The document summarizes an evaluation of the durability properties of recycled aggregate concrete incorporating fly ash and silica fume. It includes a literature review on previous studies of recycled aggregate concrete. An experimental program involved developing mix designs for control concrete and concretes with 50% and 100% replacement of natural coarse aggregate with recycled aggregate. Specimens were tested for properties like acid resistance, sulfate resistance, carbonation rate, and water impermeability. Results showed recycled aggregate concretes had higher weight loss in acid, higher strength reduction due to acid and sulfate exposure, and higher carbonation rates compared to control concrete, with effects increasing with higher recycled aggregate content.

1. Evaluation of Durability Properties of Recycled Aggregate
Concrete Incorporating Flyash And Silica Fume
Prepared by:
Parth B. Patel
Dr. Urmil V. Dave
Prof. Tejas M. JoshiDepartment of Civil Engineering
Institute of Technology
Nirma University
Ahmedabad
33rd National Convention of Civil Engineers
The Institution of Engineers (India)

2.  Introduction
 Literature Review
 Experimental work
 Results
 Conclusion
 References
Flow of Presentation

3. Introduction
Recycled Aggregate
 Recycling is the act of processing the used material for use in
creating new product.
 To reduce the use of natural aggregate we can use recycled
aggregate.
 Recycled aggregate are comprised of crushed, graded
inorganic particles processed from the materials that have
been used in the constructions and demolition debris.

4. Application of Recycled Aggregate
 Concrete kerb
 Manhole covers
 Precast toilet blocks
 Precast walls
 Concrete planters
 Granular base
 Embankment fill
 Paving block
 Backfill material

5. Literature

6. Paper Observations
A.M. Knaack, Y.C. Kurama, “Design of
Normal Strength Concrete Mixtures with
Recycled Concrete aggregates”, Structures
Congress, (2011), pp. 3068-3079. [1]
Investigation included three methods for aggregate replacement: direct
weight replacement, equivalent mortar replacement, and direct volume
replacement. From this investigation it is concluded that direct volume
method and equivalent mortar methods gives best and worst
workability respectively.
Claudio Javier Zega, Angel Antonio Di
Maio. “Recycled Concretes Made with
Waste Ready-Mix Concrete as Coarse
Aggregate”, Journal of Materials in Civil
Engineering, Vol. 23(3), (2011), pp. 281-
286.[2]
Investigation included replacement ration as 25%, 50% and 75%.
Results shows that when the amount of added water was increased
according to the absorption of the recycled aggregate, a increased
slump observed and on the contrary, mix in which the amount of
mixing water was kept same in all concretes, a slump decrease was
noted.
Marco Pepe, Romildo Dias Toledo Filho,
Eduardus A.B. Koenders, Enzo Martinelli.
“A novel mix design methodology for
Recycled Aggregate Concrete”, Construction
and Building Materials, Vol. 122, (2016), pp.
362-372.[3]
The experimental programme included different water cement ratio
that is 0.4, 0.5 and 0.6; different ratio of NA to RA that is 0%, 50%
and 100%; and different moisture condition of aggregates that is dry
and saturated. Control concrete was designed for 50 MPA. Results
shows that compressive strength decreases as replacement ratio
increases, as water cement ratio increases.

7. Paper Observations
Kanish Kapoor, S.P. Singh, Bhupinder
Singh. “Durability of self-compacting
concrete made with Recycled Concrete
Aggregates and mineral admixtures”,
Construction and Building Materials, Vol.
128, (2016), pp. 67-76.[4]
In this study replacement ratio of NA to RA was kept as 0%, 50%
and 100%. Flyash and silicafume were used as 20% and 10%
partial replacement of cement respectively. Result shows that the
compressive strength across all the curing ages reduced marginally
with increasing content of RCA relative to the control mix made
with 100% NCA.
Md Shakir Ahmed, H S Vidyadhara.
“Experimental study on strength behaviour
of recycled aggregate concrete”,
International Journal of Engineering
Research Technology, Vol. 2, (2013), pp.
76-82.[5]
Investigation included 0%, 20%, 40%, 60% 80% and 100%
replacement of NA to RA. RCA is separated from concrete by
hammering. Mortar of recycled aggregate is also removed as much
as possible. Results shows that split tensile strength, flexural
strength and modulus of elasticity of RAC decreases at all the ages
as recycled aggregate content increases.
B.M. Vinay Kumar, H. Ananthan, K.V.A.
Balaji. ”Experimental studies on
utilization of coarse and finer fractions of
recycled concrete aggregates in self
compacting concrete mixes“, Journal of
Building Engineering, Vol. 9, (2017), pp.
100-108.[6]
Effect of acid exposure on recycled aggregate concrete was studied.
Natural coarse and fine aggregates were replaced by recycled
coarse and fine aggregate at ratio of 20%. RAC was immersed in
solution of 3% H2SO4 for 30 days. Results shows that
compressive strength after acid attack is decreased by 39.57% as
compared to control concrete.

