Search results for "CONSTRUCTION"
showing 10 items of 2670 documents
Considerations on factors affecting biochar densification behavior based on a multiparameter model
2021
The optimization of upscaled biochar pelleting is limited by lack of knowledge regarding the effects of process parameters. A multiparameter model, coupled to a single pellet press unit, was for the first time applied to biochar production to predict the upscaled biochar pelleting process behavior. The model permits to estimate in a time and cost-effective way how the die friction forces, quantified through the pellet exiting pressure, are affected by the key process parameters. It was observed that to achieve acceptably low exiting pressures (in the order of 100 MPa), it was critical to produce biochar at high temperatures (e.g. 600 °C). Addition of water as a binder is also beneficial, wh…
Anisotropy of the stiffness and strength of rigid low-density closed-cell polyisocyanurate foams
2016
The cells of polymer foams are usually extended in the foam rise direction, causing a geometrical anisotropy, the degree of which, characterized by the cell aspect ratio R, depends on foam density and production method. Such elongated cell shape translates into anisotropy of the mechanical properties of foams. Rigid low-density closed-cell polyisocyanurate foams of apparent density ranging from ca. 30 to 75 kg/m3, containing polyols derived from renewable resources, have been produced and tested for the stiffness and strength in the foam rise and transverse directions in order to experimentally characterize their mechanical anisotropy. Analytical relations for foams with rectangular paralle…
Experimental investigation on compressive behavior of bottle-shaped struts
2011
The goal of this investigation was the experimental verification of the dispersion of compression in bottle-shaped struts. Two typical bottle shapes were generated under load in compression concrete—both drilled and undrilled—and were reinforced concrete prismatic members with loading steel plate having a reduced area with respect to the entire cross section of the members. Axial load, and axial and lateral strains were recorded during the tests to evaluate the effects of key parameters. The comparative analysis of the experimental results showed that: 1) the presence of a hole produces a variation on the stress and strain distribution and a reduction in the load-carrying capacity; 2) the r…
Novel method of phosphorescent strontium aluminate coating preparation on aluminum
2018
This work was supported by the ERDF , European-Union Project No. 1.1.1.1/16/A/182 .
Investigation on fracture of epoxy-filled composites by acoustic emission
2016
Acoustic emission (AE) technique is widely used to monitor failure processes in composite materials includ-ing development of cracks and plastic deformations within the polymer matrix, fracture and debonding of inclusions, etc. In this study, the AE technique was applied investigating failure character of epoxy polymers with different content of nanofiller – fine polyethersulfone (PES) powder. Variation of material properties of the epoxy with 0, 5%, 7.5%, 10%, and 12.5% concentration (by weight) of the PES was assessed experimentally. Correlation between the PES content and the modulus of elasticity was found negligible. The same was characteristic for the tensile strength. Whereas, such a…
Flexural behaviour of concrete corbels containing steel fibers or wrapped with FRP sheets
2005
In the present paper an analytical and experimental investigation referring to the flexural behaviour of reinforced concrete corbels subjected to vertical forces is presented. For fixed shape and dimensions of the corbels the experimental investigation analyses the effects of the following: longitudinal and transverse steel reinforcements; fiber reinforced concrete (FRC) with hooked steel fibers; external wrapping retrofitting technique with a thin layer of carbon fiber sheet (CFRP). The analytical model based on equivalent truss structures, allows one to determine the bearing capacity of corbels, distinguishing the different ultimate states reached. The analytical results are then compared…
Numerical Modeling Approaches of FRCMs/SRG Confined Masonry Columns
2019
The Fabric Reinforced Cementitious Matrices (FRCMs) and Steel Reinforced Grout (SRG) are a promising strengthening solution for existing masonry since inorganic matrix is considerably compatible with historical substrates. The present paper is focused on a Finite Element (FE) analysis of masonry columns confined with FRCM composites developed by Abaqus-code. The masonry columns were modelled using a macro model approach. The model was performed by using the following functions Concrete Damage Plasticity (CDP) and the Plastic (P) in order to describe the constitutive laws of material for masonry columns and external reinforcement, respectively. Typical failures of FRCM-systems are slippage o…
Laboratory mix design of asphalt mixture containing reclaimed material
2014
This paper presents a study on the production of asphalt test specimens in the laboratory containing reclaimed asphalt. The mixtures considered were stone mastic asphalt concrete mixtures containing up to 30% of reclaimed asphalt. Specimens were compacted to the reference density obtained from the Marshall mix design. Gyration compaction method was used for preparing specimens for the experimental programme, while coring and cutting methods and X-ray computed tomography (CT) were used to investigate the change in properties within the specimens and to validate the selected methodology. The study concluded that gyratory compaction is suitable to produce homogeneous test specimens also for mi…
Effect of mixing time on reclaimed asphalt mixtures: An investigation by means of imaging techniques
2015
This paper presents an application of imaging techniques to investigate the distribution of reclaimed asphalt and air voids within gyratory compacted specimen. Stone Mastic Asphalt specimens containing reclaimed asphalt, were produced at five different laboratories participating in the collaborative project Re-Road: University of Nottingham, Belgium Road Research Centre, Danish Road Directorate, TU Braunschweig and Laboratoire Centrale de Ponts et Chaussees (now IFSTTAR). This study applies the X-ray Computed Tomography and Optical Microscopy techniques to view the internal structure of the specimen with particular focus on the air voids and reclaimed asphalt distributions within the specim…
Effects of weathering on the performance of self-cleaning photocatalytic paints
2019
Abstract The use of photocatalytic products for the surface coating of buildings is spreading more and more, because of the reduction of atmospheric pollutants and the colour maintenance of the paints over time with reduction of the maintenance costs and the improvement of the aesthetic appearance. The study reports the evaluation of the effects of the atmospheric conditions on three commercial photocatalytic paints containing TiO2. In particular tests were carried out by using samples subjected to accelerated aging inside a climate chamber and naturally aged by exposure for two years to the external environment of the city of Palermo (representative of a coastal environment of the Mediterr…