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Journal ArticleDOI

Sulphate Attack in Lime-Treated Marine Clay

01 Jan 2005-Marine Georesources & Geotechnology (Taylor & Francis Group)-Vol. 23, pp 93-116
Abstract: The use of lime to improve the properties of soft clays is not new. Recently the deep lime mixing technique has been extended to coastal regions for improving the behavior of weak marine clays. But lime treatment technique should be approached carefully for clay containing a high percentage of sodium sulphate. The presence of sulphate in lime-treated clays may result in high swelling due to the formation of the expansive mineral, ettringite. A limited study of lime-treated marine clays has shown a need to further explore the formation of ettringite and its stability with time. In this article, a laboratory investigation was carried out to examine the influence of sodium and calcium sulphates on the behavior of lime column treated marine clay. Scanning electron microscopy (SEM) was used to identify the formation of various reaction products, including ettringite. Test results indicate that the formation of ettringite in the lime-sodium sulphate-clay system adversely affects the engineering behavio...
Topics: Lime (62%), Ettringite (57%)
Citations
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Journal ArticleDOI
01 May 1958-Agronomy Journal

6,493 citations


Journal ArticleDOI
Abstract: In this study, the compressive and tensile behavior of polymer treated sulfate contaminated CL soil was investigated. Based on the information in the literature, a field soil was contaminated with up to 4 % (40,000 ppm) of calcium sulfate in this study. In addition to characterizing the behavior of sulfate contaminated CL soil, the effect of treating the soil with a polymer solution was investigated and the performance was compared to 6 % lime treated soil. In treating the soil, acrylamide polymer solution (15 g of polymer dissolved in 85 g of water) content was varied up to 15 % (by dry soil weight). Addition of 4 % calcium sulfate to the soil decreased the compressive and tensile strengths of the compacted soils by 22 and 33 % respectively with the formation of calcium silicate sulfate [ternesite Ca5(SiO4)2SO4)], magnesium silicate sulfate (Mg5(SiO4)2SO4) and calcium-magnesium silicate (merwinite Ca3Mg(SiO4)2). With the polymer treatment the strength properties of sulfate contaminated CL soil was substantially improved. Polymer treated sulfate soils had higher compressive and tensile strengths and enhanced compressive stress–strain relationships compared to the lime treated soils. Also polymer treated soils gained strength more rapidly than lime treated soil. With 10 % of polymer solution treatment, the maximum unconfined compressive and splitting tensile strengths for 4 % of calcium sulfate soil were 625 kPa (91 psi) and 131 kPa (19 psi) respectively in 1 day of curing. Similar improvement in the compressive modulus was observed with polymer treated sulfate contaminated CL soil. The variation of the compacted compressive strength and tensile strength with calcium sulfate concentrations for the treated soils were quantified and the parameters were related to calcium sulfate content in the soil and polymer content. Compressive stress–strain relationships of the sulfate soil, with and without lime and polymer treatment, have been quantified using two nonlinear constitutive models. The constitutive model parameters were sensitive to the calcium sulfate content and the type of treatment.

73 citations


Cites background from "Sulphate Attack in Lime-Treated Mar..."

  • ...1) and its exposure to moisture variations from seasonal changes result in differential heaving, which in turn causes cracking of pavement structures built on the treated soils (Rajasekharan and Rao 2005; Pillai et al. 2007)....

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Journal ArticleDOI
Abstract: The effectiveness of nano-MgO in strength properties and microstructure characteristics of cement stabilized soft soil were analyzed in this study. Sulfuric acid attack was also taken into account, and the effects nano-MgO content and sulfuric acid concentration were mainly addressed. Based on a series of unconfined compression tests, it shows that nano-MgO content plays a significant role in the strength properties of the stabilized soil. For the cement content of 13%, the optimum nano-MgO content is 15‰ considering both with and without sulphate attack condition. The addition of nano-MgO not only improves the unconfined compressive strength (UCS) of the cement stabilized soil, but also tends to increase its ductility. Scanning electron microscopy (SEM) reveals that the addition of nano-MgO improves the microstructure of the stabilized soil, while overuse of nano-MgO may generate cracks inside of the structure. For the effect of sulfuric acid concentration, specimens under higher concentration solution will have lower strength and stiffness. Finally, the mechanism of sulfuric acid attack on cemented soil was revealed to be outside structure loss caused by sulfuric acid erosion and inside structure distortion caused by ettringite generation.

