Exploring the durability properties of Recycled Aggregate Concrete based on some recent researches in this area. Durability issues associated with Recycled Aggregates presented and mitigation measures suggested.

1. Ahmad Shah Kakar
2 0 1 7 C E T 2 5 3 2
IIT-Delhi
2019
Mid-term project presentation
Submitted to Professor Shashank Bishnoi
CVL871-Durability and Repair of Concrete Structures
Exploring the Durability of
Recycled Aggregate Concrete

2. IIT-Delhi
2019
Introduction
Natural
Aggregates
The world demand
for natural
aggregates will be
51.7 metric tons in
2019, and it will
rise 5.2 percent
annually.*
Construction &
Demolition waste
Construction and
Demolition Wastes
(CDWs) accounts for
25–30 % of the whole
waste generated in
the EU (1 billion tons
each year).***
Recycled
aggregates
Aggregates made from
recyclable products.
Conservation of non-renewable
raw materials
Less volumes of materials sent
to inert waste landfills.**
* Freedonia group (2016)
** Eurovia (2011)
*** Silva et al. (2014)

3. IIT-Delhi
2019
Stats from EU
Adapted form: Silva et al. (2014)
Households
9%
Mining and quarrying
activities
27%
Manufacturing
11%
Energy and
water supply
sectors
10%
Construction and Demolition
activities
34%
Other
Economic
activities
9%
Households
Mining and quarrying activities
Manufacturing
Energy and water supply sectors
Construction and Demolition
activities
Other Economic activities
Waste generated by economic activity in the European Union.

4. IIT-Delhi
2019
Market Growth
Source: FACT.mr
Incremental opportunity in the RA market by region
For the Asia
Pacific region
excluding
Japan, highest
compound
annual growth
rate (CAGR) is
expected for
the 2019-
2027 period.

5. IIT-Delhi
2019
Processing
Figure adapted from Marinković et al. (2011)
*Portland Cement Association (2018)
Recycling of concrete is a relatively simple
process. It involves breaking, removing, and
crushing existing concrete into a material
with a specified size and quality.
ACI 555 (2001) provides guidelines on
processing old concrete into recycled
concrete aggregates. The quality of concrete
with RCA is very dependent on the quality of
the recycled material used. Reinforcing steel
and other embedded items, if any, must be
removed, and care must be taken to prevent
contamination by other materials that can be
troublesome, such as asphalt, soil and clay
balls, chlorides, glass, gypsum board,
sealants, paper, plaster, wood, and roofing
materials.*

6. IIT-Delhi
2019
Permeability
48 50 52 55
6060
65
70
75 77
68 70
75
80 82
0
10
20
30
40
50
60
70
80
90
0 Percent RA 25 Percent RA 50 Percent RA 75 Percent RA 100 Percent RA
DepthofPenetration(mm)
Percentage Replacement of RA
w/c=0.4 w/c=0.5 w/c=0.6
Adapted from: Adnan et al. (2008)
Depth of Water Penetration for 28-d for Various Percentage Replacement of RA

7. IIT-Delhi
2019
Chloride ingress
Adapted from: Guo et al. (2018)
Relative charge passed against coarse RA content
The passed charge of RAC increases with
the increase of RA replacement ratio.
Total charge passed increases with the
increase of coarse RA content regardless
of the quality of RA.
This is consistent with its effect on
impermeability. There is a 95%
probability that the total passed charge
of RAC with 100% coarse RA content is
about 2.07 times greater than that of
NAC. The effect of fine RA on chloride
penetration is more obvious than that of
coarse RA due to the higher amount of
adhered mortar and clay content.

8. IIT-Delhi
2019
Carbonation
Adapted from: Silva et al. (2015)
Carbonation depth for concrete prepared with 100% coarse RA content can be
up to 2.5 times greater than the corresponding Natural Aggregate Concrete
(NAC).

9. IIT-Delhi
2019
ASR
Adapted from: (Li et al. 2006; Shehata et al. 2010)
• RAC containing reactive aggregates from parent concrete will have a
potential risk of ASR.
• The expansion hazard of recycled aggregates obtained from ASR-affected
concrete is similar to parent concrete.
• the processing procedures have a significant influence on the mechanical
and durability of properties of recycled aggregate concrete.
• Crushing method affect the expansion of RA.
• Smaller size of coarse RA will exhibit more expansion
• It is possible to mitigate the influence of ASR on recycled aggregate concrete
by using supplementary cementitious material (SCM).

