Experimental, statistical and simulation analysis on impact of micro steel – Fibres in reinforced SCC containing admixtures

Construction and Building Materials 246 (2020) 118450

Contents lists available at ScienceDirect

Construction and Building Materials journal homepage: www.elsevier.com/locate/conbuildmat

Experimental, statistical and simulation analysis on impact of micro steel – Fibres in reinforced SCC containing admixtures V. Athiyamaan, G. Mohan Ganesh ⇑ School of Civil & Chemical Engineering, Vellore Institute of Technology, Vellore, India

a r t i c l e

i n f o

Article history: Received 10 February 2019 Received in revised form 3 February 2020 Accepted 13 February 2020

Keywords: Self-compacting concrete Micro steel fibres SEM analysis Mechanical properties Statistical analysis ABAQUS Alignment

a b s t r a c t Self-compacting concrete is one of the special concretes that flow in its own weight, which is used in the densely reinforced concrete structures. This concrete requires higher binder content. Higher cement content leads to uneconomical design, higher heat of hydration, higher shrinkage, etc. These factors can be counteracted by addition of mineral admixtures. Hence, Fly ash (30%) and micro silica fume (10%) are mineral admixtures replaced with cement. Concrete is having a poor flexural properties; this can be enhanced by using fibrous materials. Addition of steel fibres improves the strain softening property of composite system. Hence hooked ended micro steel fibres are used in this study. In order, to study the fresh and mechanical properties of SCC, totally eight mix (M1 to M8) designs are developed using Nan Su proposed method of mix design, with varying steel fibres (0.0%, 0.25%, 0.50% and 0.75%) and varying binder content. To evaluate the impact of steel fibres in reinforced concrete; four mixes (C-1 to C-4) of prism dimension 0.1 m
0.15 m
1 m were cast with optimized steel fibres and mineral admixtures content and tested using standard UTM. The key properties such as deflection, strain softening and effect of orienting the steel fibres along the direction of flow of concrete were studied. Later the experimental work was virtually modeled and analyzed using ABAQUS. In rheological study, the mix containing mineral admixtures showed better fresh concrete properties. Addition of fibres reduced the flowing ability of SCC. There is no significant change in compression strength due to addition of steel fibres. Flexural strength increased by 63% by addition of 0.75% of steel fibres. The SEM analysis helped to study the hydration process and morphological behaviors in concrete structures. The statistical analysis were carried out and regression equations have been developed for the better understanding in the field of micro steel fibre-reinforced self-compacting concrete containing admixtures. Stress-Strain behavior of mix C3 and C4 is more linear compared to C1 and C2, due to presence of micro steel fibres, which is arrested the development of micro-cracks. C4 shows better strength compared to C3, showing steel fibres are aligned align the direction of flow of concrete in between the reinforced structures. The analyzed theoretical model, developed used ABAQUS showed similar displacement results. Ó 2020 Elsevier Ltd. All rights reserved.

1. Introduction 1.1. General Fibre reinforced self-compacting concrete (FR-SSC) is the concept of using fibrous materials in self-compacting concrete. As the continuous evolution of composite materials, concrete is getting better, by enhancing the physical and mechanical properties of concrete. Using fibres in concrete is not new; it has been in existence from late 18th century. Research in new fiber-reinforced

⇑ Corresponding author. E-mail addresses: [email protected] (V. Athiyamaan), gmohanganesh@ vit.ac.in (G. Mohan Ganesh). https://doi.org/10.1016/j.conbuildmat.2020.118450 0950-0618/Ó 2020 Elsevier Ltd. All rights reserved.

concretes continues till today. The idea of composite materials appeared in the year of 19500 s among which fibre reinforced concrete (FRC) has become one of the vital areas for researchers [1]. With the continuous evolvement of optimizing the concrete, considering the feasibility, strength, durability and performance, self-compacting concrete was developed in the year 1988 [2]. It was developed with the general prototype, without any fixed target mix design that satisfices the guidelines introduced by EFNARC [3,4]. Later with the few design methods has been introduced and optimized for designing the mix proportions for SCC [5,6]. In order to utilize the rheological properties and to enhance the flexural property, steel fibres added to self-compacting concrete. Which is considered to be more effective compared to other fibrous materials [7]. It was seen that the concrete flowability properties adapt

