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The IES Journal Part A: Civil & Structural Engineering , 2015 Vol. 8, No. 2, 111120, 120, http://dx.doi.org/10.1080/19373260.2015.1014304
TECHNICAL PAPER Effects of PET fiber arrangement and dimensions on mechanical properties of concrete Comingstarful Marthong* Marthong* Civil Engineering Department, National Institute of Technology Technology Meghalaya, Shillong, 793003, India ( Received 11 December 2014; accepted 28 January 2015) 2015) Concrete Con crete has low tensile strength strength and crack resistance. resistance. Its weakness weaknesses es could could be enhanced enhanced with the addition addition of fiber. fiber. Polyethylene terephthalate (PET) fibers are generally used in concrete as discrete reinforcement in substitution of steel fiber. Fibers obtained by hand cutting of PET bottles are in the form of straight slit sheets, which impart weaker bonding in concrete matrix. The bonding of the fibers however may be improved by using other geometries such as flattened-end sheet pattern. So far, there are no guidelines for defining the geometry and dimensions of PET fibers. Therefore, this paper focuses on the use of fibers with different geometries and dimensions and investigates their effects on the mechanical properties of concrete. Test results show that geometry of fibers has a small effect on the workability of concrete. The use of smaller dimensions of fiber improves the workability. Enhancement in the strength and energy dissipation capacity of fiber concretes was observed from the use of flattened-end fibers of smaller dimensions. Furthermore, a higher ultrasonic pulse velocity value was observed for concrete made from smaller fibers as compared to fibers of larger dimensions. Keywords: polyethyl polyethylene ene terep terephtha hthalate late (PET) fibers concrete; concrete; fiber geometry geometry and dimension dimensions; s; mechanica mechanicall bonding bonding;; physical and mechanical properties
1. Introd Introduct uction ion
Though concrete Though concrete has low tensile strength and crack resistance, however it has been used in structural members from the historical historical time. The implicatio implications ns to overcome the limitation of concrete have been developed day by day. Inclusion of reinforcing materials in concrete is one of the methods that can overcome their weaknesses. Steel, glass and polymeric fiber are the main fibers commonly used use d as concre concrete te reinfo reinforci rcing ng materi materials als.. The polymer polymeric ic fibers used as concrete concrete reinforcem reinforcements ents are nylon, nylon, aramid, aramid, polypropylene, polyethylene, polyester, etc. Polyethylene terephthalate (PET) has been replaced glass bottles as a storage container due to easy handling, storage and lightweight wei ght.. The PET bottle bottle produc productio tions ns and dispos disposal al have have increased exponentially as time passes. Use of these waste bottles in any form would be benefitted not only in the prevention of environmental pollutions but also energy saving in their disposals. Study on the use of PET as fiber reinforcement in concrete considered considered various various types of fibers characteristi characteristics cs such as geometry, dimensions and slenderness. Research on the use of PET fibers in concrete has been explored by 2010)) use three types of many man y research researchers ers.. Kim et al. al. ((2010 fiber geometry such as crimped, crimped, twisted and embossed embossed pattern and the effect of these fibers on the mechanical properties of concrete were studied. The fibers used were obtain obt ained ed throug through h mechan mechanica icall sli slitti tting ng of a plasti plasticc sheet sheet *Email: commarthong@ *Email:
[email protected] nitm.ac.in
2015 The Institution of Engineers, Singapore
