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1.
水泥固化重金属污染土的强度特性试验研究 总被引：5，自引：0，他引：5
土体受到重金属离子污染后,会引起土的工程性质的改变,重金属离子的渗出也会给周围环境带来严重的危害。在国外,目前常采用水泥固化技术来处治重金属污染土;而在我国,这方面的研究成果还很少。主要通过系统的室内试验和理论分析,研究了在不同污染物掺量、污染物类型、水泥掺量以及养护龄期条件下固化污染土的强度特性。试验结果表明,金属污染物的存在会导致土体无侧限抗压强度较小幅度的降低,但随着水泥掺入量及养护龄期的增加,土体强度会有显著提高。试验结果还发现,不同的污染物类型及掺入量对固化污染土强度存在不同的影响,NaCl能促进水泥固化土早期强度的提高,而CuCl2和AlCl3则会阻碍水泥与土的固化反应。 相似文献
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工业废渣加固土强度特性 总被引：3，自引：0，他引：3
工业废渣的资源化是解决工业废渣环境污染的有效途径之一。以粉煤灰和高炉矿渣为固化剂,石灰为碱性激发剂,对黏土进行加固。通过室内试验的方法,分析固化剂掺入量、养护龄期等对固化土无侧限抗压强度、pH值和饱和度等发展规律的影响。试验结果表明,固化土的无侧限抗压强度随固化剂掺入量的增加而增大,随养护龄期的增加而增大,提出一个综合反映固化剂掺入量、养护龄期和压实度等因素对固化土强度影响规律的综合影响因子,固化土强度与综合影响因子呈负指数函数关系;粉煤灰+石灰和高炉矿渣+石灰可有效改良土体无侧限抗压强度特性;石灰是一种有效的碱性激发剂,可提供工业废渣发生火山灰反应的高碱性环境。试验成果为工业废渣改良不良土质的设计提供试验依据。 相似文献
3.
城市地铁盾构进出洞及联络通道施工中常常采用水泥土预先加固辅以人工冻结法补充加固的施工工艺,为掌握冻结水泥土的力学性能及相关设计参数,开展了系列冻结水泥土无侧限抗压性能室内试验研究,研究结果表明:水泥土无侧限抗压强度随温度的降低、水泥掺入比的增加呈线性增大,随养护龄期的增加呈对数增大;水泥土的抗压强度和弹性模量随着温度的降低基本呈线性增大,在常温下随水泥掺入比呈线性增大,在-10℃下随水泥掺入比呈指数增大,并随着养护龄期的增加呈对数增大;温度、水泥掺入比和龄期三个因素中温度对水泥土抗压强度的影响最大;随水泥掺入比、龄期的增加,冻结水泥土与常温水泥土强度及弹性模量差异呈指数规律减小,最终趋于稳定比值. 相似文献
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固化淤泥重塑土力学性质及其强度来源 总被引：3，自引：2，他引：1
对不同水泥掺加量的固化淤泥及其重塑土进行了无侧限抗压强度试验和直接剪切试验,并对固化土和重塑土的应力-应变关系曲线、无侧限抗压强度、黏聚力和内摩擦角进行了比较分析。结果表明：随着水泥量和龄期的增加,固化淤泥的脆性增强,塑性减弱;重塑土的应力-应变关系受水泥量和龄期的影响不大,随着应变的增加,应力增长缓慢,塑性变形非常大。固化土的无侧限抗压强度、黏聚力均随着水泥量和龄期的增加而增大,而内摩擦角则有减小的趋势。重塑土相对于原状土无侧限抗压强度和黏聚力都有较大程度的折减,并且水泥量和龄期越大,折减越多;内摩擦角随着水泥量和龄期的增加有小幅度提高。重塑土强度主要来源于破碎固化土团间的摩擦和咬合作用,因此,在固化淤泥重塑土的实际工程应用中,初始固化土的处理强度不应太高。 相似文献
6.