2

V. Athiyamaan, G. Mohan Ganesh / Construction and Building Materials 246 (2020) 118450 &

  Fig. 1. Typical stress strain curves.

the bingham model [8]. Where, steel fibres and coarse aggregates were isolated and evenly distributed in the medium of matrix (binder, sand and water). Generally SCC requires higher binder content and the traditional volume based mix proportioning further maximize the binder content, which is uneconomical and leads to higher water/ binder ratio, heat of hydration, creep, shrinkage, etc. [9]. These factors can be over thrown by addition of mineral admixtures. Such as fly ash, micro slica fume, metakaolin, rice ash dusk, bentonite, GGBS, etc, [10], which are considered as waste by-products, creating hazards to environment. Using fly ash as a partial replacement of cement reduces the water/binder ratio, because of its spherical shape and also reduces the heat of hydration due to pozzolanic reaction [11]. The delayed in early strength can be overcome by the addition micro silica fume up to 5%-10%. These addition of ternary binders, makes the concrete more compacted and well packed [12]. One of the phenomenal properties observed in composite concrete, normal reinforced and fibre reinforced concrete is strain softening [13]. Strain softening is the linear fall in strength of the material that occurs immediately post peak of plasticity limit as shown in Fig. 1. There were several studies carried out in examining mechanical behavior of fibre reinforced concrete [14]. Only minimal research has been done in analyzing the mechanical properties of fibre reinforced self-compacting concrete (FRSCC) containing admixtures and only minimum study was carried out in analyzing the impact of fibres in reinforced self-compacting concrete structure and the study on alignment of fibres in reinforced structures [15]. The addition of steel fibres reduces the flowability of fresh SCC [16]. It was seen that the steel fibres in SCC has a tendency to get oriented along direction of concrete flow and perpendicular to the fracture plane [17]. Steel fibres having length more than 30 mm has shown reduction in rheological properties of SCC. Hence, hooked ended micro steel fibres of aspect ratio (l/d) 60 were used in this study, to have better filling ability throughout the reinforced structure. In order to study real time application, the prisms were designed with under reinforcement section and analyzed. To avoid shear failure and to avoid the blockage of fibres during the free flow of SCC singly reinforced prism is designed. The reinforcement design is opted according to EN ISO 3766:2003 [18], C-shaped bend-up bars were used and the extra wide line was restricted up to the shear length of the prism, to study the contribution of micro steel fibres during the failure. There were several studies has been carried out in validating the experimental work by modeling the specimen using theoretical value [19]. The study helps to assess the stress distribution throughout the modeled specimen. Thus ABAQUA/CAE was used to develop the model to evaluate the specimen.



  

To compare the mechanical properties of control mix concrete, containing only cement as a binder with varying different parameters such as  Micro Steel fibers (0% and 0.75% by volume of concrete)  Fly-ash content (30%)  Micro silica fume (10%) To investigate the influence of micro steel fibres and to suggest the optimized mix proportion containing micro steel fibres. To study the SEM image of various days of SCC containing cement and mineral admixture. To develop the regression equation between variables like steel fibres and admixtures Vs responses like mechanical properties for the future study in this field. To study the strain softening property of FRSCC. To evaluate the impact of micro steel fibres in alignment and strain softening of reinforced SCC. To develop the theoretical model using ABAQUS and to analysis it.

