46 research outputs found
Evaluación del comportamiento a macro-fisuración por fatiga de mezclas bituminosas modificadas con polvo de neumático
The use of crumb rubber modified bitumen (CRMB) in asphalt mixes is a road engineering technology
that has become increasingly important in recent years. Given the many economic and environmental
benefits of this type of binder, the goal is to give CRMB the same level of performance as conventional polymermodified
bitumen. The appearance and propagation of cracks due to fatigue phenomena is one of the most
common distresses affecting road pavements. Since crumb rubber enhances the mechanical properties of asphalt
mixes, it can provide a viable solution for fatigue cracking. This paper presents the results of a comparative
analysis of the fatigue-cracking behavior of asphalt mixtures manufactured with crumb rubber modified bitumen
and polymer-modified bitumen.El empleo de betunes modificados con polvo de neumático usado en la fabricación
de mezclas bituminosas es una de las técnicas que mayor auge está teniendo en los últimos años en la
ingeniería de carreteras. Dadas sus grandes ventajas económicas y ambientales, este tipo de ligantes pretende
conseguir prestaciones similares a la de los betunes modificados con polímeros utilizados habitualmente.
La aparición de fisuras debido a fenómenos de fatiga es una de las patologías más comunes en firmes de
carretera. Debido a las mejoras de las propiedades mecánicas del betún aportadas tras la incorporación
de polvo de neumático, las mezclas fabricadas con estos ligantes se postulan como una posible solución a
dicho problema. En este artículo se lleva a cabo un análisis comparativo del comportamiento a fisuración
por fatiga realizado sobre mezclas bituminosas fabricadas con betún modificado con polvo de neumático y
con polímeros.This research was carried out within the framework
of the R + D + i project entitled Proyecto Integrado
de Investigación, Desarrollo y Demostración de
Tecnologías para la aplicación de neumáticos fuera
de uso en firmes de carretera resistentes a la propagación
de grietas (ref. IDI-20091076), funded by the
Center for Industrial Technological Development
(CDTI) of the Ministry of Science and Innovation
in Spain
Porphyromonas gingivalis Participates in Pathogenesis of Human Abdominal Aortic Aneurysm by Neutrophil Activation. Proof of Concept in Rats
International audienceBACKGROUND: Abdominal Aortic Aneurysms (AAAs) represent a particular form of atherothrombosis where neutrophil proteolytic activity plays a major role. We postulated that neutrophil recruitment and activation participating in AAA growth may originate in part from repeated episodes of periodontal bacteremia. METHODS AND FINDINGS: Our results show that neutrophil activation in human AAA was associated with Neutrophil Extracellular Trap (NET) formation in the IntraLuminal Thrombus, leading to the release of cell-free DNA. Human AAA samples were shown to contain bacterial DNA with high frequency (11/16), and in particular that of Porphyromonas gingivalis (Pg), the most prevalent pathogen involved in chronic periodontitis, a common form of periodontal disease. Both DNA reflecting the presence of NETs and antibodies to Pg were found to be increased in plasma of patients with AAA. Using a rat model of AAA, we demonstrated that repeated injection of Pg fostered aneurysm development, associated with pathological characteristics similar to those observed in humans, such as the persistence of a neutrophil-rich luminal thrombus, not observed in saline-injected rats in which a healing process was observed. CONCLUSIONS: Thus, the control of periodontal disease may represent a therapeutic target to limit human AAA progression