Marcelo Bustos

Calibration of Distress Models from the Mechanistic-Empirical Pavement Design Guide for Rigid Pavement Design in Argentina

This paper presents the main results of a calibration of distress models from the Mechanistic–Empirical Pavement Design Guide (MEPDG) to local conditions in Argentina to be used in rigid pavement structural design. Test sections with rigid pavements were selected to cover a wide range of climatic conditions in the central region of the country. Local road agencies provided information about pavement structure, traffic volume, and load spectra. Field distress data and international roughness index (IRI) values were collected and processed with MEPDG software; calibration factors were determined for the different distress models of rigid pavements. The accuracy of distress prediction was significantly improved if calibration factors that considered additional influence of climatic conditions, soil and base type, slab length, and pavement age were incorporated into the transverse joint-faulting and transverse-cracking models. Through the use of calibrated factors instead of default values provided in MEPDG models, the errors in distress predictions were reduced by more than one-half in all cases. Construction procedures seemed to influence the IRI roughness prediction. Better calibration results were obtained if different after-construction IRI values were considered for pavements constructed before and after the 1990s to reflect the difference between older and newer constructive techniques.

CALIBRATION OF PERFORMANCE MODELS FOR JOINTED PLAIN CONCRETE PAVEMENTS USING LONG-TERM PAVEMENT PERFORMANCE DATABASE

A methodology for calibrating performance models for jointed plain concrete pavements (JPCP) is presented; it is based on statistical analysis of data from the Long-Term Pavement Performance (LTPP) database. The methodology provides calibration factors to pavements in four climatic regions (dry-freeze, dry-nonfreeze, wet-freeze, and wet-nonfreeze) for the JPCP performance models in HDM-4: joint faulting, transverse cracking, joint spalling, and roughness. The procedure allows calculation of global calibration factors, which does not affect significantly the quality of the prediction compared with the quality achieved through the use of regional factors.

Evaluation of the Use of Magnesium Chloride for Surface Stabilization and Dust Control on Unpaved Roads

Gravel roads are an important portion of the road network in western Argentina, and their maintenance requires a huge amount of economic and human resources. Recently, the use of alternative treatments based on the application of mineral salts such as hydrous magnesium chloride, also known as bischofite, has been introduced in this region. Such treatments are being applied for dust control and surface stabilization on unpaved roads. This paper presents the main results obtained during a research project carried out by the National University of San Juan, Argentina, along with local road agencies and companies. Test sections of gravel roads were treated with bischofite applied in two ways. Over 18 months, measurements of surface roughness and dust emission were made on those sections. The main results show that the use of bischofite contributed to a notable reduction in the evolution of roughness and dust emission as compared with untreated gravel sections. Bischofite appears to be appropriate not only for the environment but also for road agencies and road users; important cost savings were verified through economic assessments that compared treated and untreated gravel road sections.

Concrete Pavement Performance in Midwestern Argentina Compared with Long-Term Pavement Performance Data: HDM-4 Distress Models

Portland cement concrete pavements have been constructed in many areas in Argentina that feature heavy traffic and freeways and highways in freezing areas. To predict their performance, computational programs such as the World Banks HDM-4 may be used. This particular software includes distress models that need to be adjusted to local conditions in order to optimize the evaluation of maintenance strategies and resource allocation. The main objective of this study is to evaluate the performance of concrete pavements in the midwestern region of Argentina by using the HDM-4 software to obtain calibration coefficients for each distress model. A specific methodology for model calibration was applied to concrete pavements of the national road network located in the provinces of San Juan, Mendoza, and Cordoba. Such roads include jointed plain and jointed reinforced concrete pavement (JPCP and JRCP), with an ample range of traffic levels and climate conditions. Calibration coefficients were determined individuall...

Evaluating Accessibility of High-Altitude Valleys: Application to Andean Region of San Juan, Argentina

The high-altitude mountain valleys of Calingasta, located in the province of San Juan, central western Argentina, along the border with Chile, are isolated and scarcely populated territories, rich in natural resources, scenic attractions, and grazing land. In spite of its economic potential, the development of the region has barely begun. A methodology is described that is designed to analyze accessibility to such valleys by roads located almost entirely in high mountain zones. A comprehensive study of regional resources was first developed, and the main sites of interest related to tourism, mining, and historical attractions were clearly identified. Alternative paths for the access roads were then traced following balanced criteria that considered not only the distance from the roads to sites of interest but also the real possibilities constrained by the complex topography of the area. In this study, maps, aerial photos, satellite images, and modern computational tools were used to define the alignments of the roads. Expeditions were also made to gather topographic data and information on soils, natural profiles, drainage patterns, and other terrain aspects, with intensive collection and use of Global Positioning System data. Afterward, different access alternatives were designed and their costs estimated, and life-cycle cost analysis was performed to select the most convenient ones. This study is a significant contribution to the long-delayed development of a vast region located in the southwest frontier in the province of San Juan.