2.1. State of Art- fibre reinforced – SCC In Fibre reinforced concrete, addition of steel fibres gained more popularity among other fibrous material due to its condescending performance [20]. Usage of steel fibres prevents the inner crack development, which is considered as a major cause for shear failure of the concrete [21]. In many studies the percentage and distribution of the fibres affects the strength of the concrete. However, the fibres are randomly directly added during the concrete mix [22]. Hence it was necessary to study the optimization of fibre content, according to the requirement. The aspect ratio of steel fibres plays the vital role in performance of the concrete [23]. Such as, tensile strength, workability, filling ability, orientation of fibres, homogeneity of the concrete [24,25]. Hence, micro steel fibres of aspect ratio 60 were used in the study. The NVC (normally vibrated concrete) and SCC varies only by its composition of materials [26]. Since concrete is one of the vital materials used next to water, it is important to reduce/replace the non-renewable resources used in concrete. In order to make the concrete more economical, sustainable and durable, high volume of pozzolanic materials were added, this eventually reduces the content of HRWRA because of it texture (spherical shape) of the particle [27,28]. Fly ash based reinforced concrete increases resistance against acid attack, the sulphate attack, chloride penetration, reduces water absorption and porosity compared to traditional OPC concrete [29]. Using steel fibres in SCC has major advantage over Normally Vibrated Concrete (NVC), i.e. since the density of steel fibres (7800 kg/m3) is higher among the composite materials due to which steel fibres could get isolated to the base of mould or the formwork during improper vibration in NVC. This causes uneven scattering of fibres and affecting the homogeneity of the blend. Hence, by taking advantage of the better flowing and passing ability (rheological properties) of SCC at fresh state that fills the formwork without vibration, the micro steel fibres can be added to the concrete matrix up to certain percentage to the total volume of the concrete to produce Micro-Steel Fibre Reinforced Self-Compacting Concrete (MS-FRSCC) with a maximum uniform dispersion of fibres in a highly workable composite matrix. Hence the steel fibres blended with SCC at proper ratio, optimizing the performance of the concrete and such concrete is termed to be Micro Steel-Fibre Reinforced Self-Compacting Concrete (MS-FRSCC). 3. Experimental program

2. Research significance 3.1. Materials To access the advantages of mineral admixtures in replacement with cement, mix design was developed using Nan Su method of mix design [6].

Cement-OPC confirming to IS: 12269-1987 of 53 Grade was used in this study [30], Fly ash–Fly ash used in this experimental

3

V. Athiyamaan, G. Mohan Ganesh / Construction and Building Materials 246 (2020) 118450

investigation acquired from Neyveli Lignite Corporation thermal power plant, confirming to IS: 3812:2003 [31]. This plant is situated in Neyveli, Tamil Nadu, India. Fine aggregate–Fine aggregates sieved with 2.36 mm sieve were used in this study and conforming to IS: 383-1987. Course aggregate – The Coarse aggregate passed through 12.5 mm sieve and retained in 10 mm sieve size, confirming to IS: 383-1987 is used in this study, Super Plasticizer-Master Glenium SKY 8233 was the super plasticizer used in this study to improve the workability and micro Steel fibers – aspect ratio (l/ d) of 60 was used in this study. These were the materials used for preparing all the test mixtures and it is important to understand their properties which are discussed in detail in previous study [6]. 3.2. Methodology  For this study, M50 grade of concrete was designed as per proposed method of mix design. The mix ID and material content followed in this work is showed in Table 1.  In totally four concrete mixtures were designed in order to compare the varying proportions of 40% replacement with cement and steel fibers in concrete.  The M1 and M2 mixture are the conventional self-compacting concrete, in which M1 contains only cement as a binder and M2 contains replacement of fly ash (30%) and micro silica fume (10%) with cement.  In the M3, M4 and M5 mixtures, cement, fine aggregates and coarse aggregate kept constant and the steel fibres percentages are varied by 0.25%, 0.50% and 0.75% respectively.  The M6, M7 and M8 mixtures contain the same percentage of coarse aggregate, fine aggregate, water content, the binder content replaced by 30% of fly ash and 10% of micro silica fume, with varying steel fibres percentage of 0.25%, 0.50% and 0.75%. 3.3. Mixture proportions The mix proportions arrived as per the optimized mix design using proposed method of Nan Su method, given in Table 2. This satisfies the properties of SCC as per the guidelines proposed by EFNARC.

Table 3 Recommended limitation for fresh concrete properties of SCC. S. No

Experiment

Property

Limitation

1. 2. 3. 4. 5.

Slump Flow T500mm V-funnel L-Box (H2/H1) J-Ring

Flow ability and workability Flow ability Flow through ability Filling ability and Passing ability Resistance to segregation Flow ability and Passing ability

