Durability of High-Performance Mortars Containing Contaminated Marine Sediments in Aggressive Environments

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Title: Durability of High-Performance Mortars Containing Contaminated Marine Sediments in Aggressive Environments

Author(s): G. Ferrari, T. Cerulli, P. Clemente, C. Pistolesi, D. Salvioni, and F. Surico

Publication: Special Publication

Volume: 192

Issue:

Appears on pages(s): 659-676

Keywords: durability; high-performance concretes; leaching; marine atmospheres; pozzolans; stabilization; superplasticizers; wastes

Date: 4/1/2000

Abstract:
Solidification/stabilization (S/S) is an effective management of toxic wastes, consisting in mixing a waste product with a binder and other ingredients, if any, to reduce the mobility or solubility of contaminants. In the present work, a contaminated marine sediment of the Venice lagoon was treated with cement, aggregates and different amounts of an acrylic superplasticizer to produce cement mortars with different W/C. The characteristics of the resulting mortars were evaluated by compressive strength, water permeability, observation of microstructure of the comment past, and leaching of contaminants. The durability in aggressive environments of the best performing mortar, corresponding to the mixture with W/C=.38, was evaluated in comparison to a reference mortar. The results of the test indicated that W/C affects no only the strength of the mortars but also improves the leaching characteristics of the stabilized waste. This could be ascribed mainly to the reduction of the micro porosity of the mortars with lower W/C. The durability test indicated that the mortar containing the sediment is less sensitive to the attack of CaCl2 in comparison to the reference mortar, as confirmed by the higher strength after different periods of immersion in a 30% aqueous solution of CaCl2 at 5 degrees C. Furthermore, the linear expansion in sulphate solution seems not to be substantially influenced by the presence of the sediment. Thermal and XRD analyses suggested that these results could be ascribed to a pozzolanic effect of the sediment. The results of the present work confirmed the possibility of producing high performance concrete by using the contaminated sediments of the Venice lagoon.