8. Experimental Work

9.  Concrete laboratory waste recycled at Kesarjan Building Centre Pvt Ltd, Ahmedabad.
Process of making Recycled Aggregates

10. Material Properties
Sr.
No.
Properties Units
Natural
Aggregates
RA
(Lab. Waste)
20 mm 10 mm 20 mm 10 mm
1 Fineness modulus 7.29 6.03 7.31 5.97
2 Loose density kg/m3 1444 1311 1264 1195
3 Compacted density kg/m3 1671 1584 1446 1407
4 Specific gravity 2.82 2.79 2.44 2.38
5 Water absorption % 1.37 1.27 5.25 6.0
6 Moisture content % 0.9 0.86 1.1 1.0
 Recycled aggregate has lower density and higher water absorption as compared to natural
aggregate due to attached mortar on aggregates.
Comparison of Properties of aggregate

11. Mix Design
Grade designation M25
Type of cement OPC 53 grade
Maximum nominal size of aggregate 20 mm
Minimum cement content 300 kg/m3
w/c Ratio 0.5
Workability 100 mm slump
Exposure condition Mild
Method of concreting Non-pumpable
Chemical admixture Super plasticizer
 Data to develop a mix design for M25 grade of control concrete.
Specific gravity of cement 3.2
Specific gravity of CA (20mm) 2.81
Specific gravity of CA (10mm) 2.79
Specific gravity of FA 2.75
Specific gravity of chemical admixture 1.15
Fine aggregate zone II

12. Mix Design
Material Unit Content
Cement kg/m3 316
CA 20 mm kg/m3 775
CA 10 mm kg/m3 516
Sand kg/m3 728
Water lit/m3 158
Admixture % 0.4
w/c - 0.5
Mix Contents of Control Concrete

13. CC RAC50 RAC100
Cement % 100 75 75
Fly ash % 0 15 15
Silica fume % 0 10 10
Cement kg/m3 316 237 237
Fly ash kg/m3 0 47.4 47.4
Silica fume kg/m3 0 31.6 31.6
Sand kg/m3 728 789 850
NCA 20mm kg/m3 775 388 0
NCA 10mm kg/m3 517 259 0
RCA 20mm kg/m3 0 335 671
RCA 10mm kg/m3 0 221 441
Water kg/m3 158 187 216
Admixture % 0.4 0.4 0.4
Slump mm 105 115 105
Final Mix Design

14. Durability Properties Size Specimens 28 Days 56 Days
Acid Attack 150×150×150 Cube 3 3
Sulphate Attack 150×150×150 Cube 3 3
Accelerated carbonation 100×200 Cylinder 3 0
Water Impermeability 150×150×150 Cube 3 0
RCPT
100×50 Cylinder 3 0
Sorptivity test
Casting of Specimens for durability properties

15.  The concrete specimen size 150 mm × 150 mm × 150 mm is casted for evaluating change in
compressive strength and change in mass.
 The acid resistance of three mixes of concrete is determined by measuring the residual
compressive strength and change in mass after acid exposure at 28 and 56 days of time
intervals.
 After 28 days of water curing, cubes are immersed in 5% sulfuric acid (H2SO4) solution with
pH maintained at 3.
Acid attack (IS:4456-1987)

16. Mix
28 days 56 days
Before After Before After
CC
8.51 8.13 8.80 8.23
8.29 7.96 8.51 7.96
8.86 8.40 8.67 8.13
Average 8.55 8.16 8.66 8.11
RAC50
8.18 7.75 8.23 7.59
8.24 7.81 8.34 7.71
8.10 7.63 8.15 7.50
Average 8.17 7.73 8.24 7.60
RAC100
7.98 7.41 7.89 7.15
8.01 7.40 7.69 6.98
7.89 7.33 7.76 7.01
Average 7.96 7.38 7.78 7.05
Acid attack (IS:4456-1987)

