Combined use of waste concrete and glass as a replacement for mortar raw materials.

The construction industry offers one of the most attractive options in the use of recycled materials due to its large consumption of raw materials and high construction work rates. Also, the debris from construction and demolition is responsible for a high participation rate in the generation of waste, with concrete being a major contributor in this category. Waste glass powder, on the other hand, is a material that offers an excellent alternative to replace cement due to its well-known pozzolanic properties. Hence, the combined behaviour of fine recycled concrete aggregates and glass powder of different particle sizes in mortars has been studied. Different mixtures are analyzed with the aim of minimizing losses in mechanical properties and durability in an attempt to maximize the amount of replaced materials. Due to the delayed pozzolanic reaction by the glass powder, the samples present highly satisfactory results at 90 days of curing, with values of their properties close to those of the control mortar. The results are encouraging when glass powder with a smaller particle size is used due to its filler effect combined with its pozzolanic activity, making it possible to replace up to 20% of glass powder with a maximum size of 38 µm, with up to 30% of fine recycled concrete aggregates. Finally, the evaluation of greenhouse gases showed that the simultaneous incorporation of both types of waste reduces the CO2 emissions associated with concrete by up to 19%.

Summertime conditions of a muddy estuarine environment: the EsCoSed project contribution.

As part of the Estuarine Cohesive Sediments (EsCoSed) project, a field experiment was performed in a highly engineered environment, acting as a natural laboratory, to study the physico-chemical properties of estuarine sediments and the associated hydro-morphodynamics during different seasons. The present contribution focuses on the results obtained from the summertime monitoring of the most downstream part of the Misa River (Senigallia, Italy). The measured hydrodynamics suggested a strong interaction between river current, wave forcing and tidal motion; flow velocities, affected by wind waves traveling upstream, changed significantly along the water column in both direction and magnitude. Surficial salinities in the estuary were low in the upper reaches of the estuary and exceeded 10 psu before the river mouth. Montmorillonite dominated the clay mineral assemblage, suggesting that large, low density flocs with high settling velocities (>1 mm s(-1)) may dominate the suspended aggregate materials.

Particle size, size distribution and morphological evaluation of glass fiber reinforced plastic (GRP) industrial by-product.

The waste management of glass fiber reinforced polymer (GRP) materials, in particular those made with thermosetting resins, is a critical issue for the composites industry because these materials cannot be reprocessed. Therefore, most thermosetting GRP waste is presently sent to landfill, in spite of the significant environmental impact caused by their disposal in this way. The limited GRP waste recycling worldwide is mostly due to its intrinsic thermosetting properties, lack of characterization data and unavailability of viable recycling and recovery routes. One of the possibility for re-using GRP industrial by-product is in form of powder as a partial aggregate replacement or filler addition in cement based composites for applications in sustainable construction materials and technologies. However, the feasibility of this kind of reutilization strongly depends on the morphology and particle size distribution of a powder made up of polymer granules and glass fibers. In the present study, the use of image analysis method, based on scanning electron microscopy (SEM) and ImageJ processing program, is proposed in order to evaluate the morphology of the particles and measure the particle size and size distribution of fine GRP waste powder. The obtained results show a great potential of such a method in order to be considered as a standardized method of measurement and analysis in order to characterize the grain size and size distribution of GRP particles before exploiting any compatibility issue for its recycling management.

Recycling of rubble from building demolition for low-shrinkage concretes.

In this project concrete mixtures were prepared that were characterized by low ductility due to desiccation by using debris from building demolition, which after a suitable treatment was used as aggregate for partial replacement of natural aggregates. The recycled aggregate used came from a recycling plant, in which rubble from building demolition was selected, crushed, cleaned, sieved, and graded. Such aggregates are known to be more porous as indicated by the Saturated Surface Dry (SSD) moisture content. The recycled concrete used as aggregates were added to the concrete mixture in order to study their influence on the fresh and hardened concrete properties. They were added either after water pre-soaking or in dry condition, in order to evaluate the influence of moisture in aggregates on the performance of concrete containing recycled aggregate. In particular, the effect of internal curing, due to the use of such aggregates, was studied. Concrete behavior due to desiccation under dehydration was studied by means of both drying shrinkage test and German angle test, through which shrinkage under the restrained condition of early age concrete can be evaluated.