Page 109 - ICJ Jan 2023

TECHNICAL PAPER COLLECTOR’S EDITION

The term ‘sustainable construction materials’ has specifications should encourage appropriate use
increasingly been adopted throughout the concrete of aggregates for function and performance in
industry; but usually incorrectly as a synonym for order to drive further the sustainable construction
recycled materials. Since recycled materials do not agenda.
necessarily mean greater sustainability, since they
in turn require energy to produce, it is perhaps CURRENT KNOWLEDGE BASE ON THE
better to not use this term and instead consider the USE OF RECYCLED AGGREGATES IN
appropriate use of materials for both performance CONCRETE
and function. 4 There has been considerable increase in the
amount of data and knowledge on the use of
For example, in most instances, it can be expected recycled aggregates for use in construction, and in
that the performance of new concrete products particular concrete over the past 20 years, and this
using aggregates conforming to BS EN 12620 has grown considerably over the past 5 years as
will surpass the minimum acceptable level researchers and research sponsors have recognised
of performance, but will decline towards this the need for sustainability in construction. Whilst,
level during service as a result of deterioration there were a number of seminal works on use of
5
processes. However, similar service life can be recycled aggregate in concrete prior to 1996, it was
achieved through a number of different routes, the from 1996 until 2002 that the main knowledge base
two extremes being: on use of recycled concrete aggregate (RCA) was
formed since at that time these materials reflected

To create a high quality product using the best the highest and most consistent quality of all
aggregates available that will deteriorate slowly. recycled aggregates available.

To create a lower quality product using lower Whilst, there continues to be some work
quality aggregates that will deteriorate quicker; undertaken on RCA, studies at the major centres
thus requiring repair during service life. for recycled aggregate research have tended, since

In terms of sustainability, the most appropriate
option in terms of balancing the socio-economic
effects, waste and pollution described above, will
almost always lie somewhere in between these
two extremes. As a result industry needs to be
encouraged to discard with the current practice
of specifying high quality aggregates regardless
of the end product and to select aggregates that
will most appropriately meet the requirements at
minimal environmental damage and cost (Figure
1). Indeed, through the adoption of performance
based specifications, engineers will have greater
flexibility in selecting aggregates, and these

110 The Indian Concrete Journal | November 2018