Effect of granulated rubber on shear strength of fine-grained sand

Review of the literature related to the mixture of shredded tire and sand shows that,despite of the increase in shear strength due to addition of tire chips,granulated rubber causes reduction in shear strength of sand.In this study,the shear behavior of mixtures of fine-grained sand and 1-5 mm granulated rubber is investigated.Sixty direct shear tests were conducted on sandegranulated rubber mixtures with various rubber contents(0%,5%,10%,20% and 30%) at different relative densities(50%,70% and 90%) and different normal stresses(34.5 kPa,54.5 kPa,74.5 kPa and 104.5 kPa).The obtained results show that the granulated rubber improves the shear strength of fine-grained sand at medium relative density and low normal stress.The degree of improvement in shear strength is a function of rubber content,relative density and normal stress.The results show that at relative density of 50%,by adding 5% granulated rubber,the internal friction angle of sand increases from 35.1° to 39.2°.However,at relative densities of 70% and 90%,addition of granulated rubber to sand decreases its internal friction angle.The results also indicate that the behavior of sand becomes more ductile with increasing granulated rubber content.Adding granulated rubber leads to greater yielding strain and less tangent stiffness of sand.The maximum dilation angle decreases with the decrease in granulated rubber content.The stress ratio of sample at critical state(ψ= 0°) decreases with increasing granulated rubber content.     

早强剂对煤矸石-粉煤灰泡沫混凝土性能的影响

以普通硅酸盐水泥为粘合剂,用煤矸石和粉煤灰部分水泥,研究掺加不同的早强剂对此种泡沫混凝土的强度、吸水率以及孔结构的影响。结果表明:早强剂的种类对此这种泡沫混凝土的强度、吸水率以及孔的结构形态有显著的影响。     

岩桥渐进弱化的Jennings抗剪强度准则

Jennings 抗剪强度准则以节理和岩桥抗剪强度参数按连通率加权平均的方式求取非贯通节理岩体的峰值抗剪强度,未考虑直剪试验过程中岩桥力学参数逐步弱化的影响,计算所得的抗剪强度与直剪试验结果存在较大偏差.基于人工齿状共面非贯通节理岩体的直剪试验,采用以剪切位移为变量的岩桥弱化度模型考虑岩桥力学参数弱化对抗剪强度的影响,提出改进的Jennings抗剪强度准则.考虑岩桥力学参数弱化的Jennings抗剪强度准则的计算结果更为接近试验值,表明考虑岩桥力学性质弱化是合理的.     

不同剪切速率下煤散体抗剪强度试验研究

采用TYJ-500 k N电液伺服岩石剪切流变试验机,从煤散体物理参数测试与直剪试验两方面,研究了不同剪切速率下煤散体的抗剪强度,指出随着剪切速率的增加,煤散体的抗剪强度呈先增大、后减小趋势。     

粉煤灰高性能混凝土抗剪性能试验研究

本文采用正交试验方法,研究了水胶比,超细粉煤灰（ultra fine fly ash,简称UFA）掺量以及胶凝材料总用量对粉煤灰高性能混凝土抗剪强度的影响,并通过优选的配合比,考虑粉灯灰高性能混凝土与普通混凝土抗剪强度之间的差异,试验结果表明,水胶比对粉煤灰高性能混凝土的28d抗剪强度影响显著;粉煤灰高性能混凝土的抗剪强度7d时较不掺UFA的基准混凝土低,在28d时可赶上甚至超基准混凝土。     

粉煤灰颗粒特性对其水泥性能的影响

主要研究了对粉煤灰进行机械力化学活化处理后,不同粉磨时间粉煤灰的颗粒特性和粉煤灰水泥性能的变化,结果表明：随着粉磨时间的增加,粉煤灰颗粒的密度、粒度分布都呈有规律的变化,其矿物结晶程度降低,粉磨5 h时掺量为30%的复合水泥达到了纯硅酸盐水泥的强度值。     

GFRP复合材料与粘土砖单剪粘结试验研究

采用玻璃纤维复合材料-粘土砖单剪试验方法,考虑GFRP粘结长度、粘结宽度、粘结树脂的类型及粘贴层数等因素,对GFRP与粘土砖之间的极限粘结荷载进行了深入研究。研究结果表明,粘结破坏有GFRP剥离破坏和GFRP断裂破坏两种形式;GFRP粘结长度、粘结宽度、粘结树脂的类型、粘贴层数及砖抗压强度等因素对极限粘结荷载有显著影响。     

