Performance assessment and ranking of natural and recycled granular materials for road subbase layers by precision cyclic triaxial testing (EN 13286-7)

The cyclic load triaxial test is a laboratory test that allows investigating the mechanical behaviour (resilient and permanent strains) of unbound granular materials used in subbase and capping layers of roads. The resilient modulus and permanent strains are required to assess material performance and serve as key input properties in modelling and designing roads. This paper will present the investigation of resilient and permanent strains as specified by European standard EN 13286-7, for a limestone aggregate and recycled materials (one crushed concrete aggregate and two blended crushed waste aggregates) used in subbases and capping layers of road structures in Belgium. Method B (constant confining pressure) was used in most of the tests for resilient strains. The influence of water content was also analysed. Permanent strains were analysed after conditioning by 20,000 cycles of single-stage loading. The paper will also present the results obtained on the limestone aggregate only in analysing resilient strains with both axial and confining cyclic loading – method A. The resilient moduli were deduced from the test results and compared to those obtained with method B. The calibration of the LDT’s in air proved to remain valid when they were used in water (variable confining pressure tests). The natural and recycled materials were ranked starting from the characteristic values of resilient modulus and characteristic permanent axial strain. This ranking based on a mechanistic approach was compared with conventional ranking based on indicative properties determined in empirical tests. This research work produced an excellent set of findings for the mechanical characterization of unbound subbase materials through the cyclic triaxial test, thus contributing to a more widespread and common use of recycled materials in geotechnical engineering

Characterizing natural and recycled granular materials for (sub)base layers of roads by cyclic triaxial testing

The cyclic load triaxial test is a laboratory test which makes it possible to study the mechanical behaviour (resilient and permanent deformations) of unbound granular materials used in base and subbase layers of roads. This paper describes the equipment of the Belgian Road Research Centre and presents the first results obtained for a natural material commonly used in Belgium and two recycled materials (crushed concrete aggregate and steel slag). The influence of water content and the compaction method on resilient strains is analysed.University of Illinois at Urbana-Champaig, Illinois Center for Transportation, Center of Excellence for Airport Pavement Research, University of Illinois Railroad Engineering Program, Illinois Department of Transportation, U.S. Department of Transportation, Federal Aviation Administration, Association of American Railroads, Transportation Research Board, American Society of Civil Engineer

Mechanical behavior of natural and recycled granular materials for roads

This paper presents a study on resilient and permanent strains measured with the precision cyclic load triaxial test on a limestone aggregate (reference material) commonly used in subbase or capping layers in Belgium and on two recycled materials (steel slag and crushed concrete aggregate) also used in subbase or capping layers. The influence of stress level, water content, density, and compaction method (vibrating hammer or vibrocompaction) was analyzed. Tests with one cyclic stress level on one specimen (single stage loading) and tests with several cyclic stress levels on the same specimen (multi-stage loading) were performed, in order to evaluate the prediction capability of the multi-stage loading test. The latter test procedure is quicker and more practical. Although the permanent strains obtained by the two test procedures were different, the multi-stage loading method did indicate the trend of the long-term behavior of the material. The test results showed that in comparison with the reference material, the recycled materials, particularly the steel slag, exhibited good mechanical behavior (high stiffness, high strength, and good resistance to permanent strains) under-well controlled conditions of water content

Septicémie à Arcanobacterium haemolyticum (Corynebacterium haemolyticum) et Streptococcus milleri

[Septicemia caused by Arcanobacterium haemolyticum (Corynebacterium haemolyticum) and Streptococcus milleri ] Arcanobacterium haemolyticum (Corynebacterium haemolyticum) and Streptococcus milleri were isolated from the blood of a 15-year old boy presenting with unilateral tonsillitis, pulmonary abscesses and septicaemia. This report summarizes the clinical presentation and the bacteriological findings of the case

Stable biofilms of Rhodococcus erythropolis T902.1 in draining pavement structures for runoff water decontamination

Permeable Pavement Systems (PPS) are sustainable devices designed to collect, store and treat urban stormwater before its release into the ground. However, this system must sufficiently retain pollutants brought by water runoff in order to comply with the current legislation. This study aims at evaluating the implementation in PPS of a hydrocarbonoclastic bacterium, Rhodococcus erythropolis T902.1, in terms of resilience and improvement of the degrading capacity. First results revealed that this strain could durably colonize the different gravels used in the construction of PPS. A 15-month experience in a real parking area showed that this biofilm remained viable without any replenishment of nutrients or bacteria. During accelerated pollution tests at a pilot scale, the structure bioaugmented with pre-coated biofilms was more efficient than a non-inoculated structure to limit hydrocarbon leaching below 50 μg L−1 and to degrade hydrocarbons adsorbed to the gravels. Over the long term, this innovative assembly should maintain the degrading capacity of PPS and ensure an effective treatment of stormwater before its infiltration into the soil.dPo

Phenotypical characterization of alpha-galactosidase A gene mutations identified in a large Fabry disease screening program in stroke in the young.

OBJECTIVE: In the Belgian Fabry Study (BeFaS), the prevalence of Fabry disease was assessed in 1000 young patients presenting with stroke, unexplained white matter lesions or vertebrobasilar dolichoectasia. The results of the BeFaS suggested that Fabry disease may play a role in up to 1% of young patients presenting with cerebrovascular disease. However, the clinical relevance was unclear in all cases. We report on detailed phenotyping in subjects identified with alpha-galactosidase A (alpha-Gal A) enzyme deficiency or GLA mutations identified in the BeFaS (n=10), and on the results of family screening in this population. METHODS: Family screening was performed to identify additional mutation carriers. Biochemical and/or clinical evaluation of all subjects (BeFaS index patients and relatives carrying a GLA mutation) was performed. RESULTS: Genetic family screening revealed 18 additional GLA mutation carriers. Bloodspot alpha-Gal A enzyme activity was normal in all GLA mutation carriers, even in 2 males with the p.A143T mutation. Plasma Gb3 and lyso-Gb3 levels were normal in all subjects. Elevated Gb3 in urine was detected in 2 subjects. Some classic clinical signs of Fabry disease, like angiokeratoma or cornea verticillata, could not be detected in our population. Cardiac symptoms of Fabry disease were found in 6 out of 10 p.A143T carriers. No signs of cerebrovascular disease were found in the relatives with a GLA mutation. CONCLUSIONS: We could not identify mutations causing the classical clinical phenotype of Fabry disease in our cerebrovascular disease population. Enzyme activity analysis in bloodspots and plasma may fail to identify late-onset variants of Fabry disease. We recommend genetic testing when an atypical, late-onset variant of Fabry disease is suspected in a male cerebrovascular disease patient. However, this may lead to the identification of non-disease causing or controversial genetic variants