بررسی تاثیر استفاده از افزودنی های میکرونیزه تکتوسیلیکاتی بر بهبود خواص فیزیکی و مکانیکی اندود سنتی کاهگل

نوع مقاله: علمی - پژوهشی

نویسندگان

1 دانشجوی دکتری مرمت آثار تاریخی و فرهنگی، دانشگاه هنر اصفهان، اصفهان، ایران

2 استاد، دانشگاه صنعتی اصفهان، اصفهان، ایران

3 دانشیار، دانشگاه هنر اصفهان، اصفهان، ایران

4 دانشیار، دانشگاه صنعتی اصفهان، اصفهان، ایران

چکیده

کاهگل یکی از قدیمی‌ترین ملات‌های سنتی ایران است که قابلیت‌ها و تجربیات استفاده از آن در طول تاریخ، نشان‌دهنده آن است که می‌توان از آن، به عنوان یک پوشش مناسب برای حفاظت ساختارهای معماری خاکی استفاده نمود ولی لزوم تجدید دائمی آن، پس از هر بار فرسایش در مقابل بارندگی، حکایت از ناپایداری آن در مقابل رطوبت دارد؛ بنابراین یافتن روشهای علمی مناسب به منظور افزایش دوام و طول عمر مفید اندود کاهگل، بسیار ضروری به نظر می‌رسد. بررسی تاثیر مواد افزودنی مختلف تکتوسیلیکاتی میکرونیزه در ترکیب با ملات کاهگل به منظور افزایش دوام آن، نشان داد که با استفاده از 3 درصد افزودنی تکتوسیلیکاتی 45 میکرون میکروسیلیس تا 20 درصد، با زئولیت تا 6/85 درصد و با فلدسپات میکرونیزه تا 73 درصد می‌توان ضریب نفوذپذیری کاهگل را کاهش داد. به علاوه، افزودن 3 درصد وزنی میکروسیلیس، زئولیت و فلدسپات میکرونیزه 45 میکرون، مقاومت فشاری کاهگل را نیز نسبت به نمونه‌های شاهد به ترتیب تا 5/73، 36 و 5/71 درصد ارتقاءمی‌دهد. از سوی دیگر، ارزیابی میزان دوام نمونه‌های آزمایشگاهی تحت بارش مصنوعی با دستگاه شبیه‌ساز باران نشان داد که استفاده از 3 درصد وزنی میکروسیلیس، زئولیت و فلدسپات، میزان هدر رفت ماده جامد در نمونه‌ها را به ترتیب تا 8/15، 34 و 5/10 درصد کاهش و دوام آنها را در مقابل فرسایش ناشی از بارندگی افزایش می‌دهد. این مطالعات بیانگر آن است که با کاهش اندازه ذرات و دانه‌بندی ماده افزودنی، میزان تاثیر مثبت آنها نیز در بهبود خواص فیزیکی و مکانیکی ملات کاهگل افزایش می‌یابد. این مطالعات همچنین نشان داد که درصد بهینه استفاده از مواد افزودنی تکتوسیلیکاتی میکرونیزه برای بهسازی اندود کاهگل 3 درصد وزنی است و افزایش میزان ماده افزودنی، تاثیر چندانی در ادامه روند بهسازی خواص فیزیکی و مکانیکی کاهگل ندارد.

کلیدواژه‌ها

موضوعات


عنوان مقاله [English]

The effect of tectosilicates micronized additives on physical and mechanical properties improvements of Cob (Kahgel) plaster

نویسندگان [English]

  • Masoud Bater 1
  • Jahangir Abedi 2
  • Hossein Ahmadi 3
  • Rahmatoolah Emadi 4
1 PhD Student, Department of Conservation and Restoration of Cultural Properties, Art University of Isfahan, Isfahan, Iran
2 Professor, Isfahan University of Technology, Isfahan, Iran
3 Associate Professor, Isfahan University of Art. Isfahan, Iran
4 Associate Professor, Isfahan University of Technology, Isfahan, Iran
چکیده [English]

Kahgel (Cob) is one of the oldest traditional mortars in Iran. Kahgel plaster consists of high clay content, dried mud and a portion of straw fibers to defend the mortar against shrinkage cracks. The ancient waterproof covering is very efficient at protecting the building dry during the heavy rain showers, but low durability and the need for renewal of plaster due to erosion of rainfall suggest that Kahgel plaster is weak and unstable. So, it is very essential and necessary in finding appropriate scientific methods to enhance the durability and lifespan of Kahgel plaster. Studies on the stabilization and improvement of Kahgel plaster properties indicated that using some special tectosilicatesadditives can be improved significantly the physical and mechanical properties of earth and earthen materials such as Kahgel plaster. The effect of different micronized tectosilicatesadditives used to build the different samples of Kahgel plaster on physical and mechanical properties to enhance the durability of Kahgel plaster showed that Microsilica at 6% (by weight of Khahgel), reduced hydraulic conductivity of the Kahgel plaster at 33% level and micronizedZeolite at 3% (by weight of Khahgel), is increased by 85%.  In addition Microsilica and micronizedZeolite at 3% (by weight of Khahgel), increased compression strength of the Kahgel plaster at 73% and 36%, respectively. In addition micronized Kaolin and Bentonite, increased uniaxial compression strength of the Kahgel plaster at 39 % and 33 %, respectively. In addition evaluation of water erosion of  the samples during rainfall by rainfall simulator showed that use of Microsilica, Feldspar, Zeolite and Kaolin 3% (by weight of Khahgel), the minimum sample’s total dry material loss of the Kahgel plaster reduced to 10/5% and the maximum decrease to 37/7%  and increase durability of the Kahgel plaster against water erosion. Experimental results indicated that in addition to the type and percentage of additives, particle size plays an important role on the physical and mechanical properties of Kahgel plaster.

کلیدواژه‌ها [English]

  • Earthen architecture Kahgel
  • Micronized additives
  • Tectosilicates
  • Conservation

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