In this article are presented the experiences obtained in the use of basaltic slags called in Mexico "tezontles", as asphaltic pavement layers. These materials are found in a great number of cinder cones, located in a wide zone of the country, being therefore, abundant materials and of low-cost in its exploitation. The "tezontles" are lava fragments of vescular structure, and have similar aspects ot the melting slags and colors that vary from black to the red, depending of its degree of oxidation; when exploited they produce materials with particles of different sizes that vary from fragments to silty sands and have as principal characteristics: low bulk unit weight (8 to 11 kN/m3), high resistance values (CBR>100%) and degradable nature. These materials have been used in the country for many years, for highway construction in different functions, from earthworks to pavement layers, most successful as embankments on soft soils. In pavement layers its behavior has been irregular due to the degradation that the "tezontles" have suffered. It is recently, we have found the solutions for this problem, that consists in an adequate construction procedure and a protective layer of the effects of the traffic, formed by an asphalt concrete surface, with a maximum thickness of 2 mm. The article presents two cases, in which, due to the shortage of hard rock, sifted basaltic slags were used, as sub-base and base courses, completing the pavement an asphalt concrete surface of high quality of 150 and 200 mm of thickness respectively. This avoided the production of a greater volume of crushed rock aggregates and carrying it over very long distances. In each case are presented: the previous studies including test sections,the philosophy of the project, the structural models used, and the constructive procedures. The behavior studies cover three to four years of operation, and conclude that the operation has so far been satisfactory, emphasizing a Present Serviceability Index of 4.0 for each of the highways. (A)
Samenvatting