Effect of the Chemical and Mechanical Recycling of PET on the Thermal and Mechanical Response of Mortars and Premixed Screeds

In this paper, recycled polyethylene terephthalate (PET) was used to produce eco-innovative engineering materials with optimized performance, minimizing the environmental impact deriving from plastic consumption activity and limiting the continuous consumption of raw materials. The recycled PET obtained from waste bottles, commonly used to improve the ductility of concrete, has been used with a different weight percentage as plastic aggregate in the replacement of sand in cement mortars and as fibers added to premixed screeds. In detail, the effect of PET treatment (chemical or mechanical) on the thermal performance was evaluated. Non-destructive physical tests were conducted to determine the thermal conductivity of the investigated building materials. The performed tests showed that chemically depolymerized PET aggregate and recycled PET fibers derived from plastic wastes can reduce the heat conduction capacity of the cementitious materials with limited reduction in compressive strength. The results of the experimental campaign have made it possible to evaluate the influence of the recycled material on the physical and mechanical properties and its feasibility in non-structural applications

Dynamics of a Flexible Roof Test Model under Ambient Vibrations Measurements

Flexible roofs are sensitive to wind actions because they are light, and their deformability can induce local or global instability. In most cases, their design requires experimental wind tunnel testing to investigate the aeroelastic phenomena and the structural response under the wind. However, the reduced scale necessary in wind tunnels makes the dynamic identification of the test model difficult. Several approaches of multi-modal dynamic identification can be used, even if a specific approach is not defined for geometric nonlinear flexible roofs. Many times, the choice of the position of the sensors is affected by the unknown roof dynamics. This paper investigates the ambient vibration time-dependent accelerations for a flexible roof scaled model through Singular Value Decomposition (SVD) and their spatial correlations with the purpose of analyzing the signal structure and its acquisition to perform the dynamic identification of the test model

Preliminary results of shaking-table tests on a full-scale flat-bottom manufactured steel silo filled with wheat

This paper presents the preliminary results of a series of shaking-table tests on a full-scale flat-bottom manufactured steel silo filled with a granular material. A 3.64 m-diameter 5.5 m-height cylindrical silo has been tested in fixed-base and isolated-base configurations. The isolators put between the table and the r.c. plate are Curved Surface Sliders friction pendulum devices. Mono-axial shaking-table tests have been performed using random signals, low-frequency sinusoidal inputs and earthquake records (both artificial and real). The results are relevant to: the identification of the basic dynamic properties (frequency, damping ratio, amplification) of the grain-silo system, the experimental assessment of the static pressure (during filling phase) and seismic dynamic over-pressures and the effectiveness of the isolation system at the base of the silo