green recycled aggregate concrete (grac)
TRANSCRIPT
3 May 2023
INFLUENCE OF MINERAL ADDITIONS ON THE PERFORMANCE OF GREEN
RECYCLED AGGREGATE CONCRETE
DAYAL KURIAN VARGHESE
1
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2 OVERVIEW
Introduction Green recycled aggregate concrete (GRAC) Recycled concrete aggregate (RCA) Case study-1 Case study-2 Conclusion References
Mobile Recycling Unit
3 May 2023
3 INTRODUCTION
By the end of the 20th century, sustainable development and environmental protection became key goals of modern society
Main problems that industry of construction materials faces were:
natural aggregate depletion
high consumption of Portland cement and associated high emission of carbon dioxide
large amount of generated construction and demolition (C&D) waste
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4 GREEN RECYCLED AGGREGATE CONCRETE (GRAC)
GRAC made with recycled concrete aggregate, low cement content and high content of different mineral supplements
Such concretes belong to ‘‘green’’ or ‘‘eco’’ concretes
Here GRAC produced with
fine river aggregate
coarse recycled aggregate
Portland Cement
Silica fume (SF), fly ash (FA), Metakaolin (MK), GGBS
Enterprise Park
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5RECYCLED CONCRETE
AGGREGATE (RCA)
Collection of C&D wastes Screening Vibrating
feederPlant
crusher
Jaw crusher
Magnetic separatorcone crusher
vibratory screens
storage compartment
Recycled aggregate
Sampling & Testing
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6 CASE STUDY-1
“Comparisons of natural and recycled aggregates concretes prepared with the addition of different mineral admixtures”
Kou et al. (2011) conducted studies on GRAC prepared with different mineral admixtures such as SF (10%),MK (15%),FA (35%), GGBS (55%)
The coarse aggregates were replaced with 50% and 100% of RCA
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7 MATERIALS USED
Portland cement (PC) Metakaolin (MK) Silica fume (SF) Fly ash (FA) Ground granulated blast slag (GGBS) Natural fine aggregate Recycled coarse aggregate
GGBS
Fly ash
Recycled concrete material
Silica fume Metakaolin
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8
Contents Cement
Fly ash
Silica fume
Metakaolin
GGBS
SiO2 21 56.79 85-86 53.2 44.6Al2O3 5.9 28.21 - 43.9 13.3Fe2O3 3.4 5.31 - 0.38 0.9CaO 64.7 <3 - 0.02 33.8MgO 0.9 5.21 - 0.05 4.8Na2O - - - 0.17 1.0K2O - - - 0.10 -TiO2 - - - 1.68 -SO3 2.6 0.68 0.3-.7 - 1.3Specific gravity (g/cm3) 3.15 2.31 2.22 2.62 2.98Specific surface (cm2/g) 3520 3960 1865
012680 5350
Physical and chemical properties of cement, fly ash, silica fume, GGBS and metakaolin
(Source: Shi-cong Kou et al. (2011))
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9 SPECIMEN PREPARATION AND CURING
Three series of concrete mixtures were prepared in the laboratory using a Pan mixer
SF, MK, FA and GGBS were used as cement replacements on a weight basis
A constant water/binder ratio at 0.50 was used Series I concrete mixtures used natural aggregate
as the coarse aggregate C (control, natural aggregate with 100% OPC),
C-SF10 (natural aggregate with 10% SF),C-MK15,C-FA35,C-GGBS55
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10 Contd…….
In Series II mixes, recycled aggregates were used to replace 50% of natural coarse aggregate
R50,R50-SF10,R50-MK15,R50-FA35,R50-GGBS55
In Series III mixes, recycled aggregates were used to replace 100% of natural coarse aggregate
R100,R100-SF10,R100-MK15,R100-FA35,R100-GGBS55
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11
Constitution (kg/m3)
Composite of binder
Sand
Series I Series II Series III
Water Cement Mineral admixtures
Coarse natural agg.
Coarse natural agg.
Coarse recycled agg.