低等级粉煤灰混凝土的力学性能研究

介绍了采用化学激发、水热激发与机械磨细相结合的高效复合活化技术对低等级粉煤灰进行活化处理,对不同掺入量的C30粉煤灰混凝土立方体试样进行了试验及力学性能分析,试验证明这种技术处理能够显著提高粉煤灰混凝土的早期强度和后期强度。     

双掺超细活性混合材对高强混凝土性能的影响

对比研究了普通硅酸盐高强混凝土(PCC)、大掺量粉煤灰高强混凝土(HFAC)，以及双掺超细粉煤灰和矿渣混合料的高强混凝土(GGFAC)在不同养护方式下的强度发展特性。同时观测了各混凝土在7d龄期时的微观结构特征，对混合材的作用机理进行了初步探讨。     

刚性剪力键力学性能分析

通过有限元分析了组合梁刚性剪力键在极限荷载下的位移、应力,得出荷载一滑移曲线及应力分布规律,并对其构造尺寸进行了参数化分析,最后根据经验公式及有限元计算结果推出了其极限承载力简化公式。分析表明,刚性剪力键能够有效的传递混凝土与钢粱间的纵向剪力。     

Effect of interfacial properties on mechanical stability of ash deposit

The paper presents a study on the cohesion of volcanic ash particles using surface free energy determination and zeta potential analyses.This is a subject of great interest in physical volcanology,as many researches on volcanic particle aggregation are frequently reported.In this case,special attention is paid to the role of structural or hydration forces between hydrophilic surfaces,which are a consequence of the electron-donor/electron-acceptor character of the interface.From this point of view,the results are potentially interesting as they could give valuable insights into this process.The results are presented in terms of the total energy of interaction between dispersed particles,computed from the extended DLVO theory.Contributions to the total free energy of interaction were determined from the zeta potential and surface free energy of ash,measured under different experimental conditions.Two samples of basaltic volcanic ash(black and white)with silica contents of 44% and 63% respectively are studied.The surface free energy and zeta potential were analysed for ashes immersed in different electrolytes(NaCl,CaCl_2,FeCl_3).The presence of electrolytes changes the surface properties of the solid materials.The analysis of total interaction energy between the ash particles in aqueous medium shows that soil cohesion strongly depends on ash surface properties,chemical nature,the adsorbed cation on the surface,and p H value.     

蒸压粉煤灰砖基本力学性能研究

按照《砌墙砖试验方法》(GB/T2542-2003)对蒸压粉煤灰砖进行砖的含水率、抗压强度、抗折强度试验。确定蒸压粉煤灰砖的基本力学指标,为编制辽宁省地方标准《蒸压粉煤灰砖建筑技术规范》提供试验依据。结果表明,蒸压粉煤灰砖含水率为2.96%,抗压强度为11.46MPa,抗折强度为1.68MPa,在实际工程上可替代普通烧结砖使用。     

金属橡胶材料剪切力学性能的研究

针对现阶段金属橡胶材料剪切力学性能研究尚未普及的状况,开展了金属橡胶试件承受剪切荷载的试验,分析了加载方向、循环加载次数、加载频率、应力幅值、成型密度等因素对剪切力学性能的影响规律,实验数据表明:金属橡胶材料的剪切性能不受加载方向、加载次数和加载频率的影响,随着应力幅值、成型密度的增加而增大。     

Influence of particle shape on the shear strength and dilation of sand-woven geotextile interfaces

