Cost-effective Rehabilitation Strategy Research Articles

Development of Rehabilitation Strategies Based on Structural Capacity for Composite and Flexible Pavements

AbstractThe selection of long-lasting and cost-effective rehabilitation strategies is crucial to pavement engineers. Development of rehabilitation and preservation decision trees and support tools ...

Mechanistic-empirical methodology for the selection of cost-effective rehabilitation strategy for flexible pavements

A well-planned rehabilitation approach helps agencies to optimise the allocation of annual investment in pavement rehabilitation programs. Currently, many agencies are struggling with the selection of an optimal time-based and cost-effective rehabilitation solution to address the long-term needs of pavements. This study offers the use of a mechanistic-empirical methodology to develop a series of time-based rehabilitation strategies for high traffic volume flexible pavements located in Oklahoma. Six different pavement family groups are identified in the state, and comprehensive evaluation of existing pavements are conducted through analysis of falling weight deflectometer data and performance measures available in Oklahoma Pavement Management System database. The inadequacy of performance measures to fully characterise the condition of existing pavements are indicated, and damage factor determined from FWD data are suggested as trigger factor to select rehabilitation candidates. Three levels of rehabilitation activities including light, medium and heavy are considered as potential alternatives for rehabilitation candidates. A mechanistic-empirical methodology is employed to obtain an estimate of the performance of rehabilitation and extension in service lives of pavements. Also, an assessment output matrix is developed, which can be served as a supplemental tool to help the decision-makers in the highway agency with the rehabilitation related decision-making process. Cost-effectiveness of rehabilitation alternatives is determined through life cycle cost analysis, and three time-based renewal solutions are developed for pavement family groups that are in need of rehabilitation.

Biochar as possible long-term soil amendment for phytostabilisation of TE-contaminated soils.

Soils contaminated by trace elements (TEs) pose a high risk to their surrounding areas as TEs can spread by wind and water erosion or leaching. A possible option to reduce TE transfer from these sites is phytostabilisation. It is a long-term and cost-effective rehabilitation strategy which aims at immobilising TEs within the soil by vegetation cover and amendment application. One possible amendment is biochar. It is charred organic matter which has been shown to immobilise metals due to its high surface area and alkaline pH. Doubts have been expressed about the longevity of this immobilising effect as it could dissipate once the carbonates in the biochar have dissolved. Therefore, in a pot experiment, we determined plant metal uptake by ryegrass (Lolium perenne) from three TE-contaminated soils treated with two biochars, which differed only in their pH (acidic, 2.80; alkaline, 9.33) and carbonate (0.17 and 7.3%) content. Root biomass was increased by the application of the alkaline biochar due to the decrease in TE toxicity. Zinc and Cu bioavailability and plant uptake were equally reduced by both biochars, showing that surface area plays an important role in metal immobilisation. Biochar could serve as a long-term amendment for TE immobilisation even after its alkalinity effect has dissipated.

Full-Depth Reclamation: Cost-Effective Rehabilitation Strategy for Low-Volume Roads

Full-depth reclamation with or without various stabilizers has been successfully used as a rehabilitation strategy in California since 2001. Long-term field monitoring on a number of full-depth reclamation projects that use foamed asphalt with portland cement as the stabilizer combined with a comprehensive laboratory study resulted in the preparation of guidelines and specification language for this rehabilitation strategy in 2008. However, the design criteria were essentially empirical in line with California design procedures for this level of rehabilitation project. There has been growing interest in the use of full-depth reclamation with no stabilizer as a rehabilitation option for lower-volume roads and in the use of mechanistic design in a greater range of rehabilitation projects. Consequently, the research initiative was extended to a second phase to include accelerated load testing on an instrumented test track constructed with four full-depth reclamation strategies to gather data for the development of performance models that can be included in mechanistic–empirical rehabilitation design procedures. This paper summarizes the results of a set of tests in this accelerated loading study, which compared dry and wet performance of a pavement rehabilitated with full-depth reclamation without any stabilizer. The section performed well in terms of expected low-volume traffic (i.e., up to 500,000 equivalent single-axle wheel loads). Poorer performance under wet base course conditions emphasized the need for appropriate drainage on low-volume road structures. The findings indicate that full-depth reclamation with no stabilizer, followed by the placement of an appropriate surface treatment or thin asphalt concrete layer, is a potentially cost-effective rehabilitation strategy for distressed low-volume pavements.