500–800 mm 2–5 sec 6–12 sec  0.8  600

aggregate, water, super plasticizer and steel fibers were taken in proportions as arrived earlier for desired volume including wastage and poured into the pan mixer. The mixers makes 25 to 30 revolutions per minute and are made to run until the materials are mixed together forming a uniform concrete. After mixing the concrete were taken for conducting the fresh concrete properties such as slump flow, L-Box, V-funnel, J-ring, T500, according to EFNARC guidelines, the recommended boundaries is represented in Table 3. The placing of concrete was done within 45 min, immediately after conducting the freshen properties. The casting was done without any machine vibrators or manual compaction. After casting, the moulds were kept at room temperature for 24 h. Then the specimens were demoulded and kept in the curing tanks. All the specimens were cured and tested to their respective testing days. The specimens were tested for compressive strength, splitting tensile strength, and flexural behavior. All these tests were conducted in order to find the mechanical properties of the concrete. The detailed work plan followed in this study is shown in Table 4. The specimen samples of 7 days and 28 days were collected for performing the SEM (Scanning Electron Microscope) analyzes. These images were used to study the morphological compositional information of the concrete structure [32]. SEM helps to study the evolution of concrete from liquid state to plastic state. It helps to investigate the C-S-H gel formation and via EDX, chemical composition can be studied [33]. It also helps to classify the concrete according to the hydration process. 4. Results and discussion 4.1. Fresh concrete properties

3.4. Mechanical properties Concrete mixtures were made with the help of pan mixer. The cement, fly ash, micro silica fume, water, fine aggregate, coarse

Fresh concrete properties such as slump flow, L-Box, V-Funnel, J-Ring and T500mm were conducted for mix M1, M3, M4 and M5 and these results were compared with M2, M6, M7 and M8

Table 1 Replacement content and material proportions. Mix ID

M1 M2 M3 M4 M5 M6 M7 M8

Binder Content

Variable content

Cement

Fly Ash

MSF

Fine agg Kg/m3

Coarse agg Kg/m3

W/C

SP

100% 60% 100% 100% 100% 60% 60% 60%

0% 30% 0% 0% 0% 30% 30% 30%

0% 10% 0% 0% 0% 10% 10% 10%

710 710 710 710 710 710 710 710

935 935 935 935 935 935 935 935

0.4 0.4 0.4 0.4 0.4 0.4 0.4 0.4

1.70% 1.70% 1.70% 1.70% 1.70% 1.70% 1.70% 1.70%

Percentage of steel fiber by volume of concrete 0% 0% 0.25% 0.50% 0.75% 0.25% 0.50% 0.75%

Table 2 Mix proportion as per Nan Su method [6]. Total Binder kg/m3

Fine Aggregate kg/m3

Coarse Aggregate kg/m3

Water kg/m3

HRWR kg/m3

S/A

Packing Factor

525

935

710

215

8.925

0.56

1.10

4

V. Athiyamaan, G. Mohan Ganesh / Construction and Building Materials 246 (2020) 118450

Table 4 The specimen and details. Tests

Compressive Strength

Tensile Strength

Flexural Behavior

Size of Specimens Days No. of Specimens on each day M1 M2 M3 M4 M5 M6 M7 M8 Total

100
100
100 mm 7, 28, 56 3 9 Cubes 9 Cubes 9 Cubes 9 Cubes 9 Cubes 9 Cubes 9 Cubes 9 Cubes 72 Cubes

100 mm Ø x 200 mm Depth 7, 28, 56 2 6 Cylinders 6 Cylinders 6 Cylinders 6 Cylinders 6 Cylinders 6 Cylinders 6 Cylinders 6 Cylinders 48 Cylinders

100
100
500 mm 7, 28, 56 2 6 prism 6 prism 6 prism 6 prism 6 prism 6 prism 6 prism 6 prism 48 prism

respectively. The Figs. 2–5 shows the experimental works of fresh concrete properties. After mixing, the concrete was taken to conduct the rheological properties as per EFNARC guidelines for M1, M3, M4 and M5 (contains only cement as a binder content) which were compared with M2, M6, M7 and M8 (contains mineral admixtures). The values are calculated and given in Table 5 and Fig. 6 represents the bar chart of slump flow and J-Ring. The behaviors of the fresh concrete properties of SCC are  When compared to M1, M2 (40% replacement of mineral admixtures) flow is increased by 2.8% in slump, 1.98% in J-Ring, 5.8% in L-Box and 16% in V-Funnel flow, this shows that addition of mineral admixtures (30%-Fly ash and 10%-Micro

Fig. 4. L-Box.

Fig. 2. Slump flow set-up.

Fig. 5. Flowability of M2.

Fig. 3. J-Ring set-up.

