。研究发现，在本文研究工况下混杂纤维的引入对材料的抗压强度无明显影响，但是提高了压缩峰值应变。钢纤维对HyF/SHCC压缩韧性的影响较为显著，且随着钢纤维掺量的增大，HyF/SHCC的压缩韧性逐渐提高。基于损伤力学理论，从能量的角度提出了一种新的单轴压缩本构模型，通过与试验曲线的对比，发现该模型可以较好地预测SF-PVA/SHCC的压缩应力-应变关系。      

The low velocity impact response of non-woven hemp fibre reinforced unsaturated polyester composites

Hemp fibre reinforced unsaturated polyester composites (HFRUPE) were subjected to low velocity impact tests in order to study the effects of non-woven hemp fibre reinforcement on their impact properties. HFRUPE composites specimens containing 0, 0.06, 0.10, 0.15, 0.21 and 0.26 fibre volume fractions (V_f) were prepared and their impact response compared with samples containing an equivalent fibre volume fraction of chopped strand mat E-glass fibre reinforcement. Post-impact damage was assessed using scanning electron microscopy (SEM). A significant improvement in load bearing capability and impact energy absorption was found following the introduction hemp fibre as reinforcement. The results indicate a clear correlation between fibre volume fractions, stiffness of the composite laminate, impact load and total absorbed energy. Unreinforced unsaturated polyester control specimens exhibited brittle fracture behaviour with a lower peak load, lower impact energy and less time to fail than hemp reinforced unsaturated polyester composites. The impact test results show that the total energy absorbed by 0.21 fibre volume fraction (four layers) of hemp reinforced specimens is comparable to the energy absorbed by the equivalent fibre volume fraction of chopped strand mat E-glass fibre reinforced unsaturated polyester composite specimens.     

Application of high performance polypropylene fibers in concrete lining of water tunnels

In this study, the application of high performance polypropylene fibers (HPP fibers) in concrete lining of water tunnels, was investigated experimentally. A comparison between the behavior of steel fiber reinforced concrete and HPP fiber reinforced concrete with ordinary concrete is drawn. Advantages and shortcomings of HPP fibers used for concrete lining of water tunnels are also presented.The obtained results showed that the HPP fibers were not effective in compressive strength when compared to steel fibers, but the effects of HPP fibers on tensile strength, flexural strength, toughness and energy absorption of concrete were significant. Based on the results, the effects of HPP fibers on concrete characteristics such as the flexural toughness, concrete permeability and resistance to chloride penetration were higher than those of steel fibers. The results also showed that with application of HPP fibers, durability and serviceability of the concrete linings can be improved.