Sistema Regional de Información
en línea para Revistas Científicas de América Latina,
el Caribe, España y Portugal

According to the needs of professionals, researchers, builders, inspectors and all those involved in the road sector, there is then a guide to basic tests required in quality control in three general stages during construction of asphalt pavements. This article will refer to the specifications and relevant national and international, norms and and standard procedures used in LanammeUCR for sampling and assessment the behavior of different materials that make an asphalt pavement.

This paper is about a series of recommendations to assure the reliability of concrete strength results sampled in the field. Each of the steps to achieve this goal is described. Those are: sampling, molding, curing, protecting and testing. The provided recommendations are based on a deep study of the practices and standards as well as the experience acquired in the process of testing concrete cylinders at LanammeUCR. This paper is intended mainly for testing laboratories which execute sampling and testing of concrete but also for engineers and professionals that work in the construction of buildings.

Thermogravimetry is a technique that has been used for characterization of materials, especially coal and clays. In recent years, the technique has been extended to other materials. This technique, in addition to other thermal techniques, provides a source of information not only thermal but also chemical. It is important to note that this method does not reveal the chemical composition of the material that is being studying nor identify the thermal changes that are not associated with mass changes such as crystallization or glass transition. Thermogravimetry analyses the mass changes as a result of a variation in temperature or by subjecting a material to a set temperature for a defined period. The mass changes identified can determine under what conditions the materials decompose. The results are expressed graphically by thermograms.

Costa Rica has used asphalt emulsions for different purposes quite extensively over the years. Nevertheless, asphalt emulsion preparation and its storage care needs have been overlooked by users who employ these emulsions on a regular basis. This article intends to provide details about the procedures involved in different asphalt emulsion lab preparation. In addition, the article also gives a series of recommendations about how to properly handle these emulsions during and after the manufacturing process so that the specific desired application outcome can be achieved.

This document presents a brief explanation of the shear strength theory, an overview of the main types of triaxial tests that are performed more frequently in a geotechnical laboratory and a detailed listing of the different components that make up the triaxial test equipment acquired by the LanammeUCR Geotechnical Laboratory. Finally it presents the assembly and some of the results from the execution of a UU triaxial test

The characterization includes asphalt emulsions assay to quantify the distillation bitumen content. This test is performed for a long time, both in Costa Rica and other countries. It is a traditional and accurate method, which has been a very good choice for the recovery of residual asphalt bitumen emulsion, but is time consuming and requires the skills of the analyst to identify key moments of separation. Given that new technologies can be used to quantify the composition of asphalt emulsions, it intends to apply instrumental techniques thermogravimetric analysis. The first phase of the project is to determine the parameters to be used in a thermogravimetric analyzer (TGA) to get comparable results with the method of distillation. For which the temperature ramp and the heating rate in each of the samples are varied. Although the results show no statistically significant differences, the effect of parameter changes in the thermogravimetric analysis results in perceived. The results show that it is possible to use the instrumental thermogravimetric analysis to determine the percentage of asphalt emulsion residue, but also allows establishing the conditions to be defined as part of a process of analysis should be selected according to the results heating rates 10 ° C / min or less than 5 ° C / min. It also determined that rates of warming modulated not give good results. In the next phase of the project the methods will be compared using emulsions manufactured in the laboratory, considering the parameters defined in this phase.

Due to problems related to water in many pavements around the world it has been searched a way to improve the materials that compose asphalt mixtures. For this purpose different test methods have been developed to measure the properties of the materials related with moisture damage. The test methods that are described are known as goniometry test and asphalt bond strength test (ABS). Many researches in this field are focused on the physicochemical properties of asphalts related with adhesion failure. This article aims to describe two of the main test methods that are used in laboratories in order to measure the work of adhesion in asphalt binders and emulsions. Procedures described here can be of interest to engineers and professionals that work in pavement design and related areas.

In 2004 there were not available standardized methods of reducing a large sample of hot mix asphalt and the quartering methods for aggregates were taken as reference, but these do not take into account the temperature at which the mix should be heated to ensure workability and the way to not affect the properties of the mixture within other details. It is for this reason that LanammeUCR implemented a completely new method to be able to certify the sampling of hot mix asphalt in the truck transports, so this study was used to include the quartering method to show that the sub-samples are representative of the lot. An experimental design was developed which included the new quartering method for multiple sampling boxes and then measure the asphalt content and gradation with the ignition test for each subsample and also the maximum theoretical specific gravity was performed, it was shown that with this method it is possible to obtain representative subsamples with good repeatability and also found that the segregation of the mixture was eliminated using the gutter system that in one step the desired subsamples are obtained. This method has 11 years of implementation and the advantages over the standard method AASHTO R 47, published in 2008, is that in this approach the care that must be taken when handling hot mix asphalt are detailed, such as the temperatures at which the sample must be heated and the heating times are established as this significantly affects the material properties. Besides the use of simple hand tools that are easy and economical to manufacture they take into account an ergonomic criteria to ensure that the procedure was safe and practical.

The current article describes the testing process and analysis of 40 deformed steel bars for concrete reinforcement, which where instrumented with a conventional extensometer and a laser extensometer simultaneously. A statistical analysis was used to determine the accuracy of the measurements and data calculated from the laser extensometer's output information in comparison with that of the conventional extensometer. The observed behavior determines that the laser extensometer indicates different results when used to determine the elasticity modulus, however, it does not lead to significant differences for the determination of all the mechanical properties required by the ASTM standards A615 and A706.

This research paper presents the study of 16 samples of deformed steel wires, which were applied to tensile tests using two types of extensometers: contact and laser. The main objective of the analysis is to determine if the results obtained by the laser extensometer have sufficient accuracy to determine the tensile mechanical properties properly, in order to validate the use if laser extensometer in standard laboratory tensile tests, as well as determine a methodology of the obtainment of the mechanical properties of steel samples with an undefined yield point. From the results, it is concluded that the laser extensometer, as well as the methodology used, produce results which are quantitative similar to the contact extensometer, therefore validating its use for standard laboratory tensile testing of materials with an undefined yield point.