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In this study, the effects of the usage of soybean oil on bituminous binder properties have been examined and the hot mixture performances of binders modified with soybean oil have been evaluated differently from the studies in the literature. Modification of bitumen with soybean oil was carried out at 1 %, 2 % and 3 % additive ratios, at 160°C temperature, using a mixing speed of 2,000 rpm for 60 minutes. Conventional bitumen tests and adhesion and stripping tests were applied on both reference binder and bituminous binders modified with soybean oil. In addition, optimum bitumen contents, indirect tensile strengths, and moisture susceptibilities of hot mix asphalt samples prepared with bituminous binders modified with soybean oil have been determined by using the Superpave Volumetric Mix Design. According to the results, the consistency and viscosity of the binders decreased as the amount of soybean oil added to the bituminous binder increased. In addition, while the maximum indirect tensile strength was achieved for the 1 % soybean oil additive, an increase in resistance to moisture susceptibility was observed for all additive ratios.

Bu çalışmada, Cocamide Diethanolamide kimyasalının bitüm modifikasyonunda kullanımı araştırılmıştır. Katkı malzemesi olarak Cocamide Diethanolamide kimyasalı seçilirken kimyasal ve bitüm arasındaki sıcaklığa bağlı davranış, kimyasal yapı gibi özelliklerin benzer olması etkili olmuştur. Buna ilaveten, Cocamide Diethanolamide kimyasalının bitüm modifikasyonunda ilk kez kullanılmış olması, bu çalışmayı ayırt edici kılmaktadır. Bitümün kimyasal ile %1, %3 ve %5 katkı oranlarında, 155 °C ve 165 °C modifikasyon sıcaklıklarında, 30, 60, 90 dakika boyunca 1000 rpm karışım hızı kullanılarak birden fazla kez modifikasyonu sağlanmıştır. Bu modifikasyonlar sonucunda her biri üç numune içeren 6 adet deney seti elde edilmiştir. Farklı parametrelerin modifiye edilmiş numuneler üzerine etkileri yumuşama noktası, penetrasyon, düktilite, dönel viskozimetre deneyleri ile araştırılmıştır ve Cocamide Diethanolamide kimyasalının, bitümü yumuşattığı ve bitümün işleme sıcaklığını düşürdüğü görülmüştür. Katkı oranı arttıkça karıştırma ve sıkıştırma sıcaklıklarında görülen düşüş hem ekonomik hem de çevresel olarak fayda sağlamaktadır. In this study, the usage of Cocamide Diethanolamide chemical for bitumen modification were investigated. When selecting Cocamide Diethanolamide chemical as the additive material, it has been effective that the properties such as behavior, chemical structure depending on the temperature between chemical and bitumen are similar. In addition, the usage of Cocamide Diethanolamide chemical for the first time in bitumen modification makes this study distinctive. Modification of bitumen with chemical was achieved more than once at the 1%, 3% and 5% additive ratios, 155 °C and 165 °C modification temperatures, using a mixing speed of 1000 rpm for 30, 60, 90 minutes. As a result of these modifications, 6 testing sets, each of them contains three sample, were obtained. The effects of different parameters on modified samples were investigated by softening point, penetration, ductility, rotational viscometer tests and it has been observed that Cocamide Diethanolamide chemical softens bitumen and lowers the processing temperature of bitumen. As the additive ratio increases, the decrease in mixing and compaction temperatures is beneficial both economically and environmentally.

In this study, effect of aggregate specific gravity, which is directly related to origin of aggregates used in hot mix asphalt on optimum bitumen content, indirect tensile strength and tensile strength ratio of hot mix asphalt, was investigated. Specific gravity (SG) values of one kind of limestone aggregate were calculated according to Turkish Standard (TS), American Society for Testing and Materials (ASTM) and American Association of State Highway and Transportation Officials (AASHTO) standards, separately. Although one kind of limestone aggregate and 50/70 penetration grade bitumen are used in the mixtures, different values were obtained in terms of optimum bitumen content, indirect tensile strength and moisture sensitivity due to differences in the specific gravity values of the aggregates. Optimum bitumen contents were found by using TS, ASTM and AASHTO standards as 5.03%, 4.75% and 4.59%, respectively. According to the cost – benefit analysis, it can be said that changes in aggregate specific gravity values, which were calculated, based on different standards provide economic benefit. Overall, the results indicated that specific gravity values of one kind of limestone aggregate used in hot mix asphalt have significantly affected optimum bitumen content and indirect tensile strength of the mixtures.