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1.
The present study investigates the use of natural pozzolana combined with lime for ground improvement applications. Laboratory
tests were undertaken to study the effect of natural pozzolana, lime or a combination of both on the physical and the mechanical
characteristics of cohesive soils. Natural pozzolana, lime and natural pozzolana-lime were added to two cohesive soils at
ranges of 0–20 and 0–8%, respectively. Consistency, compaction, undrained traxial shear and unconfined compressive strength
tests were performed on untreated and treated soil samples to assess the physical and mechanical characteristics of the soil.
Treated samples were cured for 1, 7, 28 and 90 days. The results show that the cohesive soils can be successfully stabilized
by combining natural pozzolana and lime. 相似文献
2.
Physical and engineering properties of soil are improved with various binders and binder combinations. Fly ash and lime are commonly used to improve the properties of expansive soils. An attempt has been made, in this paper, to examine the role of gypsum on the physical and strength behaviour of fly ash-lime stabilized soil. The change in strength behaviour is studied at different curing periods up to 90 days, and the mechanism is elucidated through pH, mineralogical, microstructural and chemical composition study. The strength of soil-fly ash mixture has improved marginally with the addition of lime up to 4 % lime and with curing period for 28 day. Significant increase in strength has been observed with 6 % lime and enhanced significantly after curing for 90 days. The variations in the strength of soil with curing period is due to cation exchange and flocculation initially, and binding of particles with cementitious compounds formed after curing. With addition of 1 % gypsum to soil-fly ash-lime, the strength gain is accelerated as seen at 14 day curing. The accelerated strength early is due to formation of compacted structure with growth of ettringite needles within voids. However, strength at curing for 28 day has been declined due to annoyance of clay matrix with the increase in size of ettringite needle; and again increased after curing for 90 days. The rearrangement of clay matrix and suppression of sulphate effects with formation of cementitious compounds are observed and found to be the main responsible factors for strength recovered. 相似文献
3.
石灰稳定红黏土强度的长期碳化效应 总被引：1，自引：0，他引：1
碳化效应是石灰稳定土强度增长机理之一,但长期的碳化作用是否对其强度一直起促进作用？如果没有压实作用,碳化效果到底如何？这些关键问题还没有得到充分的论证。采用灰土拌和后击实养护和养护后再击实的不同制样方法,通过承载比CBR试验,探讨压实作用对碳化效应的影响。制备4种初始含水率的击实试样,开展碳酸溶液和纯水浸泡下的CBR试验,论证长期碳化对石灰稳定土强度的作用效果。结果表明,自然养护90 d后再击实试样的CBR值明显低于击实后养护的试样;初始含水率为34%时前者约为后者的12倍。另外,碳酸溶液浸泡15 d后的试样CBR值均小于纯水浸泡的试样CBR值,但初始含水率越大其影响程度越小,当初始含水率大于34%后两者之间的强度基本没有差别。为进一步佐证长期碳化作用能弱化石灰稳定土的强度,开展不同浸泡时间的无侧限抗压强度试验,发现石灰土的强度呈现先增大后减少的变化趋势,再次证实长期的碳化作用弱化石灰稳定土的强度。最后,利用热重分析法测试经过碳酸溶液浸泡前后的石灰稳定土,发现长期碳化溶解了部分石灰土中的碳酸钙和硅酸盐类胶结物。借助扫描电镜图片和孔隙尺寸分布曲线,从微观角度揭示不同击实和养护方式对石灰稳定土强度的影响机制。 相似文献
4.
Long-term behavior of lime-stabilized kaolinite clay 总被引：1，自引：1，他引：0
Clay soils create many problems for highway construction and they have to be replaced or improved by stabilization for satisfactory performance. Lime stabilization is a well-established technique to improve the performance of clays. Cementitious minerals form upon mixing of clay with lime causing an improvement in strength and durability. In the study, the changes in the microfabric of long-term cured lime-stabilized kaolinite clay using X-ray diffraction pattern, scanning electron microscope and unconfined compressive strength (UCS) is presented. Unconfined compression test samples at two different lime contents (4 and 12% by weight) were prepared and cured in a humidity room for long time curing. The UCS of pure kaolinite was originally 125 kPa, which increased to 1,015 kPa after 1 month and to 2,640 kPa (21 times the initial value) after 10 years for cured lime-stabilized kaolinite samples. Similar long-term strength increases were also observed for stabilized kaolinite with 12% lime. Calcium aluminate silicate hydrate minerals were detected in the structure of the kaolinite. This suggests pozzolanic reactions with lime stabilization may continue in the long-term for up to 10 years. 相似文献
5.
