湿排粉煤灰固化强度试验研究

通过对海水湿排粉煤灰、水泥固化粉煤灰进行室内无侧限抗压强度试验和三轴压缩试验,以及对海水湿排固化粉煤灰材料强度形成机理分析,得到了水泥固化海水湿排粉煤灰基本力学性质及指标．通过设计试验对不同龄期、水泥固化剂掺量及养护条件影响因素进行分析,得到水泥固化海水湿排粉煤灰在不同条件下的强度变化规律．试验结果表明,水泥固化海水湿排粉煤灰具有良好的稳定性和耐久性,拌和固化混合料强度随龄期稳定增长,随水泥掺量增加强度提高．该试验研究对挡土结构、路基加固及地基处理等工程应用有重要的理论与实践研究价值．     

广州南沙地区软土采用水泥和粉煤灰固化试验研究

通过室内试验,研究广州市南沙地区软土采用水泥和粉煤灰加固力学特性。考虑水灰比、水泥粉煤灰混合固化剂掺量、粉煤灰掺量的变化对固化土无侧限抗压强度的影响,建立固化土强度-龄期一系列函数公式。研究显示:水泥起到提高固化土强度的主要作用,粉煤灰的掺量应有所限制;对于不同的混合固化剂配比,有各自的最佳水灰比。水灰比小于0.5,加大混合固化剂掺量不能显著提高固化土强度。广州南沙软土采用水泥粉煤灰搅拌桩加固,混合固化剂掺量取15%~18%,粉煤灰掺量取20%~30%,水灰比取0.53左右,比较合理。     

水泥粉煤灰搅拌桩复合地基的离心模型试验及现场实测效果研究

在水泥桩体中掺入一定量的粉煤灰不仅可以节约资源,还可以增强桩体在酸性地基中的抗腐蚀性能。为了研究水泥粉煤灰搅拌桩处治饱和黄土地基的适用性,以蒲渭高速公路为工程依托,以水泥与粉煤灰不同重量比组成的固化剂及其不同掺入比配制的试件进行的无侧限抗压强度试验、直剪试验和固结压缩试验为基础,选择最佳配比后进行水泥粉煤灰搅拌桩的离心模型试验,并与现场实测结果相对比。结果表明:当水泥与粉煤灰的重量比不小于2∶1时,粉煤灰的添加对试件的抗剪强度影响不大;固化剂掺入比达到15%以后,水泥粉煤灰土与水泥土试件的强度相差值减小;离心模型试验所得工后沉降量小于0.3m;现场实测工后沉降量和桩体强度均符合设计要求。水泥粉煤灰搅拌桩处理饱和黄土地基是经济可靠的。     

复合固化剂固化某淤泥质土的试验研究

为了改善青弋江分洪道工程淤泥质土地基的物理力学性能,选用普通硅酸盐水泥、粉煤灰、水玻璃以及木质素磺酸钠组成的水泥基复合固化剂,以青弋江芜湖段典型淤泥质土样作为试验土样,进行了室内固化试验研究,分析了固化剂掺量、淤泥质土初始含水率以及养护龄期的改变对固化土无侧限抗压强度和抗剪强度参数的影响关系。研究结果表明:对于提高青弋江淤泥质土强度,试验所用固化剂作用效果明显,90d龄期养护条件下,掺入复合固化剂处理的固化淤泥质土无侧限抗压强度最高为单掺水泥条件下固化土无侧限抗压强度的4.2倍,同时前者抗剪强度也明显大于后者;固化土无侧限抗压强度随固化剂掺量增加而提高,但增长速率逐渐减缓,同时还随着养护龄期的增加而提高,两者呈明显的对数关系。     

固化粉煤灰抗压强度试验及固化机理研究

将具有优异性能的固化剂作为外掺剂应用于粉煤灰的固化研究。通过室内无侧限抗压强度试验,探讨了固化剂掺入比和龄期对固化粉煤灰强度的影响规律;通过固化粉煤灰X射线衍射（XRD）试验,研究了固化粉煤灰各组分在强度形成过程中的变化规律;通过扫描电镜（SEM）测试,分析了固化粉煤灰的微结构特点及微结构形成过程;在分析粉煤灰-石灰体系反应基本原理的基础上,提出了固化粉煤灰的固化机理,该研究将为固化粉煤灰在工程中的进一步应用奠定理论和试验基础。     

