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The effects of weathering on limestone used for building the cemetery wall in Tel Kaif-North Iraq
تأثيرات التجوية على صفات الحجر الجيري المستخدم في بناء جدار مقبرة تلكيف- شمال العراق

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Abstract

The purpose of this study is to evaluate the impact of weathering on rocks used in construction during a defined period of these rocks. The field study involves weathering and rock strength measurements using a geological hammer. Laboratory testing for both wall limestone and fresh quarry limestone was performed to determine the bulk density, the porosity and absorption of water, and the durability test was performed for fresh quarry limestone. A polarized microscope and scan electron microscope, petrographic analysis has been conducted for various weathering rates.Field notes explain the moderate and high degree of weathering and low strength in the bottom of the wall, whilst the top is slightly weathered and high strength. Laboratory notes through stone crushing show a change from white to beige for slightly weathered samples to moderately and highly weathered samples in powder color. Increasing weathering reduces bulk density and insoluble residues, from 13% in non-weathered rocks to 25% in high-weathered rocks the level of insoluble residue increases. Water absorption in non-weathered rocks and high weathering rocks rises from 6% to 14% and porosity from 14% to 27% respectively. Durability tests show that calcarenite exceeds very high durability, high durability calcirudite and calcilutite, and moderately durable calcisiltite. Four types of porosity, intergranular, intragranular, mold and microfracture appear in the petrographic study using a polarized microscope. Clay minerals and iron oxides surrounding the pores appear in weathered specimens, not in fresh, calcite crystal oxidation and secondary calcite growth on the inner surface of voids have also been shown in the scanning of electron microscopes

تهدف الدراسة الى تعيين تأثير عمليات التجوية على الصخور المستخدمة في البناء خلال فترة زمنية معلومة والتي يتم من خلالها معرفة ديمومة هذه الصخور. تمت الدراسة من خلال وصف أحجار الجدار من حيث درجة التجوية وتقدير مقاومتها باستخدام المطرقة الجيولوجية. أجريت فحوصات الكثافة الكلية والمسامية ونسبة امتصاص الماء لصخور الجدار وصخور المقلع غير المعرضة للتجوية، كما تم فحص نسبة تآكل صخور المقلع لبيان نسبة ديمومتها. أجريت دراسة بتروغرافية لأحجار الجدار المتأثرة بدرجات تجوية مختلفة وذلك باستخدام المجهر المستقطب والماسح الالكتروني للنماذج. أظهرت الملاحظات الحقلية أن الجزء الأسفل من الجدار يمتاز بدرجة تجوية متوسطة إلى عالية ومقاومة واطئة، بينما الجزء العلوي يمتاز بدرجة تجوية قليلة ومقاومة عالية. كما أظهرت النتائج المختبرية بان لون مسحوق الصخرة ذات التجوية العالية يكون بني فاتح بينما في درجة التجوية المتوسطة والقليلة غالبا ما يكون لون المسحوق ابيض. بينت الفحوصات الفيزيائية تناقص الكثافة الكلية ونسبة الفضالة غير الذائبة للأحجار بازدياد درجة التجوية اذ ترتفع نسبة الفضالة غير الذائبة من 13% في الصخور غير المتجوية الى 25% في الصخور عالية التجوية. بينما يحصل زيادة في نسبة امتصاص الماء من 6% الى 14% والمسامية من 14% الى 27% في الصخور غير المتجوية والصخور عالية التجوية وعلى التوالي. وضحت نتائج فحص التآكل أن صخور الكالكارينايت تمتاز بديمومة عالية جدا بينما كانت صخور الكالسيسلتايت متوسطة الديمومة و كالسرودايت وكالسيلوتايت عالية الديمومة. أعطت الدراسة البتروغرافية بالمجهر المستقطب أربعة أنواع من المسامية هي مسامية ضمن الحبيبات، ومسامية بين الحبيبات، ومسامية القالب ومسامية الشقوق الدقيقة. بينت الدراسة البتروغرافية بالماسح الالكتروني تواجد أكاسيد الحديد و المعادن الطينية حول المسامات الصخرية والتي لم تظهر في الصخور غير المتجوية. كما بينت دراسة الماسح الالكتروني تآكل وذوبان بلورات الكالسايت لتشكيل المسامات، فضلا عن نمو بلورات الكالسايت الثانوي على السطح الداخلي للمسامات.


Article
The effect of aging on tensile strength of two maxillofacial silicone materials before and after pigmentation

Authors: Afeiaa Lateef Jassim --- Mohammed Abdul Hussain
Journal: Journal of Oral and Dental Research مجلة طب الفم والاسنان ISSN: 23106417 Year: 2019 Volume: 6 Issue: 1 Pages: 40-50
Publisher: Iraqi Association for Oral Research الجمعية العراقية لبحوث طب الفم

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Abstract

Background The approximate life span of a silicone maxillofacial prosthesis is as short as after 4-14 months of usage, then a new prosthesis should be fabricated. But now many researchers have been directed toward improvement of properties silicone elastomeric materials. The objective of this study is to evaluate the effect of aging on tensile strength of two types of silicone materials used in the maxillofacial prostheses (VST-30 and VST-06) after artificial weathering for 100, 200 and 300 hours, and then comparing between the two selected materials in terms of selected artificial weatheringperiods. Material and methods a sample of 160 specimens were prepared anddivided into two main groups according to the types of elastomeric silicone (VST-30 and VST-06). Then each group subdivided into 8 divisions, (n=10). Two groups, one for clear and one pigmented as control groups before experimental weathering .While the experimental groups divided into clear and pigmented groups treated with artificialweathering for 100, 200 and 300 h. Results after different weathering cycles theresults show that there was no significant difference in the tensile strength for VST-30 silicone material pigment before and after weathering. While there was a highly significantdifference in the tensile strength for VST-06 pigmented silicone before and after weathering. Both VST-30 and VST-06 non-pigmented groups showed a highly significant change in the tensile strength after different weathering cycles. Conclusionsthe superior type for mechanical properties after difference cycles weathering was for VST-30 and incorporation of rayon flocking prevents the silicone materials from rapid degradation under artificial weathering and this may lead to increase in the service life of silicone prosthesis.

Keywords

Background The approximate life span of a silicone maxillofacial prosthesis is as short as after 4-14 months of usage --- then a new prosthesis should be fabricated. But now many researchers have been directed toward improvement of properties silicone elastomeric materials. The objective of this study is to evaluate the effect of aging on tensile strength of two types of silicone materials used in the maxillofacial prostheses --- VST-30 and VST-06 after artificial weathering for 100 --- 200 and 300 hours --- and then comparing between the two selected materials in terms of selected artificial weathering periods. Material and methods a sample of 160 specimens were prepared and divided into two main groups according to the types of elastomeric silicone --- VST-30 and VST-06. Then each group subdivided into 8 divisions --- n=10. Two groups --- one for clear and one pigmented as control groups before experimental weathering .While the experimental groups divided into clear and pigmented groups treated with artificial weathering for 100 --- 200 and 300 h. Results after different weathering cycles the results show that there was no significant difference in the tensile strength for VST-30 silicone material pigment before and after weathering. While there was a highly significant difference in the tensile strength for VST-06 pigmented silicone before and after weathering. Both VST-30 and VST-06 non-pigmented groups showed a highly significant change in the tensile strength after different weathering cycles. Conclusions the superior type for mechanical properties after difference cycles weathering was for VST-30 and incorporation of rayon flocking prevents the silicone materials from rapid degradation under artificial weathering and this may lead to increase in the service life of silicone prosthesis.

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