into a thin strand. The performance of recycled PET fiberreinforced concrete (RPETFRC) were thus compared with a polypropylene fiber-reinforced concrete. The test results show a decrease in compressive strength, ductility index and energy capacity beyond a fiber volume fraction of 0.5 0.5%. %. A stu study dy presen presented ted by Foti Foti (2011) shows that by adding 0.5% PET fibers in a lamellar and “O” forms lead to an improvement of the mechanical properties of concrete. Further studies on the possible use of long PET fiber strips and half bottle reinforcement was also reported by (2013).. Fraternali Fraternali et al. al. (2011) (2011) reported reported that the addiFoti (2013) Foti tio tion n of long filamen filamentt fibers fibers with a fiber fiber dosage dosage of 1% improved the thermal resistance, mechanical strength and ductility ductil ity of RPETFRC. RPETFRC. Pereira de Oliveira Oliveira and CastroCastroGomes (2011 Gomes (2011)) reported the use of recycled PET fiber as reinforcement on cementlime mortar. They concluded that by adding PET fibers in the mortar specimens, the flexural strength and toughness indices were significantly improved. The excellent contribution of PET fibers on the durability aspect was reported by, Won et al. (2010). He observed that PET fibers concrete were unaffected by salt, CaCl2 and sodium sodium sulpha sulphate te under under long-t long-term erm exposu exposure. re. The inclusions of PET fibers in concrete also greatly influenced the plastic shrinkage cracking of concrete. Banthia reported that fiber geometry plays a sigand Gupta (2006) Gupta (2006) reported nific nificant ant role role in co cont ntro roll llin ing g th thee sh shri rink nkage age.. Th They ey al also so reported that finer and longer fibers are more efficient in
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controlling controllin g shrinkage shrinkage than the coarser coarser and shorter one. Simila Sim ilarr observ observati ations ons were were als also o report reported ed by Kim Kim et al. (2007) 2007) i.e. fiber geometry plays a significant role in controlling plastic shrinkage cracking but, up to a fiber volume fraction of 0.25%. A review of the open literature reveals that a recycled PET fiber, which is commonly used as a reinforcing fiber in concrete, is in the form of short dispersed fibers. The
constant at 400 £ 100 £ 100 mm and 150 £ 300 mm , respectively, while the dimensions of fibers were varied. Fibe Fiberr vo vollume ume frac fracti tio ons of 0.5% 0.5% an and d 1.0% 1.0% were ere considered.
fibers have The an excellent abilitygenerally in enhancing concrete properties. fiber content variesthe from 0.1% to 1.0%. However, in most of the studies fiber volume fractions of 0.5% was reported as an optimum percentage. Research also revealed that PET fiber in concrete has a significant signi ficant role in influencing influencing the bonding bonding and strength al. 2010). ). Nev(Panyakapo and Panyakapo 2007 Panyakapo 2007;; Kim et al. 2010 ertheless, PET fiber has a very weak bonding with cement paste. In order to improve the bonding strength, the fibers may be drawn into different geometries and dimensions. Different Diff erent types of commerciall commercially y available available fiber geometry are straight slit, crimped, twisted or embossed as a result from from drawin drawing g throug through h a mechan mechanica icall sli slitti tting ng of plasti plasticc sheet into thin strands. The hand cutting cutting PET fibers are in the form of the straight slit sheet either in a short or long
Ordinar Ord inary y Portland Portland Cement of 53 grades grades conform conforming ing to Indian standard (IS) 12269 (1987) was used. Aggregates of about 12 mm size from crushed basalt rock and river sand were used as coarse and fine aggregates, respectively. All materials used have been tested as per relevant codes of IS Part 1 and Part 3 (1963a, b). b). 2386, Part 2386, 1 and Part 3
(Kim et al. 2010 al. 2010;; Foti 2011, 2013 2011, 2013). ). However, the straight slit sheet fibers typically have a low bonding strength with the concrete matrix as compared to the other geometry (Kim (Kim et al al.. 2010 2010). ). Theref Therefore ore,, in order order to improv improvee the mechanical bonding of PET fiber in the concrete matrix. Two types of fibers geometry namely straight slit sheet and flattened-en flattened-end d slit sheet having different different dimensions dimensions were considered herein. The fibers have been obtained by hand cutting from a post-consumer PET bottle. Since no standard guidelines could be found for hand cutting of PET fiber in regards to dimensions and geometry. Therefore, fore, by maintai maintainin ning g approx approxima imately tely the same same area area the fibers geometry used in this study was of similar shape like that of steel fibers as per guidelines provided by ACI Committee 544 (1996) 544 (1996)..
2. Experi Experimen mental tal design designss
Experimental Experiment al investigat investigations ions were carried carried on beam and cylindrical specimens as shown in Table 1. 1. The dimensions of the beam and cylindrical specimens were kept
2.1. 2.1.
Ma Mate teri rial alss
2.1.1. 2.1. 1.
2. 2.1. 1.2. 2.
