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Demolishing and construction waste materials create from buildings debris cause an environmental and economical problems in developing countries. The current study represents a practical research about feasibility of utilizing recycled concrete aggregate(RCA) in the binder course of hot mix asphalt (HMA) as a partial substitute of coarse and fine a...
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A perforation model is developed to predict the attitude deflection in the oblique perforation of concrete targets by a rigid projectile, in which the inertial moment of the projectile is introduced, together with taking the attitude deflection during the shear plugging sub-stage into account, and the shape of the plug formed on the rear surface of...
Citations
... Fatemi and Imaninasab (2016) investigated the use of RA in improving rutting resistance and found that the use of 30% RA provides sufficient resistance among all replacement percentages used. Mahmoud et al. (2018) found that a mixture with 50% RCA at higher temperatures improved rutting resistance. Ebrahim Abu El-Maaty Behiry (2013) conducted a study to assess the practicality of using RCA in addition to traditional limestone aggregate. ...
Cement Treated Base (CTB), when used in base course, has shown better performance against rutting than conventional base materials. This study focuses on the use of recycled coarse aggregates (RCA) as partial replacement of natural coarse aggregates (NCA) in CTB and hot mix asphalt (HMA) layers of flexible pavements. 30% NCA were replaced with RCA to study the rutting performance of flexible pavements by using 100 mm thick rutting samples prepared with 50 mm thick layers of CTB and HMA each. Four types of specimens with 100% NCA, 30% RCA and 70% NCA in CTB only, 30% RCA and 70% NCA in HMA only, and 30% RCA and 70% NCA in both CTB and HMA were used. Specimens were tested at 40°C, 50°C, and 60°C at a constant number of 10,000 passes (5,000 load cycles). It was concluded that the CTB has a significant impact on the overall rutting performance of the samples due to its rigidity. Use of 30% RCA as a replacement of NCA was found to be acceptable, except for pavements with RCA in both layers. A statistical model was also developed and predicted responses from the proposed relationship were in close agreement with the experimental results.
... As depicted in Table 9, all asphalt mixtures satisfied the standard requirement in terms of rut depth. Mahmoud, Shubber and Jabur [59] asserted that the rut depth decreased when waste aggregates replacement was increased at 60°C. At 45°C, the rut depth was increased with increment of waste aggregates replacement. ...
... As depicted in Table 9, all asphalt mixtures satisfied the standard requirement in terms of rut depth. Mahmoud, Shubber and Jabur [59] asserted that the rut depth decreased when waste aggregates replacement was increased at 60°C. At 45°C, the rut depth was increased with increment of waste aggregates replacement. ...
The palm oil industry has been projected to increase annually, hence resulting in a large number of waste materials being dumped into landfills. In order to decrease the adverse effects of these wastes on the environment, they may be used to substitute conventional aggregates in building roadway pavements. Having that said, this study assessed the effect of using palm oil clinker (POC) as a substitute to fine aggregate on the mechanical properties of SMA mixtures. A range of asphalt mixtures were prepared by replacing the fine aggregate with different POC contents (0%, 20%, 40%, 60%, 80%, and 100%). Additionally, 50% of palm oil fuel ash (POFA) was used as filler in the asphalt mixtures. Resilient modulus, wheel tracking, dynamic creep, indirect tensile strength, and Cantabro durability tests were conducted on all the prepared asphalt mixtures. The results signified the suitability of POC for 100% substitution of fine aggregate in SMA mixture, as it enhanced resilient modulus, resistance to rutting, tensile strength, and resistance to moisture damage. Conclusively, SMA20 mixture between 40% and 60% displayed better mechanical properties, when compared to other mixtures.
... Lime produces pozzolanic reactions that may resume for years and as a result, there will be a continued increase in strength and stiffness. Also, lime has a good impact on earthworks cost [17,20,[22][23][24][25][26]. The best stabilization methods will be the ones with the smallest ...
Some natural resources such as gravel are not renewable, therefore, it is necessary
to reduce the use of such resources and replace them with other recycled,
economic, and environmentally friendly materials. Recycled crushed concrete
aggregates demolished from old buildings can be used to replace natural
aggregates. There are hundreds and thousands of tons of concrete blocks used as
fences and now considered as wastes after removing these security fences, so it’s
important to recycle these materials and use them in the improvement of a wide
range of soft soils. The present study focuses on using recycled crushed concrete
in the improvement of the chemical and geotechnical properties of soft soils
having undrained shear strength of 6.78 kPa, field density of 1.71 g/cm3,
and
natural water content of 16.5 %. The soft soil samples were mixed with 5, 10, 15,
20, and 30% of crushed concrete. Such aggregates are lighter than natural
aggregates and provide a good deformation modulus. The results of tests showed
an increase in the undrained shear strength of the soft soil by 40-145% and a
reduction in the compressibility of the soft soil, where the compression index
decreased by 25-47%. Also, mixing the soft clay with crushed concrete causes
increasing the sulfate content and alkalinity of the soil.
... Mahmoud et al (2018) use different percentages of RCA (0, 10, 20, 30, 40, 50, 60, 70 and 80) % from the weight of total mix were mixed with pure crushed aggregates and compacted using superpave mix design process to produce hot mix asphalt specimen to find the optimum asphalt content for these ratios. The results indicated that O.A.C of waste concrete aggregate is much higher compared with that of pure crushed aggregates and increased with increasing of RCA content in the mixtures due to greater porosity of waste concrete and higher attached mortars on the surface of the crushed concretes [23]. ...
The distress of moisture induced damage in flexible pavement received tremendous attention over the past decades. The harmful effects of this distress expand the deterioration of other known distresses such as rutting and fatigue cracking. This paper focused on the efficiency of using the waste material of demolished concrete to prepare asphalt mixtures that can withstand the effect of moisture in the pavement. For this purpose, different percentages of waste demolished concrete (0, 10, 20, 30, 50, 70 and 100) were embedded as a replacement for coarse aggregate to construct the base course. The optimum asphalt contents were determined depending on the Marshall method. Then after, two parameters were founded to evaluate the moisture susceptibility, namely: the tensile strength ratio (TSR) and the index of retained strength (IRS). To achieve this, the indirect tensile strength test and the compressive test were performed on different fabricated specimens. The results show that mixtures with a higher percentage of demolished concrete possess higher optimum asphalt content as this parameter increased from 3.9 % for control mixture to 4.5 % for mixture with coarse aggregate that fully replaced by demolished concrete. This work indicated that optimum percent of waste demolished concrete that can be utilized in the asphalt mixtures is 30 %, whereas this percent recorded higher value of increased increments for TSR and IRS by 10.6 % and 7.9 % respectively.
