Review Topic - Sustainable Utilisation of Quarry
By-products
Quarry by-products include overburden, waste rock rejected at
the face, quarry fines, and dusts, and are produced during the
extraction and processing of aggregates. The focus of this
review is quarry fines and dusts, which are often taken to be
material less than 6mm and can form an integral part of many
aggregate products. However, they are sometimes produced in
excess quantities that do not match market demand. Where a
production/market imbalance exists, aggregate producers need to
identify alternative utilisation routes, some of which have been
researched in ALSF projects.
End uses for quarry fines can be divided into bound and unbound
applications.
Unbound
Fines are commonly used in reclamation of mineral workings
and other bulk filling applications. Several case studies are
highlighted in an ALSF report. Quarry fines can also find
application in road pavement construction.
Quarry fines are considered a valuable additive for soil
enhancement and can also be included in artificial soils, where
ALSF projects have shown that limestone fines can help to
remediate acidic material. ALSF projects have also investigated
the combination of basaltic quarry fines with organic process
residues for the development of composts.
Unbound fines have also been investigated for use as fillers,
the production of Portland cement and in new, innovative
products, such as in green roofs and earth construction
applications.
Bound
In the field of controlled low-strength materials,
one ALSF project has investigated the use of quarry
fines as the main component of pumpable infill grout.
Other case studies are included in an ALSF report.
The use of quarry fines in concrete is well established,
but ALSF projects have highlighted that there is little
data on the technical suitability and market
availability for quarry fines to be used in concrete or
mortar. Utilisation in heavy ceramics such as bricks,
pipes and tiles is more limited, but still possible. The
production of lightweight artificial aggregates by
mixing waste plastics and quarry fines is being explored
and the use of energy saving microwave technology is the
subject of another ALSF project.
Hydraulically bound mixtures (used in road and paving
construction, shore and slope protection, dams, etc.)
comprise a combination of aggregates with binder
mixtures that set and harden in the presence of water. A
current ALSF project is aiming to develop specifications
for HBMs with quarry fines in their structure.
Quarry fines may also be used in asphalt paving and
surface treatment as fine aggregate or/and filler.
Barriers to utilisation
ALSF projects have highlighted a number of issues
which prevent quarry by-products from being used more
than they are. Geographical location and distance from
end-use market is possibly the main reason, although
lack of fines characterisation, lack of awareness of
possibilities, lack of fit-for-use specifications and
the effect of the Aggregates Levy are also considered to
contribute.
To view and download the full review "Sustainable
Utilisation of Quarry By-products"
please go to the Reviews & Project Reports
section of this website.
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