Mohamed A. Sakr Mohamed A. Shahin Yasser M. Metwally 《Geotechnical and Geological Engineering》2009,27(1):105-113
This paper presents the results of geotechnical and mineralogical investigations on lime-treated soft clay soil from Idku
City, Egypt, where high organic matters of about 14% exist. Lime was added in the order of 1%, 3%, 5% and 7% by weight and
laboratory experiments after 7, 15, 30 and 60 days were conducted including the mineralogical and microstructural examinations,
grain size analysis, plasticity limits, unconfined compressive tests, vane shear tests and oedometer tests. The results indicate
that soft clay soil of high organic content of 14% can be stabilized satisfactorily with the addition of 7% lime. The results
also demonstrate that the changes in the mineralogical contents and soil fabric of high organic lime-treated soft clay improve
soil plasticity, strength and compressibility. 相似文献
6.
P. K. Kolay M. R. Aminur S. N. L. Taib M. I. S. Mohd Zain 《Geotechnical and Geological Engineering》2011,29(6):1135-1141
This paper describes a study on tropical peat soil stabilization to improve its physical properties by using different stabilizing
agents. The samples were collected from six different locations of Sarawak, Malaysia, to evaluate their physical or index
properties. Out of them, sample having the highest percentage of organic content has been selected for stabilization purposes.
In this study, ordinary portland cement (OPC), quick lime (QL), and class F fly ash (FA) were used as stabilizer. The amount
of OPC, QL, and FA added to the peat soil sample, as percentage of dry soil mass, were in the range of 5–20%; 5–20% and 2–8%,
respectively for the curing periods of 7, 14, and 28 days. The Unconfined Compressive Strength (UCS) test was carried out
on treated/stabilized samples with the above mentioned percentages of the stabilizer and the result shows that the UCS value
increases significantly with the increase of all stabilizing agent used and also with curing periods. However, in case of
FA and QL, the UCS value increases up to 15 and 6%, respectively with a curing period of 28 days but decreases rather steady
beyond this percentage. Some UCS tests have been conducted with a mixture of FA and QL to study the combined effect of the
stabilizer. In addition, Scanning Electron Microscope (SEM) study was carried out on original peat soil and FA, as well as
some treated samples in order to study their microstructures. 相似文献
7.
Lime stabilization is an effective way of stabilizing expansive clays, which cause significant environmental problems both as earth and foundation materials. There are considerable environmental benefits in using the in situ lime-stabilized expansive soils in the construction of road pavements, fill or foundations instead of importing valuable granular materials. However, due to high plastic nature of these clays, achieving appropriate pulverization in field applications is a difficult task. This paper presents the results of a laboratory investigation to determine the effects of soil pulverization quality on lime stabilization of a local expansive clay. Effect of mellowing the soil–lime mixtures for 24 h was also studied to find out whether this would compensate for poor pulverization. The clay studied had swelling pressures varying between 300 and 500 kN/m2 and free swell potential as high as 19%. In this study, 3, 6 and 9% lime by dry weight were used for lime-stabilized samples. Unconfined compression strength, failure strain and Secant Elasticity Modulus values were measured through unconfined compression strength testing. The results of the study showed that lime stabilization improved plasticity, workability, compressive strength, elastic moduli and swelling and compressibility behavior of the expansive clay. While mellowing did not have a definite effect on the measured strength and moduli values, soil pulverization quality considerably affected the unconfined compression strength and Secant Elasticity Modulus values. The higher the percentage passing No. 4 sieve, the higher the effectiveness of lime treatment. Based on the data obtained in this study, two original equations were derived to assign Secant Elasticity Modulus based on unconfined compression strength, for different soil pulverization qualities. Microfabric investigations conducted by Environmental Scanning Electron Microscope and Mercury Intrusion Porosimetry exposed the effect of lime stabilization on fabric, porosity and pore size distributions. The results of the study clearly demonstrated that if enough time and effort were not given to soil pulverization process in lime stabilization works in field applications, lower performance and therefore increased environmental problems should be expected. 相似文献
8.
