- Email: [email protected]
Concrete Containing Recycled Rubber Steel Fiber
Available online at www.sciencedirect.com
ScienceDirect StructuralScienceDirect Integrity Procedia 00 (2019) 000–000
Available online at www.sciencedirect.com Structural Integrity Procedia 00 (2019) 000–000
ScienceDirect
www.elsevier.com/locate/procedia www.elsevier.com/locate/procedia
Procedia Structural Integrity 18 (2019) 101–107
25th International Conference on Fracture and Structural Integrity 25th International Conference on Fracture and Structural Integrity
Concrete Containing Recycled Rubber Steel Fiber Concrete Containing Recycled Rubber Steel Fiber Sana Gula*, Sohaib Naseerb Sana Gul *, Sohaib Naseer
a and Technology, Islamabad, b Pakistan National University of science Capital University of Science and Technology, Islamabad, Pakistan a National University of science and Technology, Islamabad, Pakistan b Capital University of Science and Technology, Islamabad, Pakistan a
b
Abstract Abstract To dispose waste rubber tire is one of the major environmental issue all over the world. Every year large number of tires are buried or discarded all over the world causing a serious threat to the environment. Mostly waste rubber tires are used by some industries To dispose waste rubberthis tirekind is one the major environmental issueeffect all over world. Every year large numberitofistires are buried as fuel but as we know ofof waste utilization has hazardous andthe can be uneconomical. Therefore, needed to use or all over world causing threat to the Mostly waste rubber are used by some industries thisdiscarded kind of waste in athe such away so thataitserious might not affect theenvironment. environment at any cost. This papertires presents the use of scrap rubber as fuel as we knowtothis kind of in waste hazardous effect and be uneconomical. Therefore, is needed to use tires as but an alternative steel fiber fiberutilization reinforcedhas concrete. Four types of can concrete mix were prepared, the ittest batch and the this kindbatch of waste in a such it might not the environment any cost. paper presentsofthe use of respectively. scrap rubber control containing 1 %away and 5so%that replacement of affect steel fiber and recycledatrubber steelThis fibers by volume concrete tires as ankept alternative steel fiberfield reinforced concrete. types of concrete mix were prepared, the Results test batch and thea W/c was constanttoso thatfiber the in actual condition can beFour replicated that are normally adopted at sites. showed control batch containing % and 5 % replacement of20% steeland fiber14% andfor recycled rubber steeloffibers volume of concrete reduced compressive and1split tensile strength up to 1% replacement RRSFbyrespectively. For 5% respectively. replacement W/c was akept constant that the42% actual condition can be replicated thattensile are normally at sites. Results showed of RRSF reduction of so 38% and wasfield observed for compressive and split strength adopted respectively. It was concluded thata reduced compressive strength up to of 20% and 14% 1% replacement of RRSF 5% replacement for replacement rates and up tosplit 1% tensile of RRSF by volume concrete didfor influence the compressive andrespectively. split tensile For strength of concrete of a reduction of 38% and 42%steel wasfibers observed for compressive split behaviour tensile strength It wasbehaviour concluded can that butRRSF the samples with recycled rubber has somehow showedand ductile ratherrespectively. than brittle. Such for replacement rates to 1% of RRSF by volume of impact concreteresistance did influence the compressive and split tensiletostrength of concrete prove beneficial forupstructures that require good properties. It is recommended use such kind of but the samples recycled rubber steelweight fibers has somehow showed ductile behaviour rather than brittle. Such behaviour can concrete for thewith construction of light concrete structures.
prove beneficial for structures that require good impact resistance properties. It is recommended to use such kind of concrete for the construction of light weight concrete structures.
© 2019 2019The TheAuthors. Authors. Published by Elsevier © Published by Elsevier B.V. B.V. Peer-review under responsibility of the Gruppo Italiano Frattura (IGF) ExCo. Peer-review under responsibility of the Gruppo Italiano Frattura (IGF) ExCo. © 2019 The Authors. Published by Elsevier B.V. Peer-review under responsibility of the Gruppo properties; Italiano Frattura (IGF) ExCo. Keywords: Scrap rubber tires; steel fiber; mechanical Recycled Rubber Steel Fiber (RRSF) Keywords: Scrap rubber tires; steel fiber; mechanical properties; Recycled Rubber Steel Fiber (RRSF)
* Corresponding author. E-mail address: [email protected] * Corresponding author. E-mail address: [email protected] 2452-3216 © 2019 The Authors. Published by Elsevier B.V.