17.  From results it can be seen that in mix
RAC50 and RAC100 weight loss is
higher as compared to CC.
 Weight loss is increasing as recycled
aggregate content is increasing.
 Reason behind this is less bonding
between old mortar of recycled
aggregate and new mortar.
Acid attack (IS:4456-1987)

18. Mix
Avg Comp strength before Comp strength after Avg Comp strength after
28 days 56 days 28 days 56 days 28 days 56 days
CC 32.15 35.41
30.22 27.35
29.81 27.2429.95 26.89
29.26 27.49
RAC50 26.37 31.33
22.92 20.26
22.75 20.1723.85 20.55
21.49 19.69
RAC100 24.07 29.63
20.19 17.25
19.69 16.6119.65 16.21
19.23 16.36
Acid attack (IS:4456-1987)

19.  From results it can be seen that in mix
RAC50 and RAC100 compressive
strength reduction is higher as
compared to CC.
 Compressive strength reduction is
increasing as recycled aggregate
content is increasing.
 Reason behind this is less bonding
between old mortar of recycled
aggregate and new mortar.
Acid attack (IS:4456-1987)

20.  The concrete specimen size 150 × 150 × 150 mm is casted for evaluating change in
compressive strength and change in mass.
 The sulphate resistance of three mixes of concrete is determined by measuring the residual
compressive strength and change in mass after sulphate exposure at 28 and 56 days of time
intervals.
 After 28 days of water curing, cubes are immersed in 5% sodium nitrate (Na2SO4) solution
with pH maintained at 8.
Sulphate attack (IS:4456-1987)

21. Mix
28 days 56 days
Before After Before After
CC
8.87 8.89 8.16 8.19
8.51 8.54 8.36 8.38
8.93 8.95 8.79 8.82
Average 8.77 8.79 8.44 8.46
RAC50
8.02 8.07 8.11 8.17
8.16 8.21 7.92 7.97
7.98 8.05 8.19 8.26
Average 8.05 8.11 8.07 8.13
RAC100
7.96 8.04 7.64 7.73
7.82 7.90 7.85 7.94
7.75 7.82 7.77 7.84
Average 7.84 7.92 7.75 7.84
Sulphate attack (IS:4456-1987)

22.  From results it can be seen that in mix
RAC50 and RAC100 little weight gain
is noted as compared to CC.
 Weight gain is increasing as recycled
aggregate content is increasing.
 Reason behind this is more absorption
of recycled aggregate.
Sulphate attack (IS:4456-1987)

23. Mix
Avg Comp strength before Comp strength after Avg Comp strength after
28 days 56 days 28 days 56 days 28 days 56 days
CC 32.15 35.41
31.16 32.85
31.24 33.3331.69 33.89
30.88 33.26
RAC50 26.37 31.33
24.92 28.51
25.07 28.9725.53 28.82
24.75 29.59
RAC100 24.07 29.63
23.47 26.61
22.86 26.5222.93 26.04
22.19 26.90
Sulphate attack (IS:4456-1987)

24.  From results it can be seen that in mix
RAC50 and RAC100 compressive
strength reduction is more as compared
to CC.
 Compressive strength reduction is
increasing as recycled aggregate
content is increasing.
 Reason behind this is less bonding
between old mortar of recycled
aggregate and new mortar.
Sulphate attack (IS:4456-1987)

25.  3 cylinders of 100 mm diameter and 200 mm height for each mixes is casted and placed in
the carbonation chamber.
 Carbon dioxide gas is supplied from a standard industrial cylinder fitted with a regulator. The
temperature of the system is controlled by keeping it in a room at a 28°C and a CO2
concentration of 4% with 60% relative humidity.
 At completion of test, the specimens is taken out of the chamber and the depth of carbonation
is measured by treating the surface of a freshly sliced specimen with a pH indicator that was
1% solution of phenolphthalein in water.
Accelerated Carbonation Test (CEN 12390)

26. Equipment capacity
Max. Temperature : 60°C
Humidity range : 40% to 80%
Max. CO2 concentration : 4.5%
Test parameters
Temperature : 28°C
Humidity :60%
CO2 concentration :4%
Accelerated Carbonation Test (CEN 12390)