Aslı Boz Alper Sezer Tuba Özdemir Gül Ece Hızal Özlem Azdeniz Dolmacı 《Arabian Journal of Geosciences》2018,11(6):122
In this paper, a comparative experimental study was carried out to evaluate the effect of inclusion of different fiber types on strength of lime-stabilized clay. In this scope, a series of unconfined compressive strength tests were carried out on specimens including basalt and polypropylene fiber compacted under Standard Proctor effort (i.e., 35% by weight of soil). The effects of curing period (1, 7, 28, and 90 days), fiber type (basalt and polypropylene), fiber content (0, 0.25, 0.5, 0.75, 1%), fiber length (6, 12, and 19 mm), and lime content (0 and 9%) on strength properties were investigated. The results revealed that both basalt and polypropylene fibers increased the strength without inclusion of lime. For specimens including lime, strength of polypropylene fiber-reinforced specimens was remarkably higher than that reinforced with basalt fiber for lime-stabilized clay. However, greatest strength improvement was obtained by use of 0.75% basalt fiber of 19 mm length with 9% lime content after 90-day curing. Additionally, results of strength tests on specimens including 3 and 6% lime and 12-mm basalt fiber after 1, 7, 28, and 90-day curing were presented. It is evident that the use of 6-mm basalt fiber and 12-mm polypropylene fiber were the best options; however, efficiency of fiber inclusion is subject to change by varying lime contents. It was also observed that the secant modulus was increased by use of lime; however, strength of the correlations among secant modulus and unconfined compressive strength values was decreased by increasing amount of lime for specimens including both basalt and polypropylene fibers. 相似文献
9.
Ettringite related swelling in lime-stabilized sulphate bearing clay soil systems has only been reported within the last decade although similar expansive behaviour has been reported in concrete over many years. The use of ground granulated blastfurnace slag (GGBS), an industrial by-product, is well established as a binder in many cement applications where it provides enhanced durability and high resistance to sulphate attack. This paper reports on efforts to extend the use of GGBS to highway and other foundation layers by determining the beneficial effect of the suppression of swelling of lime-stabilized clay soils, particularly in the presence of gypsum. The paper describes the results of laboratory tests on lime-stabilized kaolinite containing different levels of added gypsum and on lime-stabilized gypsum (selenite) bearing Kimmeridge Clay to which, in both cases, the lime has progressively been substituted with GGBS. The tests determine the linear expansion behaviour of compacted cylinders, during moist curing in a humid environment at 30°C and during subsequent soaking in de-ionized water. The results illustrate that substitution of lime with GGBS produces significant reduction in linear expansion of lime-stabilized clay soils particularly those containing gypsum. 相似文献
10.
11.
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
12.
高含水率淤泥生石灰材料化土击实方法初探 总被引：3，自引：0，他引：3
为了击实高含水率淤泥生石灰材料化土,通过改进标准击实仪,设计了4种不同击实冲量的击实情形,对不同掺灰比的材料化土在不同闷料期进行击实试验,分析了击实冲量及击实功与淤泥生石灰材料化土干密度的关系,提出了材料化土的击实方法及击实评价方法。建议根据材料化土的含水比 选择击实冲量适宜的击实方法,通过土的干密度随击次变化规律判断材料化土是否击实。特别从工程角度出发,测试了击实材料化土不同龄期的无侧限抗压强度,初步探讨了高含水率疏浚淤泥生石灰材料化土作为工程填料的可行性。 相似文献
13.
长余高速公路稳定土强度试验研究 总被引：1，自引：2，他引：1
将长余高速公路三个路段的天然土，配成不同比例的石灰土和二灰土，并通过不同的时期养生，对各土样进行无侧限抗压强度试验和抗拉强度试验。总结了配合比、期龄对混合料强度特性的影响规律，为高速公路路堤填土设计提供指南。 相似文献
14.