Silica Fume) influences the rheological properties which is due to the finer materials, more surface area and gives more packing effects.  The same pattern followed between the mix containing only cement as a binder and mix containing 40% of mineral admixtures.

5

V. Athiyamaan, G. Mohan Ganesh / Construction and Building Materials 246 (2020) 118450 Table 5 Result of rheological properties. Mix ID

Slump mm

J-Ring mm

L-Box (H2/H1)

V-Funnel Sec

M1(0%) M2(0%) M3(0.25%) M4(0.50%) M5(0.75%) M6(0.25%) M7(0.50%) M8(0.75%)

715 735 695 687 641 705 692 660

706 720 650 500 490 650 510 490

0.85 0.9 0.74 0.61 0.5 0.77 0.68 0.55

7 6 8 9 10 7 8 9

Rhelogical properes mm

Segregaon resistance, Flow and Filling ability 800 700 600 500 400 300 200 100 0

(CaO)6 (Al2O3) (SO3)3xH2O making the concrete more brittle. Further hydrolysis reaction is with water. The C3S (calcium tri silicate) and C2S reacts with water forms C-S-H gel, anhydrate CH particles and lots of energy. This CH (Calcium hydroxide) particle stays idol throughout the hydration process. The C–H gel formations during the hydration process are shown in Figs. 7–10. This process is explained by simple chemical reaction is shown is Eqs. (1) and (2).

2Ca3 SiO5 þ 7H 2 O ! 3CaO:2SiO2 :4H 2 O þ 3CaðOH Þ2 M1

M2

M3

M4

M5

M6

M7

M8

slump flow mm

715

735

695

687

641

705

692

660

J-Ring mm

706

720

650

500

490

650

510

490

þ energyðkJÞ 2Ca2 SiO4 þ 5H 2 O ! 3CaO:2SiO2 :4H 2 O þ 3CaðOHÞ2 þ energy

Fig. 6. Rheological properties.

 When the mixes M3, M4 and M5 were compared with M1 there was 2.8%, 3.92% and 10% fall in flowability respectively, this shows that addition of steel fibres affects (reduces) the rheological property of the SCC.  Similar results were found in the mix M6, M7 and M8. In both the cases there was an abrupt fall in flow for mix M5 and M8, containing 0.75% of steel fibres  Though the results were falling within the premises of the EFNARC guidelines, it is vital to determine the optimal fibrous content. Though mixes M5 and M8 having 0.75% of micro steel fibres shows flowability that falls within EFNARC guidelines, it shows poor filling and passing ability. This is considered as important criteria for reinforced concrete structures. Hence 0.5% sorted out to be the best mix ratio.

ð1Þ

ð2Þ

After the hydration process nearly 20%–30% of CH (calcium hydroxide) is left isolated in the concrete system. This byproduct leads the concrete to poor strength development, causes porosity, stays as a medium for chemical attacks [34,35]. The replacement pozzolanas such as fly ash and micro-silica fume (30%–40%) that is rich in silica content reacts with trouble causing isolated CH forming a cementious material (CSH). The initial stage and later CSH get formation can be seen in Figs. 8 and 9. This reaction make the concrete highly durable, resist to chemical attacks, eco-friendly, reduces the heat of hydration and helps to develop high strength concrete [36]. This process is explained in Eq. (3)

CaðOHÞ2 þ H 4 SiO2 ! CaH 4 SiO4 :H 2 O

ð3Þ

4.3. Hardened properties 4.2. SEM analysis SEM analyses were conducted for different days (7 days and 28 days) on the samples containing OPC and OPC with mineral admixtures by using a scanning electron microscope (SEM) to understand the exact morphological changes. Fig. 7 shows the initial stages of hydration process and the formation of ettringite

Composite matrix (concrete) poured in mould with zero external compaction or vibration. After the curing period of 7, 28 and 56 days, three cubes, two prism and two cylinder specimens from each mixture were taken out from the curing tank and tested with surface dried condition. The total casted specimens (Fig. 11a) along with the testing machine; compression testing machine (Fig. 11b),

Fig. 7. 7 days image of M1.

6

V. Athiyamaan, G. Mohan Ganesh / Construction and Building Materials 246 (2020) 118450

Fig. 8. 28 days of M1.

Fig. 9. 7 days image of M2.

