بررسي اثر تخلخل و رطوبت در مكانيزم شكست ملات سيمان با استفاده از پارامتر هاي انتشار آوايي (AE)

Assessment of moisture and porosity effects in failure mechanism of mortar using Acoustic Emission

در مكانيك شكست سنگ از روش‌هاي متعددي براي رفتار‌نگاري رشد ترك و شكست استفاده مي‌شود. يكي از روش‌هايي كه براي بررسي ريزترك‌ها در نمونه‌ تحت تنش استفاده مي‌شود، روش انتشار آوايي است. وجود تخلخل و رطوبت در ساختار بتن، خاك و سنگ اثرات مختلفي بر روند ايجاد و رشد ريزترك‌ها و در نهايت شكست آنها خواهد داشت. در اين تحقيق اثر تخلخل و رطوبت در رشد ترك و شكست در سنگ بررسي شده است. از چهار پارامتر بسيار موثر در روند رفتار‌نگاري شكست در روش انتشار آوايي يعني هيت، كانت، دوام موج و انرژي شكست استفاده شده است. براي داشتن درصد تخلخل يكسان و همسان در نمونه‌ها از ملات سيمان(سنگ مصنوعي) استفاده شد. با استفاده از ماده روان كننده Panplast R نمونه با تخلخل بين 17 تا 35 درصد در پنج تخلخل مختلف نمونه‌هاي استوانه‌اي با قطر 54 ميليمتر با نسبت طول به قطر دو ساخته شد. نمونه در دو حالت خشك و اشباع از آب تحت آزمايش تك ‌محوره فشاري قرار گرفتند. در حين آزمايش اطلاعات انتشار آوائي ثبت شد. از تحليل داده‌هاي بدست آمده از روش انتشار آوايي مشخص شد كه مود شكست غالب در آزمايش فشارشي تك‌محوره در نمونه‌هاي ملات سيمان خشك با افزايش تخلخل، به سمت مود كششي افزايش‌ يافته و با افزايش تخلخل و افزايش رطوبت ريز ترك هاي كمتري در نمونه ايجاد ميشود.

Different methods are being used for monitoring of crack growth and failure mechanism in rock fracture. Acoustic Emission (AE) is one the methods used for micro crack monitoring in samples under pressure. Existence of porosity and humidity in rock and soil structure cause different effects on process of micro cracks and growth of micro cracks and finally their fracture. In this study, effects of porosity and humidity in micro crack growth and rock fracture are being analyzed. Four parameters which are highly effective in AE method namely hit, count, wave durability and fracture energy are used. Mortar (synthetic rock) was used to have a constant porosity ratio in samples. Cylindrical samples with 54 mm diameter and 110 mm length with 5 different porosity ratios ranging from 17 to 35 percent were made using Panplast lubricant. Samples were subjected to uniaxial compression test in two dry and saturated conditions and AE data were recorded. Data analysis showed that the dominant failure mode on samples of dry mortar with increasing porosity, increase toward the tension mode. With increasing of porosity and moisture content the numbers of micro crack decreases. Different methods are being used for monitoring of crack growth and failure mechanism in rock fracture. Acoustic Emission (AE) is one the methods used for micro crack monitoring in samples under pressure. Existence of porosity and humidity in rock and soil structure cause different effects on process of micro cracks and growth of micro cracks and finally their fracture. In this study, effects of porosity and humidity in micro crack growth and rock fracture are being analyzed. Four parameters which are highly effective in AE method namely hit, count, wave durability and fracture energy are used. Mortar (synthetic rock) was used to have a constant porosity ratio in samples. Cylindrical samples with 54 mm diameter and 110 mm length with 5 different porosity ratios ranging from 17 to 35 percent were made using Panplast lubricant. Samples were subjected to uniaxial compression test in two dry and saturated conditions and AE data were recorded. Data analysis showed that the dominant failure mode on samples of dry mortar with increasing porosity, increase toward the tension mode. With increasing of porosity and moisture content the numbers of micro crack decreases. Different methods are being used for monitoring of crack growth and failure mechanism in rock fracture. Acoustic Emission (AE) is one the methods used for micro crack monitoring in samples under pressure. Existence of porosity and humidity in rock and soil structure cause different effects on process of micro cracks and growth of micro cracks and finally their fracture. In this study, effects of porosity and humidity in micro crack growth and rock fracture are being analyzed. Four parameters which are highly effective in AE method namely hit, count, wave durability and fracture energy are used. Mortar (synthetic rock) was used to have a constant porosity ratio in samples. Cylindrical samples with 54 mm diameter and 110 mm length with 5 different porosity ratios ranging from 17 to 35 percent were made using Panplast lubricant. Samples were subjected to uniaxial compression test in two dry and saturated conditions and AE data were recorded. Data analysis showed that the dominant failure mode on samples of dry mortar with increasing porosity, increase toward the tension mode. With increasing of porosity and moisture content the numbers of micro crack decreases