59 citations


Journal ArticleDOI
Abstract: Dredged or excavated soft marine clay can be improved by mixing it with cement or lime. However, these treatments are usually expensive. It is shown in this paper that soft marine clay can be strengthened through a bioencapsulation method in which the shear strength of clay aggregates can be substantially increased after the aggregates are treated with urease-producing bacteria, calcium chloride, and urea. We found that the bioencapsulation had increased the unconfined compressive strength of marine clay aggregates with a size of 5 mm from almost zero to more than 2 MPa. The strength of the bioencapsulated clay aggregates decreases with the increase in the size of the aggregate when the size is greater than 5 mm.

45 citations


Journal ArticleDOI
Abstract: In this study, the effect of up to 4 % calcium sulfate contamination on the soil properties of a natural clay with low liquid limit (CL) soil with and without polymer treatment was investigated and compared to 6 % lime treated soil. X-ray diffraction (XRD) and thermogravimetric analysis (TGA) methods were used to identify and quantify the changes in the contaminated CL clay soil. XRD analyses showed the major constituents of the soil were calcium silicate (CaSiO3), aluminum silicate (Al2SiO5), magnesium silicate (MgSiO3), and quartz (SiO2). With 4 % calcium sulfate contamination, the liquid limit (LL) and plasticity index (PI) of the CL soil increased by 30 and 45 %, respectively. The addition of calcium sulfate resulted in the formation of calcium silicate sulfate (Ternesite Ca5(SiO4)2SO4) and aluminum silicate sulfate (Al5(SiO4)2SO4). TGA analyses showed a notable reduction in the weight of calcium sulfate contaminated soil between 600 and 800°C, possibly due to changes in soil mineralogy. In addition, the total weight loss at 800°C for 1.5 % polymer treated soil was about 40 % less than the 4 % calcium sulfate contaminated soil, and it was similar to the weight loss observed in the uncontaminated CL soil. The maximum dry density of compacted soil decreased and the optimum moisture content increased with 4 % of calcium sulfate. The addition of 4 % calcium sulfate increased the free swelling of compacted soil by 67 %. The addition of 6 % lime resulted in the formation of ettringite (Ca6Al2 (SO4)3(OH)12·26H2O). Polymer treatment decreased the LL, PI, swelling index, and optimum moisture content of the soil and increased the compacted maximum dry density. Behavior of sulfate contaminated CL soil with and without treatment was quantified using a unique model that represented both linear and nonlinear responses. Also the model predictions were compared with published data in the literature.

44 citations


References
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Book
01 Jan 2014-
Abstract: Soil chemical analysis , Soil chemical analysis , مرکز فناوری اطلاعات و اطلاع رسانی کشاورزی

13,425 citations


Journal ArticleDOI
01 May 1958-Agronomy Journal

6,493 citations


"Sulphate Attack in Lime-Treated Mar..." refers methods in this paper

  • ...Procedures suggested by Jackson (1958) were used for chemical analysis of samples such as organic content, pH, exchangeable ions, and base exchange capacity....

    [...]


Journal ArticleDOI
Abstract: Expansive reactions between lime and sulfate-bearing clay soils have attracted little attention until relatively recently. Lime treatment of Stewart Avenue in Las Vegas, Nevada, had induced heave in excess of 12 in. Heaved areas are found to contain abundant thaumasite, a complex calcium-silicate-hydroxide-sulfate-carbonate-hyd rate mineral. Thaumasite forms a solid solution series with ettringite, a calcium-aluminum-hydroxide-sulfate-hy drate mineral. In the presence of aluminum, ettringite forms first and is replaced by thaumasite only at temperatures below 15°C. The mechanism of heave is a complex function of available water, the percentage of soil clay, and ion mobility. Only the long-term possolanic chemistry of normal lime-soil reactions is disrupted. Cation exchange, agglomeration, and carbonation are unaffected. With the present state of knowledge, lime-induced heave is difficult to predict for all but most obvious conditions.