Integrating Asset Management Across Fremantle Ports

Asset ownership is a significant cost to Fremantle Ports and developing a best practice strategic asset management (SAM) framework that provides a simple, logical and innovative approach for optimising the whole of life cycle cost of asset delivery in meeting the agreed levels of service and risk exposure has been a corporate priority over the past years. With the development and implementation of the SAM framework well underway, Fremantle Ports now focuses on the integration of asset management practices across the business, from operational through to tactical and strategic planning. A pilot project has been proposed to assess and improve asset management practices across one of Fremantle Ports’, most critical asset classes, the wharves and jetties. This paper reviews the findings and challenges of this project and the various tools that were developed, including a life cycle cost model. This model is based on asset condition and related deterioration curves that allow for the estimation of remaining life. In addition, the model enables the selection of most cost effective rehabilitation strategies while considering risk profile and available funding, assisting Fremantle Ports in optimising the decision making process by providing an actual and an optimised life cycle cost plan.

Integrating asset management across Fremantle Ports

Asset ownership is a significant cost to Fremantle Ports and developing a best practice strategic asset management (SAM) framework that provides a simple, logical and innovative approach for optimising the whole of life cycle cost of asset delivery in meeting the agreed levels of service and risk exposure has been a corporate priority over the past years. With the development and implementation of the SAM framework well underway, Fremantle Ports now focuses on the integration of asset management practices across the business, from operational through to tactical and strategic planning. A pilot project has been proposed to assess and improve asset management practices across one of Fremantle Ports' most critical asset classes, the wharves and jetties. This paper reviews the findings and challenges of this project and the various tools that were developed, including a life cycle cost model. This model is based on asset condition and related deterioration curves that allow for the estimation of remaining life. In addition, the model enables the selection of most cost effective rehabilitation strategies while considering risk profile and available funding, assisting Fremantle Ports in optimising the decision making process by providing an actual and an optimised life cycle cost plan.

The Application and Early-Age Behaviors of Continuously Reinforced Bonded Concrete Overlay of Distressed Jointed Concrete Pavements

Abstract Considerable efforts and money are spent to maintain and repair the distressed jointed concrete pavement (JCP) sections by providing partial-/full-depth repair, under sealing, and patching; however, a lot of distresses reoccur frequently. For severe distresses, overlay was constructed on the JCP. Resurfacing with a bonded concrete overlay (BCO) over the existing pavement to form a monolithic structure has proven to be a cost-effective rehabilitation strategy. Continuously reinforced concrete pavement (CRCP) bonded overlay was constructed for the rehabilitation of a 2000 ft long JCP section on U.S.75 in Sherman, Texas, United States which had been subjected to numerous rehabilitations to construct the guidelines of the CRCP bonded overlay. The pavement design and concrete mix design selected are discussed and introduced in this article. In order to reduce the reflective cracking at the location of the JCP joints, geotextile was placed at the joint location before the overlay construction. For the study on the function of the geotextile, the geotextile was not placed at 20 JCP joints for the comparison. One week after the BCO construction, the investigation for the CRCP cracking was carried out at three stages. The investigated results revealed that the cracks at the transverse steel location are much more than those between the transverse steel. Falling weight deflectometer testing was run on the pavement surface before and after the overlay construction to measure the deflection behavior of the pavement. The performance of the overlay shows that the bonded CRCP is appropriate for the JCP resurfacing.