Classification,shear strength,and durability of expansive clayey soil stabilized with lime and perlite 总被引：1，自引：0，他引：1
An experimental study was performed to investigate the effect of perlite and perlite–lime admixtures on classification, shear strength, and durability properties of an expansive soil containing smectite clay minerals. Two types of mixtures, namely soil–perlite and soil–perlite–lime, were prepared with different percentages of perlite and compacted with standard Proctor energy at their optimum water contents. Samples of 38 mm diameter and 76 mm height for durability tests and square samples of 60 mm edge for shear box test were taken and preserved until test time in a desiccator. Disturbed samples were also taken to determine liquid and plastic limits. The expansive soil shows behavior of fine sand and silt due to pozzolanic reactions in microstructure caused by addition of lime and perlite. Although apparent cohesion of treated soil decreased with increasing amount of perlite for both types of samples, perlite–lime-treated samples had higher apparent cohesion than only perlite-treated samples. Large increments in angle of shearing resistance were obtained with increasing usage of perlite. Samples stabilized with only perlite could not show enough durability at the durability tests based on volumetric stability and unconfined compression strength. However, samples stabilized with lime and more than 30 % perlite proved to have enough durability and shear strength. 相似文献
15.
B. R. Phanikumar Jagapathi Raju m Ramanjaneya Raju e 《Geomechanics and Geoengineering》2020,15(1):64-77
ABSTRACTExpansive soil subgrades, which are subjected to dual swell-shrink problem consequent upon absorption and evaporation of water, need to be improved by chemical stabilization or compacted cushion or geosynthetic reinforcement in order that pavements constructed over them are even, stable and safe. This paper presents extensive experimental data on plasticity, free swell index (FSI) and compaction characteristics of a highly swelling expansive clay stabilized with varying silica fume contents. In another series of tests on a laterite soil to be used as a cushion over the expansive clay subgrade, plasticity properties, compaction characteristics and strength characteristics were determined at varied silica fume contents. Further, CBR of the expansive clay subgrade was determined in the laboratory stabilizing it with varied silica fume contents and providing a cushion of 50 mm thickness of silica fume-stabilized lateritic soil. Liquid limit (LL), plasticity index (PI) and free swell index (FSI) of the expansive clay decreased with increasing silica fume contents. The compaction and strength characteristics of both the soils improved with silica fume stabilization. The CBR of the expansive clay provided with silica fume-stabilized cushion improved significantly. 相似文献
16.
Effect of polypropylene fibre and lime admixture on engineering properties of clayey soil 总被引：2，自引：0，他引：2
In order to reduce the brittleness of soil stabilized by lime only, a recent study of a newly proposed mixture of polypropylene fibre and lime for ground improvement is described and reported in the paper. To investigate and understand the influence of the mixture of polypropylene fibre and lime on the engineering properties of a clayey soil, nine groups of treated soil specimens were prepared and tested at three different percentages of fibre content (i.e. 0.05%, 0.15%, 0.25% by weight of the parent soil) and three different percentages of lime (i.e. 2%, 5%, 8% by weight of the parent soil). These treated specimens were subjected to unconfined compression, direct shear, swelling and shrinkage tests. Through scanning electron microscopy (SEM) analysis of the specimens after shearing, the improving mechanisms of polypropylene fibre and lime in the soil were discussed and the observed test results were explained. It was found that fibre content, lime content and curing duration had significant influence on the engineering properties of the fibre–lime treated soil. An increase in lime content resulted in an initial increase followed by a slight decrease in unconfined compressive strength, cohesion and angle of internal friction of the clayey soil. On the other hand, an increase in lime content led to a reduction of swelling and shrinkage potential. However, an increase in fibre content caused an increase in strength and shrinkage potential but brought on the reduction of swelling potential. An increase in curing duration improved the unconfined compressive strength and shear strength parameters of the stabilized soil significantly. Based on the SEM analysis, it was found that the presence of fibre contributed to physical interaction between fibre and soil whereas the use of lime produced chemical reaction between lime and soil and changed soil fabric significantly. 相似文献
17.
Su Li Cui Jia Ding Wang Xiao Dong Wang Yan Feng Du Xue Pan Wang 《Arabian Journal of Geosciences》2018,11(17):521
In this study, the effects of cement kiln dust (CKD) on the swelling properties, strength properties, and microstructures of CKD-stabilized expansive soil were investigated. Samples were prepared and stabilized with different CKD content ratios, ranging from 0 to 18% by dry mass. The results obtained show that the maximum swelling pressures decrease exponentially with increases in CKD content. Both the cohesion and unconfined compressive strength (UCS) increase at ratios below 10% CKD and then decrease slightly, above that ratio. CKD can also improve the strength of saturated, expansive soil. There is no visible change of UCS for soil without CKD when cured, while the UCS of a sample with 10% CKD content after curing for 90 days is higher than that after curing for only 1 day. This indicates that CKD can improve the long-term strength of expansive soil. Finally, microstructure analysis reveals that the addition of CKD reduces the montmorillonite content of expansive soil and decreases its swelling properties. The addition of CKD also changes the pore volume distribution, both the size and amount of macro-pores and micro-pores decrease with increase in CKD content. For saturated samples, the size of macro-pores is obviously reduced, while that of micro-pores is slightly increased for both treated and untreated soils. Hydration and saturation processes make the soil structure become dispersive which results in a lower strength, and adding CKD can restrain this process. The suggested optimal CKD content is between 10 and 14% and with a curing time of more than 27 days. 相似文献
18.