Peer-review under responsibility of the Gruppo Italiano Frattura (IGF) ExCo. 2452-3216 © 2019 The Authors. Published by Elsevier B.V. Peer-review under responsibility of the Gruppo Italiano Frattura (IGF) ExCo.
2452-3216 2019 The Authors. Published by Elsevier B.V. Peer-review under responsibility of the Gruppo Italiano Frattura (IGF) ExCo. 10.1016/j.prostr.2019.08.144
Sana Gul et al. / Procedia Structural Integrity 18 (2019) 101–107 Sana Gul/ Structural Integrity Procedia 00 (2019) 000–000
102 2
1. Introduction To dispose waste rubber tire is one of the major environmental issue all over the world1. Every year large number of tires are buried or discarded all over the world causing a serious threat to the environment1. It is well known that the service life of almost one billion tires ended and about 50% of the these are discarded regularly1.according to literature scrap rubber tires contain some materials which can not be decompose in any condition thus causing serious threats to the environment2. One of the options is to burn them but again that would cause other harmful effects2.Therefore, causing a serious threat to the ecology. Tires are not easily biodegradable waste. Therefore, it is required to disposed of these tires efficiently. In the recent years a progress has been made in the management of polymeric wastes such as tires and it is becoming a potential source of valued raw materials3.One of the solutions to overcome this problem is to use tires as aggregate in the concrete by partially replacing the concrete by scrapped rubber tires3 as already discussed waste from rubber tires cannot be disposed of even after a long span landfill treatment4 therefore, they should be recycled and reused. In some research rubber tires are even used as fuel for kiln but again because of emission of carbo black from burning of these fuels causes serious environmental threats5 .The best way to reused scrap rubber tires is to use them in concrete as in concrete they will act as a filler and won’t make any chemical bonding thus making it environmental friendly6 . Although previous studies showed that using scrap rubber tires as a replacement of aggregate can cause reduction in compressive strength but showed lower unit weight and good workability as compared to plain concrete, so it can be used for the production of light weight aggregate7. Also, good energy absorption and ductility within the range was absorbed for rubberized concrete as compared to plain cocneret8. Rubberized concrete showed increased water absorption capability9,10. Nomenclature SF RRSF XRF LD OPC ACI ASTM UTM
Steel Fiber Recycled Rubber Steel Fiber X-Ray Florescence Laser Diffraction Ordinary Portland Cement American Concrete Institute American Standard for Testing Materials Universal Testing Machine
2. Experimental Program 2.1. Materials Used Ordinary Portland cement (OPC), grade 53, manufactured in Pakistan, confronting to ASTM standard11 C150-04, locally available course aggregate, fine aggregate, steel fibers, and scrap rubber steel fiber. 2.2. Chemical and Physical Characterization The aggregates were characterized using sieve analysis for the average particle size, and Laser diffraction technique for avrage particale size of the cement also X-Ray Florscence technique for the elemental analysis of the cement used shown in table.1. Fig.1. (a) and (b) shows the particle size distribution of fine and coarse aggrigate. Table 2 shows the physical properties of materials used.
Sana Gul et al. / Procedia Structural Integrity 18 (2019) 101–107 Sana Gul/ Structural Integrity Procedia 00 (2019) 000–000
103 3
Table 1 Chemical Characterization of Cement (XRF) Constituent (wt. %) Type I Cement SiO2
Constituent (wt. %) Type I Cement 19.19
TiO2
0.29
Al2O3
4.97
Fe2O3
3.27
MnO
0.04
MgO
2.23
CaO
65.00
Na2O
0.58
K2O
0.51
P2O5
0.08
LOI
3.84
Table 2 Physical Properties of Cement, Fine and Coarse aggregate Parameters
OPC
Fine aggregate
Coarse aggregate
Particle Size (D50), microns
16.4
650
9600
BET Surface Area (m /g)
0.822
_
_
Density (g/cm3)
3.17
2.5 kg/m³
81.6 lb/yd³
Fineness Modulus
_
2.4
2.5
Water absorption
_
_
2%
2
a
b
Fig. 1. Particle size distribution of aggregate (a) fine aggregate; (b) coarse aggregate
Sana Gul et al. / Procedia Structural Integrity 18 (2019) 101–107 Sana Gul/ Structural Integrity Procedia 00 (2019) 000–000
104 4
2.3. Shredding of Rubber Tires Tires were shredded by using tire shredding machine. Thin thread like shreds were made of rubber tires. Along with the rubber threads the steel fibers in rubber tires were also cut into standard sizes ranging from 1 to 4 inch.
