تأثیر شرایط مختلف عمل‌آوری بر دوام خاک‌های رسی تثبیت‌شده با آهک (مطالعه‌ی ریز‌ساختاری و درشت‌ساختاری)

نوع مقاله : مقاله پژوهشی

نویسندگان

1 دانشجوی دکترای عمران، مکانیک خاک و پی، دانشکده مهندسی، دانشگاه شهید باهنر کرمان

2 دکترای مهندسی عمران، مکانیک خاک و پی، دانشکده مهندسی، دانشگاه شهید باهنر کرمان

3 استاد مهندسی عمران، مکانیک خاک و پی، دانشکده مهندسی، دانشگاه شهید باهنر کرمان

چکیده

خاک­های رسی عموماً در حالت خشک، سختی و مقاومت مناسب دارند. اما در حضور آب، دچار افت سختی و مقاومت زیاد شده، که موجب کاهش ظرفیت باربری و افزایش نشست و تراکم­پذیری خاک می­گردد. در پروژه­های عمرانی، خاک­های رسی، بخصوص رس­های نرم، با استفاده از آهک تثبیت می‏شوند. در پژوهش حاضر، نمونه­های خاک رسی کائولینیت، با 10، 15 و 20 درصد آهک تثبیت و در دمای 27 درجه سلسیوس و رطوبت نسبی 2±98 درصد عمل­آوری شدند. سه سری خاک مطالعه شد: نمونه­های اول پس از 14 روز، نمونه­های دوم پس از 28 روز و نمونه­های سوم پس از 14 روز عمل­آوری در آب، مستغرق شده و سپس آزمایش ­گردیدند. در راستای مطالعه درشت­ساختاری نمونه­ها تحت آزمایش تک­محوری و مطالعه ریزساختاری و ترکیبات سیمنتاسیون حاصل از واکنش خاک- آهک، آزمایش پراش اشعه ایکس (XRD)، عکس­های میکروسکوپی الکترون پویشی (SEM) و طیف­سنجی پراش انرژی پرتو ایکس (EDS یا EDX) انجام گردید. نتایج نشان داد که با استفاده از 10% آهک، نمونه­هایی که بعد از 14 روز عمل­آوری و 14 روز در آب مستغرق شده­اند، در مقایسه با نمونه­ها 28 روزه، به­واسطه­ی نفوذ آب و به دنبال آن شکسته و ضعیف شدن استحکام ترکیبات سیمنتاسیون، 65% کاهش مقاومت داشتند. همچنین، در هر دوی مطالعات درشت‏ساختاری و ریز‏ساختاری، برای دست‏یابی به مقاومت مناسب، میزان آهک بهینه حدود 10% است.

کلیدواژه‌ها

عنوان مقاله [English]

The Influence of Different Curing Conditions on Durability of Lime-Stabilized Clay Soils (Micro- and Macro- Structure Study)

نویسندگان [English]

  • Sanaz Soltaninejad 1
  • Salaheddin Hamidi 2
  • Seyed Morteza Marandi 3
1 PhD Candidate in Civil Engineering, Faculty of Engineering, Shahid Bahonar University of Kerman, Kerman, I. R. Iran.
2 PhD in Civil Engineering, Faculty of Engineering, Shahid Bahonar University of Kerman, Kerman, I. R. Iran.
3 Professor, Department of Civil Engineering, Shahid Bahonar University of Kerman, Kerman, I. R. Iran.
چکیده [English]

Clay soils have generally appropriate strength and stiffness in dried conditions. However, their strength parameters such as bearing capacity, unconfined compression strength, and shear strength, are reduced, and compressibility and settlements are increased significantly in the presence of water. In various civil engineering projects, clay soils, especially soft clays, are usually stabilized by using lime. In this research, kaolinite clay samples were stabilized using 0, 10, 15 and 20 percent by weight of lime at temperature of 27 ºC and relative humidity of 98±2 percent. Three series of samples were studied: the first series after 14 days curing, the second series after 28 days curing, and the third series were submerged in water 14 days after curing and then were tested. For macro-structure study, the specimens were tested under unconfined compressive strength test, and for micro-structure studies, and due to cementation of soil-lime-reaction, X-ray Diffraction (XRD) analysis, Scanning Electron Microscope (SEM), and Energy Dispersive X-Ray Spectroscopy (EDS or EDX) were carried out. Results showed that using 10% lime in samples with 14 days curing time and submerged in water for 14 days have 65% lower strengths in comparison with the samples cured for 28 days. This was due to the infiltration of water and breaking and weakening of strength of cementation compounds. Also, for both macro and micro structure studies, optimum lime content is 10% in order to reach the proper soil strength.

کلیدواژه‌ها [English]

  • Clay soil
  • Soil stabilization
  • Lime
  • Uniaxial strength
  • Micro-structure experiments

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سابقه مقاله

  • تاریخ دریافت: 26 مهر 1396
  • تاریخ بازنگری: 22 خرداد 1397
  • تاریخ پذیرش: 05 تیر 1397

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