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Volume 9, No. 18Journal 18

DOI:https://doi.org/10.15517/3qe0t678

Published October 21, 2025

Scientific Papers

  1. Álvaro Ulloa Calderón , William Vargas Monge (Author)

    Simplified Methodology for the Evaluation of Geotechnical Vulnerability of Embankments on Mountain Roads in Costa Rica

    This article presents a simplified evaluation method of the geotechnical vulnerability of road embankments on hill slopes that can be applied in risk management of mountainous roads. It is based on a theoretical stability analysis using different geometric configurations and geotechnical properties to simulate the most frequent conditions found in the mountainous routes of Costa Rica. 

    This investigation evaluates the stability of three models with different geometric, physical and geotechnical characteristics: "Varablanca", based on a real site and composed by two materials (foundation soil and fill), "infinite slope" and "Terrace embankment", composed by a single material type. The failure occurrence mechanisms in drained and undrained conditions were studied using the Bishop and modified Janbu methods and a computational software. The influence of parameters that affect stability was evaluated by changing the geometric configuration (height, width, angles of slopes, grading), geotechnical properties (water table level, humidity content, voids ratio, unit weight of materials, drained and undrained shear strength) and seismic coefficient. 

    As a general conclusion, the study confirms that failure occurs most frequently in undrained condition and it is caused by soil saturation. In drained condition, the maximum slope angle of the embankment is directly related to the friction angle of the material. In undrained condition, the maximum height of the embankment is directly related to the strength normalized by the unit weight of the material. These results show the importance of an adequate design, construction and maintenance of drainage structures to prevent damage or loss of the infrastructure. 

    The results of the study are presented in the form of equations and graphics that relate the stability safety factor with geometric, geotechnical and seismic characteristics. The use of the equations, which substitute detailed analysis for quick determination of the safety factor or the failure conditions, requires only the evaluation of material resistance parameters (φ' and c) and physical properties (ϒ), as well as the seismic coefficient (kh). 

    Five different real failure cases were analyzed in order to validate the use of simplified equations for the computation of the safety factor, the height of failure or the normalized strength. An overall error of less than 10% in all the parameters was obtained. In addition, the equations were used to propose preliminary evaluation criteria of the geotechnical vulnerability of slopes in mountainous roads. These are tools useful for risk management of mountainous roads. 

  2. Rodrigo Miró Recasens, Mauricio Centeno Ortiz, Adriana Martínez, Félix Pérez Jiménez (Author)

    Evaluation of Pavement Recycling and Rehabilitation Methods Based on the Analysis of Experimental Sections from the European PARAMIX Project

    The recycled material from milled aged asphalt pavements used to make new asphalt mixtures allows to reduce the use of new materials (aggregates and asphalt) as well as the quantity of asphalt residues left in the dumps. This represents huge advantages from the economic and ecological point of view, wich make pavement recycling to become a great alternative to be used more and more in the conservation and rehabilitation of pavements. 

    This research try to increase the experience and knowledge about recycled mixtures performance, through an analysis of the pavements structural response on hot mixtures as well as cold ones on trial sections made in the european research project PARAMIX (Road pavement rehabilitation techniques using enhaced asphalt mix), sponsored by the European Union. The fundamental objective was to improved materials design and construction techniques for pavements rehabilitation using recycled mixtures. 

    First of all, this research describes the rehabilitation actions and what types of mixtures were used in the different trial sections. In adition, deflections are analyzed before and after each rehabilitation, as well as the test laboratory results made with extracted samples, wich make possible to estimate the service period of the different pavement sections. 

  3. Breno Salgado Barra, Leto Momm (Author)

    Empirical-mechanistic evaluation of flexible pavement structures through a comparison of computational tools and laboratory fatigue test data

    The main target of this paper is to evaluate the mechanical performance of asphalt concrete pavement structures designed using the method adopted by the Brazilian National Department of Transportation Infrastructure (DNIT). This method adopts the conversion principle of traffic volumes generated from different intensities of load spectra to those related to an equivalent single axle load (ESAL) of 8.2tf. The traffic volume data used to design the relevant pavement structures was taken from research studies conduced by the Brazilian Military Institute of Engineering. These studies were concerned with a highway project, called BR-163, located in the Amazon Region. This highway would constitute an important route to transport the Brazilian soy production for international exportation from Brazil's northern ports. From the traffic data, it was possible to obtain the strain levels generated in every layer of the various pavement structures, using computerized pavement design tools, such as ELSYM 5 and EVERSTRESS 5.0. Special analyses were developed for the bottom of the surface layers to compare traffic damage effect calculated by the DNIT empirical method and that provided by a laboratory fatigue equation. The fatigue equation comprised tensile microstrains generated by the 8.2tf ESAL and by a series of tandem axle loads ranging from 17.0 to 26.0tf. 

