Performance Modification of Asphalt Binders using Thermoplastic Polymers

There is a need to improve the performance of asphalt binders to minimize stress cracking that occurs at low temperatures and plastic deformation at high temperatures. Importation of used asphalt-polymers from abroad, leads to an increase in the total construction cost as compared to the cost if the used polymers were of local origin. The main objective of this research was to modify locally produced asphalt. Ten polymers were identified as potential asphalt modifiers based on their physical properties and chemical composition. After preliminary laboratory evaluation for the melting point of these polymers, five polymers were selected for local asphalt modification. In the initial stage, required mixing time was decided based on the relation between shear loss modulus and mixing time .The optimum polymer content was selected based on Superpave binder performance grade specifications.The suitability of improvement was verified through the evaluation of permanent deformation and fatigue behavior of laboratory prepared asphalt concrete mixes. The results indicated that the rheological properties of the modified binders improved significantly with sufficient polymer content (3%). The aging properties of the modified binders were found to be dependent on the type of polymer.The fatigue life and resistance to permanent deformation were significantly improved due to enhanced binder rheological properties.  Thus, local asphalts can be modified using thermoplastic polymers

Performance Modification of Asphalt Binders using Thermoplastic Polymers

There is a need to improve the performance of asphalt binders to minimize stress cracking that occurs at low temperatures and plastic deformation at high temperatures. Importation of used asphalt-polymers from abroad, leads to an increase in the total construction cost as compared to the cost if the used polymers were of local origin. The main objective of this research was to modify locally produced asphalt. Ten polymers were identified as potential asphalt modifiers based on their physical properties and chemical composition. After preliminary laboratory evaluation for the melting point of these polymers, five polymers were selected for local asphalt modification. In the initial stage, required mixing time was decided based on the relation between shear loss modulus and mixing time .The optimum polymer content was selected based on Superpave binder performance grade specifications.The suitability of improvement was verified through the evaluation of permanent deformation and fatigue behavior of laboratory prepared asphalt concrete mixes. The results indicated that the rheological properties of the modified binders improved significantly with sufficient polymer content (3%). The aging properties of the modified binders were found to be dependent on the type of polymer.The fatigue life and resistance to permanent deformation were significantly improved due to enhanced binder rheological properties.  Thus, local asphalts can be modified using thermoplastic polymers

Evaluation of Waste Engine Oil-Rejuvenated Asphalt Concrete Mixtures with High RAP Content

The use of large proportions of reclaimed asphalt pavement is necessary to meet the increasing demand for road construction materials in a sustainable way. One of the challenges of using a greater percentage of reclaimed asphalt pavement (>30%) is the greater stiffness of mixes incorporating it. While this stiffness problem is usually resolved by using different commercial rejuvenators, there are circumstances in which commercial rejuvenators are not available. Therefore, this study evaluates the potential of using waste engine oil as a substitute for commercial rejuvenators for the higher percentage of reclaimed asphalt pavement that could meet the increasing demand in a more sustainable way. To assess the possibility of using a higher percentage of reclaimed asphalt pavement in road construction, different percentages of reclaimed asphalt pavement (30%, 40%, and 50%) are used. Following the property of the aged binder, three different percentages (7%, 13%, and 20%) of waste engine oil are considered. Each percent of waste engine oil is incorporated with one of the three mixes. The mixes (with the minimum required Marshall criteria) are evaluated for different properties, namely, their indirect tensile strength, resilient modulus, and durability. Finally, those properties are compared to those of the mixes rejuvenated by commercial rejuvenators. It is observed that, for the aforementioned properties, 7% to 13% of waste engine oil is identical to the commercial rejuvenator for the mixes with 30% to 40% of reclaimed asphalt pavement

Comparative Evaluation of Waste Cooking Oil and Waste Engine Oil Rejuvenated Asphalt Concrete Mixtures

In road construction, different types of waste oil have been recommended to overcome the stiffening effect of reclaimed asphalt pavement content. However, the selection of an effective rejuvenator based on a comparative study can lead to using the resources more efficiently. In this study, waste cooking oil and waste engine oil are used to rejuvenate three different percentages (30%, 40%, and 50%) of reclaimed asphalt pavement following the current maximum industrial adaptability. The waste oil rejuvenated mixtures are compared to the fresh mixture, and mixtures rejuvenated with commercial rejuvenator. The moisture sensitivity, indirect tensile strength, and resilient modulus of the various asphalt mixtures are analyzed. Based on the statistical analyses and overall ranking, it is concluded that 7% of waste engine oil performs better till 40% of reclaimed asphalt pavement, whereas 13% of waste cooking oil can be used till 50% of reclaimed asphalt pavement.Other Information Published in: Arabian Journal for Science and Engineering License: https://creativecommons.org/licenses/by/4.0See article on publisher's website: http://dx.doi.org/10.1007/s13369-020-04523-5</p

Conformity of Physical Characteristics of Imported Tires with Government Standards: A Case Study

The Saudi Arabian Standards Organization, SASO, has established a set of tests that all passenger car tires have to pass in order to be allowed into the Country. These tests are: visual inspection, dimension measurement, bead unseating, tensile strength and elongation, aging, endurance, and high speed performance tests. This paper describes the application of the first five tests on eight different brands of tires that are taken to represent the categories of “frequently failed” and “infrequently failed” tires in the country. The results showed that the dimensions of almost all the tested tires were somewhat different from those documented in the SASO standards. On the other hand, all the tested tires passed the bead unseating and strength tests. All tires in the “frequently failed” category failed the tensile strength test. In contrast, all tires from the “infrequently failed” category passed this test. The average values of the test for these two tire categories were statistically different at a 95% confidence level

Global economic burden of unmet surgical need for appendicitis

Background There is a substantial gap in provision of adequate surgical care in many low- and middle-income countries. This study aimed to identify the economic burden of unmet surgical need for the common condition of appendicitis. Methods Data on the incidence of appendicitis from 170 countries and two different approaches were used to estimate numbers of patients who do not receive surgery: as a fixed proportion of the total unmet surgical need per country (approach 1); and based on country income status (approach 2). Indirect costs with current levels of access and local quality, and those if quality were at the standards of high-income countries, were estimated. A human capital approach was applied, focusing on the economic burden resulting from premature death and absenteeism. Results Excess mortality was 4185 per 100 000 cases of appendicitis using approach 1 and 3448 per 100 000 using approach 2. The economic burden of continuing current levels of access and local quality was US $92 492 million using approach 1 and$73 141 million using approach 2. The economic burden of not providing surgical care to the standards of high-income countries was $95 004 million using approach 1 and$75 666 million using approach 2. The largest share of these costs resulted from premature death (97.7 per cent) and lack of access (97.0 per cent) in contrast to lack of quality. Conclusion For a comparatively non-complex emergency condition such as appendicitis, increasing access to care should be prioritized. Although improving quality of care should not be neglected, increasing provision of care at current standards could reduce societal costs substantially