Necati Kuloğlu

Effects of two-phase mixing method on mechanical properties of hot mix asphalt

ABSTRACT In this research, in order to improve the mechanical properties of hot mix asphalt, the mixing method was considered. The new method is mainly based on precoating the coarse aggregate with an appropriate amount of optimum binder content. Then the coated coarse aggregate was mixed with fine aggregate + filler and remaining optimum asphalt content. Three types of asphalt cement AC-5, AC-10 and AC-20 was used as binder. To investigate the effectiveness of two-phase mixing method on modified mixtures, the styrene-butadiene-styrene (SBS, Kraton D 1101) modified AC-10 was also used. Basalt was used as aggregate. In conclusion, two-phase mixing method increased the Marshall Quotient, stiffness, creep stiffness, fatigue life and decreased the moisture-induced damage of the hot mix asphalt. It was determined that the efficiency of two-phase mixing system on modified mixtures was greater than that of the unmodified mixtures. A mixing plant for two-phase mixing method was designed to manufacture hot mix asphalt.

Investigation of Mechanical Properties of Short- and Long-Term Aged Asphaltite Modified Asphalt Mixtures

AbstractIn this study, the effects of asphaltite and long-term aging (LTA) on the mechanical properties of hot-mix asphalt were investigated. The asphaltite entrained as filler at five different proportions into the hot-mix asphalt samples, and the obtained results were compared against the control mixtures. The pure and asphaltite-containing compacted mixtures were exposed to LTA in an oven. Marshall stability, resistance to moisture-induced damage, and resistance to crack propagation tests in accordance with the principles of elastic-plastic fracture and linear-elastic fracture mechanics were carried out on the mixtures. It was determined that the optimal proportion of asphaltite usage as filler with respect to volumetric design is 3% by weight. The test results demonstrated that asphaltite use enhances resistance against permanent deformation, moisture-induced damage, and crack propagation, especially at normal temperatures, albeit at the cost of causing the hot-mix asphalt to exhibit a more brittle be...

Evaluation of the mechanical properties of natural asphalt-modified hot mixture

Abstract The objective of this study is to evaluate the usage of natural asphalt in hot mix asphalt by means of determining the Marshall stability, stiffness modulus, indirect tensile strength, and dynamic creep tests. Natural asphalt, which consists of 17% asphalt fraction and 83% mineral fraction, was obtained from Syrian. The optimum bitumen content was determined to be 1% lower for natural asphalt-modified mixtures compared to control mixtures. The stiffness modulus values of the natural asphalt-modified mixtures were higher than those of the control mixtures. The moisture susceptibility of natural asphalt-modified mixtures and control mixtures were evaluated during different freeze–thaw cycles. The natural asphalt-modified mixtures were not as susceptible as control mixtures to moisture damage. Adding natural asphalt to mixtures remarkably decreased susceptibility to permanent deformation. The results presented here demonstrate the positive effects of using natural asphalt.