飞灰固化工程材料在碳化条件下的强度及环境特性研究

螯合剂常用于固定重金属污染物,水泥可有效提升材料的强度,而碳化效应对水泥基材料工作性能有着显著影响。因此,采用水泥和螯合剂对固体废弃物焚烧飞灰进行协同处理制备固化飞灰复合工程材料,并探究碳化效应对其强度及环境友好性的影响。结果表明,常规养护28 d的飞灰复合材料强度达到3~6 MPa,高达规范中水泥土强度标准的7.5倍,且其强度随着龄期及水泥掺量的增加而增大,而碳化效应可有效的提升材料的强度特性;经处理后的飞灰复合材料中重金属Cd、Pb、Ni和Cr的浸出分别仅为原灰的2.0%,1.0%,19.2%和14.1%,碳化试样浸出略高,但仍满足固废浸出标准;碳化深度随养护龄期的增加而增大,与水泥掺量呈反比。优良的工作性能和环境友好性使材料在建设工程领域展示出极大的资源化利用潜力和价值。     

水泥固化法处理重金属污染土的强度特性研究

通过室内无侧限抗压强度试验,对水泥固化稳定后的重金属镍污染土的强度特性进行了研究,并对不同镍离子浓度、水泥掺入量和龄期对水泥固化土强度特性的影响进行了分析,对比分析了不同重金属离子对水泥固化土强度特性的影响,最终得到了水泥固化土强度预测公式。     

Parameters Controlling Strength of Industrial Waste-Lime Amended Soil

Unconfined compression tests and suction measurements were carried out in the present work on sandy specimens with distinct Class F fly ash amounts, lime contents, porosities and curing periods to assess key parameters controlling strength of fly ash-lime amended soil. A special effort has been allocated in order to develop a dosage methodology for fly ash-lime improved soils based in a rational criterion, as it exists in the concrete technology where the water/cement ratio plays a fundamental role in the assessment of the target strength. The results show that the unconfined compressive strength (UCS) increased linearly with the amount of lime for soil-fly ash-lime mixtures at all curing time periods studied. A power function fits better the relation UCS-porosity for soil-fly ash-lime mixtures. The bigger the amount of fly ash and the curing time, the larger the UCS for any given porosity and lime content. Finally, the porosity/volumetric lime content ratio, in which volumetric lime content is adjusted by a coefficient (in this case a unique value-0.12-was found for all soil-fly ash-lime mixtures and all curing periods studied) to end in single correlations for each curing period, show to be a good parameter in the evaluation of the unconfined compressive strength of the soil studied (UCS varies non-linearly with the porosity/volumetric lime content ratio in the case of fly ash-lime addition).     

Effect of fly ash and polypropylene fibres content on the soft soils

Fly ash is a waste produced from the burning of coal in thermal power stations. The staggering increase in the production of fly ash and its disposal in an environmentally friendly manner is increasingly becoming a matter of global concern. Efforts are underway to improve the use of fly ash in several ways, with the geotechnical utilization also forming an important aspect of these efforts. An experimental program was undertaken to investigate the effects of multifilament and fibrillated polypropylene fibre on the compaction and strength behavior of CH class soil with fly ash in different proportions. The soil samples were prepared at two different percentages of fibre content (i.e. 0.5 and 1% by weight of soil) and two different percentages of fly ash (i.e. 10 and 15% by weight of soil). A series of tests were prepared including optimum moisture content and laboratory unconfined compression strength tests, compaction tests and Atterberg limits test. The fibre inclusions increased the strength of the fly ash specimens and changed their brittle behavior into ductile behavior.     

粉煤灰混凝土抗压强度计算模型

粉煤灰混凝土抗压强度动态计算模型建立了粉煤灰强度效应因子与粉煤灰火山活性指数、粉灰掺量、水胶比、龄期等主要参数之间的直接系数。根据模型可由试验测出２８天时粉煤灰活性指数及选用的原材料配合比等,用于预测不同龄期时粉煤灰强度效应,对高掺量粉煤灰混凝土的设计提供指导。     

