Behavior of Recycled Asphalt Pavement and Recycled Concrete Aggregate as Unbound Road Base - read free eBook in online reader or directly download on the web page. Select files or add your book in reader. Download and read online ebook Behavior of Recycled Asphalt Pavement and Recycled Concrete Aggregate as Unbound Road Base write by Ozlem Bozyurt. This book was released on 2011. Behavior of Recycled Asphalt Pavement and Recycled Concrete Aggregate as Unbound Road Base available in PDF, EPUB and Kindle.
Freeze-Thaw Effects on Stiffness of Unbound Recycled Road Base
Freeze-Thaw Effects on Stiffness of Unbound Recycled Road Base - read free eBook in online reader or directly download on the web page. Select files or add your book in reader. Download and read online ebook Freeze-Thaw Effects on Stiffness of Unbound Recycled Road Base write by James M. Tinjum. This book was released on 2013. Freeze-Thaw Effects on Stiffness of Unbound Recycled Road Base available in PDF, EPUB and Kindle. A major concern for using recycled pavement material as an unbound base or subbase layer is the effect of changing seasons on the properties of the recycled material. Three sources of recycled concrete aggregate (RCA) and recycled asphalt pavement (RAP), and one conventional base aggregate, were used to investigate the effect of freeze-thaw cycles on the stiffness of unbound road base/subbase layers. Effects of freeze-thaw cycling on the mechanical behavior of three gradations (coarse, medium, fine) of recycled materials were systematically evaluated to determine how climatic factors and aging affect the resilient modulus. Sealed specimens were exposed to 5, 10, and 20 sets of freeze-thaw cycles. Resilient modulus tests were conducted according to NCHRP 1-28A after the final freeze-thaw cycle. Freeze-thaw cycling caused a decrease in the stiffness (i.e., the summary resilient modulus) of RAP samples and class 5 aggregate because of the effect of the water retained in the pores. An increase in the stiffness of RCA was observed over 20 freeze-thaw cycles and is attributed to self-cementitious behavior of crushed concrete. Seismic modulus testing was used to investigate the continuous rate of change (daily) of the stiffness for RCA and class 5 aggregate. The seismic modulus test confirmed the trends observed in resilient modulus testing and served as a non-destructive method for tracking changes in stiffness over time and freeze-thaw cycling.
Recycled Unbound Materials
Recycled Unbound Materials - read free eBook in online reader or directly download on the web page. Select files or add your book in reader. Download and read online ebook Recycled Unbound Materials write by Tuncer B. Edil. This book was released on 2012. Recycled Unbound Materials available in PDF, EPUB and Kindle. The objective of this project was to characterize the properties of crushed recycled concrete (RCA) and asphalt pavement (RAP) as unbound base without being stabilized, to assess how RCA and RAP behave in the field and to determine how pavements can be designed using RCA and RAP. Issues to be considered include variability in material properties, purity of material, climatic effects, how to identify and control material quality, and leaching characteristics. This project included laboratory specimen and large-scale model tests and evaluation of field data from MnROAD test sections constructed using recycled materials. To identify the characteristics of RAP and RCA typically available in different parts of the country, samples were obtained from eight states: California, Colorado, Michigan, Minnesota, New Jersey, Ohio, Texas, and Wisconsin covering a geographically diverse area. A conventional base course was used as a control material. The extensive investigation undertaken on RCA and RAP indicate that these materials are generally suitable for unbound base course applications and they show equal or superior performance characteristics compared to natural aggregates in terms of stiffness, freeze-thaw and wet-dry durability, and toughness. Their typical compositional and mechanical properties and their variability are defined in this study providing a basis for design considerations. Their relative differences from natural aggregate such as temperature sensitivity, plastic deformations, and water absorption and retention characteristics are also well established. It is noted that some RAP may be sensitive to temperature change that may lead to rutting. This aspect needs to be considered in design.