Cement Cement and aggregates aggregates
PET PET fibers fibers
The main components of the polymeric fiber used in this study were PET fibers. The fibers as shown in in Figure 1 were produced by hand cutting of post-consumers PET bottle with 1 litre capacity. The geometry of PET fibers used in this study was of a similar shape to that of steel 1996). ). The fiber dimensions fibers (ACI Committee Committee 544, 1996 of different geometries are shown in Figure in Figure 1(d) 1(d) and all fibers are having thickness of 0.5 mm. Smaller fibers were obtained by scaling down at 0.5 times the dimensions of the bigger fibers. By maintaining the same cross-sectional area, different different geometries geometries of fibers namely straight slit sheet and flattened-end slit sheet were added to concrete at volume fractions of 0.5% and 1.0%.
2.2.
Castin Casting g and curin curing g of specimens specimens
The mix for ordinary ordinary concre concrete te was was design designed ed for target target strength of 25 MPa at 28 days curing time with a water cementt ratio of 0.5. PET fiber with fiber volume fractions cemen fractions of 0.5% and 1.0% were added to concrete. A conventional Figure shows step of mixing themixing materials was adopted. Figure adopted. 2and the step-by-step procedure. A total of 362 shows 18 numbers of cylindrical and beam specimens, respectively, weree cast. wer cast. Test Test specim specimens ens were were design designate ated d as SP1A, SP1A, SP2A, SP2B, SP3A and SP3B as illustrated in Table 1. 1. Dosages of concrete mixture relating to individual constitue uent ntss of th thee sp spec ecim imen enss are are su summ mmar aris ised ed in Tabl Tablee 2.
Tablee 1 Tabl 1.. Specimens Specimens design. design. Specimen
Beam (mm)
Cylindrical (mm)
SP1A SP2A SP2B
400 £ 100 £ 100 400 £ 100 £ 100 400 £ 100 £ 100
150 £ 300 150 £ 300 150 £ 300
SP3A SP3B
400 £ 100 £ 100 400 £ 100 £ 100
150 £ 300 150 £ 300
2
Fiber size (cm )
10.0 and 2.5 10.0 and 2.5 10.35 and 2.57 10.35 and 2.57
Fiber contents
0% fiber 0.5% straight slit sheet fiber 1.0% straight slit sheet fiber 0.5% flattened sheet fiber 1.0 flattened sheet fiber
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Figure 1. Fibers geometry obtained obtained by hand hand cutting from PET bottle (a) cutting cutting process, (b) st straight raight slit sheet sheet fiber, (c) flattened-end flattened-end slit sheet fiber and (d) fiber dimensions.
Concrete Concr ete containing containing no fiber was used as reference specimen men (S (SP1 P1A) A).. The The sp spec ecim imen enss were were demo demoul ulded ded af afte ter r 24 hours of casting and were kept in a water tank for 28 days curing period. 2.3 2.3..
Testin Testing g method methodolo ology gy
In order to obtain obtain the fresh concrete properties, properties, the slump test were conducted as per guidelines of IS 1199 (1959 ( 1959). ). The hardened concrete specimens were tested for com pressive, tensile and flexural strength. All tests were carried out in a hydraulic compression testing machine of capacity 1000 kN. Ultrasonic scanning of the specimens was also performed to know the homogeneity and integrity of PET fibers concrete.
2.3.1. 2.3. 1.
Compressi Compressive ve and splitt splitting ing tensile tensile streng strength th test test
Compressive strength test was carried out in accordance to IS 516 (1959) (1959).. The specimens were placed on base
plate and axial compressive load was applied at the top of the specim specimen en til tilll it reache reachess the ult ultima imate te str streng ength. th. The compressiv compr essivee strength strength was then calculated calculated by dividing dividing the maximum load by its cross-sectional area. In the splitting test, a standard cylindrical sample was placed horizontally with the axis parallel to the platen (IS 5816, 1999). 1999). The compressive load was applied along the opposite generator of the concrete cylinder specimens.
2.3.2. 2.3. 2.
Flexural Flexural strength strength test
To measure the flexural strength, beam specimens were made as shown in Table in Table 1. 1. Testing of the specimens was carried out as per standard guidelines of IS 516 (1959). (1959). The beam is placed on two supports near the two ends with the distance of 300 mm and the loads were applied with a centre-point loading. All loads in the flexural test were applied till the specimens attained approximately the same displacement level or collapsed whichever occurred earlier. This procedure is
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Figure 2.
C. Marthong
Mixing and casting of specimens. specimens.
adopted to facilitate the comparative study on their behaviour. iou r. Howev However, er, for specim specimens ens under under compre compressi ssive ve and splitting tensile strength loading were applied until failure and the maximum loads were recorded.
