The paper shows the results of an experimental tests campaign carried out on concretes with recycled aggregates added in substitution of sand. Sand, in fact, has been totally replaced once by blast-furnace slag and fly ashes, once by blast-furnace slag and microsilica. The aim is both to utilize industrial by-products and to reduce the use of artificial aggregates, which impose the opening of pits with high environmental damage. The results show that in the concretes so made the water absorption capacity has reduced and durability has improved. The test campaign and the results described in the present article are certainly useful and can be especially utilized for research on a larger scale in this field.

Recent seismic events, all over the world, demonstrated that masonry constructions are prone to brittle collapses when shear or compression capacity is reached. It is clear that, in many real cases, masonry columns need to be strengthened for enhancing their load-carrying capacity and to develop a more ductile response. The Fiber Reinforced Polymers (FRPs) confinement of masonry columns is a well-known technique that may produce these advantages. Unfortunately, full-wrapping insulates the column from the environment; so interstitial humidity can easily occur and cause the acceleration of the masonry's decay. In order to prevent it, partial-confinement is commonly assessed instead of total-jacketing. For this reason, a research was led, consisting of an experimental and theoretical study focused on the discontinuous FRP-confinement. Thus, two different series of masonry columns were confined with Glass-FRP (GFRP) and Carbon-FRP (CFRP) strips bonded to the column with an epoxy resin. Different schemes of FRP-wrapping were investigated by means of uniaxial compression tests. Moreover, an analytical method for the prediction of the experimental results was also provided. The proposed model was based on the relationship between the different lateral deformations of the confined and unconfined regions (experimentally recorded by using strain gauges). The new iterative procedure was found able to provide theoretical stress vs. strain curves; which demonstrated to accurately match the experimental recordings. The proposed model was also validated by parametric analyses, presented in the paper.

Nanoparticles are used in innovative mortars in order to improve their engineering properties. In this paper, recycled PET (polyethylene terephthalate) nanoparticles were used as a substitute for sand in mortars. PET aggregates were obtained cutting water bottles wastes into many small sized pieces and the plastic fibres were treated through chemical depolymerization process. Mortars with different percentages of PET were tested to determine their physical and mechanical (flexural and compressive strength) properties. Specific attention is given to the heat-transfer capacity of the cement pastes investigated. The results of the mechanical tests showed a reduction of the flexural and compressive strength values when the amount of PET nanoparticles increase. The thermal conductivity tests showed that chemically depolymerized PET nanoparticles derived from plastic wastes reduced the heat conduction capacity of the mortar. Therefore, the innovative mortars here tested can be considered for thermal insulation applications in the construction field with the advantage of recycling waste PET.