复合方法改良膨胀土无侧限抗压强度试验研究

本文以改良膨胀土标准养护7 d的无侧限抗压强度为研究对象,分别在膨胀土中掺入水泥、石灰、粉煤灰、风化砂来进行单一方法改良,测试其无侧限抗压强度;在膨胀土中分别掺入水泥和风化砂、石灰和风化砂、粉煤灰和风化砂来进行复合方法改良,进行无侧限抗压强度试验。试验结果表明,在膨胀土中分别单一掺入水泥、石灰、粉煤灰、风化砂均能有效提高改良膨胀土的无侧限抗压强度,而且石灰、粉煤灰、风化砂的掺入量均有一个最佳值,使改良膨胀土的无侧限抗压强度达到最大值,从提高膨胀土无侧限抗压强度的角度来讲,单一方法改良的效果由好到差依次是水泥、石灰、风化砂、粉煤灰。而在膨胀土中分别掺入水泥和风化砂、石灰和风化砂、粉煤灰和风化砂来进行复合方法改良,无侧限抗压强度值均有了大幅度的提升,从提高无侧限抗压强度的角度来看,水泥和风化砂复合改良的效果要优于石灰和风化砂复合改良的效果,粉煤灰和风化砂复合改良的效果最差。通过复合改良方法与单一改良方法对比,可以发现,在相同条件下,复合改良方法的无侧限抗压强度值要比单一改良方法大得多,复合改良方法要大大优于单一改良方法。     

电石渣-火山灰质胶凝材料固化盐渍土试验研究

以电石渣、粉煤灰和碱激发剂作为原材料制备一种盐渍土固化剂,采用正交试验方法研究各因素对固化盐渍土击实性能和抗压强度的影响,并探索电石渣-火山灰质胶凝体系固化盐渍土的固化机理和水化产物。结果表明:各因素对固化盐渍土抗压强度的影响顺序为:碱激发剂>胶凝材料掺量>m(电石渣)∶m(粉煤灰);固化盐渍土养护7 d抗压强度和水稳定性满足实际工程中对固化盐渍土强度的需求;在电石渣和碱激发剂双重激发下粉煤灰发生火山灰反应,反应产物以水化硅酸钙凝胶、钙矾石和二水石膏为主。当养护龄期为360 d时,试件内未发现明显的Ca(OH)2存留,说明固化土试件养护360 d时,火山灰反应基本完成。     

石灰粉煤灰稳定黄土的无侧限抗压强度研究

以石灰粉煤灰稳定黄土为对象,通过标准击实试验、无侧限抗压强度试验,研究养护龄期和石灰粉煤灰掺量对稳定黄土最佳含水率、最大干密度及无侧限抗压强度的影响。结果表明,随石灰粉煤灰掺量的增加,稳定黄土最佳含水率增大,最大干密度减小;石灰粉煤灰掺量一定时,随粉煤灰掺量的增加,最大干密度增大,最佳含水率减小;无侧限抗压强度随养护龄期的增长、石灰粉煤灰掺量的增加而增大。通过对试验数据的拟合回归,建立了稳定黄土无侧限抗压强度与孔隙率、粉煤灰与石灰的比值（F/L）及石灰粉煤灰总体积掺量的关系。     

Evaluation of shear strength and mechanical properties of granulated coal ash based on single particle strength

The authors have been studying the mechanical properties of granulated coal ash formed by the milling process with a small amount of cement added, with particles almost equivalent in size to sand or fine gravel. The use of granulated coal ash has many advantages, such as the suppression of leaching of heavy metals and the possibility of outdoor curing. In addition, since granulated coal ash is produced artificially, their particle strength can be understood easily. Another advantage is that it is possible to control the particle strength, something which cannot be performed in natural sands. The present research was carried out in order to investigate the possibility of putting such advantages to good use.Single particle crushing tests were carried out on various kinds of granulated coal ash to evaluate the crushing characteristics of each individual grain. Also, the characteristics of the individual particle, such as shape, were investigated. Next, one-dimensional compression tests were conducted to investigate their compression characteristics. Finally, drained monotonic triaxial compression tests were performed under different confining pressures. The effects of the confining pressure on the shear characteristics, as well as their relation to shear strength, were examined with the single particle crushing strength taken into account.Contrary to observations in natural sands, the single particle crushing strength of granulated coal ash did not depend on particle size. Regarding compression characteristics, granulated coal ash compressed very easily because the crushing strength of a single particle was low. Therefore, the yield stress of granulated coal ash was found to be smaller than that of natural sands. Moreover, the crushing strength affected the shear characteristics, i.e., as the crushing strength increased, the shear stiffness became higher and the compressive volumetric strain became smaller. Therefore, crushing strength can be a useful parameter in evaluating the shear characteristic of granulated coal ash.     