2.3.3. Ultrasoni 2.3.3. Ultrasonicc pulse pulse velocit velocityy (UPV) (UPV) testing testing Ultrasonic scanning is a recognised non-destructive test method to assess the homogeneity and integrity of a concrete structure. An ultrasonic electronic machine (Pundit Lab plus with model PLO2) with an accuracy of 0.1 ms was used. The equipment supported by a broad range of transducers that varies from 24 to 500 kHz. Vaseline was
used to join the sensor surface to the concrete specimen surface as per manufacturer guidelines. Ultrasonic pulse velocity (UPV) of concrete specimens was measured as 1992). ). Assessments of per guidelines of IS 13311 Part 1 (1992 concrete quality containing with or without fibers were carried out on each beam specimens.
3.
Resul Results ts and discussions discussions
3.1. 3.1.
Fre Fresh sh con concret crete e properti properties es
During the plastic state, concrete should be a workable concrete. Thus, the workability of concrete indicates the
Table 2. Mixture used to manufacture the specimens of ordinary ordinary and fiber fiber reinforced concrete. concrete. Specimen
Concrete (kg)
Cement (kg)
Aggregate (kg)
SP1A SP2A SP2B
48.83 48.60 48.60
12.21 12.21 12.21
36.62 36.62 36.62
SP3A SP3B
48.60 48.60
12.21 12.21
36.62 36.62
Fibers (g)
Water (lit)
244.2 244.2
6.11 6.11 6.11
244.2 244.2
6.11 6.11
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an and d va vari riati ation on of sl slum ump p wi with th fiber fiber co cont nten ent. t. It can can be observed obser ved that the slump of the mixture decreases decreases with the increase of the fiber contents. A lower slump value of 50 mm was observed from concrete made with 1.0% fiber. At the same fiber content, concrete made from smaller fiber dimensions presented a higher slump value. Irrespectiv tivee of the fibers geomet geometry, ry, a compar comparabl ablee slu slump mp was ac achi hiev eved ed by th thee co conc ncre rete te mixt mixtur ures es in th thee resp respec ecti tive ve dimensions fibers. Thus,onitthe indicates that the of fibers hasof small effects workability of geometry concrete. Howe Howeve verr fiber fiber di dime mens nsio ions ns pl play ay a si sign gnifi ifica cant nt role role in achieving achie ving good workable workable concrete. In all test, mixtures mixtures presented a “medium” to “high” degree of workability as per guideline of IS 456 (2000).
(a) 150 120
3.2. 3.2.
) m 90 m ( p m u 60 l S
Larger size: straight slit fiber Smaller size: straight slit fiber
30
Large size: flattened-end sheet fiber Smaller size: flattened-end sheet fiber
0 0
0.5 Fiber content (%)
1
(b)
Fig Figure ure 3. (a) Measurem Measurement ent of slu slump mp and (b) variati variation onss of slump with respect to fiber content.
degree of fluidity or mobility and surface finishing without detachment. detach ment. The workabilit workability y measuring measuring is called a slump that is necessary for the design and it is the counter-point of the mixture hardness. The slump was measured at each stage of the mix. Figure 3 shows 3 shows a typical measurement
Com Compre pressiv ssive e str streng ength th
The compressive strength was evaluated by the equation P f c D p4 D where f f c is the compressive strength (MPa), P (MPa), P the the 2 where maximum crushing load resisted by the specimen before failure and D the D the diameter of the cylinder specimen (mm). 3 shows shows the average compressive strength test for Table 3 each type of specimens design. Test results revealed that the the ad addi diti tion on of PET PET fiber fiberss in co conc ncre rete te marg margin inal ally ly enhanced enhan ced the compressiv compressivee strength strength of specimens. specimens. As it can be seen in Figure in Figure 4, 4, the improvement was observed to be better for specimens made from a smaller fiber dimension as compared compared to the counter larger fiber. However, However, on fu furt rthe herr in incr crea easi sing ng th thee fiber fiber co cont nten ents ts beyo beyond nd 0.5% 0.5% a decrease in compressive strength was observed. Owing to good mechanical mechanical bonding bonding behaviour behaviour imparted by the flattene tened-e d-end nd sh shee eett fiber fibers, s, th thee gain gain in st stre reng ngth th was was al also so sli slight ghtly ly better better as compar compared ed to the concre concrete te made made with with straight slit sheet fiber. Figure fiber. Figure 5 demonstrates 5 demonstrates that a similar brittle failure behaviour of 0% and 0.5% straight slit sheet fibers concrete in comparison to the wedge failure behaviour imparted by concrete made from a 0.5% flattened-end sheet fiber.