Fig. 2. size distribution of steel fibres
3. Sample Preparation 3.1. Formulations Mixing Regime A typical formulation such as formulation-2 shown in Table 3 can be read as having 1% OPC Cement 2 % fine aggregate, 4 % coarse aggregate, and 1% replacement of SRSF by volume of concrete for 12x6 inches standard cylinders according to ACI mix design method. Rest of the formulations can be understood accordingly. Table 3 Formulations and mixing regime Cement
SF
SRSF Kg
Fine Aggregate
Coarse aggregate
Kg /m³
Kg /m³
/m³
Kg /m³
Kg /m³
Formulation-1
174.38
12.2
0
348.77
697.54
Formulation-2
174.38
0
12.2
348.77
697.54
Formulation-3
174.38
61
0
348.77
697.54
Formulation-4
174.38
0
61
348.77
697.54
S. No.
Water to cement ratio was 0.5 for all the batches.
3.2. Casting Concrete specimens having standard size 12 inches x 6 inches were casted to determine compressive strength and split tensile strength after 28 days of curing. For uniform consistency, concrete mixer was used for preparation of
Sana Gul et al. / Procedia Structural Integrity 18 (2019) 101–107 Sana Gul/ Structural Integrity Procedia 00 (2019) 000–000
105 5
concrete mix. After mixing, the cylindrical molds were filled in layers being placed on vibrating table for proper compaction and to remove the air entrapped in voids. 4. Testing Procedures 4.1. Compressive Strength Test Cylindrical specimens of dimension 6 in x 12 in were tested according to ASTM C 39 test standard12. To keep the load uniform and distributed, cylinders were capped with sulfur mortar (ASTM C 617). Sulfur caps were applied two hours before testing. The loading rate on a hydraulic machine were kept in range of 20 to 50 psi/s. 4.2. Split Tensile Strength Test For split tensile strength, the samples were tested according to ASTM C 496-96 13. The specimens were placed in Universal Testing Machine (UTM) along the length. In this test a diametral compressive force were applied along the length of the cylindrical specimen at a given rate un till failure occurs. 5. Results and Discussion 5.1. Compressive strength test
Compressive Strength (MPa)
From Figure 4 it can be seen that compressive strength reduced up to 20% and 38% for 1% and 5% incorporation of RRSF as compared to the specimens containing SF respectively. Specimens containing recycled rubber steel fiber (RRSF) showed notable ductility before failure under compression loading. Horizontal cracks were observed for RRSF specimens. This reduced compressive and flexural strength for RRSF might be because of improper bonding between the cement particles and RRSF as compared to cement and SF 14,15. This might lead to the non-uniformity of the applied load. The compressive strength of concrete depends on the bond between cement, aggregate and the fibers use11. In case of RRSF this bond seems to be weak that is why the strength degradation occurred for the specimens containing RRSF.
60
1% SF and RRSF
5% SF and RRSF
50 40 30 20 10 0
SF
RRSF
Fig. 3. Compressive Strength Test Results
5.2. Split Tensile Strength Test From figure 5 it can be seen that the split tensile strength tests up to 14% and 42 % reduction of strength were observed for 1% and 5% replacement of RRSF respectively. The percentage reduction of split tensile strength was
Sana Gul et al. / Procedia Structural Integrity 18 (2019) 101–107 Sana Gul/ Structural Integrity Procedia 00 (2019) 000–000
106 6
almost triple for 1% and 5% replacement of RRSF as compared to SF. This reduction in split tensile again might be due to the week bonding between cement, aggregate, and RRSF. Which lead to reduction in strength11. The reduction in strength increases with increasing percentage of rubberized fiber.