活性粉末混凝土配制技术的试验研究

首先研究了各种减水剂和配合比设计对活性粉末混凝土(RPC)性能的影响。试验对水胶比以及硅灰、粉煤灰、磨细石英粉和钢纤维等原材料的掺配比例对RPC的抗折强度、抗压强度和流动性的影响规律进行了研究。结果显示,掺入粉煤灰取代部分水泥用量,可较好地改善RPC的强度和工作性能。最后提出了一种通过热水养护,抗压强度可以超过200MPa的超高强混凝土。     

季冻区高速铁路路基改良填料冻融性能研究

针对季冻区高速铁路路基填料冻融性能问题,将水泥和水泥粉煤灰掺入级配碎石作为改良措施。为了研究水泥和水泥粉煤灰改良碎石填料的抗冻融耐久性能,对填料的水稳定性、冻融变形特性和冻融耐久性进行试验,分析改良剂的种类、掺量以及养护龄期等因素的对路基填料性能的影响规律。研究结果表明：水泥改良填料相较于水泥粉煤灰改良填料有较高的无侧限抗压强度;填料单向冻胀量随着水泥掺量的增加而降低,掺入粉煤灰后会提高填料的冻胀率;水泥粉煤灰改良填料在28 d养护后水稳定性性能较水泥改良填料更佳优异,抗冻融性能则会低于水泥改良填料。     

红层泥岩改良土特性室内试验研究

宜巴高速公路穿越巴东组紫红色泥岩地层。直接将泥岩风化物作为路基填料填筑,产生了路面鼓包,翻浆冒泥和路基不均匀沉降、承载力不足等工程问题。为了消除泥岩路基土不良特性,采用石灰、水泥、粉煤灰对泥岩风化物进行改良试验研究。开展击实、承载比、无侧限抗压强度试验,利用自制崩解仪、大环刀进行改良土崩解试验及土水特性测试,利用环境电镜扫描改良土微观结构,研究分析泥岩改良土的工程特性及改良机制。在综合评价改良效果及分析膨胀指标、承载比、无侧限抗压强度等常规改良效果评价指标基础上,尝试结合耐崩解性、土水特性指标全面对比分析改良效果。结果表明：改良剂消除泥岩路基土的膨胀特性,大幅提高其承载力及抗压强度指标,其耐崩解性及水稳定性也得到提高和改善;水泥改良路基土效果最佳,掺比5%为最优;石灰改良效果次之,最佳掺比为7%;粉煤灰改良效果最差,掺比11%为最优,适当提高粉煤灰掺量改良效果会更佳。     

粉煤灰炉渣加固土的室内无侧限抗压强度试验研究(英文)

给出了用粉煤灰、炉渣等工业废料加固土的室内无侧限抗压强度试验结果,分析了加固土无侧限抗压强度与外加剂掺量、养护龄期之间的影响规律,得出了针对不同工业废料加固土所用外加剂的最佳掺量。     

水泥粉煤灰稳定碎石中粉煤灰对水泥作用的缓冲效应研究

通过研究水泥剂量对于不同级配集料以及不同粉煤灰掺量的材料其7 d无侧限抗压强度的影响,探讨粉煤灰对水泥"缓冲效应"的作用规律;并在分析水泥稳定粒料强度形成机理的基础上,通过计算粒料单位面积裹附水泥颗粒的增量,进一步揭示了该种"缓冲效应"的作用机理,为水泥粉煤灰稳定粒料的强度标准制定以及配合比设计方法研究提供了理论依据.     

玻璃纤维水泥土强度及抗硫酸盐侵蚀性能试验研究

通过无侧限抗压强度试验,探究水泥、粉煤灰、玻璃纤维掺量、硫酸盐侵蚀对水泥土抗压强度的影响规律。研究发现:水泥掺量与水泥土抗压强度成正比关系。粉煤灰掺量适当时(不超过6%)可以提高水泥土抗压强度,粉煤灰对水泥土强度增长作用主要在于粉煤灰的微集料效应和活性效应。玻璃纤维掺量为0.2%时,水泥土抗压强度最高,玻璃纤维对水泥土强度的贡献主要在于玻璃纤维的加筋作用。受不同浓度Na2SO4溶液侵蚀作用后,随着侵蚀时间的延长,水泥土抗压强度均先提高后降低。