Tablee 3. Strength Tabl Strength of concre concrete te spe specimen cimens. s. Average compressive strength (MPa)
Flattened-end sheet fiber
Flexural strength (kN)
Bigger fiber’s dimension
Smaller fiber’s dimension
Bigger fiber’s dimension
Smaller fiber’s dimension
Bigger fiber’s dimension
Smaller fiber’s dimension
SP1A SP2A SP2B SP1A
22.52 22 2 2.64 17 17.83 22.64
22.52 24.33 19.24 22.64
4.38 4.41 4.16 4.38
4.38 4.58 4.36 4.38
10.76 11.66 8.11 11.13
10.76 13.23 9.56 11.13
SP3A SP3B
23 2 3.20 19 1 9.13
25.46 20.37
4.41 4.19
4.75 4.36
11.98 8.23
14.87 10.15
Specimens design Straight slit sheet fiber
Average tensile strength (M (MP Pa )
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30 ) a P 25 M ( h t 20 g n e r t s 15 e v i s s 10 e r p m o 5 C 0
C. Marthong 3.3.
In this test, the loading was applied uniformly along two opposite lines on the surface of the cylinder as per guidelines of IS 5816 (1999) 5816 (1999).. The tensile strength as presented T in Table in Table 3 was 3 was calculated by using the equation f c D p2 LD where T where T is is the maximum splitting tensile strength (MPa) and L is L is the length of cylinder specimen. The variations of tensile strength for different concrete design are shown in
Larger size: straight slit fiber Smaller size: straight fiber Larger size: flattened-end fiber Smaller size:flattened-end fiber 0
0.5
Split Splitting ting tensile tensile strength strength test
1
Fiber content (%) Figure Figu re 4. Variation Variationss of compress compressive ive strength strength with respect respect to fiber content.
Figure 6. Owing to good dispersions of short fibers which Figure result resulted ed in a better better bridgi bridging ng act action ion in concre concrete te matrix matrix,, smaller fibers dimensions showed improvement in the tensile strength. However, the tensile strength decreases with an increa increase se of fiber fiber conten contents ts more more than than 0.5%. 0.5%. Furthe Further, r, 7 shows a typical failure of concrete with and withFigure 7 shows out fibers. The concrete containing no fibers suddenly split out once the concrete cracked. Meanwhile the PET fibers concrete exhibited cracking but did not fully separate out.
Figure 5. Typical Figure Typical failur failures es of specimen specimenss under compressiv compressivee test (a) 0% fiber content, content, (b) 0.5% straight straight slit sheet fiber content content and (c) 0.5% flattened-end sheet fiber content.
The IES Journal Part A: Civil & Structural Engineering 5 4 ) a P M 3 ( h t g n e r 2 t s e l i s n 1 e T
Smaller size: straight slit fiber Larger size: flattened-end fiber Smaller size:flattened-end fiber
0 0.5
1
Fiber content (%) Figure 6. 6. Variations of splitting splitting tensile tensile strength strength with respect to fiber content.
This shows that PET fibers-reinfor fibers-reinforced ced concrete concrete has the ability in dissipating the energy in the post-cracking state.
3.4 3.4..
Flexur Flexural al stre strengt ngth h
In each size of the specimen, two samples were cast and their flexural strengths were determined. Figure 8 shows 8 shows the testin testing g arrang arrangeme ement nt and the failur failuree patter pattern n of the specimens at the end of the test. The load carrying capacities of the specimens are tabulated in Table 3 and they show marginal enhancement with the addition of fibers. Figure 9 further 9 further demonstrates that a decrease of load carrying capacity of the specimens beyond 0.5% fiber contents was observed. At each percentage of fiber content, concrete made with flattened-end sheet fibers shows a significantt improvement nifican improvement over the straight slit fibers. fibers. Such behaviour may be attributed to the effect of fibers geometry that imparted a good bonding behaviour in the concrete matrix. The typical load versus displacement curves resulted the flexural on are beam prism ing 0.5%from flattened-end slittest fibers shown inincorporat10. Figure 10.