The influence of particle shape on the mechanical behavior of sand-woven geotextile interfaces over a wide domain of soil density and normal stress is studied. A uniformly graded angular fine sand, and a blend of well rounded glass beads with identical particle size distributions, were selected as granular material. Experiments revealed the impact of particle shape on peak and residual friction angles as well as the maximum dilation angle of interfaces between both granular media and woven geotextile. It was observed that the residual friction angles of interfaces between angular sand/glass-beads and woven geotextile are very similar to the residual friction angles of angular sand and glass-beads in soil–soil direct shear test. It is understood that the peak friction angle and maximum dilation angle of angular sand-woven geotextile were slightly lower than corresponding values for angular sand in soil–soil direct shear test. While the peak friction angle and maximum dilation angle of angular sand-woven geotextile interface decrease with the increase in normal stress, experiments showed that these factors are insensitive to normal stress for glass beads-woven geotextile interfaces, at least for the range studied herein. All interfaces with woven geotextile as the contact surface exhibit an abrupt loss of shear strength in the post-peak regime of behavior. Finally, a unified stress-dilation law for the angular sand-woven geotextile, glass beads-woven geotextile, and angular sand-roughened steel interfaces is obtained.     

基于强度指标的粉煤灰基地质聚合物设计

以粉煤灰为主要原材料,少量的硅灰为SiO2调节材料,以水玻璃和NaOH溶液作激发剂,制备了粉煤灰基地质聚合物材料,探讨了影响粉煤灰基地质聚合物强度的主要因素,结果表明:养护温度对地质聚合物强度影响最大,NaOH溶液摩尔浓度次之,NaOH溶液与水玻璃的质量比影响最小。     

Effect of shale addition on properties of sintered coal fly ash

Shale can be used as a substitute for clay in sintered fly ash, due to the similar physical and chemical property to clay. In this paper, these characteristics of sintered fly ash with or without shale (binder) were investigated by physical property, X-ray diffraction and scanning electron microscopy. The results show that shale addition ranging from 30% to 50% (in weight) can be beneficial for properties of sintered products at temperature ranging from 950 to 1050 °C. However, a higher amount of shale easily caused significant bloating at 1100 °C. Considering energy saving and best performance, the sintering mix for shale and fly ash (50% in weight respectively, the same as below) fired at 1000 °C for 2 h was an optimal option. XRD results of the sintering mix show that intensity of hercynite increases with the increasing temperature, but intensity of quartz decreases on sintering. SEM confirms that addition of shale can improve microstructure and sintering of fly ash.     

基于路面弯拉强度的再生混凝土力学性能研究

基于路面弯拉强度分别为4. 0、4. 5、5. 0、5. 5 MPa设计了一组再生混凝土,其中再生粗骨料掺量分别为0、20%、40%、60%、80%、100%,并对再生混凝土力学性能进行了试验研究。结果表明,当再生粗骨料掺量控制在一定范围时,通过该方法设计的再生混凝土可满足路面使用力学性能要求。同时也通过试验数据回归分析整理得到再生混凝土各力学性能指标间的关系,可为再生混凝土在路面中的工程应用提供参考。     

煤粉炉渣细度和掺量对粉煤灰砖强度的影响

0引言我国大多数火电厂以煤粉作为主要燃料。在锅炉的运行过程中,除产生大量的粉煤灰外,同时从锅炉底部排出经水淬急冷而成的煤粉炉渣。根据各地煤质和电厂锅炉燃烧情况不同,煤粉炉渣的排放量一般占电厂总燃煤量的5%～10%,约为粉煤灰排放量的25%。可见,煤粉炉渣已成为一种仅次于粉煤灰的电厂主要工业固体废弃物。但是,目前煤粉炉渣的应用还未引起人们足够重视,仍在大量地积存。本文以充分利用电厂煤粉炉渣和低质粉煤灰为出发点,主要研究煤粉炉渣的细度与掺量对粉煤灰砖强度的影响,以提高其利用率,降低产品成本,获得良好的社会和经济效益。1…     

基于抛物线形库仑-莫尔准则的钢筋混凝土板抗冲切承载力

在刚塑性冲切计算模型的基础上,采用二次抛物线形库仑 莫尔混凝土强度准则,运用虚功原理,建立考虑混凝土板中抗弯钢筋销栓作用的冲切承载力计算式。根据已有板冲切试验研究成果,如冲切角和破坏时刻抗弯钢筋应力等数据,对板冲切承载力计算式进行简化,给出简化计算式。与国内外混凝土板冲切试验数据进行计算比较后发现,简化计算式的计算结果较好地符合实测承载力;抗弯钢筋的销栓作用约占钢筋混凝土板总冲切承载力的6%～11%,而忽略抗弯钢筋的销栓作用会给计算结果带来较大影响。