Split Tensile Strength (MPa)
1% SF and RRSF
5% SF and RRSF
30 25 20 15 10 5 0
SF
RRSF
Fig.4. Split Tensile Strength Test Results
6. Conclusions From the results it can be concluded that increasing the percentage replacement of RRSF the compressive and split tensile strength of concrete reduces as compared to specimens containing steel fiber. The main reason for this trend might be the weaker bond between the concrete mix and recycled rubber steel fiber. However, notable ductility was observed before failure of the sample after testing. In destructive tests, the specimens containing RRSF stayed intact indicating that recycled rubber steel fibers may be absorbing forces that are acting upon it. The failure was somehow ductile rather than brittle for the samples containing recycled rubber steel fiber Such behavior can prove beneficial for structures that require good impact resistance properties. Furthermore, the strain at failure also increased. Higher tensile strain at the point of failure shows higher energy absorbent capability of the mixture. 7. Recommendations The long-term performance of these mixes is not known in field. So, the use of such mixes is recommended in places where high compressive and tensile strength of concrete is not important e.g. sidewalks, pavement sections etc. References [1] [2] [3] [4] [5]
Thomas, Blessen Skariah, and Ramesh Chandra Gupta. "A comprehensive review on the applications of waste tire rubber in cement concrete." Renewable and Sustainable Energy Reviews 54 (2016): 1323-1333. Abdollahzadeh, A., R. Masoudnia, and S. Aghababaei. "Predict strength of rubberized concrete using atrificial neural network." WSEAS Transactions on Computers 10.2 (2011): 31-40. Sienkiewicz, Maciej, et al. "Progress in used tyres management in the European Union: a review." Waste management 32.10 (2012): 17421751. Abdollahzadeh, A., R. Masoudnia, and S. Aghababaei. "Predict strength of rubberized concrete using atrificial neural network." WSEAS Transactions on Computers 10.2 (2011): 31-40. Güneyisi, Erhan, Mehmet Gesoğlu, and Turan Özturan. "Properties of rubberized concretes containing silica fume." Cement and concrete research 34.12 (2004): 2309-2317.
[6] [7] [8] [9] [10] [11] [12] [13] [14] [15] [16]
Sana Gul et al. / Procedia Structural Integrity 18 (2019) 101–107 Sana Gul/ Structural Integrity Procedia 00 (2019) 000–000
107 7
Siddique, Rafat, and Tarun R. Naik. "Properties of concrete containing scrap-tire rubber–an overview." Waste management 24.6 (2004): 563569. Pacheco-Torgal, F., Yining Ding, and Said Jalali. "Properties and durability of concrete containing polymeric wastes (tyre rubber and polyethylene terephthalate bottles): An overview." Construction and Building Materials 30 (2012): 714-724. Batayneh, Malek K., Iqbal Marie, and Ibrahim Asi. "Promoting the use of crumb rubber concrete in developing countries." Waste management 28.11 (2008): 2171-2176. Aiello, Maria Antonietta, and F. Leuzzi. "Waste tyre rubberized concrete: Properties at fresh and hardened state." Waste Management 30.8-9 (2010): 1696-1704. Ganjian, Eshmaiel, Morteza Khorami, and Ali Akbar Maghsoudi. "Scrap-tyre-rubber replacement for aggregate and filler in concrete." Construction and building materials 23.5 (2009): 1828-1836. Sofi, A. "Effect of waste tyre rubber on mechanical and durability properties of concrete–a review." Ain Shams Engineering Journal (2017). American Society for Testing and Materials, ASTM C150-04: standard specification for Ordinary Portland Cement. Annual book of ASTM standards, vol. 04.02, Philadelphia, 2001. American Society for Testing and Materials, ASTM C39/C39M-01:standard test method for compressive strength of cylindrical concrete specimens. Annual book of ASTM standards, vol. 04.02, Philadel-phia, 2001. p. 18–22. American Society for Testing and Materials, ASTM C-617:standard test method for split tensile strength of cylindrical concrete specimens. Annual book of ASTM standards, vol. 04.02, Philadel-phia, 2001. Ganjian, Eshmaiel, Morteza Khorami, and Ali Akbar Maghsoudi. "Scrap-tyre-rubber replacement for aggregate and filler in concrete." Construction and building materials 23.5 (2009): 1828-1836. Pelisser, Fernando, et al. "Concrete made with recycled tire rubber: effect of alkaline activation and silica fume addition." Journal of Cleaner Production 19.6-7 (2011): 757-763.
