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TECHNICAL PAPER

RECYCLED CONCRETE

AGGREGATES IN NEW

CONCRETE – FULL SCALE

DEMONSTRATION IN

NAVI MUMBAI CHRISTIAN J. ENGELSEN
KSHEMENDRA NATH P.
SIVAKUMAR KANDASAMI*

Abstract heavy inorganic part (from concrete, masonry and soil) could
be processed and refined into recycled aggregates. This type
A full-scale pilot project has been conducted to demonstrate the of aggregates could substitute natural aggregates in a range
use of fine recycled concrete aggregates (RCA) for two different of user applications like road construction, landscaping and
concrete qualities with high replacement of natural aggregates. concrete production. This will save natural resources, minimize
The fine RCA replaced the crushed stone sand fraction in the the waste sent to landfills, re-absorb CO 2 from the air through
grade slab (M20) and in the lean concrete (M10) at replacement increased carbonation and in many cases reduce the cost of
levels of 50% and 100%, respectively. The RCA concrete concrete. In Europe, more than 500 million tons are generated
was used in the newly constructed precast concrete factory annually. For India the estimates of C&D waste generation
for the affordable housing project of the City and Industrial vary from 25-30 million tons up to around 500 million tons . In
[1]
Development Corporation of Maharashtra Limited (CIDCO).
Delhi, the C&D waste generation is estimated to be 2000-4000
Concrete rubble was recycled into RCA 0/2 mm by a wet tons per day and the same generation volume can roughly be
recycling process. The aggregate properties complied with assumed for Mumbai.
IS: 383 (2016) and the grading achieved was Zone II. The An Indo-Norwegian project has been initiated between Central
obtained fresh and hardened concrete properties were fully Public Works Department (CPWD) and SINTEF where the
comparable with the reference concrete. The site engineers aim is to increase the treatment and recycling capacity for
expressed satisfaction on their experience of using RCA as construction and demolition wastes in India . The project will
[2]
replacement for CSS, as no placement and finishability issues strive to implement international best practice, perform various
were encountered. The pilot project has created a desire to capacity building activities and conduct pilot demonstrations.
continue exploring future opportunities for the use of RCA in It has focused on the production of mixed recycled aggregate
concrete.
(RA) and recycled concrete aggregate (RCA) from C&D waste
The price of the fine RCA was competitive even with significant with a documented consistent quality [3-4] , polices and business
[5]
longer transport distance to the construction site than for the strategies as well as the potential of sustainable construction
[6]
CSS aggregates. Hence, there is a potential for significant cost in India .
savings in the Mumbai region.
The performance of recycled aggregate concrete (RAC) has
Keywords: C&D waste, Climate change, ESG, Recycled been reported in a number of studies in the past 25 years.
aggregates concrete (RAC), Recycled concrete aggregates Several reviews have recently been reported regarding the
(RCA), Sustainability, Waste valorisation. performance of recycled aggregates in mortar and concrete. It
comprises extensive studies that focus on a broad number of
1. INTRODUCTION aspects regarding the use of RCA [7-8] . In addition, a cascade of
reviews have been published regarding specific effects of RCA
Construction and Demolition (C&D) waste is one of the biggest used in concrete including; improved microstructural properties
solid waste streams globally. It usually contains wood, plastic, and methods for removal of the residual mortar [9-10] , challenges
paper rejects, ceramics, mortar, concrete etc. In many demolition of assessing the effective water to cement ratio [11] , carbonation
projects, the C&D waste is also mixed with excavated soil. The of RCA [12] , impacts of fine RCA [13] , change in autogenous and

THE INDIAN CONCRETE JOURNAL | JANUARY 2022 49
*Corresponding author : Sivakumar Kandasami, Email: drks@lntecc.com