27. Split
Cylinder
Side
Carbonation depth (mm)
Avg.
Carbonation
depth (mm)
Near
top
Near
middle
Near
bottom
1
2.99 3.45 3.11
3.22
3.05 3.56 3.18
2
2.95 3.42 3.16
3.01 3.53 3.22
 Based on the carbonation depth values
carbonation coefficient is calculated using
following formula :
X = C × √t
X = Carbonation depth in mm,
C = Carbonation coefficient in mm/day0.5
t = exposure time in days
Accelerated Carbonation Test (CEN 12390)

28. Accelerated Carbonation Test (CEN 12390)
Mix
Carbonation
depth
(mm)
Rate of
Carbonation
(mm/day0.5)
Avg. rate of
Carbonation
(mm/day0.5)
CC
3.22 1.22
1.313.48 1.32
3.72 1.41
RAC50
3.59 1.36
1.443.85 1.46
4.02 1.52
RAC100
4.13 1.56
1.544.25 1.61
3.82 1.44

29. Accelerated Carbonation Test (CEN 12390)
 From results it can be seen that mix
RAC50 and RAC100 has rate of
carbonation more as compared to CC.
 Rate of carbonation is increasing as
recycled aggregate content is
increasing.

30. Water Impermeability Test (DIN1048)
 The specimens are tested for impermeability test according to German standard DIN-1048 part-5.
 During this test three concrete specimen are kept as shown in fig. Water pressure is maintained at 5
kg/sq.cm. by compressor attached to the impermeability test setup. After 3 days of exposure to
pressurized water the specimen are removed from the test setup. Cubes are then split in to two half
and penetration depth is measured.

31. Water Impermeability Test (DIN1048)

32. Water Impermeability Test (DIN1048)
Split Cube Side
Water penetration depth (mm)
Avg. water penetration
depth (mm)Near left end Near middle Near right end
1 20.7 22.4 21.8
20.68
2 20.9 22.2 22.1
Mix Penetration depth (mm) Avg. penetration depth (mm)
CC
20.68
20.3619.95
20.45
RAC50
21.89
21.4121.13
21.21
RAC100
22.56
23.1223.84
22.96

33. Water Impermeability Test (DIN1048)
 From results it can be seen that mix
RAC50 has 5.16% and RAC100 has
13.56% higher water penetration as
compared to control concrete.

34. Rapid Chloride Penetration Test (ASTM 1202C)
 Specimens of 100 mm diameter and 50 mm length is submerged in the 5% Sodium Chloride
solution in a tank, after 28 days of curing period for a 28 days exposure.
 Then specimens is tested as per standard procedure of (ASTM C1202-97) for 6 hrs.

35. Rapid Chloride Penetration Test (ASTM 1202C)
 Area under the curve of current versus time
duration is the total charge passing through the
respective concrete specimens which can be
calculate by trapezoidal rule as mentioned
below:
Q = 900 (I0 + 2I30 + …. + 2I300 + 2I330 + 2I360)
Where Q = charge passed (Coulombs)
I0 = current (Ampere) immediately after voltage is
applied
It = current (Ampere) at t minute after voltage is
applied.
Time (min)
Current in amp
CC RAC50 RAC100
0 0 0 0
30 0.005 0.009 0.011
60 0.018 0.022 0.026
90 0.028 0.033 0.039
120 0.045 0.049 0.059
150 0.053 0.064 0.071
180 0.066 0.075 0.085
210 0.087 0.099 0.109
240 0.111 0.12 0.134
270 0.1375 0.158 0.171
300 0.175 0.186 0.203
330 0.2125 0.232 0.255
360 0.25 0.265 0.286
Cumulative current 2.2524 2.49 2.739
Charge passed 2027.16 2241 2465.1
Chl Ion Permeability Moderate Moderate Moderate

36. Rapid Chloride Penetration Test (ASTM 1202C)
 Control concrete current
readings are lower as compared
to recycled aggregate concrete.
RAC50 and RAC100 concrete
mixes showed similar current
values at starting.

37. Rapid Chloride Penetration Test (ASTM 1202C)
 Figure shows the percentage
increase in total charge passed
through specimen with respect
to control concrete. It can be
observed that mixes RAC50
and RAC100 has higher
chloride ion penetrability
compared to control concrete.