ScienceDirect StructuralScienceDirect Integrity Procedia 00 (2019) 000–000
Available online at www.sciencedirect.com Structural Integrity Procedia 00 (2019) 000–000
ScienceDirect
www.elsevier.com/locate/procedia www.elsevier.com/locate/procedia
Procedia Structural Integrity 18 (2019) 101–107
25th International Conference on Fracture and Structural Integrity 25th International Conference on Fracture and Structural Integrity
Concrete Containing Recycled Rubber Steel Fiber Concrete Containing Recycled Rubber Steel Fiber Sana Gula*, Sohaib Naseerb Sana Gul *, Sohaib Naseer
a and Technology, Islamabad, b Pakistan National University of science Capital University of Science and Technology, Islamabad, Pakistan a National University of science and Technology, Islamabad, Pakistan b Capital University of Science and Technology, Islamabad, Pakistan a
b
Abstract Abstract To dispose waste rubber tire is one of the major environmental issue all over the world. Every year large number of tires are buried or discarded all over the world causing a serious threat to the environment. Mostly waste rubber tires are used by some industries To dispose waste rubberthis tirekind is one the major environmental issueeffect all over world. Every year large numberitofistires are buried as fuel but as we know ofof waste utilization has hazardous andthe can be uneconomical. Therefore, needed to use or all over world causing threat to the Mostly waste rubber are used by some industries thisdiscarded kind of waste in athe such away so thataitserious might not affect theenvironment. environment at any cost. This papertires presents the use of scrap rubber as fuel as we knowtothis kind of in waste hazardous effect and be uneconomical. Therefore, is needed to use tires as but an alternative steel fiber fiberutilization reinforcedhas concrete. Four types of can concrete mix were prepared, the ittest batch and the this kindbatch of waste in a such it might not the environment any cost. paper presentsofthe use of respectively. scrap rubber control containing 1 %away and 5so%that replacement of affect steel fiber and recycledatrubber steelThis fibers by volume concrete tires as ankept alternative steel fiberfield reinforced concrete. types of concrete mix were prepared, the Results test batch and thea W/c was constanttoso thatfiber the in actual condition can beFour replicated that are normally adopted at sites. showed control batch containing % and 5 % replacement of20% steeland fiber14% andfor recycled rubber steeloffibers volume of concrete reduced compressive and1split tensile strength up to 1% replacement RRSFbyrespectively. For 5% respectively. replacement W/c was akept constant that the42% actual condition can be replicated thattensile are normally at sites. Results showed of RRSF reduction of so 38% and wasfield observed for compressive and split strength adopted respectively. It was concluded thata reduced compressive strength up to of 20% and 14% 1% replacement of RRSF 5% replacement for replacement rates and up tosplit 1% tensile of RRSF by volume concrete didfor influence the compressive andrespectively. split tensile For strength of concrete of a reduction of 38% and 42%steel wasfibers observed for compressive split behaviour tensile strength It wasbehaviour concluded can that butRRSF the samples with recycled rubber has somehow showedand ductile ratherrespectively. than brittle. Such for replacement rates to 1% of RRSF by volume of impact concreteresistance did influence the compressive and split tensiletostrength of concrete prove beneficial forupstructures that require good properties. It is recommended use such kind of but the samples recycled rubber steelweight fibers has somehow showed ductile behaviour rather than brittle. Such behaviour can concrete for thewith construction of light concrete structures.
prove beneficial for structures that require good impact resistance properties. It is recommended to use such kind of concrete for the construction of light weight concrete structures.
© 2019 2019The TheAuthors. Authors. Published by Elsevier © Published by Elsevier B.V. B.V. Peer-review under responsibility of the Gruppo Italiano Frattura (IGF) ExCo. Peer-review under responsibility of the Gruppo Italiano Frattura (IGF) ExCo. © 2019 The Authors. Published by Elsevier B.V. Peer-review under responsibility of the Gruppo properties; Italiano Frattura (IGF) ExCo. Keywords: Scrap rubber tires; steel fiber; mechanical Recycled Rubber Steel Fiber (RRSF) Keywords: Scrap rubber tires; steel fiber; mechanical properties; Recycled Rubber Steel Fiber (RRSF)
* Corresponding author. E-mail address: [email protected] * Corresponding author. E-mail address: [email protected] 2452-3216 © 2019 The Authors. Published by Elsevier B.V.
Peer-review under responsibility of the Gruppo Italiano Frattura (IGF) ExCo. 2452-3216 © 2019 The Authors. Published by Elsevier B.V. Peer-review under responsibility of the Gruppo Italiano Frattura (IGF) ExCo.