Coarse recycled agg.
Control 195 390 0 678 1107 527 539 1078
SF10 195 351 39 664 1107 527 539 1078
MK15 195 331.5 58.5 669 1107 527 539 1078
FA35 195 253.5 136.5 640 1107 527 539 1078
GGBS55 195 175.5 214.5 658 1107 527 539 1078
Concrete mix proportion
(Source: Shi-cong Kou et al. (2011))
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12 Contd……. Workability measured using the slump cone test Concrete cubes of size 100 mm casted for
determining compressive strength 100mm x 200mm concrete cylinders casted to
determine the tensile splitting strength 100mm x 50mm concrete cylinders casted to
determine the chloride ion penetration 75mm x 75mm x 285mm prisms were casted for
determining drying shrinkage
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13 RESULTS
Slump of concrete mixtures
Slump value
(Source: Shi-cong Kou et al. (2011))
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14 Compressive strength
Development of compressive strength of concrete mixtures in Series I
C-FA35 : 66.2%C-GGBS55 : 66.5%C-SF10 : 41.7%C-MK15 : 43.3%
Compressive strength gain
(Source: Shi-cong Kou et al. (2011))
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15 Compressive strength
Development of compressive strength of concrete mixtures in Series II
RA50-FA35 : 68.6%RA50-GGBS55 : 67.2%RA50-SF10 : 49.8%RA50-MK15 : 52.2%
Compressive strength gain
(Source: Shi-cong Kou et al. (2011))
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16 Compressive strength
Development of compressive strength of concrete mixtures in Series III
RA-FA35 : 70.9%RA-GGBS55 : 69.1%RA-SF10 : 55.7%RA-MK15 : 56.8%
Compressive strength gain
(Source: Shi-cong Kou et al. (2011))
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17 Tensile strength
Tensile splitting strength of concrete mixturesTensile strength gain
C:17.2%,C-SF10:23.1,C-MK15:26.4,C-FA35:35.3,C-GGBS55:33
R50:23.9%,R50-SF10:34.9,R50-MK15:36.9,R50-FA35:40.5,R50-GGBS55:38.8
R100:24.6%,R100-SF10:46.2,R100-MK15:40.8,R100-FA35:48,R100-GGBS55:44.9
(Source: Shi-cong Kou et al. (2011))
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18 Drying shrinkage
Drying shrinkage of concrete mixtures at 112 days(Source: Shi-cong Kou et al. (2011))
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19 Chloride ion penetration The total charge passed increased with the use of RA.
Total charge passed in coulombs of concrete mixtures
(Source: Shi-cong Kou et al. (2011))
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20 DISCUSSION The compressive strength of RAC was lower than
that of the control specimen, but could be compensated by the use of 10% SF or 15% MK
However 35% FA or 55% GGBS lowered the compressive strength
The tensile strength of natural and RAC made with SF and MK was higher than that of the corresponding control concrete at all test ages
FA and GGBS decreased the tensile strength
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21 Contd……. The drying shrinkage values of the natural and RAC
made with SF and MK was higher than that of control
The chloride ion penetration test indicated that the concrete containing recycled aggregate had a more open pore structure, compared to the control concrete
The test results show that SF and MK can improve both strength and durability properties of RAC
FA and GGBS significantly improved the durability performance of the recycled aggregate concrete
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22 CASE STUDY-2
“Experimental analysis of properties of recycled coarse aggregate (RCA) concrete with mineral additives”
Ö. Çakır (2014) observed compressive strength and splitting tensile strength of GRAC prepared with incorporation of SF and GGBFS
The RAC was prepared by using 5%, 10% of SF and 30% ,60% of GGBFS whereas coarse aggregates were replaced with 50% and 100% of RCA
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23 MATERIALS USED
Portland cement (PC) Silica fume (SF) Ground granulated blast slag (GGBS) Natural fine aggregate Recycled coarse aggregate
GGBS
Recycled concrete material
Silica fume
