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Effects of fillers on morphological, mechanical, flow and thermal properties of bituminous composites

Tayfun, Ümit
There are many different types of fillers used for bitumen modification such as; silica, limestone, basalt, mica, oyster shells. Filler gives rigidity, stiffness or hardness, regulates thermal expansion and shrinkage, improves heat resistance, and modifies rheological properties of bituminous composites. The main objective of this study was to determine the effect of filler type and ratio on mechanical, thermal properties and morphologies of bitumen based composites. It was also aimed to improve the heat resistivity of the bituminous composite to obtain a material with good mechanical and heat isolation properties. Bituminous composites were prepared by using Brabender Plasti-Corder, PLV 151. Mixing was made at 180 ºC with 60 rpm for 15 minutes. Two grades of bitumen as 20/30 and 50/70 penetrations were used. CaCO3, CaO, mica, baryte, kieselguhr and silaned kieselguhr were used as fillers in this study. Ethylene vinyl acetate copolymer, styrenebutadiene rubber, and styrenebutadienestyrene block copolymer were used as polymers. According to the test results, using mica at low percentages had the effect of decreasing the viscosity of the bitumen due to its flow alignment property. Baryte gave high heat capacity and low heat conductivity to bituminous material. EVA containing samples showed the best combination on mechanical properties. The silanation process decreased the pore sizes as observed in mercury porosimetry experiments. A decreased amount of bitumen impregnation was obtained by the silanation process, clearly observed in SEM micrographs.