2452-3216 2019 The Authors. Published by Elsevier B.V. Peer-review under responsibility of the Gruppo Italiano Frattura (IGF) ExCo. 10.1016/j.prostr.2019.08.144
Sana Gul et al. / Procedia Structural Integrity 18 (2019) 101–107 Sana Gul/ Structural Integrity Procedia 00 (2019) 000–000
102 2
1. Introduction To dispose waste rubber tire is one of the major environmental issue all over the world1. Every year large number of tires are buried or discarded all over the world causing a serious threat to the environment1. It is well known that the service life of almost one billion tires ended and about 50% of the these are discarded regularly1.according to literature scrap rubber tires contain some materials which can not be decompose in any condition thus causing serious threats to the environment2. One of the options is to burn them but again that would cause other harmful effects2.Therefore, causing a serious threat to the ecology. Tires are not easily biodegradable waste. Therefore, it is required to disposed of these tires efficiently. In the recent years a progress has been made in the management of polymeric wastes such as tires and it is becoming a potential source of valued raw materials3.One of the solutions to overcome this problem is to use tires as aggregate in the concrete by partially replacing the concrete by scrapped rubber tires3 as already discussed waste from rubber tires cannot be disposed of even after a long span landfill treatment4 therefore, they should be recycled and reused. In some research rubber tires are even used as fuel for kiln but again because of emission of carbo black from burning of these fuels causes serious environmental threats5 .The best way to reused scrap rubber tires is to use them in concrete as in concrete they will act as a filler and won’t make any chemical bonding thus making it environmental friendly6 . Although previous studies showed that using scrap rubber tires as a replacement of aggregate can cause reduction in compressive strength but showed lower unit weight and good workability as compared to plain concrete, so it can be used for the production of light weight aggregate7. Also, good energy absorption and ductility within the range was absorbed for rubberized concrete as compared to plain cocneret8. Rubberized concrete showed increased water absorption capability9,10. Nomenclature SF RRSF XRF LD OPC ACI ASTM UTM
Steel Fiber Recycled Rubber Steel Fiber X-Ray Florescence Laser Diffraction Ordinary Portland Cement American Concrete Institute American Standard for Testing Materials Universal Testing Machine
2. Experimental Program 2.1. Materials Used Ordinary Portland cement (OPC), grade 53, manufactured in Pakistan, confronting to ASTM standard11 C150-04, locally available course aggregate, fine aggregate, steel fibers, and scrap rubber steel fiber. 2.2. Chemical and Physical Characterization The aggregates were characterized using sieve analysis for the average particle size, and Laser diffraction technique for avrage particale size of the cement also X-Ray Florscence technique for the elemental analysis of the cement used shown in table.1. Fig.1. (a) and (b) shows the particle size distribution of fine and coarse aggrigate. Table 2 shows the physical properties of materials used.
Sana Gul et al. / Procedia Structural Integrity 18 (2019) 101–107 Sana Gul/ Structural Integrity Procedia 00 (2019) 000–000
103 3
Table 1 Chemical Characterization of Cement (XRF) Constituent (wt. %) Type I Cement SiO2
Constituent (wt. %) Type I Cement 19.19
TiO2
0.29
Al2O3
4.97
Fe2O3
3.27
MnO
0.04
MgO
2.23
CaO
65.00
Na2O
0.58
K2O
0.51
P2O5
0.08
LOI
3.84
Table 2 Physical Properties of Cement, Fine and Coarse aggregate Parameters
OPC
Fine aggregate
Coarse aggregate
Particle Size (D50), microns
16.4
650
9600
BET Surface Area (m /g)
0.822
_
_
Density (g/cm3)
3.17
2.5 kg/m³
81.6 lb/yd³
Fineness Modulus
_
2.4
2.5
Water absorption
_
_
2%
2
a
b
Fig. 1. Particle size distribution of aggregate (a) fine aggregate; (b) coarse aggregate
Sana Gul et al. / Procedia Structural Integrity 18 (2019) 101–107 Sana Gul/ Structural Integrity Procedia 00 (2019) 000–000
104 4
2.3. Shredding of Rubber Tires Tires were shredded by using tire shredding machine. Thin thread like shreds were made of rubber tires. Along with the rubber threads the steel fibers in rubber tires were also cut into standard sizes ranging from 1 to 4 inch.
