Portland Cement Concrete Overlays

Portland Cement Concrete Overlays
Author: Kurt D. Smith
Publisher:
Total Pages: 200
Release: 2002
Genre: Pavements
ISBN:

This report presents the latest information on the design, construction and performance of portland cement concrete (PCC) overlays. It describes the four types of PCC overlays that are commonly used in highway pavement applications: bonded PCC overlays, unbonded PCC overlays, conventional whitetopping and ultra-thin whitetopping. Recommended applications, critical design elements, current overlay design methodologies, recommended construction practices, and performance highlights are described for each overlay type. Information is also provided on the selection of PCC overlays as possible rehabilitation alternatives for existing pavements. Taken together, this document addresses the current "state of the technology" of PCC overlays placed on both existing PCC pavements and on existing hot-mix asphalt pavements.

Bonded Cement-Based Material Overlays for the Repair, the Lining or the Strengthening of Slabs or Pavements

Bonded Cement-Based Material Overlays for the Repair, the Lining or the Strengthening of Slabs or Pavements
Author: BenoƮt Bissonnette
Publisher: Springer Science & Business Media
Total Pages: 197
Release: 2011-03-16
Genre: Technology & Engineering
ISBN: 9400712391

Among different approaches that can be considered for concrete rehabilitation, bonded overlays are often the most economical alternative. The primary purpose of overlays is to extend the life of the candidate structures, either by restoring the quality and integrity of the surface and/or the re-establishing or improving the load-carrying capacity. Nevertheless, the durability of bonded overlay systems still draws concerns in the technical community because of bond sustainability problems encountered in a number of cases. At this time, there is still no accepted design approach or methodology that can warrant the practitioner a successful outcome of the repair. This State-of-Art report summarizes the findings with respect to all aspects involved in the overlaying process.

Delamination of Bonded Concrete Overlays at Early Ages

Delamination of Bonded Concrete Overlays at Early Ages
Author: James Ray Lundy
Publisher:
Total Pages: 100
Release: 1991
Genre: Laminated materials
ISBN:

A procedure is developed by which the likelihood of delamination of bonded concrete overlays on continuously reinforced concrete pavements is reduced. The procedure compares the early age interface stress to the expected interface bond strength for a variety of environmental conditions. When the calculated stress exceeds the expected strength, it is recommended that overlay placement be curtailed until the possibility of debonding is reduced. A finite element method program is used to determine the early age stresses resulting from temperature and shrinkage induced volume changes. Stresses were determined for a variety of environmental and material combinations and overlay thicknesses. Analyses show that a significant reduction in stress results from the use of overlay materials which have a lower modulus and thermal coefficient than those of the existing slab. The stresses for a given combination of materials and environmental conditions are compared to the interface bond strength at early ages. Early age interface shear and tensile strengths are estimated from 7-day strength test results. The estimated strength, together with the variability of the interface strength, are used to calculate the likelihood of delamination for a given type of overlay and time of placement. This likelihood can be reduced through the selection of a different overlay material or time of placement.