Application of biochar on mine tailings: Effects and perspectives for land reclamation

Mine tailings represent a source of toxic pollutants, mainly heavy metals, which may spread to the surrounding areas. Phytostabilization, a long-term and cost-effective rehabilitation strategy, can be achieved by promoting the establishment of vegetation to reduce the risk of pollutant transfer. In this work, the application of pyrolyzed biomass (biochar) was studied to evaluate the amelioration of the mine tailings properties for potential use as a phytostabilization technology. Four substrates were obtained by mixing the mine tailings from a dumping site in Cave del Predil (NE, Italy) with biochar from orchard prune residues at four dosages (0%, 1%, 5% and 10% biochar in the mine tailings). The physical and chemical properties were determined and the bioavailability and leachability of the contaminants were estimated. The pH, the nutrient retention in terms of cation exchange capacity and the water-holding capacity increased as the biochar content increased in the substrates and the bioavailability of Cd, Pb, Tl and Zn of the mine tailings decreased. The changes promoted by the biochar seem to be in favor of its use on mine wastes to help the establishment of a green cover in a phytostabilization process.

Pavement Rehabilitation Strategy Selection for Steel Suspension Bridges Based on Probabilistic Life-Cycle Cost Analysis

Field inspections on long-span steel suspension bridges in China reveal that the pavements undergo a fast deterioration process attributed to the flexibility of suspension bridges and the heavy traffic loads. Such extensive damage and enormous repair costs call for a cost-effective rehabilitation strategy for these bridges. In this paper, the pavement rehabilitation strategy is investigated for the Runyang Suspension Bridge in China with the aid of the life-cycle cost analysis (LCCA). Three alternatives are compared for their economic efficiency, and both agency costs and user costs are taken into account. To consider the uncertainties that abound in the LCCA, probabilistic analyses are made in which the Latin hypercube method is used to provide samples of random variables. According to the LCCA results, the user costs are a considerable proportion of the total costs so that the selection of rehabilitation strategies is significantly influenced by the user costs. In this regard, the second alternative, the double-layer pavement (guss asphalt plus stone matrix asphalt) is the most cost-effective rehabilitation strategy for the bridge. Additionally, sensitivity analyses show that the traffic growth rates, the discount rate, the work zone duration, and the delay cost rate for passenger cars are the most sensitive variables in the user costs. The methodologies and approaches introduced herein can be easily implemented by practitioners and would be of benefit to pavement rehabilitations for steel suspension bridges.

Historic Buildings and Rehabilitation Expenditures: A Panel Data Approach

Using a panel data set, a hedonic model is estimated to determine the characteristics of buildings that have influenced the market value assessments of a set of historic and non-historically designated buildings. Holding constant the characteristics of buildings, the findings indicate higher assessed values for some classes of historic buildings. Furthermore, using a two-stage Heckman sample selection model, the findings show that the expenditures on renovations contribute significantly to the change in assessed values of buildings, although less than might be expected. These and other results may be helpful in the design of cost effective rehabilitation strategies for historic preservation.

Pavement Rehabilitation Selection Based on Mechanistic Analysis and Field Diagnosis of Falling Weight Deflectometer Data: Virginia Experience

The effectiveness of using the field diagnosis and falling weight deflectometer (FWD) mechanistic analysis in reducing a 65-km (40-mi) segment of asphalt pavement to project level segments is discussed, along with selecting a cost-effective rehabilitation strategy. A mechanistic-based analysis was performed on the deflection basins measured from I-85 in Virginia to backcalculate the layer moduli. The 65-km segment was divided into structurally homogeneous sections based on the back-calculated layer moduli. The data of each homogeneous section were analyzed further to assess the in situ structural capacity, to identify weak layers, to estimate the remaining structural life, and to determine the current and future rehabilitation needs. It was found that some sections have almost no remaining structural life, and others have remaining structural life of more than 10 years. A comparison was made between the FWD–field diagnosis rehabilitation program and a visual inspection rehabilitation program. Results of the comparison indicated that the visual inspection rehabilitation program resulted in selecting thicker overlays for some of the project sections (overdesigned) and thinner overlays for the other sections (underdesigned). It is estimated that the difference between the FWD–field diagnosis rehabilitation program and the visual inspection rehabilitation program for the overdesigned sections is in the range of 45 percent of the construction cost (savings). Life-cycle cost analysis (LCCA) was performed to quantify the difference between the two rehabilitation programs for the underdesigned sections. Results of the LCCA indicated that the FWD–field diagnosis rehabilitation program would result in 26 percent and 42 percent reduction in the construction cost and user delay cost, respectively.