固化风沙土强度特性及固化机制试验研究 总被引：6，自引：0，他引：6
通过PX固化剂对库布其沙漠风沙土进行加固。对不同含水状态、不同固化剂掺量、不同养护龄期下固化风沙土的强度特性进行试验研究。试验结果表明,不同含水状态下风沙土的强度特性是不同的,相同固化剂掺量、相同养护龄期时,固化风沙土在最优含水率下的无侧限抗压强度远远大于饱和含水率下的强度。相同含水状态下固化风沙土无侧限抗压强度随固化剂掺量增加、养护龄期延长而增大,且在养护初期强度增长较快,当固化剂掺量为8 %、养护龄期为28 d时,固化风沙土强度满足国际上对固沙强度的要求。最优含水率下固化风沙土抗剪强度较风沙土有较大提高;当固化剂掺量为8 %时,固化风沙土凝聚力和内摩擦角均达到最大,此时固化风沙土抗剪强度约为风沙土的1.8倍。进而,通过扫描电镜对风沙土固化前后微观结构变化进行试验研究。研究结果表明,风沙土中掺入PX固化剂后,颗粒间由原来的弱连接变为胶结连接,解释了固化风沙土较风沙土强度得以提高、稳定性得以改善的内在原因。 相似文献
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高含水率疏浚淤泥新型复合固化材料试验研究 总被引：3，自引：1，他引：2
基于传统水泥固化处理方法,提出了水泥-生石灰-高分子添加剂新型复合固化材料处理高含水率疏浚淤泥的新方法,以期快速降低淤泥含水率并提高固化淤泥的无侧限抗压强度,拓展水泥固化淤泥的含水率范围,达到高效廉价固化处理高含水率疏浚淤泥的目的。通过系列室内试验,探讨了该方法处理后高含水率淤泥的无侧限抗压强度变化规律以及各材料掺入比对强度的影响规律。研究结果表明,水泥掺入比低于7%的新型固化材料处理初始含水率2倍液限的高液限淤泥,早期强度大于0.5 MPa,28 d强度大于1 MPa;固化淤泥强度随龄期、水泥和生石灰掺入比的增大而增大;给出了考虑多因素多水平的无侧限抗压强度预测公式,预测值与实测值基本一致 相似文献
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水泥土强度试验主要影响因素的探讨 总被引：2，自引：0，他引：2
对软土中掺入不同量的水泥,以不同的水灰比(水和水泥的质量比)制成的水泥土试块在不同的养护条件下、不同的龄期对其无侧限抗压强度进行对比试验。分别讨论了掺入比(水泥和湿土的质量比)、水灰比及养护条件对其无侧限抗压强度的影响。 相似文献
10.
本文开展了一系列不同液限高分子吸水树脂固化工程泥浆无侧限抗压强度试验, 探讨了泥浆土液限对固化效率的影响规律, 对比研究了掺入高岭土对泥浆固化强度的改进程度, 最后基于XRD和SEM试验揭示了液限和高岭土对固化泥浆强度影响的微观机理。结果表明: 随着泥浆土液限的增大, 固化泥浆土强度逐渐降低, 固化效率随着泥浆土液限增大显著衰减, 当液限增加10%, 固化泥浆土强度qu平均减少48.2%。然而高岭土的掺入则显著提升了固化泥浆土的强度, 并且强度增长率随着龄期逐渐增大, 对于龄期为90天时, 增加40%高岭土能够提升固化泥浆土强度qu 1.17倍。微观结构试验表明泥浆土液限变化对水化产物产量的影响较小, 固化泥浆土强度随泥浆土液限减小主要是由于固化泥浆土孔隙随着泥浆土液限增大而增多, 使得微观结构松散从而导致强度降低。高岭土的掺入则显著提升了固化泥浆土的水化产物产量, 增强了固化泥浆土胶结强度, 从而提升了固化泥浆土强度。因此, 在实际工程中, 一方面可以通过调配泥浆土液限来提高固化效率; 另一方面可以通过掺入高岭土或者一些高岭土基废弃物(如高岭土尾矿)来提高固化强度, 实现“以废制废”绿色环保的理念。 相似文献
11.
