ارزيابي نقش فيلر سيمان و آهك بر خصوصيات مكانيكي مخلوط‌هاي بازيافتي كف قير و ارايه مدل رياضي

خرده‌هاي آسفالت بازيافتي پس از تراشيده شدن، نوعي از مواد زائد محسوب مي‌شوند كه از نظر زيست محيطي اثرات نامطلوبي بر محيط اطراف خود دارند. از طرفي هزينه سنگين احداث راههاي جديد و خسارت‌هاي ناشي از خرابي راه‌هاي موجود، مشكلات زيادي را بوجود مي‌آورد. هدف اين پژوهش بررسي اثر توام درصد قير با تغيير فيلر بر خصوصيات مكانيكي مخلوط‌هاي كف قيري آسفالت بازيافتي مي‌باشد. روش تحقيق آزمايشگاهي است. نمونه‌هاي ساخته شده با افزودن فيلر‌هاي سيمان، آهك با درصد قير متفاوت و در شرايط عمل‌آوري خشك، اشباع و ذوب-يخبندان بررسي شدند. نمونه‌ها با فيلر سيمان (5/1 درصد)، آهك (5/1 درصد) و تركيب سيمان، آهك (75/0+75/0 درصد) و يك نمونه شاهد ساخته شدند. سپس آزمايش‌هاي مقاومت فشاري تك محوري، مدول برجهندگي، استحكام مارشال و مقاومت كشش غيرمستقيم براي تعيين خصوصيات مكانيكي انجام گرديد. در ادامه با استفاده از نتايج تست مدول برجهندگي مدل‌سازي اجزا محدود با استفاده از نرم‌افزارهاي اباكوس و KenLayer انجام و اثر تغيير مدول برجهندگي بر تعداد تكرار بار منجر به خرابي خستگي بررسي شد كه در نهايت يك مدل رياضي جهت پيش بيني نسبت TSR ارايه گرديد. نتايج اين تحقيق مي‌دهد در آزمايش مقاومت فشاري تك محوري و استحكام مارشال، در كليه طرح‌ها با افزايش قير از 1 به 2 درصد نتايج افزايش سپس با افزايش قير از 2 به 3 درصد كاهش مييابد. همچنين نتايج آزمون مقاومت كشش غيرمستقيم نشان مي‌دهد كه با افزايش قير از 1 به 3 درصد در همه طرح‌ها مقاومت كشش غيرمستقيم در حالت عمل‌آوري خشك، اشباع به‌طور پيوسته افزايش مي‌يابد. فيلر سيمان با آهك در تمامي حالت‌هاي عمل‌آوري بيشترين تاثير را در افزايش مقاومت كشش غيرمستقيم دارد و تاثير افزايش مقاومت در نمونه‌هاي حاوي فيلر در شرايط عمل‌آوري اشباع بيش از حالت خشك است. نتايج مدل‌سازي سه بعدي نشان داد كه با افزايش مدول برجهندگي لايه اساس، تعداد تكرار منجر به خرابي خستگي را به شدت افزايش مي‌يابد.

Recycled asphalt chips after shaving are considered to be a waste material that has an adverse environmental impact on the environment. On the other hand, the heavy cost of constructing new ways and damages caused by the destruction of existing roads will cause many problems. Therefore, the aim of this study was to investigate the effect of mixed bitumen with filler change on mechanical and functional properties of asphalt foam mixtures of recycled materials. Research method is field study. All experiments were carried out at the Technical and Mechanical Laboratory of the Ministry of Construction in Tehran. In this project, aggregates consumed from asphalt tracks of the 29th straight Shahid Dastgheib International Airport in Shiraz were prepared. The bitumen used in this research was selected as bitumen from Tehran refinery in Tehran. Also, Portland cement fillers of type 425-1, lime and cement and lime mixture as active filler were used and the amount of active filler added in all designs was considered the same. Samples were made by adding cement fillers, lime with different bitumen content and under dry and saturated treatment conditions. Samples were made with filler cement (1.5%), lime (1.5%) and cement, lime (0.75% and 0.75%) and a control sample. Then, the experiments were performed on the modulus of resilience, the strength of the marshall and the indirect pull resistance. To increase the number of observations and increase the accuracy of the mathematical model, samples with cement filler with a ratio of 1 and 2 percent with bitumen 1, 2 and 3 were constructed using Marshall Hammer. Marshall Strength tests, modulus of resistivity and indirect pull resistance were carried out in dry and saturated conditions. Using the results of the modulus of resilience test, the finite element modeling was performed using ABAQUS and KenLayer software, and the effect of changing the modulus on the number of load repetitions that resulted in fatigue failure was evaluated. Finally, a mathematical model was presented. The results of this study, using SPSS and Statisca software, show that in Marshall's strength test, in all plans, increasing the bitumen from 1 to 2 percent, the Marshall Strength increases and then decreases with increasing bitumen by 2 to 3 percent. Marshall Strength ratio (obtained by dividing the Marshall strength of saturated samples to the Marshall strength of dry specimens) revealed that these types of mixtures are sensitive to moisture conditions and at best (2% bitumen and with cement lime filler) this amount reaches 0.46. Also, results of indirect resistance test show that, with increasing bitumen from 1 to 3%, in all designs, indirect resistance is increased during drying, saturation is continuously increased. The cement filler with lime in all treatment modes has the greatest effect on increasing the indirect pull resistance, and the effect of increasing the strength of the filler-containing specimens is more than dry in terms of saturation processing. The results of three-dimensional modeling of Abacus showed that increasing the modulus of the base layer, the number of repetitions leads to fatigue failure greatly increases. Also, half-life parameters, expansion ratio and index of bitumen were measured and the parameters of these parameters were plotted against water percent.