335 citations


"Sulphate Attack in Lime-Treated Mar..." refers background in this paper

  • ...Recent studies of lime treated clays have reported swelling and pavement failures are caused by the formation of expansive type minerals such as ettringite (Ca6 Al2(OH)12(SO4)3 26H2O) and thaumasite (Ca3 (H2O)12(CO3) (SO4)[Si(OH)6)] (Mitchell 1986; Hunter 1988; Rajasekaran 1994)....

    [...]

  • ...Hunter (1988) reported the formation of ettringite and thaumasite in sulphate enriched soils....

    [...]

  • ...Several researchers (Mehta and Klien 1966; Hunter 1988; Mitchell and Dermatas 1992) have brought out the influence of temperature on ettringite formation....

    [...]

  • ...Provide sufficient lateral drainage to remove any oxidation products or keep high pH environment Hunter (1988) Avoid ponding of soils and provide good surface drainage, use utility trenches with impermeable synthetic liners along the slopes and construction joints Raja (1990) Add barium chloride…...

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  • ...The fluctuation of lime content values in the above system during the first 30 days may be due to the consumption of Ca2þ ions in ettringite formation (Mitchell 1986; Hunter 1988)....

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Journal ArticleDOI
Abstract: In spite of our present very advanced analytical capabilities, our present ability to predict actual field behavior is, in many cases, woefully inadequate. Four cases are described to illustrate one of the reasons why actual and predicted performances are sometimes so widely divergent—namely, failure to understand how a soil might respond over time to changed conditions. The four cases are: (1) The aging of quick clay after sampling, in which the remolded strength increases in samples maintained at constant water content; (2) time effects in freshly densified or deposited sand, in which natural sand deposits can lose strength if disturbed but regain strength over time periods of weeks to months; (3) apparently sound lime‐stabilized soil that swells and disintegrates starting a few years after construction; and (4) the failure of excess pore pressures to dissipate as predicted during the consolidation of soft clays. Study of each of these problems has led to an understanding of the responsible phenomena an...

277 citations


"Sulphate Attack in Lime-Treated Mar..." refers background in this paper

  • ...The fluctuation of lime content values in the above system during the first 30 days may be due to the consumption of Ca2þ ions in ettringite formation (Mitchell 1986; Hunter 1988)....

    [...]

  • ...Recent studies of lime treated clays have reported swelling and pavement failures are caused by the formation of expansive type minerals such as ettringite (Ca6 Al2(OH)12(SO4)3 26H2O) and thaumasite (Ca3 (H2O)12(CO3) (SO4)[Si(OH)6)] (Mitchell 1986; Hunter 1988; Rajasekaran 1994)....

    [...]

  • ...Ettringite induced swelling in sulphate-enriched soils has been explained in detail by several researchers (Mitchell 1986; Hunter 1988; Rollings et al. 1999), but the increase in swelling pressure has been noted only under certain conditions (Stuble 1986)....

    [...]

  • ...This may be due to ettringite formation which is accompanied by an increase in the liquid limit values (see Mitchell 1986) after 15 days....

    [...]


Book
01 Oct 1994-
Abstract: This book reviews the subject of soil stabilization which is the process whereby soils and related materials are made stronger and more durable by mixing with a stabilizing agent. The process enables materials to be employed in the construction of road pavements which without stabilization would be unsuitable for use. The use of stabilized soils in place of natural aggregates can have considerable environmental and economic advantages. Although other stabilizing agents can be used, cement and lime are by far the most important and the book therefore concentrates on their use. The book begins with an outline of the principles of stabilization followed by a review of the methods of testing and the specifications in use in different parts of the world. The physical and chemical factors affecting the strength of stabilized soils are dealt with in depth, and then the book goes on to describe the practical aspects of the technology including the design process, construction techniques, quality control procedures, and problem areas. In the final chapter the environmental and economic benefits of the techniques are reviewed and summarized.

265 citations


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