The ability ofto a structural member to resist the fracture when subjected static or to dynamic or impact loads depends to a large extent on its capacity to dissipate its energy. The energy absorption by the specimen is represented by the area form under the load versus displacementt curves men curves.. The load load versus versus displa displacem cement ent curves curves of concrete made with smaller fibers dimensions are more than those of bigger fibers. fibers. Therefore, Therefore, addition addition of smaller fiber dimensions in concrete reflects a better performance in energy dissipation capability.
3.5. 3.5.
Ultimate Ultimate state of specimens specimens under splitting splitting tensile tensile
Ult Ultraso rasonic nic tes test t
In order to investigate the structure of PET fibers concrete, UPV test was conducted on beam specimens. Figure 11 shows sho ws the typica typicall locati location on of transd transduce ucers rs on the specispecimens. The UPV values recorded recorded are in the range from 3.5 to 4.5 km/sec for 0.5% fibers concrete. A slight higher value of UPV was observed from specimens made with smaller fibers dimensions due to the compactness structure imparted by the fibers. Since the concrete mixture containing 1.0% fiber is more porous in comparisons to 0.5 0.5% % fiber fiber conten contents, ts, the UPV results results als also o presen presented ted a lower value which ranges from 3.0 to 3.5 km/sec. Therefore, as per guidelines of IS 13311 Part 1 (1992 ( 1992)) the quality of concrete falls in the “medium” to “good” scale. The performances of concrete with the additions of various types of polymer fibers reported by various researchers including inclu ding present study are summarise summarised d in in Table 4. 4. It is observed that the addition of polymers in concrete produces improvement in many aspects such as improvement in mechanical mecha nical properties properties of concrete, concrete, ability ability in dissipatin dissipating g more energy and capability in reducing plastic shrinkage. The PET fiber used herein which was formed from hand cutting of post-consumer bottle also shows similar behaviou iour. r. Furthe Further, r, this this stu study dy reveale revealed d that that fibers fibers of smalle smaller r dimensions with flattened-end geometry show a better performance as compared to straight slit fiber.
4.
Figure Figu re 7. test.
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The curves also depict that additions of PET fibers enable a greater capability of resisting more tensile stress especially at the post-cracking stage. Plain concrete failed suddenly with lower displacement capacity as compared to the fibers concrete. It is also observed that curves resulted from the smaller fibers concrete are above the larger one indicating a better load carrying capacity at each displacement level.
Larger size: straight slit fiber
0
Summar Summary y and concluding concluding remarks
In thi thiss paper, paper, comparati comparative ve studie studiess were were carrie carried d out to investigate the effect of fibers geometry and dimensions on the physical physical and mechanical mechanical properties properties of concrete. concrete. Two types of fibers geometry geometry with varying dimensions dimensions were designed from a post-consumer PET bottle. The following conclusions were drawn.
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C. Marthong
Figure 8. Testing arrangement arrangement and typical failure failure of specimens specimens under flexural flexural test.
(1) For water cement cement ratio ratio of 0.5, 0.5, the worka workabili bility ty of fresh concrete decreases with the addition of PET fiber. However However,, geomet geometry ry of fibers fibers has a small effect on the workability of concrete since a comparable slump value was achieved by the concrete mixtures in the respective dimensions of fibers.
(2) The addition addition of more than than 0.5% PET fiber fiber in concrete results in the reduction of the compressive streng strength. th. The improv improveme ement nt in the compre compressi ssive ve strength also varies with the geometry and dimensions of fibers. Flattened-end sheet fiber presented an improvement in compressive strength due to the good bonding behaviour in the concrete matrix
The IES Journal Part A: Civil & Structural Engineering 25 20 ) 15 N k ( d a 10 o L
Larger size: straight slit fiber Smaller size: straight slit fiber
5
Larger size: flattened-end fiber
e t e r c n o c s r e m y l o P f o e c n a m r o f r e P
Smaller size:flattened-end fiber
0 0
0.5
1
Fiber content (%) Figure Figu re 9. Variation Variationss of load carryin carrying g capacity capacity with respect respect to fiber content. 15
SP1A SP3A-Bigger fiber size
12
SP3B-Smaller fiber size 9 ) N k ( 6 d a L o
3 0 0
1
2
3
4
5
6
7
8
9
10 10
Displacement (mm)
Fig Figure ure 10. Load Load displacement relationship.
and the fine dispersions of fibers in the concrete mixture. Concrete made with smaller fiber dimensions sions exhibi exhibited ted a higher higher compre compressi ssive ve str streng ength. th. This This sh show owss th that at geom geomet etry ry an and d dime dimens nsio ions ns of fibers play an important role in achieving a good compressive strength.
