Full-Scale Evaluation of Concrete-Asphalt Interphase in Thin Bonded Concrete Overlay on Asphalt Pavements

Author(s):  
Fabian Paniagua ◽  
Julio Paniagua ◽  
Angel Mateos ◽  
Rongzong Wu ◽  
John T. Harvey

Thin bonded concrete overlay on asphalt (BCOA) pavements rely on concrete-asphalt bonding to resist traffic loading. To investigate variables affecting bonding, experimental data were used from 15 instrumented thin BCOA sections, with 11 tested with heavy vehicle simulators (HVS). Sections included three slab sizes, four rapid-strength concrete mixes, new and old asphalt bases, and three asphalt surface texturing techniques. Analysis of strain data from HVS testing served to determine the concrete-asphalt bonding condition. Laboratory testing and forensic data from the sections were also evaluated. Overall, the performance of concrete-asphalt bonding in the sections with 1.8 × 1.8 m (6 × 6 ft) slabs was excellent. In these sections, concrete-asphalt bonding remained intact throughout the HVS testing despite the unfavorable testing conditions, which included flooding of the section, channelized traffic at the slab edge, and HVS wheel (half axle) loading of up to 100 kN (22.5 kips). The sections with 3.6 × 3.6 m (12 × 12 ft) slabs presented a delamination band between the asphalt and concrete along the perimeter of the slabs. This delamination was a tensile break occurring in the asphalt around 5–10 mm (0.2–0.4 in.) below the concrete-asphalt interphase caused by the large vertical hygrothermal deformations in the slabs. Because of this asphalt failure, the concrete and asphalt worked as two independent layers near the transverse joints. Based on laboratory procedures, it was observed that cement paste penetration into the asphalt layer caused a reinforcing effect in the concrete-asphalt interphase. It was also observed that milling and micromilling did not improve the concrete-asphalt bonding.

1997 ◽  
Vol 1574 (1) ◽  
pp. 103-108 ◽  
Author(s):  
N. J. Delatte ◽  
D. W. Fowler ◽  
B. F. McCullough

For rehabilitation of concrete pavements, resurfacing with a bonded concrete overlay (BCO) may provide significantly longer life and reduced maintenance costs. Two important issues to consider in rehabilitation are bonding and rapid reopening of resurfaced sections. The purpose of accelerated or expedited concrete paving is to limit the duration of lane closure and inconvenience to the public. Expedited BCOs offer an economical method for substantially extending rigid pavement life. Research for expedited BCOs in El Paso and Fort Worth, Texas, has been carried out for the Texas Department of Transportation by the Center for Transportation Research at the University of Texas. Results of previous expedited BCO construction are reviewed. Laboratory testing for this project included a high-early-strength mix design, bond development of that mix design, and early-age fatigue strength of half-scale BCO models. A 122-m-long test strip was cast with eight different expedited BCO designs, and accelerated traffic loading was imposed at 12 hr. Recommendations are made for construction and quality control of BCOs for early opening to traffic.


Author(s):  
J. E. Ogbezode ◽  
A. I. Adeleke ◽  
A. S. Adebayo

The high brittle nature of pavement structures have been  carefully examined based on compressive, tensile strain and the harsh effects of fatigue cycle with reference to the base layer thicknesses and elastic strains during and after construction were examined. Subjection of asphalt and concrete-cement pavements to traffic loading and tyre pressure also influences the vertical stress and strain values for the asphalt and concrete materials under the same axial loading conditions. Using various fundamental equations under linear elastic conditions for the analysis of Asphalt and Concrete Cement structure revealed that both materials do respond differently to compressive and tensile stresses under similar mechanical conditions. Effect of compressive stresses and strains on concrete pavement is larger compare to asphalt pavement due to large thickness sub-base layer of its pavement structure. Both pavement layer thicknesses are independent of fatigue cycle under harsh traffic loading. Thus, concrete pavement has shown better fatigue resistance and less tensile strain values than asphalt pavements due to high pavement layer thickness regardless of the load distribution.


2020 ◽  
Vol 2020 ◽  
pp. 1-12
Author(s):  
Rodgers B. Mugume

This paper is aimed at assessing the in-service performance of asphalt pavements in tropical climate under severe conditions. The main defect observed on the asphalt pavement was rutting of the asphaltic surfacing, with top-down cracking being experienced on a few sections and not widespread but rather intermittent. Field and laboratory investigations were conducted as well as a review of design and construction records. The defects observed were confined to the wearing course layer of the surfacing with the other underlying layers performing well. Rutting was a result of heavily loaded trucks that moved at very slow speeds due to steep gradients, hence resulting in severely loaded sections. High temperatures due to the warm tropical environment exacerbated the situation and caused the asphalt to flow, hence resulting in rutting and deformation. Also, low air voids in the asphalt mix which were below the recommended design air voids specification aggravated the situation as well as the air voids after refusal density compaction being below the specified critical minimum of 3% after secondary compaction. Top-down cracking was due to binder age hardening and embrittlement resulting from overheating of bitumen during the construction process coupled with heavy truck axles and high tyre pressures. Defects observed, therefore, resulted from an unstable asphalt mix that was not suitable for severe loading conditions; hence, the asphalt concrete laid was out of specification. The Modified Marshall Mix Design method should be used for severe sites where slow speed or heavier traffic is expected.


Author(s):  
Kevin Alland ◽  
Julie M. Vandenbossche ◽  
John W. DeSantis ◽  
Mark B. Snyder ◽  
Lev Khazanovich

Bonded concrete overlays of asphalt pavements (BCOA) consist of a concrete overlay placed on an existing asphalt or composite pavement. This technique is intended as a cost-effective rehabilitation solution for marginally distressed in-service asphalt or composite pavements. BCOA with panel sizes between 4.5 ft and 8.5 ft have become popular as they reduce curling stresses while keeping the longitudinal joints out of the wheelpath. The BCOA-ME (mechanistic empirical) design procedure and Pavement ME short jointed plain concrete pavement (SJPCP) module can both be used to design BCOA with mid-size panels. However, these design procedures differ in the assumptions used to develop the mechanistic computational model, fatigue models used to predict failure, treatment of environmental conditions, estimate of asphalt stiffness, consideration of structural fibers, the application of traffic loading, and the calibration process. This results in the procedures producing different overlay thicknesses and predicted distresses. The strengths and limitations of each procedure are evaluated and comparisons are made between the design thicknesses obtained from them.


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