水泥稳定粉砂土抗渗性能受粉砂土自身渗透性能、水泥用量、水灰比等因素影响显著,如何在提升其抗渗性能的同时降低水泥用量是提升工程经济效益的关键。通过开展不同水泥偏高岭土掺比、初始用水量、水泥偏高岭土总掺量以及养护龄期条件下的室内渗透试验,研究了上述因素对水泥偏高岭土复合稳定粉砂土抗渗性能的影响规律,探讨了上述因素及无侧限抗压强度与渗透系数之间的经验关系。结果表明：水泥与偏高岭土掺比为5:1时,水泥偏高岭土复合稳定粉砂土抗渗性能最佳,且该掺比不随水泥偏高岭土总掺量的改变而变化;水泥偏高岭土复合稳定粉砂土渗透系数随初始用水量增加呈非线性递增,随水泥偏高岭土总掺量增加和养护龄期发展呈先快后慢降低;基于试验结果归纳提出了4个关于初始用水量、水泥偏高岭土总掺量、养护龄期和无侧限抗压强度的水泥偏高岭土复合稳定粉砂土渗透系数经验模型。研究成果可为水泥稳定粉砂土抗渗性能提升提供理论参考与借鉴。 相似文献
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多年冻土区水泥稳定砂砾基层抗冻性能研究 总被引：2，自引：1，他引：1
多年冻土地区路面使用过程中的许多病害与基层状况直接相关.水泥稳定砂砾作为我国传统的半刚性基层材料,在多年冻土地区公路路面结构中得到了普遍运用.为研究水泥稳定砂砾不同水泥掺量、不同养生龄期下的抗冻性能,通过提出合理的抗冻试验方法分别进行了水泥稳定砂砾冻融温度、冻融时间、冻融次数、试件的养生龄期及抗冻指标方面的试验研究. 结果表明：水泥剂量越高,水泥稳定砂砾冻前、冻后的抗压强度值越高,说明其抗冻性能越好;水泥稳定砂砾从28 d开始抗压强度、冻融后抗压强度及冻融后劈裂强度都明显增加,证明水泥稳定砂砾从28 d开始已具有一定的抗冻性. 提出的抗冻试验方法和指标要求适合多年冻土地区半刚性基层材料,有一定的实用价值. 相似文献
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Cement stabilization of soil is a useful method to improve the mechanical behaviors and engineering performance of soils in geotechnical design and construction projects involving weak or liquefiable soils. Among the factors affecting the strength of cement-stabilized soils, water content and water–cement ratio are important but less well understood because of controversial views. This paper presents a systematic laboratory study to investigate the effects of water content and water–cement ratio on the unconfined compressive strength, with good control of the packing density and void ratio of the tested specimens. The effects of void ratio and cement content are also investigated. The strength of the cement-stabilized sand continuously decreased with increasing water–cement ratio within the range of 0.5 to about 3. A general equation is suggested to evaluate the unconfined compressive strength of cement-stabilized soil. Finally, a new conceptual characterization chart is proposed with consideration of the effects of cement content, water content, and water–cement ratio.
相似文献14.
In order to recycle the incineration fine bottom ash generated from municipal solid waste as a fine aggregate construction
material(<4.75 mm), a series of uniaxial compression tests were carried out according to the mixing ratio of bottom ash, the
curing temperature, the water–cement ratio, the mixing ratio of expanded poly styrene (EPS), and the curing time. As the results
of tests, the compression strengths cured 28 days of all specimens prepared with different mixing ratios are ranged between
87 and 220 kg/cm2. The water content of the hardened cement mortar is not much different with the curing time. Also, the water content is increased
with increasing the mixing ratio of bottom ash, the water–cement ratio, and the mixing ratio of EPS. The unit weight of the
hardened cement mortar is decreased with increasing the mixing ratio of bottom ash and the mixing ratio of EPS. The compression
strength of the hardened cement mortar is decreased with increasing the mixing ratio of bottom ash. The compression strength
of the hardened cement mortar cured at 30 ± 2°C and 40 ± 2°C is bigger than that of the cement mortar cured at normal temperature
(20 ± 2°C). However, the compression strength of the hardened cement mortar cured at 30 ± 2°C is bigger than that of the cement
mortar cured at 40 ± 2°C. The compression strength is increased at the range from 0.55 to 0.6 of water–cement ratio, and then
the compression strength is decreased over 0.65 of water–cement ratio. Meanwhile, the compression strength of the hardened
cement mortar is decreased with increasing the mixing ratio of EPS. 相似文献
