Volkan Emre Uz

Artificial neural networks–based backcalculation of the structural properties of a typical flexible pavement

Pavement evaluation is one of the foremost phases in all pavement engineering activities. In the backcalculation process, the researcher or the engineer varies the structural properties of the layers until the theoretical (calculated) deflections and the obtained (measured) deflections from FWD tests are closely matched to each other within a tolerable limit. However, this process is substantially time-consuming and poses some difficulties due to inherent inaccuracies in the results. In this study, synthetically derived deflections from a typical flexible pavement are used to estimate asphaltic concrete layer’s elastic modulus, Poisson’s ratio and thickness. Furthermore, artificial neural network (ANN) is utilized to determine the structural parameters, and it can be clearly seen that satisfactory results are obtained. ANN estimation of the three pavement layer characteristic parameters, that is, layer elastic modulus, Poisson’s ratio and layer thickness, was carried out for the first time in the study.

Use of glass waste as mineral filler in hot mix asphalt

Abstract The use of resources is increasing due to continuous increase in world population and rapid industrialization, while natural resources are being exhausted day by day. Usage of waste materials or by-products in highway construction has substantial environmental and economic benefits. In this study, the usage of cullet and waste glass bottle dust as mineral filler material in hot mix asphalt as an alternate to traditional crushed stone dust was investigated. Optimum bitumen content was determined by the Marshall mix design method by using six different bitumen contents (4.0%, 4.5%, 5.0%, 5.5%, 6.0%, and 6.5%). With the optimum bitumen content, three different mineral filler types (cullet, glass bottle waste, and stone dust) and six different filler ratios (4%, 5%, 6%, 7%, 8%, and 9%) were used to prepare asphalt mixture samples. Samples were performed using the Marshall stability test, and the results were compared. It is concluded that cullet and glass bottle waste can be used in asphalt mixtures as a mineral filler alternate to crushed stone dust if the economic and environmental factors favor it.

Investigation of chip seal performance under cold climate conditions

Abstract The chip seal is an economical type of asphalt pavement that was constructed for single- or double-layer aggregate-bitumen. Chip seals are applied to prime-sealed granular pavement surfaces in order to waterproof the surfaces of sub-layers, produce smooth and high-skid-resistance surfaces for vehicles and protect pavements against the detrimental effects of traffic and climate. Unlike bituminous hot mixtures, numerous factors can affect the performance of chip seal. One of the most important factors is climate. The aim of this study is to determine the performance variation of chip-sealed pavements under cold climate conditions. Three different chip-sealed roads in Erzurum, which is in one of the coldest regions of Turkey, were examined with non-destructive tests. Sand-patch, British pendulum, light weight deflectometer and dynamic cone penetrometer tests were performed. Chip-sealed pavements’ densities and surface temperature variation and base courses layer’s thicknesses were also measured, and deteriorations were observed and scored by researchers. Test results showed that flushing due to the higher temperatures during the short summer season, deficiency of the base course’s bearing capacity and moisture in the base course are the most important causes of deterioration in this type of chip seal, and the chip seals in this region must be resealed in <1 year because of the premature deterioration.

Pürüzlendirme Uygulamasının Kaplama Yüzeyi Makro Dokusu Üzerine Olan Etkisinin Araştırılması / Investigation of the Effect of Gritting Application on Pavement Surface Macro Texture

Turkiye Karayollari Teknik Şartnamesi (KTŞ), tas mastik asfalt (TMA) ve asfalt betonu (AB) tabakalarinda yuksek cilalanma direncine sahip (PSV≥50) agregalarin kullanilmasini zorunlu kilmistir. 2013 yilinda, KTŞ’de yuksek cilalanma direncine sahip agregalarin temininde yasanan zorluklardan dolayi belirli bolgeler icin ayricalik taninmis ve yukarida belirtilen kaplama tabakalarin insaatinda PSV≥40 degerine sahip agregalarin kullanimina izin vermistir. Ancak bu durumda, 1-3 mm boyutuna sahip magmatik agregalar ile kaplama uzerinde yuksek kayma direncine sahip yuzey elde etmek icin puruzlendirme uygulama yapilmasi zorunlu tutulmustur. Bu uygulamada, puruzlendirme malzemesi 1,5-2 kg/m 2 olacak sekilde sicak karisim uzerine birinci ve ikinci silindiraj arasinda uygulanilmasi istenmistir. Ancak, KTŞ’de farkli yuzey dokularina sahip TMA ve AB kaplama tabakalari icin de ayni uygulama onerilmektedir. Bu calismada, farkli oranlarda serpme miktarinin (1,75, 2,50 kg/m 2 ) ve agrega boyutunun (1-3, 2-5 mm) kaplama makro dokusuna olan etkisi arastirilmistir. Dere malzemesi ve metal curufu gibi farkli agrega turlerinin kullanilabilirligi de ayrica incelenmistir. Tum agregalarin ozelikleri belirlenmis ve KTŞ limitleri ile karsilastirilmistir. TMA ve AB yuzey dokusunu temsilen, Tip-II ve Tip-III harc tipi kaplamalar kullanilmistir. Sonuc olarak, puruzlendirme uygulamasinin kaplama makro dokusunda belirgin degisiklere yol actigi ve bu degisim oraninin kullanilan agrega turune, uygulama miktarina ve boyutuna bagli olarak farklilik gosterdigi gorulmustur.