38. Sorptivity (ASTM 1585)
 This test method is used to determine the rate of absorption (sorptivity) of water by cement
concrete by measuring the increase in mass of specimen resulting from absorption of water
as a function of time when only one surface of the specimen is exposed to water.
 The specimen required for the test consist of a disc of diameter 100mm 6mm and height
50mm 3mm.
 The weight of specimen are measured at time (t) : 1 min, 5 min, 10 min, 20 min, 30 min, 1
hour, every hours up to 6 hours, every day up to 3 days, 24 hours apart from 4 to 6 days and
one measurement between 7 to 9 days.
 From the change in mass with time. Water absorption and sorptivity is calculated.
Water Absorption I = Mt / (a b) where a = exposed surface area,
d = density of water (g/ mm3)
 From the water absorption, the sorptivity (S) can be calculated by equation given in ASTM
C 1585,
I = S + b

39. Initial
Sorptivity
0.0082 mm/√s
Secondary
Sorptivity
0.0026 mm/√s
Control Concrete
Sorptivity (ASTM 1585)

40. Initial
Sorptivity
0.0093 mm/√s
Secondary
Sorptivity
0.003 mm/√s
RAC50
Sorptivity (ASTM 1585)

41. Initial
Sorptivity
0.0101 mm/√s
Secondary
Sorptivity
0.0033 mm/√s
RAC100
Sorptivity (ASTM 1585)

42.  Results shows that the RAC50 and
RAC100 has higher sorptivity as
compared to control concrete.
Sorptivity (ASTM 1585)

43. Conclusions
 From investigation it can be concluded that recycled aggregate has higher water absorption as compared
to natural aggregate which need to be consider in a mix design.
 Durability properties like acid attack, sulphate attack, accelerated carbonation, water impermeability,
rapid chloride penetration and sorptivity decreases as recycled aggregate content increases.

44. 1. A.M. Knaack, Y.C. Kurama, “Design of Normal Strength Concrete Mixtures with Recycled Concrete Aggregates”, Structures Congress,
(2011), pp. 3068-3079.
2. Claudio Javier Zega, Angel Antonio Di Maio. “Recycled Concretes Made with Waste Ready-Mix Concrete as Coarse Aggregate”, Journal
of Materials in Civil Engineering, Vol. 23(3), (2011), pp. 281-286.
3. Marco Pepe, Romildo Dias Toledo Filho, Eduardus A.B. Koenders, Enzo Martinelli. “A novel mix design methodology for Recycled
Aggregate Concrete”, Construction and Building Materials, Vol. 122, (2016), pp. 362-372.
4. Kanish Kapoor, S.P. Singh, Bhupinder Singh. “Durability of self-compacting concrete made with Recycled Concrete Aggregates and
mineral admixtures”, Construction and Building Materials, Vol. 128, (2016), pp. 67-76.
5. Md Shakir Ahmed, H S Vidyadhara. “Experimental study on strength behaviour of recycled aggregate concrete”, International Journal of
Engineering Research Technology, Vol. 2, (2013), pp. 76-82.
6. B.M. Vinay Kumar, H. Ananthan, K.V.A. Balaji. ”Experimental studies on utilization of coarse and finer fractions of recycled concrete
aggregates in self compacting concrete mixes“, Journal of Building Engineering, Vol. 9, (2017), pp. 100-108.
7. Navdeep Singh, S.P. Singh, ”Carbonation and electrical resistance of self compacting concrete made with recycled concrete aggregates and
metakaolin“, Construction and Building Materials, vol. 121, (2016), pp. 400-409.
8. Shi-cong Kou, Chi-sun Poon, Francisco Agrela, ”Comparisons of natural and recycled aggregate concretes prepared with the addition of
different mineral admixtures“, Cement Concrete Composites, Vol. 33, (2011), pp. 788-795.
9. IS: 10262-2009, ”Concrete Mix Proportioning - Guidelines“, Bureau of Indian Standards”, New Delhi.
10. IS: 4456-1987, “Methods of Test for Chemical Resistant Mortars”, Bureau of Indian Standards, New Delhi.
11. CEN 12390 (Part-12)-2010, “Euro Standard for Determination of the Potential Carbonation Resistance of Concrete.
12. DIN 1048 (Part-5)-1991, ”German Standard for Determination of Permeability of Concrete“.: Testing hardened concrete - Part 12:
Determination of the potential carbonation resistance of concrete: Accelerated carbonation method
13. ASTM 1202C-1997 Standard Test Method for Electrical Indication of Concrete’s Ability to Resist Chloride Ion Penetration.
References

45. Thank you