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采用无侧限抗压强度试验和直剪试验,从单轴抗压强度、黏聚力、内摩擦角的角度探求了淤泥固化土重塑时导致的强度折减和重塑后土的强度恢复特性,并分析了重塑前养护龄期（T前）、重塑后养护龄期（T后）、水泥掺灰比（ac）的影响。试验结果表明,重塑时机的选择对淤泥固化土的强度折减程度有显著的影响：T前越长,破碎过程带来的强度折减越严重,且大致满足ac越大、强度折减越严重的规律。从强度恢复特性来看：小水泥掺灰比的固化淤泥土经过T后,其强度恢复较好;大掺灰比的重塑土其强度则较难恢复至固化土的水平,T前越长,强度恢复越不利。从而得出了大掺灰比固化土宜早重塑,小掺灰比的重塑时间可适当延长的规律。 相似文献
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Chee-Ming Chan 《Environmental Earth Sciences》2014,71(3):1061-1071
Ground improvement with soil solidification has been widely applied and has proven to be an effective pre-treatment of soft soil deposits. The solidification procedure usually involves addition and thorough mixing of hydraulic binders with in situ soils, consequently transforming the soft materials into a stronger and stiffer stratum for load bearing. Much has been done on the binder’s effectiveness and resulting enhanced properties of the soils, but not as much has been reported of the factors governing in situ mixing efficiency in producing uniform mixtures. While advancement in machinery and computerization of operations have significantly improved soil mixing, individual factors contributing to the process can be further examined to refine the effectiveness. This paper describes a series of laboratory tests, mainly unconfined compressive strength tests complemented with X-ray computer tomography, conducted on cement-stabilized dredged Kawasaki clay of different uniformities. A number of factors affecting uniformity were examined, namely the water/cement (WC) ratios, number of cement layers in the initial state as well as the number of mixing cycles adopted. Test specimens were prepared based on a systematic combination of these factors to enable a comprehensive cross-analysis of the results. It was found that the clay’s initial consistency was markedly altered by cement addition, which resulted in either enhanced or reduced workability of the mixture. While increased mixing vigor could apparently overcome poor distribution of binder in the mixture, the resulting strength remained very much affected by the WC ratio, suggesting dependency of the mixture’s overall uniformity on a combination of the factors. 相似文献
18.
An experimental study is conducted to measure small-strain shear modulus of clay-cement mixture using bender element apparatus
setup in a triaxial cell. Bender element tests were conducted on cement-treated soils and the results were analyzed to study
the variation of shear modulus properties of soil specimens at different cement contents, confining pressures, curing times,
and compaction moisture contents. Based on the obtained results increasing the cement ratio has a significant effect on the
small-strain shear modulus of the treated soils, and this effect signifies with increasing the moisture content and curing
time. Rates of shear modulus enhancements due to cement content, curing time, and compaction moisture content are quantified
and presented. In this study, a clay–cement–water ratio formulation is proposed that enables one to calculate cement and water
contents required to obtain specific small-strain shear modulus. 相似文献
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对于使用水泥与上海黏性土进行混合加固的土体,其强度增长特性与水泥含量、加固土的初期pH值、养护时间有关。以上海4类黏土为研究对象,对加固土的强度增长特性进行了试验研究;探讨了加固土的养护时间、水泥含量、初期pH等与加固土强度的关系。试验结果表明,当上海黏土中水泥含量或者加固土的初期pH值大于某一临界值时,水泥加固土的强度将迅速增加,对于上海黏土,该临界pH值为11.7,对应的水泥含量为17%～20%。但当水泥含量达到一定值后,它对土体的pH值的影响开始变小,而且水泥土的强度趋于稳定的时间变长。 相似文献
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软土型水泥土掺砂试验研究 总被引：4，自引：0，他引：4
考虑到土性对水泥土强度的影响，提出了在软土中掺砂以改进水泥土抗压强度性能的方法。选取深港西部通道填海区含有机质的淤泥，采用均匀设计法来考察水泥掺入比、砂的掺入比、龄期和水泥土抗压强度的关系；建立了其回归模型，研究了3个因素对强度的影响情况，给出了优化配比的方法；最后提出了改进机具以实现水泥土掺砂的设想。 相似文献