Figure 11.
Typical locations of transducers transducers on on specimen. specimen.
d e s u r e m y l
P o f o s e p y . T e t e r c n o c s r e m y l o p f o e c n a m r o f r e P . h 4 c l e a r e s b a e T R
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(3) Tensile Tensile strength test results results demonstrated demonstrated that the inclusion of 1.0% PET fiber decreases the tensile streng strength. th. The inclus inclusion ion of PET fiber fiber improv improved ed the tensil tensilee proper property ty and showed showed the abilit ability y in absorbing energy in the post-cracking state due to the bridging action imparted by the fibers during cracking. (4) Results Results from the flexural strength test show that
Gopinath, Gopina th, A., M. S. Kumar, Kumar, an and d A. Elayap Elayaperu erumal mal.. 20 2014 14.. “Experimental Investigations Investigations on Mechanical Properties of Jute Fiber Reinforced Composites with Polyester and Epoxy Resin Matrices.” In 12th In 12th Global Congress on Manufacturing and Management, GCMM 2014, 2014, edited by M. Anthony Xavior ior and Pra Prasad sad KDV Yarlag Yarlagadd adda, a, 20 2052 52206 2063. 3. Procedia Procedia Engineering,, Elsevier. Engineering IS 516. 1959. Method 1959. Method of Tests for Strength of Concrete. Concrete. Bureau of Indian Standard: New Delhi. IS 1199. 1959. Methods of Sampling and Analysis of Concrete. Concrete .
th thee ad addi diti tion on of 0. 0.5% 5% PET PET fiber fiber in co conc ncre rete te increases incre ases the flexural flexural strength. strength. The load versus displacement curves show a ductile behaviour for PET fiber fiber concre concretes tes.. The increa increases ses in flexura flexurall strength of concrete containing PET fiber however vary var y with with the geometry geometry and dimens dimension ionss of the fibers. Flattened-end slit sheet fiber show significant improvement over the straight slit sheet fiber in term of load carrying capacity and energy dissi pating capability. Similarly, irrespective of the geometry, short dispersed fibers have the ability to underg undergo o lar larger ger deform deformati ation on which which reflect reflectss a better energy dissipation capacity. (5) Struct Structure ure contai containin ning g 1.0 1.0% % fiber fiber is more more porous porous which causes a reduction in UPV due to its lower
Bureau of Indian Standard: New Delhi. IS 2386. 1963a. Methods of Test for Aggregates for Concrete Part 1: Particle Size and Shape. Shape. Bureau of Indian Standard: New Delhi. IS 2386. 1963b. 1963b. Methods of Test for Aggregates for Concrete Part 3: Specific Gravity, Density, Voids, Absorption and Bulking . Bureau of Indian Standard: New Delhi. IS 12 12269 269.. 19 1987 87.. Specific Specificati ation on for OPC-53 OPC-53 Grade Grade Cemen Cement. t. Bureau of Indian Standard: New Delhi. IS 13311. 1992. Method 1992. Method of Non-destructive Testing of Concrete Part 1: Ultrasonic Pulse Velocity. Velocity. Bureau of Indian Standard: New Delhi. IS 5816. 1999. Method 1999. Method of Test Splitting Tensile Strength. Strength. Bureau of Indian Standard: New Delhi. IS 450. 2000. Plain and Reinforced Concrete Code of Practice.. Bureau of Indian Standard: New Delhi. tice Jo, B., S. Park, Park, and J. Park. 2008. 2008. “Mechani “Mechanical cal Properties Properties of Polymer Concrete Made with Recycled PET and Recycled Concrete Aggregates.” Construction Aggregates.” Construction Building Materials 22: Materials 22: 228291. Kim, J. H., R. E. Robertson, and A. E. Naaman. 1995. “Structure and Properties of Poly (Vinyl Alcohol) Modified Mortar and Concrete.” Journal of Cement and Concrete Research 29: 407415. Kim, S. B., N. H. Yi, H. Y. Kim, J. J. Kim, and Y. C. Song. 2010. “M “Mat ater eria iall and and Stru Struct ctur ural al Perf Perfor orma manc ncee Ev Eval alua uati tion on of Recycled PET Fiber Reinforced Concrete.” Cement & Concrete Composites 32: Composites 32: 232240. Kim J.-H, C. C. Park, S. W. Lee, S. W. Lee, and J. P. Won. 2007. “Effect of the Geometry of Recycled PET Fiber Reinforcement on Shrinkage Cracking of Cement-based Composites.” Composite Part-B: Engineering Engineering 39: 39: 442450. Nili, M., and V. Afroughsabet. Afroughsabet. 2010. “The Effects of Silica Fume and Polypropylene Fibers on the Impact Resistance and Mechanical Properties of Concrete.” Construction and
workability. The UPV value resulted from concret cr etee made made of 0.5% 0.5% fib fiber er co cont nten ents ts has has a valu valuee ranges from 3.5 to 4.5 km/sec, which is an acceptable quality as per standard guidelines.
