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Models based on kinetic, thermodynamic and rheological equations have been developed to compute dispersion extent, batch temperature and relative batch viscosity at discrete intervals during a mix cycle in an internal mixer. The calculated relative bulk viscosity can be linked empirically to a measured variable such as rotor torque or power consumption. Solution of the models over successive time intervals allows the computation of complete dispersion, temperature, and torque/power profiles for a mix cycle. The mix models exhibit good fits to experimental torque and temperature curves for mixing natural rubber with carbon black over a wide range of carbon black loadings (0 to 50 phr) for rotor speeds ranging from 40 to 70 RPM in two lab‐scale internal mixers. The models are shown to be suitable for moderately reinforcing (ASTM N660) as well as highly reinforcing (ASTM N121) grades of carbon black. Rate constants for filler dispersion, incorporation and erosion can be extracted from the models and can be interpolated to generate dispersion, temperature and torque curves at new conditions of carbon black loading and rotor speed. The mix models could thus be used for process‐control purposes and for specifying drop targets based on batch properties in addition to the time‐temperature‐energy criteria typically used today. Polym. Eng. Sci. 44:1247–1257, 2004. © 2004 Society of Plastics Engineers.

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Aggregates are one of the most important raw materials used in the construction industry. It is almost impossible to create a structure without using aggregates. The worldwide mining industry generates 16·5 billion tons of aggregates annually. An increase in domestic and industrial areas limits the regional aggregate resources, and highlights the need to find new sources of aggregate. Difficulties in using regional resources force aggregate suppliers to transport aggregate over long distances, resulting in additional time and expense, as well as rapid deterioration of highway infrastructures. Thus, it is vitally important to use available aggregate resources effectively and to find new environmentally friendly potential aggregate resources to meet the increasing demand. Therefore, aggregate samples taken from two different aggregate resources in the Afyonkarahisar–Seydiler region of Turkey were examined. In order to determine the physical properties of crushed aggregate samples, standard tests were carried out to evaluate whether the volcanic aggregate samples were suitable to use in bituminous pavement layers. In the present study, four different aggregate samples were used: volcanic aggregate 1 (V1), volcanic aggregate 2 (V2), limestone 1 (L1) and limestone 2 (L2). The V1 and V2 samples were volcanic rocks taken from the Tekerek and Kepez areas, respectively. These samples had trachy-andesite composition based on their geochemical and petrographical observations. The L1 and L2 samples were provided from quarries in the Karacaoglan and Cobanlar areas, respectively. Both L1 and L2 samples have been currently used in hot-mix asphalt pavements. The test results indicate that the sample V1 made of volcanic aggregates displayed adequate performance on a wearing course with heavy traffic. Sample V2 did not display enough deformation resistance as a bituminous mix; however, it could be used for surface courses because of its good friction properties.

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During the manufacture of compounds in the boron mining industry a large quantity of waste boron is produced which has detrimental effects on the environment. Large areas have to be allocated for the disposal of this waste. Today with an increase in infrastructure construction, more efficient use of the existing sources of raw materials has become an obligation and this involves the recycling of various waste materials. Road construction requires a significant amount of raw materials and it is possible that substantial amounts of boron-containing waste materials can be recycled in these applications. This study investigates the usability of boron wastes as filler in asphalt concrete. For this purpose, asphalt concrete samples were produced using mineral fillers containing 4%, 5%, 6%, 7% and 8% boron waste as well as a 6% limestone filler (6%L) as the control sample. The Marshall design, mechanical immersion and Marshall stability test after a freeze-thaw cycle and indirect tensile stiffness modulus (ITSM) test were performed for each of the series. The results of this experimental study showed that boron waste can be used in medium and low trafficked asphalt concrete pavements wearing courses as filler.