Papers by Hasan Taherkhani
International Journal of Environmental Science and Development, 2015
Construction industry is among the major contributor to the production of solid wastes, which hav... more Construction industry is among the major contributor to the production of solid wastes, which have become a main problem of societies in present days. Asphalt and cement concrete are among the main engineering materials which are wasted in vast quantities every year due to the reconstruction and demolition of highways and buildings. Recycling of these materials would be an efficient measure for protection of environment and preservation of natural resources. In this research, the viability of using crushed waste asphalt and cement concrete as a replacement of primary aggregate in unbound base layer of flexible pavements has been investigated. Different portions of the natural aggregate have been replaced with the recycled materials and the physical properties of each mixture have been investigated. The physical properties including sand equivalent, toughness, water absorption, density, soundness and compaction have been evaluated for the mixtures. The results show that, they have potential to be used in unbound base layer. Inclusion of any amount of recycled cement concrete in unbound aggregate results in a mixture which satisfy the minimum required sand equivalent, toughness and soundness for unbound base.
Civil engineering infrastructures journal, 2018
This study has investigated the creep properties of asphaltic concrete modified with different do... more This study has investigated the creep properties of asphaltic concrete modified with different dosages of waste polyethylene terephthalate (PET) in two different ranges of size. Uniaxial dynamic creep test at 40°C was conducted on the cylindrical specimens of the mixtures. The load was applied in two different frequencies of 0.5 and 5Hz. Creep test results showed that the accumulated strain under dynamic loading increased with increasing PET content, with lower values for the mixtures containing finer PET particles. Moreover, it was found that the accumulated strain under the loading with higher frequency was more than that under lower frequency, with higher sensitivity to frequency for the mixtures containing finer PET. The results of dynamic creep tests were used for determination of the constants of a three stage model. The linear creep slope in the second region of the creep curve and the flow number showed that the increase of PET content and size results in decrease of permane...
Iranian Journal of Science and Technology, Transactions of Civil Engineering, 2020
In this research, the permanent deformation property of asphalt concrete containing different per... more In this research, the permanent deformation property of asphalt concrete containing different percentages of recycled asphalt pavement (RAP) and dosages of waste engine and cooking oil has been investigated using response surface methodology (RSM). 25, 50 and 75% of total aggregates have been replaced with RAP, and each rejuvenated with 5, 10 and 15% (by the weight of total binder) of waste engine oil (WEO) and waste cooking oil (WCO). Experiments were designed using composite central design method in RSM, and the permanent strain accumulated after applying 1000 cycles of 300 kPa vertical stress at a frequency of 1 Hz and temperature of 40 °C was measured. Using RSM in Design Expert program, a polynomial quadratic model was found to be capable for predicting the permanent strain. It was found that the significant terms for prediction of permanent strain are RAP and oil content, the squared oil content and type of oil. Results reveal that permanent strain decreases with increasing RAP content; however, for each RAP content, the lowest permanent strain is achieved at a certain level of oil content. At the same dosage of use, WEO results in lower strain than WCO. Interaction effect was found between RAP content and oil type, such that the decrease of strain with RAP content is higher with WCO than WEO. Using optimization in RSM, the content of oils to achieve a mixture with similar deformation property of control mix was obtained.
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Papers by Hasan Taherkhani