10. IIT-Delhi
2019
Freeze-thaw
Adapted from: (Medina et al. 2013; Richardson et al. 2011)
Relative freeze-thaw resistance versus RA content
Numerous studies show that the
freeze-thaw resistivity of RAC is
similar to NAC.
However there are studies which
reported greater strength loss for
RAC comparing to NAC due to
freezing and thawing.
The relative freeze-thaw parameter
of RAC changes with a change in
replacement percentage of RA
content.

11. IIT-Delhi
2019
Conclusions
Ahmad Shah Kakar
• The Recycled aggregates (RA) can be an appropriate alternative to natural aggregates
taking into consideration the rapid growth in demand for aggregates and the
restrictive environmental regulations in many countries.
• However, replacing entirely the natural aggregates (NA) with RA is not recommended
as far as the structural application is concerned.
• The processing procedure of RA plays a significant role in its mechanical and
durability properties.
• The porosity and water absorption of RAC mainly depends on the amount of adhered
mortar.
• As the w/c ratio and RA contents increase in a concrete mix, the performance
decreases from durability viewpoint.
• the performance becomes even poor with higher fine RA content in comparison with
coarse RA content.

12. IIT-Delhi
2019
Recommendations
Ahmad Shah Kakar
• Permeability and lower resistance to chloride ingress and carbonation are the main
flaws of RAC; it is possible to mitigate each of these issues by making changes in
materials and mix proportions.
• It is recommended to incorporate mineral admixtures for improving the durability
performance of RAC.
• It is important to take into consideration the strength of parent concrete while
replacing natural aggregates by RA.
• Higher strength of parent concrete will decrease the durability issues of RAC.
• It is recommended to mitigate the influence of chloride ion penetration by using fly
ash or some other mineral admixture.
• It is advised to incorporate fly ash and air entrainment to minimize the effect of these
deterioration processes.

13. IIT-Delhi
2019
References
Ahmad Shah Kakar
1. Evangelista, Luís, and Jorge De Brito. “Durability of Crushed Fine Recycled Aggregate Concrete Assessed by Permeability-Related Properties.” Magazine of Concrete Research, 2018, pp. 1–9.,
doi:10.1680/jmacr.18.00093.
2. Faleschin, Flora, and M.A. Zanini. “Environmental Impacts of Recycled Aggregate Concrete.”Italian Concrete Days - Giornate Aicap 2016 Congresso CTE, 2016.
3. Henry, Michael, et al. “Balancing Durability and Environmental Impact in Concrete Combining Low-Grade Recycled Aggregates and Mineral Admixtures.” Resources, Conservation and
Recycling, vol. 55, no. 11, 2011, pp. 1060–1069., doi:10.1016/j.resconrec.2011.05.020.
4. Johnson, Robert, and Medhat H. Shehata. “The Efficacy of Accelerated Test Methods to Evaluate Alkali Silica Reactivity of Recycled Concrete Aggregates.” Construction and Building
Materials, vol. 112, 2016, pp. 518–528., doi:10.1016/j.conbuildmat.2016.02.155.
5. Kapoor, Kanish, et al. “Durability of Self-Compacting Concrete Made with Recycled Concrete Aggregates and Mineral Admixtures.” Construction and Building Materials, vol. 128, 2016, pp.
67–76., doi:10.1016/j.conbuildmat.2016.10.026.
6. Xiao, J.-Zh., et al. “On Relationships between the Mechanical Properties of Recycled Aggregate Concrete: An Overview.” Materials and Structures, vol. 39, no. 6, 2006, pp. 655–664.,
doi:10.1617/s11527-006-9093-0.
7. Xiao, Jianzhuang, et al. “Mechanical Properties of Recycled Aggregate Concrete under Uniaxial Loading.” Cement and Concrete Research, vol. 35, no. 6, 2005, pp. 1187–1194.,
doi:10.1016/j.cemconres.2004.09.020.
8. Xiao, Jianzhuang, et al. “Seismic Behavior of Semi-Precast Column with Recycled Aggregate Concrete.” Construction and Building Materials, vol. 35, 2012, pp. 988–1001.,
doi:10.1016/j.conbuildmat.2012.04.062.