Julide Oner

Utilization of Recycled Asphalt Concrete with Warm Mix Asphalt and Cost-Benefit Analysis

The asphalt paving industries are faced with two major problems. These two important challenges are generated with an increase in demand for environmentally friendly paving mixtures and the problem of rapidly rising raw materials. Recycling of reclaimed asphalt pavement (RAP) is a critical necessity to save precious aggregates and reduce the use of costly bitumen. Warm Mix Asphalt (WMA) technology provides not only the option of recycling asphalt pavement at a lower temperature than the temperature maintained in hot mixtures but also encourages the utilization of RAP and therefore saves energy and money. This paper describes the feasibility of utilizing three different WMA additives (organic, chemical and water containing) at recommended contents with different percentages of RAP. The mechanical properties and cost-benefit analysis of WMA containing RAP have been performed and compared with WMA without RAP. The results indicated that, 30%, 10% and 20% can be accepted as an optimum RAP addition related to organic, chemical and water containing additives respectively and organic additive with 30% RAP content has an appreciable increase in tensile strength over the control mix. It was also concluded that the RAP with WMA technology is the ability to reduce final cost compared to HMA and WMA mixtures.

Investigation of the rheological properties of elastomeric polymer-modified bitumen using warm-mix asphalt additives

In recent years, warm-mix asphalt (WMA) is extensively used in the hot-mix asphalt industry for reducing energy requirements and emissions by lowering mixing and compaction temperatures of bitumen. In addition, the use of polymer-modified bitumen (PMB) has become a very important part of pavement construction due to its superior performance, including less ageing, enhanced rutting resistance and lower fatigue cracking properties. This paper presents an experimental evaluation of elastomeric PMB involving WMA additives. In scope of the study, base bitumen has been modified with three different concentrations of styrene–butadiene–styrene (SBS) copolymer. The prepared PMB samples have been mixed with organic and chemical types WMA additives. Following the determination of the conventional properties as well as the rheological properties of the samples using dynamic shear rheometer, rutting behaviour of bitumen samples has been evaluated by zero shear viscosity test. The results of conventional bitumen tests showed a decrease in temperature susceptibility in PMB involving WMA additives. Based on the rheological test results, it was observed that the utilisation of organic WMA additive into PMB improves rutting performance of the modified bitumen especially in the 4% concentration of SBS copolymer.

Investigation of rheological effects of waxes on different bitumen sources

Wax in bitumen has been referred to as petroleum wax and is obtained from refining of paraffinic crude oils. The effects of wax on bitumen properties depend on the following factors: the source, chemical composition and rheology of the bitumen as well as the content, type, composition and crystallisation of the wax. There is a lack of literature reviews related to the effect of waxes on the rheology and properties of bitumen. The scope of this study is to evaluate the rheological properties of waxy bitumens obtained from different sources. Following the determination of wax contents by differential scanning calorimetry (DSC) and EN 12606-1, waxy bitumen properties were evaluated using conventional methods, rotational viscosity, dynamic shear rheometer (DSR) and bending beam rheometer (BBR) tests. The intermediate and high-temperature performances levels of bitumen were also determined according to the Superpave system by a DSR test performed on aged and unaged samples. Rutting performance of bitumens has been evaluated using zero shear viscosity (ZSV) and multiple stress creep recovery (MSCR) tests.

Organik Ilık Karışım Asfalt Katkı Maddesinin Bitümlü Karışımların Yaşlanma Özellikleri Üzerine Etkilerinin İncelenmesi

