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The performance of different frost protection materials for road design
Published in Inge Hoff, Helge Mork, Rabbira Garba Saba, Eleventh International Conference on the Bearing Capacity of Roads, Railways and Airfields, Volume 2, 2022
K. Rieksts, B. Loranger, I. Hoff, J. Aksnes, K.A. Skoglund
The test site consists of seven test sections, each 50 m long. Each section is constructed with a different frost protection material. The total thickness of frost protection layer is 1.1 m. Although different frost protection material requires different thickness to achieve the same insulating effect, the thickness of each section has been equalized to fit with the rest of the constructed road for logistic purposes. The frost protection materials used were unsorted gravel (section F1), expanded polystyrene (XPS) (section F2), 0/180 mm crushed rock (section F3), foam glass (section F4), 0/32 mm crushed rock (section F5), expanded clay (section F6), and 22/180 mm crushed rock (section F7). The top part of the road consists of 0.09 m of asphalt layer (wearing and binder course) followed by 0.16 m of bound base layer. The subbase is constructed of 20/120 mm crushed rock material with a thickness of 0.8 m.
Introduction and Description of Pavements
Published in Rajib B. Mallick, Tahar El-Korchi, Pavement Engineering, 2017
Rajib B. Mallick, Tahar El-Korchi
A pavement consisting of asphalt mixes (and aggregate and soil layers) only is referred to as a flexible pavement, since the pavement layers deflect under a traffic load. The typical applied concept of a flexible (or asphalt) pavement is that a layered structure (Figure 1.2) with better materials near the top would distribute the load in such a way that the resulting stress in the bottommost layer will be small enough so as to cause no significant deformation of the layer. The bottommost layer is the existing layer or the existing layer modified with some materials. The materials and the thicknesses of the different layers will be such as to be able to withstand the different effects of temperature and moisture due to changes in season in a specific location. The subbase, in addition to providing structural support, may also serve as a platform for constructing the base and prevent the fine materials from the subgrade from contaminating the base layer. If the subgrade is of frost-susceptible material, then the subbase could be made up of non-frost-susceptible materials to prevent frost-related damage.
Applications of an innovative load bearing permeable concrete pavement
Published in Andreas Loizos, Imad L. Al-Qadi, A. (Tom) Scarpas, Bearing Capacity of Roads, Railways and Airfields, 2017
Y.H. Lee, H.W. Ker, N.S. Chou, J.W. Chen
The concept of rigid pavement design is generally based on providing surface and subsurface drainage and preventing water infiltration and pumping. The concrete slab thickness is not highly influenced by subgrade strength (Huang, 2004). The primary reason of providing a subbase layer is to prevent pumping, rather than solely to increase the structural strength of a rigid pavement (Huang, 2004). A well-designed rigid pavement normally has higher bearing capacity, longer service life, and lower maintenance fees. However, after several years of service, a rigid pavement may still have distresses such as faulting and pumping due to the combination effects of loadings, climatic conditions, and water infiltration (FHWA, 2003).
Laboratory investigation of RAP for various layers of flexible and concrete pavement
Published in International Journal of Pavement Engineering, 2020
Surender Singh, Kumari Monu, G. D. Ransinchung R. N.
The main function of providing subbase layer in both flexible as well as rigid pavements is to protect the subgrade soil from harmful effects of water ingress either from top or sides of the pavement. This issue can be overcome by providing a GSB layer above the compacted subgrade soil. In this context, the aggregate combination having a good coefficient of permeability is of utmost importance. As illustrated in Table 5, inclusions of both fractions of RAP increased the permeability coefficient considerably when compared to the control mix. This increase was observed to be more predominant for fine RAP inclusive mixes. For instances, the permeability coefficient of control mix was 2.51 × 10−4 cm/s and this was found to be increased to 33.46 × 10−4 cm/s on complete replacement of NAC by CR aggregates (i.e. 1200% increase with respect to control mix), whereas, incorporation of 100% FR aggregates was found to increase the permeability coefficient by about 1850%. Highest permeability coefficient was offered by 100% total RAP mix (100R). The improvement in the permeability values of GSB mixes may be attributed to the less moisture holding capacity of RAP aggregates which is generally due to the combined actions of open graded nature of fine RAP aggregates and presence of hydrophobic asphalt layer around the aggregates.
Developing statistical limits for using the light weight deflectometer in pavement construction quality assurance
Published in Road Materials and Pavement Design, 2018
Matthew Volovski, Samuel Labi, Kurt Sommer, Samy Noureldin, Ron Walker
Subgrades are compacted according to contract specifications and in accordance with INDOT Standard ITM 203.26. The subgrade serves two purposes; it provides a platform during the construction of the pavement system and ensures that excessive deflection of the natural soil does not negatively impact the pavement system (Christopher, Schwartz, & Boudreau, 2006). Chemically modified subgrades are used to reduce the moisture sensitivity and increase the strength of the subgrade to speed up the construction process; however the additional strength is not considered in the pavement design (INDOT, 2013). This research is not intended to replace the subgrade compaction requirements defined in each project’s contract specifications or ITM 203.26. The statistical limits developed for the various subgrade materials is intended to shed light on the interaction between subgrade and subgrade deflection. The subbase is a material consisting of aggregates of specific thickness placed and compacted to support the base and surface courses (Christopher et al., 2006). The subbase strength is considered in the pavement design. Therefore, the expected bearing strength needs to be assured during construction. The subsequent analysis used data collected in Indiana and is detailed in the forthcoming Data section of the current paper.
Effect of principal stress rotation on deformation behavior of dense sand–clay mixtures
Published in Road Materials and Pavement Design, 2021
Halil Ibrahim Fedakar, Cassandra J. Rutherford, Bora Cetin
A hollow cylinder apparatus allows four degrees of load components to be controlled independently. Therefore, it can simulate a principal stress rotation induced by complex stress paths for the specimens that are in a suitable geometry and do not exhibit large strain (Cai et al., 2015; Guo et al., 2018). Due to these capabilities, hollow cylinder tests have been successfully conducted in imposing a better simulated principal stress rotation on soil specimens in the last decade (Cai et al., 2015, 2017, 2018; Georgiannou & Konstadinou, 2014; Guo et al., 2016, 2018; Qian et al., 2016; Yang et al., 2019). Previous studies clearly indicated that the principal stress rotation and heart-shaped stress path, resulting from a vehicle wheel loading, may have a significant impact on the deformation behaviour of soils. The degree of this effect depends on soil types as well as the stress states that specimens are subjected to. A subgrade layer is a native soil that generally consists of soils with different types and particle sizes. The materials with a coarser fraction of coarse-grained (sand, in general) and a lower amount of fine-grained soil can also be used as a subbase material in a transportation infrastructure. The permanent deformation in pavement foundation layers (i.e. subbase and subgrade) due to traffic loading contributes to pavement rutting significantly (Cai, 2010; Cai et al., 2015; Chai & Miura, 2002; Puppala et al., 1999). Therefore, the soils with various types and particle sizes should be tested to better understand the deformation accumulation in a pavement structure. While there have been studies examining the behaviour of soils (i.e. sand, and soft clay materials) under traffic loads through cyclic hollow cylinder (CHC) tests (Cai et al., 2015; Cai et al., 2017, 2018; Georgiannou & Konstadinou, 2014; Guo et al., 2016, 2018; Qian et al., 2016; Yang et al., 2019), there is limited information about the permanent deformation behaviour of sand–clay mixtures under the principal stress rotation induced by a heart-shaped stress path.