RECENT DEVELOPMENTS IN SITE SPECIFIC RISK ASSESSMENT FOR POLLUTED SITES

The present note highlights the role of geotechnical expertise for Risk Assessment of contaminated sites and illustrates specific aspects related to migration modeling. Implications of neglecting the time variable and the advantages of the direct measurements of vapors, performed by application of different techniques, are described and discussed. The comparison between direct measurements of vapor emissions and modeling outcomes show how the use of measured data is able to overcome the limitations deriving by restrictive model assumptions and effectively helps in obtaining more realistic results

Cob Construction in Italy: Some Lessons from the Past

Raw earth is a construction material unknown to most people. Nowadays, raw-earth constructions are an area of growing interest, both for rescuing the heritage and for a rediscovered environmentally friendly building and eco-sustainability material. However, because raw-earth constructions are a forgotten technique, we find problems of a lack of skilled people at all levels in this area, from designers to masons, as well as problems of how to carry out compatible conservation works on earthen heritage. This paper tries to fill the gap for a peculiar historic earthen building technology, namely cob (or bauge), which is present in Macerata in the center of Italy. Results are presented on regaining possession of the material and constructional aspects and their initial structural resources, and guidelines are given on how to improve the manufacturing process to reuse the cob technique for construction and for how to accurately work on it for a compatible and sustainable conservation

Migration parameters and interaction of saline solutions through cement-bentonite cutoffs

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Trattamento a calce delle terre: tempi di reazione ed influenza delle condizioni di stagionatura sulla microstruttura e sulla compressibilità

La nota illustra i risultati di un progetto di ricerca in corso su terre di diverse caratteristiche trattate con il 5% di idrato di calcio, con l’obiettivo di confrontare le tempistiche di reazione e valutare l’effetto delle condizioni di stagionatura (presenza d’acqua) sulla quantità e tipo di prodotti di reazione nonché sulla compressibilità. Lo sviluppo delle reazioni nel tempo è stato dedotto mediante un metodo di prova basato sul valore del pH. Si è osservato che le reazioni di scambio ionico si esauriscono, per le miscele studiate, entro i primi tre giorni e quelle pozzolaniche si sviluppano pienamente entro le prime tre settimane. Il wetting immediato dei campioni di terra-calce consente una più uniforme distribuzione dei prodotti di reazione, presenti anche in forma cristallina. Una maggiore compressibilità si rileva per la stagionatura in condizioni sommerse, per alti valori (> 400 kPa) della pressione verticale efficace

Long term performance of cement-bentonite cut-offs in saline and acidic solutions

The paper presents the results of a research aimed at evaluating and predicting the long term performance of CB mixtures in terms of hydraulic conductivity, k. A low k value is the necessary (even if not sufficient) requirement for a cut-off wall to isolate polluted sites. Aqueous sulphate solutions of different nature (acidic, saline) and concentrations were used as permeants in column tests performed for long time (one year or more) in order that full effects of physical and chemical reactions may occur. Results of these tests are here analysed mainly with the aim to find a criterion to predict how long a cement-bentonite cut-off wall can keep a proper hydraulic performance