Undoubtedly, rutting in asphalt concrete pavement is considered a major dilemma in terms of pavement performance and safety faced by road users as well as the road authorities. Rutting is a bowl-shaped depression in the wheel paths that develop gradually with the increasing number of load applications. Heavy axle loadings besides the high pavement summer temperature enhance the problem of rutting. According to the AASHTO design equation for flexible pavements, a 1.1 in rut depth will reduce the present serviceability index of relatively new pavement, having no other distress, from 4.2 to 2.5. With this amount of drop in serviceability, the entire life of the pavement in effect has been lost. Therefore, it is crucial to look at the mechanism, possible reasons, as well as techniques, to reduce the rutting in order to offer long service life and safe roadways. To this end, the need has been arising for this research which deals mainly with a thorough review of the existing literature to highlight some key points for the researchers and pavement engineers related to rutting mechanism, measurement, and criteria, both intrinsic (mixture variables) and extrinsic (traffic and temperature) contributory factors to rutting, material characterization, test methods, and prediction methodologies, as well as possible ways to minimize the rutting distress in asphalt concrete pavement. So far, this research attempts to bridge the gap in the literature that frequently only addresses a single aspect of rutting by providing an in-depth review of rutting in asphalt concrete and thereby offers a complete comprehensive understanding of this major distress type.
The local asphalt concrete fracture properties represented by the fracture energy, J-integral, and stress intensity factor are calculated from the results of the three point bending beam test made for pre notches beams specimens with deformation rate of 1.27 mm/min. The results revealed that the stress intensity factor has increased by more than 40% when decreasing the testing temperature 10˚C and increasing the notch depth from 5 to 30mm. The change of asphalt type and content have a limited effect of less than 6%.
Roller Compacted Concrete (RCC) is a technology characterized mainly by the use of rollers for compaction; this technology achieves significant time and cost savings in the construction of dams and roads. The primary scope of this research is to study the durability and performance of roller compacted concrete that was constructed in the laboratory using roller compactor manufactured in local market. A total of (60) slab specimen of (38×38×10) cm was constructed using the roller device, cured for 28 days, then 180 sawed cubes and 180 beams are obtained from RCC slab. Then, the specimens are subjected to 60 cycles of freezing and thawing, sulfate attack test and wetting and drying. The degree of effect of the type of coarse aggregate (c
... Show MoreThis study presented more than twenty books that dealt with the subject of (Weights of the Tawshih art), whether their study was independent and dedicated the art of Tawshih as a part of book. Therefore, the review of the sources and references on the art of the Tawshih is not specific for place or time, it was a broad and comprehensive review of all the places where the muwashahat appeared in the east and west, Andalusia was one of the most important areas covered by the study arbic Maghreb and Iraq. The art of tawshih took different forms according to the countries in which they appeared. Muwashahat is a new art that appeared in Andalusia, its main goal was to renew the Khalilian weights and to find the poetic rhythm that fits with the so
... Show MoreObjective: To review and see the pattern of histopathological diagnoses of one year appendectomy specimens.
Methodology: This retrospective study was carried in Sulaimani Teaching Hospital over the period of one year (from 1st
of January to 31st of December 2009). All pathological reports were reviewed retrospectively for patient’s age, sex,
histopathological diagnosis and operative findings (if present). Histopathological diagnoses then were classified into
either positive or negative for acute inflammation. Any associated findings or any surgical specimen removed with the
appendix was recorded. The obtained data were analyzed by using the statistical package social sciences (SPSS) version
19; with Chi square to test
Failure in asphalt mixture and distress in pavement are major issues to roads infrastructure. Selecting an appropriate chemical composition of asphalt cement is a key component in avoiding these issues. This work aimed to investigate the effect of the chemical composition of different polar fractions on the rheological and physical properties of asphalt cement. Four types of asphalt cement with penetration grades of 20/30, 40/50, 60/70 and 85/100 were divided into four fractions. Complex shear modules, rutting resistance and rotational viscosity of the asphalt cement were determined by using a Dynamic Shear Rheometer and a Rotation Viscometer, respectively. The results show that an increase in the asphaltene content and Gastel index resulte
... Show MoreReactive Powder Concrete (RPC) can be incorporate as a one of the most important and progressive concrete technology. It is a special type of ultra-high strength concrete (UHSC) that’s exclude the coarse aggregate from its constitutive materials. In this research an experimental study had been carried out to investigate the effect of using three types of materials (porcelain aggregate) and others sustainable materials (glass waste and granular activated carbon) as a partial replacement of fine aggregate. Four percentages had considered (0, 10, 15 and 20) % to achieve better understanding for the influence of these materials upon the compressive strength of RPC. Four curing ages had included in this study, these are; 7, 28, 60 and
... Show MoreReactive Powder Concrete (RPC) can be incorporate as a one of the most important and progressive concrete technology. It is a special type of ultra-high strength concrete (UHSC) that’s exclude the coarse aggregate from its constitutive materials. In this research an experimental study had been carried out to investigate the effect of using three types of materials (porcelain aggregate) and others sustainable materials (glass waste and granular activated carbon) as a partial replacement of fine aggregate. Four percentages had considered (0, 10, 15 and 20) % to achieve better understanding for the influence of these materials upon the compressive strength of RPC. Four curing ages had included in this study, these are; 7, 28, 60 and
... Show MoreThroughout Agriculture has mostly relied on the use of natural fertilizers throughout human history, which are compounds that increase the nitrogen levels in the soil. Modern agriculture was made possible by the introduction of synthetic fertilizers at the end of the 19th centuryproduction of agriculture. Their application enhanced crop yields and sparked an agricultural revolution unlike anything the world had ever seen.In the near future, synthetic fertilizers are anticipated to continue to have a significant impa ct on human life, both positively and negatively. They are frequently utilized for producing all t ypes of crops and are essential to plant growth. The significance of synthetic fertilizers is their ability to provide the soil w
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