رفتار مكانيكي رزين پلي‌استر و بتن ‌پليمري در بارگذاري‌هاي استاتيكي و ديناميكي

Mechanical Behavior of Polyester Resin and its Polymer Concrete under Static and Dynamic Loading Conditions

در اين تحقيق با استفاده از رزين پلي‌استر تركيب جديدي براي كاهش هزينه‌ي ساخت بتن‌ پليمري ارايه شده است. مقايسه‌ي خواص مكانيكي بتن ارايه شده با بتن‌هاي پليمري اپوكسي نشان مي‌دهد كه علي‌رغم كاهش قابل توجه هزينه‌هاي توليد، تركيب جديد داراي خواص مكانيكي مطلوبي است. براي مطالعه‌ي تاثير اجزاي سازنده بر خواص مكانيكي تركيب نهايي، رفتار مكانيكي بتن ‌پليمري ارايه شده در فشار و خمش، مطالعه و با رفتار مكانيكي رزين پلي‌استر خالص مقايسه شد. نتايج آزمايشگاهي نشان‌گر افزايش پيوسته‌ي خواص استحكامي رزين پلي‌استر (افزايش 41‌درصدي استحكام كششي) و بتن پليمري (افزايش 27‌درصدي استحكام فشاري)، با افزايش نرخ بارگذاري از 1/0 تا 90 ميلي‌متر بر ثانيه است. با توجه به رفتار وابسته به نرخ كرنش رزين پلي‌استر به‌عنوان يكي از اجزاي اصلي سازنده‌ي بتن پليمري، حساسيت به نرخ كرنش بتن قابل توجيه است. اگرچه ميزان وابستگي به نرخ كرنش بتن پليمري كم‌تر است.

Polymer concretes (PCs) have superior mechanical properties and performance in comparison with traditional cement concretes. However, reducing fabrication costs is a great concern for the increasing application of PCs. In this research, fine silica sand was used instead of the common usage of a mixture of large and small aggregates, in order to minimize the void content for dry packed aggregates. Moreover, polyester resin is used as the binder of the concretes, mainly because of its lower price in comparison with conventional epoxy systems. The specimens of polyester polymer concrete (PPC) were fabricated and tested based on standard testing methods. These tests include compression and flexural tests, and the results of the tests were compared with available experimental data for PCs fabricated with an epoxy resin system. Based on the results obtained, it is concluded that the proposed composition reduced fabrication costs and has acceptable mechanical properties. In addition, the strengthening ability of polyester resin in the introduced concrete was better utilized than the polymer concrete fabricated with epoxy resin. The mechanical behavior of the suggested PPC was studied under compression and bending loading conditions, and compared with that of the neat polyester resin. Next, the influence of the applied strain rate on the mechanical response of both neat polyester and PPC was investigated. Special specimens for testing PPCs under dynamic loading conditions were designed and fabricated. Multiple experiments were performed in the range of strain rates from 0.1 to 90 mm/s. The experimental results show that the mechanical behavior of polyester resin and PPC is extremely sensitive to the loading rate. By increasing the loading rate, the tensile strength of the neat polyester resin specimens was increased by nearly 41%, while the elastic modulus did not change. Also, the results show an increase up to 27% in the compressive strength of the PPC. Considering the strain rate dependent behavior of the neat resin, which is one of the main constituents of the PC, the strain rate dependent behavior of the PPC is justifiable. However, the strain rate sensitivity of the PPC is lower than that of the neat polyester resin.