  4. Carlos Wahr Daniel, Christian Montenegro Araya (Author)

    Comparison of new flexible pavement design according to the AASHTO 93 design method, current Chilean regulations, and the NCHRP 1-37A mechanistic-empirical pavement design guide

    This research presents a new flexible pavement designs comparison between the design method presented in AASHTO 93, the valid regulations currently in Chile and the Empirical-Mechanistic Pavements Design Guide NCHRP 1-37A. This work was made for pavements of Valparaíso Region, Chile. 

    The NCHRP 1-37A design guide introduced a new concept for the traffic data: the load normalized spectrum by axles in replacement of the equivalent axles. To obtain this new variable is necessary to apply the proposed guide methodology, using the information of fixed weigh located in the Metropolitan Region. The variable associate to climate is incorporated to the design through the use of weather stations that are adjusted to the study region, created from temperature data, wind velocity, cloudiness, rainfall and relative humidity. Regarding to the pavement structure, this research choose designs that comply with the national specifications and based on asphalt mixtures properties it develope Master Curves, according to the Level 2 of the Empirical-Mechanistic Pavements Design Guide NCHRP 1-37A. To do these characterization, were employed six asphalt binders CA 60/80 from the main asphalt industries of the country and five asphalt mixtures designs actually employed. 

    From the results obtained by three programs, as a summary, is dear that the structure does not vary substantially, although it is a difference between the designs based on AASHTO 93 and PAVIVIAL: these do not estimate distress development, contrasting with the predictions obtained by the Empirical-Mechanistic Pavements Design Guide NCHRP 1-37A It's important to emphasize that in the empirical-mechanistic procedure the distress models have not been calibrated for the national realty. which impacts in the results obtained in this study. 

  5. Jorge Alarcón Ibarra, Julio Alejandro Chávez Cárdenas, Carlos Chávez Negrete, Limbert Ramón Cortés Bautista (Author)

    Study of the affinity of a crushed basalt aggregate using conventional asphalts and adhesion-promoting additives

    Traditional methodologies for quality analysis of the stone aggregates for pavements use include tests such as Los Angeles Abrasion, Density, Absorption, etc., these tests show physical properties of the stone aggregate. However, it's very difficult to analyze their performance when aggregates are mixed with asphalt. This research is intended to show the importance of analyze the affinity between aggregate and asphalt in a mechanical way, to guarantee that the asphalt mixtures perform adequately and the convenience to use additives that enhance adhesiveness in certain cases. 

    In addition, a decision was taken to do in the Laboratory of Materials of the Universidad Michoacana de San Nicolás de Hidalgo a complete research of the affinity that exists between a stone aggregate of the ales region of Morelia, Mexico and an asphalt type AC-20 using two types of additives in different proportions. For this analysis, the department decided to use the UCL Method (Universal Method of Characterization of Binders), because it shows in a clear and simple way the performance of different types of asphalt in combination with different aggregates. Besides, this analysis allows observing their behavior in an extensive work temperatures range that can vary from the -10° C to 60° C. These temperature ranges cover the possibilities that are presented in real conditions on the region.  

    It was decided to analyze a crushed material of the Municipality of Tarimbaro Michoacán that complies with all the standards to be use in asphalts mixtures, but it has faced some affinity problems in different projects. This material was mixed with a conventional asphalt type AC-20 of Salamanca and also used different additives that enhance adhesiveness, well provided by a Guadalajara Jalisco Company, to see any variation of the losses in UCL Method. 

    The results obtained clarify that this test shows very valuable information that complements the conventional tests of asphalts characterization that will be used for pavements construction and that it's useful to take decisions regarding to choose the most adequate additives for each situation.