Material engineers are continually confronted by depletion of quality construction materials for road and airfield construction.
Even if good quality construction materials for road and airfield are available, the haul costs may preclude their use. Stabilization
of soils in order to improve strength and durability properties often relies on cement, lime, fly ash, and asphalt emulsion.
These materials are inexpensive, relatively easy to apply, and provide benefits to many different soil types. In addition,
there are a variety of nontraditional soil stabilization/modification additives available from the commercial sector such
as polymer emulsions, acids, lignin derivatives, enzymes, tree resin emulsions, and silicates. These additives may be in liquid
or solid state and are often touted to be applicable for most soils. Polymers may be easy to apply in permeable materials
such as sand and may achieve good stabilization in relatively shorter periods of time. These polymer materials can be used
for stabilizing, soil in road shoulders, slopes, and pads of military and emergency airports. In addition, these types of
materials can be used to prevent the movement of the dune sands on the sides of railroads and stabilizing the dust on the
surface of access roads. Within the present research, two different polymers of wide range of dosages have been applied. Following
results have been achieved: (1) These polymers improve the compressive strength from 0.03 N/mm2 for control sample to 5.2 N/mm2
for improved sample. (2) The optimum curing time of dune sands with different polymers is 7 days. (3) The UC strength of stabilized
samples soars with an increase in the temperature, in the first 24 h of the curing process. (4) When the concentration of
salt increased from 1 to 10 percent, UC strength of stabilized samples decreased. 相似文献
19.
A. B. Salahudeen A. O. Eberemu K. J. Osinubi 《Geotechnical and Geological Engineering》2014,32(4):923-931
An expansive soil (black cotton soil) treated with up to 10 % cement kiln dust (CKD), a waste obtained from the manufacture of cement, was evaluated for use as a flexible pavement construction material. Laboratory tests were carried out on specimens compacted with British Standard light, British Standard light or standard Proctor (relative compaction = 100 %) energy. Results obtained show that the index properties of the soil improved with CKD treatment. Peak unconfined compressive strength of 357.07 kN/m2 and California bearing ratio (CBR) of 7 % as well as resistance to loss in strength of 44 % were recorded at 10 % CKD treatment. Reduction in the particle sizes with curing period was observed when samples were viewed through the scanning electron microscope. The study showed that CKD can be beneficially used to improve the subgrade of lightly trafficked roads and as admixture in lime stabilization during construction of flexible pavements over expansive soil. 相似文献
20.
Effect of Random Inclusion of Polypropylene Fibers on Strength Characteristics of Cohesive Soil 总被引：2，自引：1，他引：1
Pradip Kumar Pradhan Rabindra Kumar Kar Ashutosh Naik 《Geotechnical and Geological Engineering》2012,30(1):15-25
This paper presents the effect of random inclusion of polypropylene fibers on strength characteristics of soil. Locally available
cohesive soil (CL) is used as medium and polypropylene fibers with three aspect ratios (l/d = 75, 100 and 125) are used as reinforcement. Soil is compacted with standard Proctor’s maximum density with low percentage
of reinforcement (0–1% by weight of oven-dried soil). Direct shear tests, unconfined compression tests and CBR tests were
conducted on un-reinforced as well as reinforced soil to investigate the strength characteristics of fiber-reinforced soil.
The test results reveal that the inclusion of randomly distributed polypropylene fibers in soil increases peak and residual
shear strength, unconfined compressive strength and CBR value of soil. It is noticed that the optimum fiber content for achieving
maximum strength is 0.4–0.8% of the weight of oven-dried soil for fiber aspect ratio of 100. 相似文献