Fig. 2. size distribution of steel fibres
3. Sample Preparation 3.1. Formulations Mixing Regime A typical formulation such as formulation-2 shown in Table 3 can be read as having 1% OPC Cement 2 % fine aggregate, 4 % coarse aggregate, and 1% replacement of SRSF by volume of concrete for 12x6 inches standard cylinders according to ACI mix design method. Rest of the formulations can be understood accordingly. Table 3 Formulations and mixing regime Cement
SF
SRSF Kg
Fine Aggregate
Coarse aggregate
Kg /m³
Kg /m³
/m³
Kg /m³
Kg /m³
Formulation-1
174.38
12.2
0
348.77
697.54
Formulation-2
174.38
0
12.2
348.77
697.54
Formulation-3
174.38
61
0
348.77
697.54
Formulation-4
174.38
0
61
348.77
697.54
S. No.
Water to cement ratio was 0.5 for all the batches.
3.2. Casting Concrete specimens having standard size 12 inches x 6 inches were casted to determine compressive strength and split tensile strength after 28 days of curing. For uniform consistency, concrete mixer was used for preparation of
Sana Gul et al. / Procedia Structural Integrity 18 (2019) 101–107 Sana Gul/ Structural Integrity Procedia 00 (2019) 000–000
105 5
concrete mix. After mixing, the cylindrical molds were filled in layers being placed on vibrating table for proper compaction and to remove the air entrapped in voids. 4. Testing Procedures 4.1. Compressive Strength Test Cylindrical specimens of dimension 6 in x 12 in were tested according to ASTM C 39 test standard12. To keep the load uniform and distributed, cylinders were capped with sulfur mortar (ASTM C 617). Sulfur caps were applied two hours before testing. The loading rate on a hydraulic machine were kept in range of 20 to 50 psi/s. 4.2. Split Tensile Strength Test For split tensile strength, the samples were tested according to ASTM C 496-96 13. The specimens were placed in Universal Testing Machine (UTM) along the length. In this test a diametral compressive force were applied along the length of the cylindrical specimen at a given rate un till failure occurs. 5. Results and Discussion 5.1. Compressive strength test
Compressive Strength (MPa)
From Figure 4 it can be seen that compressive strength reduced up to 20% and 38% for 1% and 5% incorporation of RRSF as compared to the specimens containing SF respectively. Specimens containing recycled rubber steel fiber (RRSF) showed notable ductility before failure under compression loading. Horizontal cracks were observed for RRSF specimens. This reduced compressive and flexural strength for RRSF might be because of improper bonding between the cement particles and RRSF as compared to cement and SF 14,15. This might lead to the non-uniformity of the applied load. The compressive strength of concrete depends on the bond between cement, aggregate and the fibers use11. In case of RRSF this bond seems to be weak that is why the strength degradation occurred for the specimens containing RRSF.
60
1% SF and RRSF
5% SF and RRSF
50 40 30 20 10 0
SF
RRSF
Fig. 3. Compressive Strength Test Results
5.2. Split Tensile Strength Test From figure 5 it can be seen that the split tensile strength tests up to 14% and 42 % reduction of strength were observed for 1% and 5% replacement of RRSF respectively. The percentage reduction of split tensile strength was
Sana Gul et al. / Procedia Structural Integrity 18 (2019) 101–107 Sana Gul/ Structural Integrity Procedia 00 (2019) 000–000
106 6
almost triple for 1% and 5% replacement of RRSF as compared to SF. This reduction in split tensile again might be due to the week bonding between cement, aggregate, and RRSF. Which lead to reduction in strength11. The reduction in strength increases with increasing percentage of rubberized fiber.
Split Tensile Strength (MPa)
1% SF and RRSF
5% SF and RRSF
30 25 20 15 10 5 0
SF
RRSF
Fig.4. Split Tensile Strength Test Results
6. Conclusions From the results it can be concluded that increasing the percentage replacement of RRSF the compressive and split tensile strength of concrete reduces as compared to specimens containing steel fiber. The main reason for this trend might be the weaker bond between the concrete mix and recycled rubber steel fiber. However, notable ductility was observed before failure of the sample after testing. In destructive tests, the specimens containing RRSF stayed intact indicating that recycled rubber steel fibers may be absorbing forces that are acting upon it. The failure was somehow ductile rather than brittle for the samples containing recycled rubber steel fiber Such behavior can prove beneficial for structures that require good impact resistance properties. Furthermore, the strain at failure also increased. Higher tensile strain at the point of failure shows higher energy absorbent capability of the mixture. 7. Recommendations The long-term performance of these mixes is not known in field. So, the use of such mixes is recommended in places where high compressive and tensile strength of concrete is not important e.g. sidewalks, pavement sections etc. References [1] [2] [3] [4] [5]
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