Investigation of optimum modification parameters in nanoclay-SBS/EVA-bitumen modification

Although various methods can be used in the production of nanoclay/polymer/bitumen nanocomposite (PMAN), the melt blending method is the most widely used method. In the preparation of PMAN according to the melt blending method, the type of modifier and the mixing temperature, speed and time play a key role on the success of the modification. Different mixing speeds, temperatures and times have been tried to modify asphalt mixtures, but generally accepted modification parameters have not been determined yet. In this study, the most suitable modification parameters were investigated in the production of PMAN with SBS and EVA. Nanoclay is 3% by weight of bitumen, and polymers; 5% SBS, 1.8% EVA (1% Elvaloy RET + 0.8% Elvax) ratios were used. As modification parameters, mixing temperatures 160 °C, 170 °C, 180 °C; 60, 90 and 120 minutes mixing times; 3000, 4000 and 5000 rpm mixing speeds were selected. Modified bitumen was prepared in 54 different combinations for the production of SBS PMAN and EVA PMAN in selected parameters. Morphological properties of PMANs were evaluated by optical microscopy method and mechanical properties of asphalt mixture samples produced with PMAN were evaluated by indirect tensile strength, modified Lottman, repeated load creep and Marshall stability tests. In the whole study, 909 Marshall briquettes were produced and conditioning was applied to 738 of them. As a result of the tests it was observed that the change of modification parameters process the preparation of EVA PMAN and SBS PMAN had a significant effect on the mechanical properties of the final asphalt mixtures and satisfactory results were obtained in terms of the problem addressed. In consequence of all tests for SBS PMAN and EVA PMAN, optimum modification parameters were determined as 170 °C – 4000 rpm – 90 min. and 180 °C – 3000 rpm – 120 min. respectively.