Search results for "technical"
showing 10 items of 955 documents
Earth Bricks with Halloysite Nanoclay: Research and Experimentation for the Sustainability of Materials
2021
This paper illustrates the experimentation activities on rammed earth and nanotechnologies. The experimental research was carried out with the aim of improving the performance of rammed earth bricks with clay nanotubes, creating a ‘new material’ with reduced embodied energy and low CO2 emissions into the atmosphere. Specifically, the analysed performances are related to the compressive strength that expand their area of use as a building material.
Forecasts on the development of hydrogen refuelling infrastructures in Portugal
2021
In Portugal, the transition to new forms of mobility has begun in recent years, but there are still obstacles to overcome. Currently, hybrid vehicles (PHEVs) are the most widespread and accepted by the community and that is probably due to range anxiety, having in fact the possibility of double charging (both through the thermal engine and the electric battery). Furthermore, it must be considered that in addition to electric vehicles, another valid alternative to mobility in the near future is the hydrogen vehicles one. These appear to be even more sustainable from the point of view of air emissions, but on the other hand the costs for the production of hydrogen are still too high. Then, th…
Origin of Blue Sapphire in Newly Discovered Spinel–Chlorite–Muscovite Rocks within Meta-Ultramafites of Ilmen Mountains, South Urals of Russia: Evide…
2019
Blue sapphire of gem quality was recently discovered in spinel&ndash
Recommendation of RILEM TC237-SIB on fragmentation test for recycled asphalt
2019
This recommendation describes how to characterize the reclaimed asphalt through the fragmentation test. The guidelines given hereafter are based on the results of a round robin test organized by the RILEM Technical Committee 237-SIB ‘‘Testing and characterization of sustainable innovative bituminous materials and systems’’ and provide information on the testing procedure, data analysis and indications for the preparation of a test report.
Recycled aggregates derived from excavation materials — mechanical performance and identification of weak minerals
2022
AbstractThe present study investigates the mechanical performance of recycled aggregates derived from excavation materials (REM). REM is blended with different quantities of recycled phyllite materials (RPM) and is investigated by Los Angeles (LA) and micro-Deval (MD) tests. X-ray diffraction (XRD) and acid solubility test are performed on the pulverized fractions < 1.6 mm obtained from the LA and MD tests to assess the respective degree of fragmentation and wear of mineral components. The results of the materials in unblended conditions showed considerable difference between MD performance while similar performance was found for LA. Furthermore, about 40% of RPM was sufficient to blend …
Cluster analysis to support microzonation studies
2015
In recent times the use of microtremor techniques for subsoil investigation increased significantly. The use of HVSR (Horizontal to Vertical Spectral Ratio)technique for seismic microzoning studies allows in many case to obtain detailed reconstruction of the roof of the seismic bedrock and to identify areas with similar seismic behaviour. Two different algorithms of clusteringhave been tested on a HVSR datasets acquired for studies of seismic microzoning in various Sicilian urban centers. HVSR data were previously properly processed to extract frequency and amplitude of peaks by a code based on clustering of HVSR curves determined in sliding time windows.To select an optimal set of time win…
Assessment of the Reliability of the SPAC Method in Urban Areas
2015
We have carried out several long-term measures of seismic noise with triangular arrays of broad-band seismic sensors, to investigate the reliability of the SPAC method in urban areas. We investigate the stationary and anisotropy of the microtremor wave field. We have found that the anisotropy of the microtremor wave field can be evaluated analyzing the HVNSR as function the azimuth. Furthermore, we showed as strong anisotropies in the microtremors are often observable in particular at high frequencies (> 1 Hz). We have verified as microtremors can be difficult to considered as ergodic processes, and for this reason time averaging, also even over a long periods of time, cannot replace an app…
On the stationarity of the horizontal to vertical noise spectral ratio
2015
The Horizontal to Vertical Noise Spectral Ratio (HVNSR) method is nowadays widely used to estimate the resonance frequencies of geological structures. In the HVNSR method, seismic noise is considered as a stationary stochastic process. However, especially in industrialized/urbanized area, this is a very strict assumption seldom occurred. Several sources of noise can generate non stationary and anisotropic microtremor fields. To investigate the stationarity of microtremor, we have carried out several long-term measures of seismic noise with broad-band seismic sensors, in areas where the main source of anthropogenic noise is well known. The signals acquired have been analyzed both in frequenc…
Comparison of different acquisition patterns for 2D tomographic resistivity surveys
2015
A systematic comparison is presented between some 2D resistivity models and their images by the inversion of synthetic datasets relating to three different arrays, suitable for multichannel data acquisitions (dipole-dipole (DD), Wenner-Schlumberger (WS) and multiple gradient (MG)). The goal is to study how the measurement errors affects the resolution of the tomographic models and the ability to retrieve correct information on buried targets. We considered different data acquisition patterns, gradually increasing the complexity of the combinations of potential spacing and dipolar distance. To this end we increased the number of current dipoles to obtain approximately the same amount of meas…
Seismic investigation for the characterization of a gravity concrete dam
2016
Monitoring of large-scale infrastructures plays an important role for public safety and prevention. The control of the safety assessment of a dam is largely dependent on knowledge of the mechanical parameters of the actual construction, as well as its geological substratum. The application of geophysical methods can considerably contribute to the examination indicating the less consolidated material and the degradation of mechanical parameters. A seismic tomographic approach has been used in a typical gravity concrete dam without reinforcement to detect mechanical properties of the body of the dam and its geological setting. Three seismic travel time tomographies in the dam body as well as …