Re-Using Waste as Secondary Raw Material …
233
In particular, the thermal sintering process for the production of expanded glass
has proved to be the most suitable with respect to the objectives and also the most
efficient both in terms of costs and impact.
3 Applications for Building Sector
The second step of the study was the application of this “new” second raw material
in products for building construction and the verification of the performance of such
components.
Foam glass is a material that finds large application as light aggregates for concrete
products. Because the foam glass pieces that derive from waste had lower compressive strength values than those of the foam glass obtained from pure glass, the decision was made to test the usability in lightweight concrete components (lightweight
vibro-compressed concrete blocks and prefabricated panels to be used for example
as vertical partition elements or vertical closing elements in buildings for industrial,
commercial use and other civil constructions) which normally do not require high
structural performance.
The goal was to produce components able to guarantee the requested mechanical
standard but with lower thermal conductivity and weight. For this reason, a careful regulatory analysis has been carried out in order to set the minimum required
performance for blocks and panels which, subsequently, have been compared with
the market demands and the performances offered by the elements normally on the
market.
The prototypes of the blocks were realized in the production plant of Unibloc s.r.l.
using an optimal geometry
5 that would allow both the construction of a lightweight
concrete block with commonly used aggregates (e.g. expanded clay), and the use of
the expanded glass obtained in the experimental phase from the glass dust coming
from the waste.
Instead, the prototypes of the panels were produced by the laboratories of S.A.M.
Engineering S.p.A., equipped with a production control system (F.P.C.) certified by
Bureau Veritas Italia for the production of elements with CE marking.
The prototypes, both the blocs and the panels, had aesthetic characteristics absolutely akin to the corresponding products of current productions but they showed
significant differences in terms of performance.
In the case of blocks, following a refinement and sorting process of the geometries
of the block and of the aggregates in foam glass from waste it was possible to obtain a
reduction of the mass of about 25%, passing, with comparable performances, from a
concrete lightened with expanded clay block with a mass net volume of 1000 kg/m
2
5 For the definition of the optimal geometry and a comparison of the results obtained from the test
geometries, the thermal values (conductivity) defined in the UNI EN 1745 standard were used; the
cavities of the block were evaluated according to the procedure indicated in EN ISO 6946 and each
cavity was considered as an average having its own thermal resistance, from which the conductivity
in relation to the thickness was calculated.
233
In particular, the thermal sintering process for the production of expanded glass
has proved to be the most suitable with respect to the objectives and also the most
efficient both in terms of costs and impact.
3 Applications for Building Sector
The second step of the study was the application of this “new” second raw material
in products for building construction and the verification of the performance of such
components.
Foam glass is a material that finds large application as light aggregates for concrete
products. Because the foam glass pieces that derive from waste had lower compressive strength values than those of the foam glass obtained from pure glass, the decision was made to test the usability in lightweight concrete components (lightweight
vibro-compressed concrete blocks and prefabricated panels to be used for example
as vertical partition elements or vertical closing elements in buildings for industrial,
commercial use and other civil constructions) which normally do not require high
structural performance.
The goal was to produce components able to guarantee the requested mechanical
standard but with lower thermal conductivity and weight. For this reason, a careful regulatory analysis has been carried out in order to set the minimum required
performance for blocks and panels which, subsequently, have been compared with
the market demands and the performances offered by the elements normally on the
market.
The prototypes of the blocks were realized in the production plant of Unibloc s.r.l.
using an optimal geometry
5 that would allow both the construction of a lightweight
concrete block with commonly used aggregates (e.g. expanded clay), and the use of
the expanded glass obtained in the experimental phase from the glass dust coming
from the waste.
Instead, the prototypes of the panels were produced by the laboratories of S.A.M.
Engineering S.p.A., equipped with a production control system (F.P.C.) certified by
Bureau Veritas Italia for the production of elements with CE marking.
The prototypes, both the blocs and the panels, had aesthetic characteristics absolutely akin to the corresponding products of current productions but they showed
significant differences in terms of performance.
In the case of blocks, following a refinement and sorting process of the geometries
of the block and of the aggregates in foam glass from waste it was possible to obtain a
reduction of the mass of about 25%, passing, with comparable performances, from a
concrete lightened with expanded clay block with a mass net volume of 1000 kg/m
2
5 For the definition of the optimal geometry and a comparison of the results obtained from the test
geometries, the thermal values (conductivity) defined in the UNI EN 1745 standard were used; the
cavities of the block were evaluated according to the procedure indicated in EN ISO 6946 and each
cavity was considered as an average having its own thermal resistance, from which the conductivity
in relation to the thickness was calculated.