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

For a binder to provide cohesion to a granular material, it must first envelop and coat it, adhering to it. If there is no aggregate-binder adhesion, the aggregate particles will hardly remain united, and the mixture will easily disintegrate. This aggregate-binder bond, which forms easily when the aggregate is dry and the binder has a fluid consistency, can be lost in the presence of water. The aggregate has a greater affinity for water than for the bitumen, and water gradually gets between the bitumen and the aggregate, causing a stripping process.

This work describes the "RP" test, developed in Chile, which, in summary, consists of measuring the resistance to penetration under controlled temperature and speed conditions in open-graded asphalt mix specimens manufactured with varying binder contents. The optimal mix is considered to be the one that exhibits the highest resistance to penetration. The influence of temperature, aggregate characteristics, and type of binder falls outside the scope of this study. The "RP" method is parametric and empirical in nature and is currently in an exploratory stage.

Concrete pavements are usually placed continuously in widths between 7.5 m and 15.25 m. Sometimes longitudinal cracks occur in the middle of the slab. This usually happens the day after finishing the placement. These cracks appear mainly in concrete pavements placed in the morning hours on very hot days.

This article presents some experiences regarding the use of thin layer nuclear densimeters in road maintenance projects in Costa Rica. Road maintenance programs in Costa Rica must begin with basic road maintenance activities, such as drainage and vegetation cleaning, pothole repair, and the restoration of severely damaged surface areas. In these projects, the fundamental task was the construction of patches in asphalt pavements with high levels of quality, both in the mixture used and in the repair procedures.

The performance of asphalt mixtures is the result of the combination of a large number of factors: materials and processes. In order for an asphalt mixture to perform as expected (service life equal to the design life), it is required that all materials and processes be suitable and uniform.

The methodology of the Marshall design model was developed with the purpose of determining the optimal proportions of asphalt binder and aggregate (separated by sieves), which simultaneously achieve characteristics of stability, durability, flexibility, and porosity in the asphalt mixture thus produced.

The predominant trend in today's industrial activities is focused on the development of quality systems to satisfy customers. The following paragraphs provide an overview of some basic elements for developing a quality system in a construction company. The recommendations are based on the international ISO 9000 standards, which represent the global trend for organizing and supporting quality systems within service and product-based companies.

In developing countries, especially in the context of Latin America, during the 1990s a long process of analysis and reflection arose regarding the prevailing situation of the road network management models of these countries, and the consequent impact on economic development and on the quality of life of the population.

The asphalt mixtures commonly used in road construction are of the dense or coarse type. For the sake of clarity, these mixtures will hereafter be referred to as conventional. In wearing courses, dense mixtures are generally used, while in intermediate or base layers, either dense or coarse mixtures are applied.

The 'Virginia Smart Road test section' project provides an excellent opportunity to test various hypotheses regarding pavement performance, material characteristics, and their combinations. The flexible pavement section includes 12 segments of approximately 100 meters in length, which have been thoroughly studied using a complex arrangement of sensors installed beneath the roadway during its construction. During pavement construction, a Falling Weight Deflectometer (FWD) was used to collect deflection data by applying different loads on the pavement surface. In addition, the resilient modulus of the granular subbase material (21-B) was evaluated. The results of the resilient modulus for the subbase layer (21-B) in the 'Virginia Smart Road' indicate that the material modulus is a function of stress, and its behavior can be predicted using a k-θ model. The deflection results from the FWD testing confirm the stress-dependence of the moduli; however, the FWD results show a less pronounced influence of stress state on the moduli. In general, the modulus obtained through backcalculation can be compared with the modulus measured in the laboratory.