Valorizing mineral wool ash as a supplementary cementitious materials

Abstract

Fulfilling the ambition for maintaining global carbon neutrality, utilizing alternative
zero-carbon resources is becoming more essential in the design of building materials.
Among efforts to develop alternative supplementary cementitious materials are
becoming popular due to their low environmental impact in reducing CO2 emissions.
The mineral wool waste collected from construction debris could be valorized as a
potential pozzolanic material for Portland cement concrete. However, a completely
circular production can only be obtained through a “zero-waste” production route.
The ashes collected from the coke-fired hot blast kiln are a significant portion of the
waste stream generated from mineral wool production. To achieve a sustainable
circular production for mineral wools,
valorizing the waste stream obtained during production is becoming more essential
for the producer. The main goal of this study is to validate a circular
production route utilizing the waste ash generated during mineral (stone) wool
production in cementitious binders. To achieve this goal, 2 different types of waste
ash having different composition and particle size were used. The ashes were
classified as W10 is calcite based ash having an average particle size of 75 microns and
W20 is a silicate based ash with an average particle size of 22 microns. The
performance evaluation was done on cement-based samples where 20% of the
cement was replaced with waste ash. The results showed that W20 exhibits a
puzzolanic behavior and can improve the strength of the mortar even at early ages
while W10 does not contribute to strength and acts as a filler material. Both ashes
increased the initial setting time and reduced the workability of the mortar. The
outcomes of this study creates an economic value for large volumes of material
of previously zero value, while proposing a new cementitious composite product for
the mineral wool producers.