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Utilization of recycled concrete

aggregate in bituminous mixtures

India is constructing roads at a record pace: however, the
non-availability of quality aggregates is a problem. At the
same time, consumption of large quantity of aggregates
causes depletion of the natural resources. The production
of natural aggregates is environmentally harmful too
due to quarrying and blasting. This is a major concern
and challenge that the construction industry is facing
nowadays. Dr. Bhupendra Singh, Assistant Professor,
Department of Civil and Infrastructure Engineering
at IIT Jodhpur writes on the advantages of replacing
natural or virgin aggregates with C&D waste.

he majority of roads in India unbound pavement layers, cement undergo primary treatment, where
are flexible pavements, concrete, and bituminous concrete. they are broken down into more
with most having a Using C&D waste to replace natural manageable pieces, resulting in
bituminous surface layer. or virgin aggregates offers several crushed waste. The next stage
In bituminous mixtures, advantages. Firstly, it helps conserve focuses either on removing the
Tor bituminous concrete, natural resources by reducing the adhered mortar layer or reinforcing
bitumen accounts for less than it in place.
10% of the total composition, demand for virgin aggregates.
Secondly, the production of recycled
while aggregates make up over concrete aggregate consumes For removing the adhered mortar,
90%. Another significant issue several techniques are used,
is the generation of construction significantly less energy compared to including mechanical, thermal,
the production of virgin aggregates.
and demolition waste. It consists ultrasonic, and acid soaking
of various materials, including This lower energy consumption treatments. Mechanical treatment
concrete, bricks, wood, glass, translates into additional benefits, is the most common approach,
plastic, broken asphalt, and such as reduced production costs typically involving rotating
metals – essentially, anything and lower greenhouse gas emissions. equipment such as concrete mixers,
found in a building. Among The production of RCA Los Angeles abrasion machines,
these components, concrete is or specialized devices combined
the predominant constituent of The process involves several with steel balls. This process uses
construction and demolition waste. steps, beginning with the abrasion and attrition to remove
generation of construction and the mortar layer adhered to the
When these concrete blocks are demolition waste. There are aggregate surface.
recycled to extract aggregates, the two primary sources of C&D
result is known as recycled concrete In thermal treatment, the
aggregate. RCA comprises natural waste: artificial and natural. The adhered mortar is removed by
artificial source arises from routine
aggregates with an adhered layer heating the primary treated C&D
of mortar, as these aggregates construction and demolition waste to a high temperature. Due
were once part of concrete activities, while the natural source to the differing coefficients of
structures, retaining some of the results from disasters such as thermal expansion between the
original mortar. Over the years, earthquakes, floods, and cyclones. aggregate and mortar, this heating
researchers have utilized RCA in The C&D waste obtained in the generates thermal stress, causing
various applications, including form of large concrete chunks the mortar to detach from the

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