حساسيت رطوبتي مخلوط آسفالتي حاوي سرباره‌ي كوره‌ي قوس الكتريكي

Moisture Sensitivity of Asphalt Mixtures Containing E.A.F Steel Slag

ساليانه مقادير قابل توجهي سرباره‌ي صنايع فولاد به‌عنوان محصول فرعي در ايران توليد مي شود، كه به‌دليل زيادبودن حجم اشغال‌شده توسط اين مواد زايد در كشور، مسايل محيط زيستي جدي ايجاد شده است. هدف از اين پژوهش بررسي امكان استفاده از سرباره‌ي كوره‌ي قوس الكتريكي E.A.F در مخلوط آسفالتي جهت كاهش پديده ي عريان شدگي در آسفالت است. در اين پژوهش، ابتدا مشخصات فيزيكي و شيميايي سرباره‌ي فولاد مورد ارزيابي قرار گرفته و سپس با جايگزين‌كردن 50 و 100 درصد مصالح ريزدانه، 50 و 100 درصد مصالح درشت دانه و همچنين 50 و 100 درصد كل سنگ‌دانه هاي مخلوط آسفالتي با سرباره، حساسيت رطوبتي مخلوط آسفالتي حاصل مورد آزمايش قرار گرفته است. نتايج نشان مي دهد كه استفاده از سرباره‌ي كوره‌ي قوس الكتريكي به جاي درشت دانه در مخلوط آسفالتي، ضمن آنكه منجر به افزايش مقاومت و دوام مخلوط آسفالتي در برابر آسيب هاي رطوبتي مي شود، باعث افزايش استقامت مارشال، ضريب برجهندگي، و مقاومت كشش غيرمستقيم نيز مي ‌شود.

Moisture damage, sometimes called stripping, is the progressive deterioration of asphalt mixtures due to loss of adhesion between the asphalt binder and the aggregate surface and/or loss of cohesion within the binder due to the infiltration of water. Stripping usually begins in the bottom of the HMA layer, then, travels upward. A typical situation is a gradual loss of strength over a period of years, which causes rutting and shoving to develop in the wheel path. Many times, stripping is difficult to identify, because surface indicators may take years to show. This type of damage in Hot Mix Asphalt (HMA) is a major cause of pavement failure in tropical regions. There are many possible causes of stripping and inadequate surface drainage or sub-surface drainage is a primary contributor. There are many proposed remedial actions to alleviate the stripping phenomena of asphalt mixtures, such as using anti-stripping agents, lime slurry with compatible aggregates and modified binders. This study aims to investigate the feasibility of using E.A.F steel slag aggregate in HMA mixtures to reduce their stripping phenomena. Steel slag is a byproduct that makes 15 to 20% of the iron-processing product in an integrated steel mill. Every year, significant quantities of steel slag are produced as a by-product of steel industries in Iran. Although it can be used as an artificial source of aggregates in the pavement industry, it is disposed for landfills. In this research, the chemical and physical properties of the steel slag were evaluated first. Then, 50% and 100% of the limestone, as fine, coarse and total aggregate in the asphalt mixture was replaced by EAF, and the moisture sensitivity of the mixes was evaluated. The results showed that the use of steel slag as the coarse portion of the aggregates will enhance Marshall stability, resilient modulus, tensile strength and resistance to the moisture damage of HMA mixtures.