Acknowledgement The author is grateful to the staff of Civil and Mechanical Engineering Department at National Institute of Technology Meghalaya for their valuable assistance for slitting the fibers, casting and testing of all specimens.
References ACI Committee Committee 544. 1996. “Stat “State-ofe-of-thethe-art art Report Report on Fiber Fiber Reinforced Concrete,” ACI 544.1R-96 (Re-approved 2002). 2002). Farmington Hills, MI: American Concrete Institute. Anbuv Anb uvela elan, n, K., M. M. Kha Khada dar, r, M. Lakshm Lakshmipa ipathy thy,, and K. S. Sathyanarayanan. 2007. “Studies on Properties of Concretes Containing Polypropylene, Polypropylene, Steel and Reengineered Plastic Shred Fiber.” Indian Fiber.” Indian Concrete Journal 81 81 (4): 3844. Banthia, N., and R. Gupta. 2006. “Influence of Polypropylene Fiber Geometry on Plastic Shrinkage Cracking in Concrete.” Cement and Concrete Research 36 Research 36 (7): 12631267. Foti,, D. 2011. Foti 2011. “Prelimin “Preliminary ary Analysis Analysis of Concrete Concrete Reinforce Reinforced d with Waste Bottles PET Fibers.” Construction Fibers.” Construction and Building Materials 25 Materials 25 (4): 19061915. Foti, D. 2013. “Use of Recycled Waste Pet Bottle Fibers for the Reinforce Rein forcement ment of Concrete. Concrete.”” Composites Composites Structures 96: 396404. Fraternali, F., V. Ciancia, R. Chechile, G. Rizzano, F. Luciano, and L. Incarnato. 2011. “Experimental Study of the Thermal-Mechan mal-M echanical ical Propertie Propertiess of Recycled Recycled PET Fiber-Rei Fiber-Reinnforced Concrete.” Composites: Concrete.” Composites: Part B 93: B 93: 23682374.
Building Materials 24: Materials 24: 927933. Pereir Pereiraa de Olivei Oliveira, ra, L. A., and J. P. Castr Castro-G o-Gome omes. s. 20 2011 11.. “Physical and Mechanical Behavior of Recycled PET Fiber Reinforced Mortar.” Construction Construction Building Materials 25 (4): 17121717. Panyakapo, P., and M. Panyakapo. 2007. “Reuse of Thermosetting Plastic Waste for Lightweight Concrete.” Waste Management 28: 28: 15811588. Siddique, R., K. Kapoor, K. El-Hadj, and R. Bennacer. 2012. “Effect of Polyester fiber on the Compressive Strength and Abrasion Resistance of HVFA Concrete.” Construction Concrete.” Construction and Building Materials 29: Materials 29: 270278 Song, P. S., S. Hwang, and B. C. Sheu. 2005. “Strength Properties of NylonNylon- and Polyprop Polypropylen ylene-Fib e-Fiber-Re er-Reinfo inforced rced Concretes.” Cement cretes.” Cement and Concrete Research 35 Research 35 (8): 15461550. Won, J. P., C. I. Jang, S. W. Lee, S. J. Lee, and H. Y. Kim. 2010. “L “Lon ong g Term Term Pe Perf rfor orma manc ncee of Recy Recycl cled ed PE PET T Fibe FiberrReinforce Rein forced d Cement Cement Composit Composites.” es.” Construction Construction Building Materials 24: Materials 24: 660665.
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