Significant Findings from Full-scale Accelerated Pavement Testing
Significant Findings from Full-scale Accelerated Pavement Testing - read free eBook in online reader or directly download on the web page. Select files or add your book in reader. Download and read online ebook Significant Findings from Full-scale Accelerated Pavement Testing write by Wynand JvdM. Steyn. This book was released on 2012. Significant Findings from Full-scale Accelerated Pavement Testing available in PDF, EPUB and Kindle. "TRB's National Cooperative Highway Research Program (NCHRP) Synthesis 433: Significant Findings from Full-Scale Accelerated Pavement Testing documents and summarizes significant findings from the various experimental activities associated with full-scale accelerated pavement testing (f-sAPT) programs that have taken place between 2000 and 2011. The report also identifies gaps in knowledge related to f-sAPT and where future research may be needed. NCHRP Synthesis 433 is designed to expand the f-sAPT base of knowledge documented in NCHRP Syntheses 325 and 235, both with the same title of Significant Findings from Full-Scale Accelerated Pavement Testing. f-sAPT is the controlled application of a wheel loading, at or above the appropriate legal load limit, to a pavement system to determine pavement response in a compressed time period. The acceleration of damage is achieved by one or more of the following factors: increased repetitions, modified loading conditions, imposed climatic conditions, and thinner pavements with a decreased structural capacity which have shorter design lives"--
Assessment of Recycled Aggregates for Use in Unbound Subbase of Highway Pavement
Assessment of Recycled Aggregates for Use in Unbound Subbase of Highway Pavement - read free eBook in online reader or directly download on the web page. Select files or add your book in reader. Download and read online ebook Assessment of Recycled Aggregates for Use in Unbound Subbase of Highway Pavement write by Vahid Ayan. This book was released on 2011. Assessment of Recycled Aggregates for Use in Unbound Subbase of Highway Pavement available in PDF, EPUB and Kindle. Intendancy for sustainability has made it necessary for the highways industry to adapt its traditional processes to more cost-effective, energy efficient and greener technologies. This research programme was developed with a key aim of investigating the technical viability of aggregates formed with different combinations of Recycled Concrete Aggregate (RCA), Reclaimed Asphalt Pavement (RAP) and Natural Aggregates (NA) when used in construction of unbound subbases of highway pavements. As strongly evident from a comprehensive literature review carried out, little information is available on the application of RCA and RCA/RAP as subbase materials. The suitability of RCA blended with RAP and NA were investigated and compared to the British Standards, Highway Agency specifications and the AASHTO standards requirements for highway design. Having established their suitability for highway design, then the performance of the materials was assessed under traffic loading. In compliance with the requirements of the above Standards/Specifications the in-situ loaded behavior of the aforementioned materials were also investigated. This was achieved through numerical analysis of a typical pavement structures comprising subbases made of the above materials. As a consequence, a series of analyses were carried out using KENLAYER TM computer program to model the stresses and deformations in the subbases. The results of the analyses were then applied to the Mohr Coulomb failure model in order to predict the factor of safety against failure of the subbase layer. Amongst the salient findings from the research was that most of the materials tested complied with the standard requirements. From a large number of tests carried out on materials collected in the UK and Iran, it was also demonstrated that the source of a recycled material and the method of extraction had a significant influence on the engineering properties of the material, especially the CBR. In terms of compaction and CBR requirements, the 50%RAP+50%RCA mix was demonstrated as suitable for unbound subbase application. Also, the presence of RAP in the mixes of RAP/RCA was found to improve the drainage properties of an unbound subbase layer. From the viewpoint of durability and frost susceptibility, it was verified that all the materials investigated were applicable to the highest significance level (as defined by AASHTO). However, based on stiffness considerations, the materials were found to be applicable only to the lowest significance level. Now, turning to the toughness and shear strength properties, the same materials were found to fall in the middle significance levels. The results of KENLAYER TM modeling indicated that the safety factor against failure of the mixes containing RAP and RCA decreased as the stiffness decreased. Evidently the research is likely to have a number of implications on the design and construction of highways. Firstly, the demonstrated viability of mixes containing recycled materials (RCA+RAP) can lead to significant cost savings, reduced CO2 emissions, reduced exploitation of virgin materials and minimization of dumping of civil engineering waste. If embraced in industry, the suggested use of recycled materials can help support National and international targets regarding sustainability, environmental and energy conservation. The research succeeded in cataloguing the specifications of RCA/RAP and RCA/NA for practical works, followed by development and evaluation of different mixes of recycled aggregates obtained from different sources. Detailed assessment based on compliance with requirements, performance prediction and modeling was completed.
