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Description / Abstract:
INTRODUCTION
This guide provides recommendations for proportioning
normalweight concrete with ground limestone and dust-offracture
mineral fillers. It is intended to supplement ACI 211.1.
Proportioning methods for ground limestone and for dust-of-fracture
mineral filler are discussed separately.
Mineral filler is defined as a finely divided mineral product at
least 65 percent of which passes the No. 200 (75 μm) sieve. Ground
limestone is a purposefully manufactured fine product composed
primarily of calcium carbonate and with particles sized within
narrow ranges. Ground limestone has been used successfully in
concrete in Europe for decades, either added to the concrete
mixture separately from the cement or interground with clinker to
form portland-limestone cement.
Dust-of-fracture mineral filler is rock dust created during
production, processing, or handling of quarried stone. Such
materials are not purposefully manufactured and can vary in mineral
composition and other physical characteristics, depending on the
parent stone from which they are derived, the crushing process, and
the washing or air separation process.
This guide does not address precipitated calcium carbonate or
material finer than the No. 200 (75 μm) sieve in natural sand.
Although ground limestone typically falls within the definition of
mineral filler, it is dealt with separately in this guide from
other mineral fillers. It is manufactured under controlled
conditions to be a consistent product. Dustof- fracture mineral
filler consisting primarily of calcium carbonate is not considered
ground limestone.
The aggregate suspension mixture proportioning method described
in ACI 211.6T has been used to proportion concrete with ground
limestone and dust-of-fracture mineral filler.
Concrete mixture proportioning is becoming more critical with
changing government regulations and policies for sustainable
development in the construction industry. Ground limestone has a
lower embodied energy and lower CO2 emission during its
production than an equivalent mass of portland cement. This guide
can facilitate the use of ground limestone and other mineral
fillers as a means of optimizing the cementitious materials content
of concrete, thereby increasing sustainability.
Applicability of these materials is not limited to a select
class or type of concrete but can be considered for use in a wide
variety of applications and production methods. The described
proportioning methods provide a first approximation of proportions
intended for trial batches in the laboratory or field, which should
be adjusted as necessary to produce the desired characteristics of
the concrete.
Ground limestone and dust-of-fracture mineral filler can also be
used in structural lightweight concrete. The principles described
herein can be similarly used to modify ACI 211.2 to incorporate
these materials.