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Ultra-thin whitetopping for asphalt pavement rehabilitation: The influence of the interlayer in the properties of the double-layered system
Published in Inge Hoff, Helge Mork, Rabbira Garba Saba, Eleventh International Conference on the Bearing Capacity of Roads, Railways and Airfields, Volume 3, 2022
M. Pasetto, A. Baliello, G. Giacomello, E. Pasquini
Road rehabilitation practices are gaining popularity because of the progressive reduction of new constructions and the general financial straits that promote wise maintenance strategies. In recent years, whitetopping has been diffused as maintenance strategy for distressed asphalt pavements. Such intervention consists in the casting of a Portland Cement Concrete (PCC) layer over existing Asphalt Concrete (AC) wearing courses. By using standard thickened slabs over old pavements, conventional whitetopping is intended as a reinforcement designed and constructed following the typical criteria for concrete materials. In the case of Ultra-Thin Whitetopping (UTW), reduced thicknesses (from 50 to 100 mm) are used to produce overlays that result in small square-shaped slabs with substantially-near joints (Balbo and Rodolfo 1998). In the US, first successful UTWs dated back the early 1990s; then, several studies and installations pushed towards its prompt diffusion worldwide (Gucunski, 1998). This happened mainly thanks to the involved benefits principally related to the long durability and the substantial cheapness (Abhijith and Mahendra 2018).
Maintenance and Rehabilitation of Pavements
Published in Rajib B. Mallick, Tahar El-Korchi, Pavement Engineering, 2017
Rajib B. Mallick, Tahar El-Korchi
Whitetopping is a Portland cement concrete overlay on existing asphalt concrete pavement. It can be used as a road surface course where other paving materials and methods have failed due to rutting or general deterioration. There are three types of whitetopping: conventional (thickness greater than 8 in.), thin (thicknesses over 4 but less than 8 in.), and ultrathin (2–4 in.). Ultrathin whitetopping (UTW) is a bonded, fiber-reinforced concrete overlay. UTW is designed for low-speed traffic areas or areas with a lot of stop-and-go traffic, such as street intersections, bus stops, or toll booths. Joint spacing is critical to a good performing UTW. The use of a short joint spacing is common in both directions of the slab. In effect, a mini-block paver system is formed. The limited experience with UTW indicates that joint spacing should be no more than 12–18 in. each way per inch of whitetopping thickness. For example, a 3-in. UTW surface should be jointed into 3 × 3 or 4 × 4 ft2. Joints are sawed early to control surface cracking.
Urban Heat Implications from Parking, Roads, and Cars: a Case Study of Metro Phoenix
Published in Sustainable and Resilient Infrastructure, 2022
Christopher G. Hoehne, Mikhail V. Chester, David J. Sailor, David A. King
A variety of pavement designs are categorized into three classes and developed by referencing relevant literature and pavement engineering design recommendations or requirements. A summary of the range of material parameters for various pavements and bare ground is displayed in Table 1. Pavement designs are classified in one of three pavement classes: (1) asphalt pavement (primarily hot-mixed asphalt) which utilizes a bitumen binder with aggregate; (2) concrete pavement (primarily Portland cement concrete) which utilizes a cement binder with aggregate; and (3) composite asphalt-concrete pavements that combine distinct bitumen-bound and cement-bound layers in a single pavement design such as whitetopping overlaid on an asphalt pavement or rubberized asphalt overlaid on Portland cement concrete (PCC). Whitetopping is a common method where a thin PCC layer is overlaid on top of an existing asphalt pavement. Whitetopping has become increasingly popular for existing pavement rehabilitation and to increase the surface layer albedo for potential cooling benefits. Lastly, a fourth material class emulating desert soil is created to serve as a reference for undeveloped natural land that would be found in an arid region such as Phoenix.
Design and construction of low-volume concrete road: experiences from China
Published in Road Materials and Pavement Design, 2020
Ya Wei, Siming Liang, Xiang Gao, Jiliang Feng
It should be noted that similarly reduced slab size and thickness compared to that of a conventional-sized slab can also be found in ultrathin whitetopping (UTW) and normal whitetopping (WT) for asphalt pavement rehabilitation (Li & Wen, 2011; Vandenbossche, Dufalla, & Li, 2017; Wu et al., 2007). The UTW thickness is less than 102 mm, and the WT thickness is between 102 mm and 153 mm. A very short joint spacing of 0.6 m to1.8 m has been used for UTW pavements to reduce shrinkage cracking and slab curling and warping. The slab thickness and size were found to be statistically significant variables that affect the performance of whitetopping pavements. It has been found that the slab thickness of whitetopping should be greater than 102 mm and slab size should be smaller than 3.34 m2 to achieve better performance (Li & Wen, 2011). However, owing to the different applications of the small-sized slabs investigated in this study relative to those of whitetopping, small-sized slabs generally have slightly greater slab thickness than whitetopping. Therefore, a small-sized slab can be used as a pavement for low-volume roads, and whitetopping that has a thinner slab can be used for asphalt pavement rehabilitation.
Long-term performance evaluation of Iowa concrete overlays
Published in International Journal of Pavement Engineering, 2022
Yu-An Chen, Halil Ceylan, Inya Nlenanya, Orhan Kaya, Omar G. Smadi, Peter C. Taylor, Sunghwan Kim, Kasthurirangan Gopalakrishnan, Daniel E. King
Figure 1 shows the spatial distribution of the 384 concrete overlay projects included in the study. Four different types of concrete overlays have been in use in Iowa, including bonded concrete-on-concrete (BCOC), unbonded concrete-on-concrete (UBCOC), bonded concrete-on-asphalt (BCOA), and unbonded concrete-on-asphalt (UBCOA). Historically, the term whitetopping has referred to a concrete overlay of asphalt. For this study, whitetopping was divided into two categories: BCOA and UBCOA. Concrete overlays on the asphalt where slab thickness was less than or equal to 152-mm (6 in.) were designated as BCOA, whereas concrete overlays on asphalt with slab thickness of more than 152-mm (6 in.) were designated as UBCOA. This division follows historical Iowa concrete overlays practices adopted by the Iowa Department of Transportation (DOT) (Gross et al. 2017). A total of 35 overlays were known to have been reconstructed or replaced at the time of this study, but these were not considered in the analysis because there were no detailed records regarding when they were taken out of service. However, those 35 projects comprised fewer than 10% of all projects considered in the study. As shown in Table 1, 91% of the included projects were completed during the past 30 years. 82% of these projects have average daily traffic (ADT) range below 1500, meaning that most of these projects were on the county (low volume) road infrastructure system. Concrete overlays thickness ranged from 51-mm (2 in.) to 305-mm (12 in.), and transverse joint spacing ranged from 0.9-m (3 ft.) to 12.2-m (40 ft.). 94% of projects had a design thickness ranging from 102-mm (4 in.) to 203-mm (8 in.) and 92% had a transverse joint spacing of either 1.7-1.8-m (5.5-6 ft.), 3.7-3.8-m (12-12.5 ft.), or 4.6-6.1-m (15-20 ft.).