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point of view

characterisation testing to determine potential future structural
performance. The research found good correlation between the
reported properties and original constituents and the durability
performance and compressive strength, highlighting the benefit
of segregating good quality structural concrete from other
demolition arisings and the importance of additional testing to
characterise materials.

7. Further research

Further research is required to establish the durability
performance of coarse rCa structural concrete using varying
Figure 2: Segregated sections of RCA from demolition sites in the East levels of other SCMs including PFA, Silica Fume and Metakaolin,
and West Midlands, UK [3] but also tertiary blends that combine these sCMs and further
reduce the quantity of Portland cement.
(e.g. Figure 2). Segregation would help whether re-using the
material on site or transporting to a recycling plant for further 8. Possible costs
processing as the resultant material would be suitable for higher
value applications. To make this a possibility, the requirement There are costs associated with the characterisation testing of
of segregation would need to be clearly communicated to the materials; however, this could be considered negligible when
demolition contractor at an early stage so that any additional compared with the overall design and construction costs of
costs and risk can be captured. The additional testing of reinforced concrete elements and structures. If the findings
segregated demolition arisings may result in a higher initial of the research were to be incorporated into real-scale 'trial'
cost to the project; this however, would be low compared structures or structural elements, then intermittent inspection
with demolition and construction costs and provides huge and testing may be required to monitor the effects on long-
potential benefits in terms of improving sustainability. In reality, term durability and performance. This cost however, could be
segregation can be difficult for demolition contractors due minimised by using increasingly advanced and sophisticated
to time and space constraints on site, which typically results remote monitoring techniques and data logging equipment to
in mixed rCa and poor quality materials. segregation of obtain data remotely for analysis and performance monitoring.
demolition arisings may therefore only be possible at particular
sites. 9. Guidance is needed
This research has provided substantial peer-reviewed evidence
6. Research vs reality that sustainable structural concrete could be a viable option for
future sustainable infrastructure projects. There is a significant
The conclusions of the research were based upon laboratory need however, for best practice guidance, if not more standards
produced, cured and tested concretes, which are not necessarily and specifications, that encourages closer collaboration
representative of in-situ site-placed concretes. This research, between demolition contractors and the construction industry.
however, did incorporate coarse rCa sources that were The sustainability benefits of coarse RCA are optimised when
representative of 40+ years old demolition arisings, of both transportation distances are kept to a minimum. it is therefore in
known and unknown compositions. The conclusions were also the best interest for all parties involved to utilise these materials
based on five different UK RCA sources, of varying qualities and in a wider variety of applications if they are found to be suitable
properties, which, though not necessarily representative of all for use.
potential demolition arisings, did result in a broad range of final
concrete compressive strengths and properties made with rCa. It is hoped that findings and guidance would be published to
further promote the wider implementation of rCa in higher
The existing limitations in european and British standards of value applications to major asset infrastructure owners around
30% and 20% coarse rCa respectively are purposefully stringent the world, such as in highways, rail, transportation, water and
to reduce the risk of any adverse effects of rCa. This research, power.
however, has shown that the adverse effects are improbable
when sufficient quantities of SCMs are also incorporated, as a change in the design approach to specifying coarse rCa in
these materials dominate the long-term durability properties structural concrete is required if larger quantities of coarse rCa
of concrete. The risks of any adverse effects can also be are to be adopted globally, and real progress made on reducing
reduced further by carefully selecting materials and undertaking C&dW and reducing the carbon footprint of construction.

The IndIan ConCreTe Journal | augusT 2020 9