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24 SPECIMEN PREPARATION AND CURING
Three series of concrete mixtures were prepared in the laboratory using a Pan mixer
SF, GGBFS were used as cement replacements on a weight basis
A constant water/binder ratio at 0.50 was used Series I concrete mixtures used natural aggregate
as the coarse aggregate NA (control, natural aggregate with 100%
OPC), NA-SF5 (natural aggregate with 5% SF),NA-SF10,NA-GGBS30,NA-GGBS60
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25 Contd……. In Series II mixes, recycled aggregates were used to
replace 50% of natural coarse aggregate RA50,RA50-SF5,R50-SF10,RA50-GGBS30,RA50
GGBS60 In Series III mixes, recycled aggregates were used to
replace 100% of natural coarse aggregate RA100,RA100-SF5,RA100-SF10,RA100
GGBS30,RA100-GGBS60 100mm x 200mm concrete cylinders casted to determine
the tensile splitting strength 150 mm concrete cubes casted for the determination of the
compressive strength
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26RESULTS
Notation Compressive strength(Mpa) Splitting tensile strength(Mpa)
NA 42.40 3.30NA-SF5 42.90 3.30NA-SF10 46.10 3.50NA-GGBS30 34.50 3.20NA-GGBS60 32.10 3.20RA50 34.70 3.20RA50-SF5 35.50 3.30RA50-SF10 35.80 3.30RA50-GGBS30 30.10 2.90RA50-GGBS60 26.60 2.70RA100 32.10 3.00RA100-SF5 32.00 3.20RA100-SF10 35.60 3.30RA100-GGBS30 25.30 2.60RA100-GGBS60 21.90 2.50
Compressive and splitting tensile strength at 28 day
(Source: Ö. Çakır (2014))
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27 DISCUSSION
The compressive strength of the GRAC gradually decreases as the amount of RCA increases.
At 100% of the replacement level, the compressive strength decreases about 24% at 28 days. At over 50% of the replacement level, the strength reduction is more significant.
GRAC containing 5% and 10% SF increases the compressive strength. However, the use of 30% and 60% GGBFS lowered the compressive strength.
GRAC containing 5% and 10% SF increases the tensile strength. However, the use of 30% and 60% GGBFS lowered the tensile strength.
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28 Examples of Structural Application of GRAC
BRE Office Building
Enter prise park
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29 CONCLUDING REMARKS SF and MK improve both strength and durability properties
of green recycled aggregate concrete. Use of FA and GGBS improved the durability performance
of the recycled aggregate concrete. Stricter quality control of recycled concrete aggregate is
required. The resistance to chloride penetration decreases as the
percentage of recycled aggregate in concrete increases. Use of mineral admixtures enhances the resistance to
chloride attack .
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30 Contd……. Mineral admixtures contribute more to the strength
properties RAC than that of natural aggregate concrete.
In GRAC, it was finally concluded that the recycled aggregates may be used up to 50% and silica fume may be used up to 10% for obtaining best results.
Overall economy of GRAC is comparable with that of natural aggregate concrete.
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31 REFERENCES Kou S.C, Poon C.S, Agrela F (2011), “Comparisons of natural and
recycled aggregates concretes prepared with the addition of different mineral admixtures.” Cement and Concrete Composites, Vol. 33, pp. 788-795.
Ö. Çakır (2014), “Experimental analysis of properties of recycled coarse aggregate (RCA) concrete with mineral additives.” Construction and Building Materials Vol. 68, pp 17–25.
Marinkovic´ S, Radonjanin V, Malešev M, Ignjatovic´ I (2010), “Comparative environmental assessment of natural and recycled aggregate concrete.” Waste Manage Vol. 30, pp 2255–2264.
Radonjanin V, Malesev M, Marinkovic S, Al Malty A.E.S (2013), “Green recycled aggregate concrete.” Construction and Building Materials Vol. 47, pp 1503-1511.
Corinaldesi V, Moriconi G. (2009), “Influence of mineral additions on the performance of 100% recycled aggregate concrete.” Constr Build Mater Vol. 23, pp 2869–2876.
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