تاثير سنگ‌دانه‌هاي حاصل از بتن‌هاي بازيافتي، شيشه و پلاستيك‌هاي زايد در خواص بتن

Effects of Recycled Concrete Aggregate, Waste Glass and Plastic on the Durability and Mechanical Properties of Concrete

امروزه افزايش توليد زبالههاي ساختماني، دفن و بازيافت آنها يكي از مسايل مهم زيست‌محيطي به شمار ميآيد. از انواع زبالههاي ساختماني ميتوان به بتن تخريبي، شيشه و پلاستيك اشاره كرد. در اين پژوهش دانههاي حاصل از بتن تخريبي جايگزين بخشي از درشت دانه و ريزدانه شده اند. ضمناً شيشه و پلاستيك خردشده نيز به عنوان جايگزين بخشي از ريزدانه به‌كار رفته است. مقاومت هاي فشاري، كششي، خمشي، مقاومت الكتريكي، كارايي، جذب آب، وزن مخصوص بتن سخت‌شده و بسامد طبيعي مورد ارزيابي قرار گرفته اند. نتايج به‌دست‌آمده حاكي از آن است كه امكان كاربرد سنگ‌دانه-هاي حاصل از بتنهاي تخريبي و شيشه هاي بازيافتي در بتن هاي جديد وجود دارد، در حالي كه جايگزيني پلاستيك به عنوان جايگزين بخشي از ريزدانه باعث كاهش نسبي خواص مكانيكي مخلوط هاي بتني شده است.

Considering the advancement of technology and the growth in population, recycling waste material is a practical solution. Waste material can be obtained from demolished and destroyed buildings, or the debris of buildings damaged in destructive earthquakes, floods, and wars. Recycling waste material, besides saving energy and natural resources, and improving environmental conditions, could also decrease the cost of these materials when disposed in landfills. This research is focused on evaluation of the concrete made by recycled concrete, crushed waste glass and plastic. These materials are used as a substitute for natural aggregates in concrete. In order to consider the effects of these waste materials, recycled concrete was used as fine and coarse aggregate, and plastic and glass were substituted by fine aggregate. The substitution percent for waste material was 0, 5, 10, 15, and 20. For better observation, some physical and mechanical properties were considered. These tests consist of workability, compressive strength, flexural strength, tensile strength (splitting), electrical resistivity, hardened unit weight and natural frequency in a modulus of elasticity test. By substituting waste glass with natural fine aggregate, no remarkable change was observed in the mechanical properties, while water absorption and electrical resistivity were modified. In addition, recycled fine and coarse aggregates had an acceptable performance in mechanical properties, although water absorption and electrical resistivity was not as expected. In contrast, waste plastic decreased the mechanical properties dramatically, as in some cases, this mixture is not recommended at all. Of course, electrical resistivity and water absorption were modified noticeably. As a whole, crushed glass and recycled concrete play a neutral role as aggregate in concrete, and even in some cases, enhances the properties. The substituted plastic had insufficient effects on concrete and is recommended when high strength concrete is not