Son yillarda arastirmacilar, bitumlu sicak karisim asfaltin yerini alacak benzer veya tercihen daha yuksek performansli, uretim maliyetlerini azaltan, dogal kaynaklari koruyan, cevreye daha az zararli ve uygulamada daha verimli bitumlu karisimlar elde etme yolunda calismalar yurutmektedirler. Ilik karisim asfalt sistemlerinin kullanimi ile asfalt numunelerinin karistirma ve sikistirma derecelerinde fark edilebilir dusus gozlenmektedir. Uygulama sicakliklarindaki belirgin dususlerin, asfalt kaplamalarda meydana gelebilecek yaslanmadan kaynaklanan bozulmalari azaltacagi ongorulmektedir. Bu calismada, organik ilik karisim asfalt katki maddesinin bitumlu karisimlarin yaslanma ozellikleri uzerine etkileri arastirilmistir. Cesitli oranlarda organik ilik karisim asfalt katki maddesi iceren bitum ile hazirlanan asfalt karisimlari ve kontrol karisimlari; kisa donem ve uzun donem yaslanmaya tabi tutulduktan sonra yaslanma oranlari ve yaslanma indeksleri, indirekt cekme mukavemeti deneyleri ile belirlenmistir. Deney sonuclari, bitumlu sicak karisimlara kiyasla organik katki iceren ilik karisim asfalt numunelerinin yaslanmaya karsi daha direncli oldugunu gostermektedir. In recent years, researchers have been conducting studies in order to discover new alternative technologies for hot mix asphalts. These new technologies are expected to be higher in performance, lower in costs, sustainable over natural resources, environmentally friendly and easy to apply. With utilization of warm mix asphalt technologies, it is possible to decrease mixing and compaction temperatures of asphalt applications. In warm mix asphalt pavements, it is expected that ageing induced failures be less than hot mix asphalt pavements due to lower application temperatures. Within the scope of this study, the effects of an organic warm mix asphalt additive over ageing characteristics of bituminous mixtures have been investigated. In order to estimate the proportion of hardening of warm mix asphalt specimens containing different contents of organic additive and control specimens with no additive content, all specimens have been subjected to short- and long-term ageing. Afterwards, ageing indices have been calculated considering the ratio of indirect tensile strength values of both short- and long-term aged specimens over un-aged specimens. The results show that the aging indices of specimens containing organic warm mix asphalt additive are rather less than the indices of hot mix asphalt specimens. Anahtar kelimeler: Ilik karisim asfalt, Organik katki, Kisa donem yaslanma, Uzun donem yaslanma, Indirekt cekme mukavemeti.

Effect of polymers on rheological properties of waxy bitumens

DOI: 10.7764/RDLC.17.2.279 The definition of bitumen wax has been formulated to facilitate the distinction between harmful wax and less harmful or non-harmful. Since exact behaviour of waxes within bitumens is not completely determined and the absence of cooperative study related to modification of bitumens involving different amounts of waxes, the values found in the study are thought to be useful in determining which content of wax and type of polymer would be better for the needs of petroleum refineries in different countries. The scope of this study is to minimize the negative effects of waxes within bitumens obtained from different sources. For this purpose, modified bitumen samples were prepared by using different types of polymers such as elastomers, plastomers and polyethylene groups. Following the determination of the contents of wax by Differential Scanning Calorimetry and TS EN 12606-1, rheological properties of waxy bitumens and polymer modified bitumens (PMB) were evaluated using dynamic shear rheometer tests. The intermediate temperature performance levels of PMB were also determined by fatigue parameters. Besides, rutting performance of PMB was evaluated using Zero Shear Viscosity and Multiple Stress Creep Recovery tests.

Permanent deformation characteristics of warm mix asphalt

Warm Mix Asphalt (WMA) is a technology that allows lowering the production and paving temperature compared to Hot Mix Asphalt (HMA). The reduction of temperature enables various benefits over asphalt mixtures such as decreasing greenhouse gas emissions, lowering energy consumption, fuel cost saving, improved workability and easy compaction. Besides, WMA technology gives an option to use Recycled Asphalt Pavement (RAP) that provides a very economic method and eco-friendly pavements. The objective of this study was to evaluate the utilization of organic and chemical WMA additives with different percentages of RAP. Following the determination of optimum RAP contents corresponding to each WMA additive Hamburg Wheel Tracking Test is performed to obtain the permanent deformation characteristics of mixtures containing optimum RAP contents.

Evaluation of rheological effects of waxes on bitumen from different sources

Bitumen is adhesive that originates from crude oil and is temperature dependent material including hydrocarbon molecules. Paraffinic crude oils may provide bitumen of good quality or yield bitumen which is not suitable for pavement performance. Wax in bitumen has been referred to as petroleum wax and is obtained from refining of paraffinic crude oils. The effects of wax on bitumen properties depend on the following factors; the source, chemical composition and rheology of the bitumen as well as the content, type, composition and crystallization of the wax. Although high wax contents have been considered as a negative effect on the quality of the bitumen, there is no common agreement among the scientists regarding the effect on bitumen rheology and asphalt performance. The scope of this study is to evaluate the rheological properties of waxy bitumens obtained from different sources. Following the determination of wax contents by DSC (Differential Scanning Calorimetry) and EN 12606-1, waxy bitumens properties were evaluated using dynamic shear rheometer (DSR) and various conventional methods such as softening point, penetration, viscosity, and ductility. The high temperature performance levels of bitumen were also determined according to Superpave system by dynamic shear rheometer (DSR) test on samples before and after aging processes. Besides, bending beam rheometer (BBR) test has been conducted to investigate the lower critical temperatures of bitumens. Rutting performance of bitumens has also been evaluated using Zero Shear Viscosity (ZSV) and Multiple Stress Creep Recovery (MSCR) tests performed in creep mode.