Title:
Self Compacting Light-Weight Concretes With Ground Bottom Ash From Municipal Solid Waste Incinerators (MSWI)
Author(s):
Silvia Collepardi; Antonio Borsoi; Mario Collepardi and Alessandro Quadrio Curzio
Publication:
Symposium Paper
Volume:
305
Issue:
Appears on pages(s):
29.1-29.10
Keywords:
Fiber-reinforced concrete. Freezing-thawing. Ground bottom ash. Light-weight concrete. Municipal Solid Wastes Incinerators. Self-compacting concrete
DOI:
10.14359/51688589
Date:
9/1/2015
Abstract:
Bottom ash produced by burning municipal solid wastes in incinerators (MSWI) has been proposed as a mineral addition for concrete but removing the metals is still an open issue. A new process has been recently developed to completely eliminate the aluminum particles through a mechanical process. In this way the negative side-effect consisting in the formation of gaseous hydrogen due to the reaction between the aluminum and the calcium hydroxide produced by portland cement hydration is prevented. The new process also includes a special wet-grinding phase to increase the fineness of ground bottom ash (GBA), to the advantage of its pozzolanic activity. At the end of this process, GBA is used in the form of slurry (40-50% of solid content) to partly replace portland cement.
In this research project, GBA with a maximum size of 5 µm (200■10-6 in) was used in light-weight, self-compacting concretes (SCC) containing expanded clay as coarse aggregate with a maximum size of 16 mm (0,64in). All the mixtures were manufactured with a shrinkage-reducing admixture (SRA) and a CaO-based expansive agent to significantly reduce the drying shrinkage in a low RH (55%) environment. A polycarboxylate-based superplasticizer (with 30% of active polymer) was adequately dosed in order to manufacture SCCs at a given water/(cement +cementitious material) ratio of 0.37±0.02 . Moreover, the influence of steel fibers on the tensile and flexural strength as well as on ductility has been investigated.
Similar concretes for freezing-thawing exposure classes including an air-entraining agent (to guarantee an air content close to 4% by volume) were investigated.
The research has been carried out using the funding objective POR Regional Competitiveness and Employment part of the European Regional Development Fund 2007-2013 - Action 1.1.2