Recently, the use of plastic in many products has led to a huge amount of plastic waste, which is typically difficult to treat and expensive to recycle. This problem has been considered by many researchers and environmental organizations as requiring serious considerations about recycling and reusing plastic waste in different fields, such as asphalt mixtures. In this paper, aggregate passing a 4.75-mm sieve was replaced by 5, 7, 9, and 11% of plastic bottles used for drinking purposes. The dry method was adopted in this work, and the changes in the mixture’s volumetric properties were investigated using the Marshall method. A repeated indirect tensile load test was also conducted to determine the mixture’s resilient modulus. Marshall’s stability, air voids, unit weight, flow, and voids in mineral aggregates were examined. The results were compared and analyzed with the base sample. It was observed that adding plastic decreased aggregate consumption and reduced the optimum asphalt content (OAC). Additionally, the volumetric properties of the mixture improved and its service life was extended after adding plastic. It was also observed that the value of the resilient modulus (RM) increased when the percentage of added plastic increased as well. Reuse of plastic in asphalt mixtures achieves the concept of an environmentally friendly solution in the transportation area because it reduces the amount of asphalt and aggregates and reduces the costs of recycling plastic. Moreover, the optimal plastic content in this paper was achieved at 11%. Doi: 10.28991/CEJ-2023-09-04-012 Full Text: PDF
The tensile strength of asphalt mixtures is one of the main parameters of deterioration and failure in flexible pavements. Hence, in this study, the effects of reinforcing asphalt mixtures, using polypropylene fibers, on their engineering performance were experimentally investigated. A set of cylindrical specimens of asphalt mixtures was prepared and subjected to a compressive load at different testing temperatures in terms of evaluation of the indirect tensile stiffness modulus. Similarly, fatigue (four-point bending) and crack propagate (three-point bending) tests were conducted for different asphalt mixtures made with and without polypropylene fibres. The impacts of such fibres on the engineering properties of asphalt mixtures were studied. The laboratory results revealed that the reinforced mixtures with polypropylene fibres had a noticeable influence on the tensile, fatigue and cracking initiation and propagation of these mixtures.
This research aims to evaluate the effect of aggregate nominal maximum size and type of filler on Marshall properties of asphalt mixture. A planned laboratory study is implemented by preparing the asphalt samples using locally available materials and an asphalt binder of 40-50 penetration grade (AC-20). Three types of aggregate nominal maximum size according to SCRB specifications and three types of fillers including limestone dust, cement and hydrated lime were used. Three bitumen contents were used led to nine types of mixtures were prepared and tested that includes all the variables studied. The optimum asphalt content of the asphalt mixture was determined to be 4.75%w using the Marshall method of mix design. A total of 81 Marshall specimens were prepared and tested. The results showed that the aggregate nominal maximum size and filler type have a variable effect on Marshall properties while optimum asphalt content has a significant effect on Marshall Properties regardless of other variables in the mixture. Experimental results showed that using cement as a filler material can significantly increase the Marshall Stability compared to that of using hydrated lime and limestone dust.
This study focuses on assessing pedestrian walking characteristics on sidewalks. The fundamental relationships of flow – speed – density were investigated and analysed in Samawah city. The video recording method was implemented to observe pedestrian characteristics such as flow and speed at four survey sites. These data were used to develop mathematical models that figure the aforementioned relationships. To obtain the best fitting of each relationship, the coefficient of determination R2 was calculated. The results of this study were compared with the other research outputs. Finally, the level of service boundaries for pedestrians’ movements on sidewalks were defined.
Recently, the construction industry uses the Recycled Concrete Aggregates (RCA)resulting from construction and demolition waste (CDW) to achieve sustainable requirements andeconomic benefits. In this paper, asphalt paving mixes were prepared with RCA instead of naturalaggregates for the base course in flexible road pavements and walking areas used by pedestrians andcyclists. Different asphalt mixes samples were prepared with different asphalt contents to meet therequired specifications. Additionally, several laboratory tests were carried out to assess mixturebehavior including the Marshall test. The results indicated that the mixture made with aggregates ofCDW have met all the requirements of Iraqi specifications of roads and bridges (SORB/R9). Thisinvestigation could be a useful guide for road engineers in designing asphalt mixtures from RCA.
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