Search results for "laboratory tests"
showing 7 items of 7 documents
Use of bitumen-stabilised ballast for improving railway trackbed conventional maintenance
2018
Despite its many advantages, ballasted track needs frequent maintenance to ensure an adequate quality of service. However, tamping, traditionally used to correct geometry, causes ballast degradation and loosening of the already compacted ballast layer, which quickly returns the track to its pre-maintenance position. Then, other maintenance techniques such as stoneblowing, as well as diverse solutions that reinforce trackbed, have been developed to reduce ballast settlement and particles degradation. Given the need to further advance research in this field, bitumen-stabilised ballast (BSB) has started to be investigated by the authors as a feasible solution thanks to its easy and quick appl…
The Role of Laboratory Tests in Crohn's Disease.
2016
In the past, laboratory tests were considered of limited value in Crohn's disease (CD). In the era of biologics, laboratory tests have become essential to evaluate the inflammatory burden of the disease (C-reactive protein, fecal calprotectin) since symptoms-based scores are subjective, to predict the response to pharmacological options and the risk of relapse, to discriminate CD from ulcerative colitis, to select candidates to anti-tumor necrosis factors [screening tests looking for hepatitis B virus and hepatitis C virus status and latent tuberculosis], to assess the risk of adverse events (testing for thiopurine metabolites and thiopurine-methyltransferase activity), and to personalize a…
Fabric evolution and the related swelling behaviour of a sand/bentonite mixture upon hydro-chemo-mechanical loadings
2015
This experimental study investigates the swelling behaviour of an 80/20 sand/bentonite mixture and the associated fabric evolution under different hydro-chemo-mechanical loadings. Free and confined swelling tests are performed on specimens compacted to different dry densities and wetted with different pore fluids. Controlled suction confined swelling tests are performed to determine the suction–swelling pressure relationship for two different densities. An extensive microstructural characterisation is performed to relate the observed swelling behaviour to the evolution of the different pore networks during wetting. Based on the microstructural analysis, an expression is proposed to determi…
Role of particle characteristics in the compression behaviour of gap-graded sands
2019
Abstract The compression in gap-graded mixtures of sands with combined mineralogy has been investigated in recent research, focusing on the key factors that might imply the occurrence of convergent or non-convergent paths in compression (i.e., transitional or non-transitional behaviour). From previous work, the mineralogy of a matrix composed of larger grains seems to determine the possibility of the occurrence of transitional behaviour. Hence, if there is a strong and stiff matrix made of quartz sand particles, which are either larger than or at least of similar size to the other component, then non-convergent compression paths (i.e., transitional behaviour) are likely to occur. As a furth…
Agrigento Cathedral
2015
At present Agrigento Cathedral is affected by extensive damage that seems to be mainly due to partial slumping of the foundation soil. The chapter deals with the state of damage that affects the cathedral and the investigation carried out for the mechanical characterization of the construction, the formulation of an FE model and the assessment of the safety level with respect to the service loads and with respect to exceptional loads like seismic ones. In the chapter the details of the above investigation are discussed, consideration also being given to the monitoring carried out in order to understand whether the phenomenon affecting the cathedral is ongoing. The results of the monitoring …
EFFECTIVENESS OF BASALT FIBRE-REINFORCED CEMENTITIOUS SYSTEMS IN CONFINING MASONRY MEMBERS: AN EXPERIMENTAL INVESTIGATION
2020
The use of composites based on fibre-reinforced polymers (FRPs) to strengthen masonry columns has become a common practice in the last decades. FRPs, however, exhibit some shortcomings when applied to masonry substrates, due to the organic nature of their matrix. For this reason, increasing attention is paid today to composites based on fibre-reinforced cementitious matrices (FRCMs), in which the polymeric matrix is replaced with an inorganic matrix (such as cementitious mortars). Cementitious matrices guarantee higher breathability and compatibility with the substrate, less sensitivity to debonding at the interfaces, and higher resistance to fire and high temperatures. Moreover, due to the…
Experimental Investigation for Local Tank Inflow Model
2014
In the present paper the effect of private roof tanks and of the float valve characteristics on apparent losses due to water meter errors was investigated via an experimental study. The tests were carried out at the Environmental Hydraulic Laboratory of the University of Enna (Italy), on a high-density polyethylene (HDPE 100 PN16) looped distribution network. The experimental results showed that network pressure plays an important role in the characterisation of the floating ball valve emitter law, but the tank operating condition is the most relevant aspect to be considered mainly for water meter error evaluation. (C) 2014 The Authors. Published by Elsevier Ltd.