D. Sani

Used Foundry Sand in Cement Mortars and Concrete Production~!2010-03-27~!2010-05-03~!2010-07-07~!

Used foundry sands represent the highest amount of solid wastes generated by foundries. Classified by European Union regulations as non hazardous waste, they represent a relevant source to be reused in several industrial sectors, in building construction primarily. In present paper, the properties of mortars and concretes containing different dosages of used foundry sand (UFS) as partial replacement of sand were investigated in both fresh and hardened conditions. In particular, higher percentages of addition, but lower if referred to the whole aggregate (fine and coarse), were considered in concretes than in mortars. Both mortars and concretes were evaluated with respect to consistency of the fresh mixture and compressive strength of the hardened material. Elastic modulus determination of the hardened material was carried out on concretes. A low (10%) amount of used foundry sand does not change the mortars performances. In the presence of higher additions a workability decreasing can be outlined, and then a higher dosage of superplasticizer is required in order to keep it constant. Mechanical performances lower of about 20-30% than those of the conglomerate without used foundry sand are observed. The higher penalization it seems to concern to the conglomerates of better quality (i.e. lower water-cement ratio).

Soil Zinc contamination from corrosion of galvanized structures

The present work relates to galvanized structures with several years of time life subjected to atmospheric corrosion, like galvanized high tension steel pylons. The mass and fate of zinc released is evaluated both via empirical and experimental procedures. The corrosion rate determination requested atmospheric condition characterization, especially for SO 2 concentration and experimental activities focused on soil sampling around pylons. The soil zinc content, total and exchangeable, is determinates by different analytical procedures. The zinc diffusion in environment and the zinc extension under the top soil is evaluated using 1-dimensional mathematical model for miscible species in porous soil.

Persistence of heavy metals in river sediments

The objective of this study was to assess heavy metals accumulation and equilibrium phenomena in river sediment, in relation to water quality, and to assess metals lability, analysing whether and how easily heavy metals are available to generic biota. The diffuse gradient in thin film technique was used to assess the effective concentration (C E). The solid–liquid distribution coefficient of the metals labile pool (K dl) was calculated to include it in risk analysis within a more realistic frame. The Esino River was chosen for the case study. The results confirmed the need to determine K d experimentally; values of K d taken from the literature resulted in errors of some orders of magnitude. Metals speciation, environmental conditions, the type and texture of the sediment, features of the water, organic fraction, pH and salinity can all influence the outcome. The results showed that the two main parameters on which K d depends are chemical oxygen demand and specific surface area. C E, which takes into account the contribution of both the water and the labile fraction in the sediment, is a key parameter and may be 5–100×the concentration in the pore water.

Design and calibration of an organic diffusive probe to extend the diffusion gradient technique to organic pollutants.

The objective of this study was to develop a method for measuring the mobility of persistent organic pollutants in the solid phase of soils within the context of environmental pollution risk assessment. A new diffusive probe, purposely designed by adapting the diffusive gradient technique method, measures labile organic species by immobilizing them after diffusion through a thin deionized water layer. The measure of the mass accumulated is used to calculate the flow of pollutant from solid phase to pore water. Naphthalene was chosen as a model persistent organic pollutant. The probe was calibrated at different temperatures and was then tested in several microcosms at different porosity and reactivities with naphthalene (one clay soil, two sandy soils and one natural soil). The probe response showed good agreement with the expected different abilities of the solid phases in restoring the solution phase. The concentration of naphthalene in the pore water was well buffered by rapid equilibria with the solid phase in the investigated natural soil. In contrast, pore water concentration in the sandy soils decreased rapidly and the flow was slackened, especially for the sandy soil with finer particles. In clay, only a fraction of the total naphthalene content was present in the labile fraction, while the remaining was tightly bound and was not released to the pore water. Therefore, this first stage of testing points out that the diffusive gradient technique, if optimized, can properly quantify the mobility of organic pollutants in soil.

Reuse of Paper Mill Ash in Plaster Blends

This work is part of a broad research conducted to study the re-use of industrial wastes in an economical and environmentally sustainable manner. Re-use of lightweight ash from the paper mill industry in the manufacture of plaster blends is examined in this study. Lightweight ash is produced during the combustion process of de-inking sludge. Studies demonstrate that lightweight ash is an excellent ingredient in the production of cement mortars and/or pozzolanic mortars to be used as plaster. In this research, ash valorization was researched by investigating the efficacy of the ash as it is, as a substitute for very fine sand. If properly mixed at an optimal mix proportion, the mechanical strength ranges from 4÷10MPa with specific gravity between 1150 and 1350 Kg/m 3 . Water absorption may be reduced to a very low level with silane-based surface treatment.