Fig. 10. 28 days image of M2.

flexural testing machine (Fig. 11c) and split tensile test in compression testing machine (Fig. 11d) are shown in Fig. 11. The values obtained were substituted in Eq. (4) to obtain compressive strength, Eq. (5) for flexural strength and Eq. (6) for split tensile. The average strength of three tested concrete specimens is presented in Table 6. For better comparison of compressive strength and flexural strength, the values are merged in a single bar graph shown in Fig. 12.

CompressiveStrength ¼ Flexuralstrength ¼ Tensilestress ¼

2P

pl bd

pDL

2

P A

ð4Þ ð5Þ ð6Þ

4.3.1. Compression strength  The compression testing machine was used to find the ultimate failure load and the compressive strength is calculated by substituting the load in Eq. (4).  When the total binder content is replaced with 30% of fly ash and 10% micro silica fume, there is a decrease in the compressive strength of mixture M2, M6, M7 and M8 when compared with M1, M3, M4 and M5 respectively during the early days (7 days). This was due to the presence of fly ash. But it was found that compressive strength of mixture M2, M6, M7 and M8 were greater than that of mix M1, M3, M4 and M5 at 56th day of curing and showing the hydration process continuing, even after 28 days of curing.  The incorporation of micro steel fibres did not show any significant changes in compressive strength. There was a slight

7

V. Athiyamaan, G. Mohan Ganesh / Construction and Building Materials 246 (2020) 118450

Fig. 11. Testing of specimens.

Table 6 Strength of Concrete at various ages. Mix ID & Steel Fibres %

M1 M2 M3 M4 M5 M6 M7 M8

(0%) (0%) (0.25%) (0.5%) (0.75%) (0.25%) (0.50%) (0.75%)

Compressive Strength MPa

Flexural Strength MPa

Split Tensile Strength MPa

7th day

28th day

56th day

7th day

28th day

56th day

7th day

28th day

56th day

36.5 25.1 39 42 38 28 33 28

59 55 61 65 58 58 65 53

59 59.5 62 68 59 63 68 56

5.4 4.4 5.6 7 8.8 4.8 6.4 7.2

7 6.4 7.2 8.6 10 7 8.4 9.6

7.5 7.2 8 8.9 10.6 7.52 9.2 11.1

3.121 3.408 3.471 3.79 3.981 2.93 3.185 3.408

4.395 4.204 4.522 4.713 5.159 4.459 4.682 5

4.459 4.618 4.618 4.777 5.191 4.777 4.936 5.318

improvement in strength when M3 and M4 compared with M1. M6 and M7 compared with M2 respectively.  Addition of 0.25% micro steel fibres showed 8% and addition of 0.50% showed 16% of gaining in compression strength when compared with mix containing 0% of steel fibres.  There was a sudden fall in compression strength of 10% in M5 and M8 in all curing days when compared with M1 and M8. It was seen that addition of steel fibres beyond 0.50% tends to reduce the compressive strength of the concrete due to high fibre percentage. 4.3.2. Flexural strength The ultimate load values obtained from testing the beams and substituting the values in Eq. (8). The calculated flexural strength is presented in Table 6 and Fig. 12, for comparing the results.  Addition of steel fibres improved the flexural behavior of the concrete, preventing the concrete from brittle failure and

allowing the specimen to carry load even after the initial crack.  Like compression strength, the similar results have been observed in flexural strength between M1 and M2, i.e, fall in initial age strength (7 day strength).  There was a linear increase in strength with addition of micro steel fibres up to 0.75%, when mix ID of M1 (0.00%) compared with M3 (0.25%), M4 (0.50%) and M5 (0.75%). Same results were found when mix ID M2 (0.00%) compared with M6 (0.25%), M7 (0.50%) and M8.  The content of micro steel fibres is directly proportional to flexural strength. Addition of 0.75% of steel fibres showed increase in strength up to 63% when compared to M1 and M2.

4.3.3. Split tensile strength The cylinders were tested placing the specimen horizontally in compression testing machine. The ultimate load was noted along

8

V. Athiyamaan, G. Mohan Ganesh / Construction and Building Materials 246 (2020) 118450

12

80 56 68

70 60

59

61

59.5 55

58

65

62

59

68 65

63 58

38

8 50 40

28

42

33

39

36.5

6 28

25.1

30

7th day (com)

10

53

4

Flexural strength MPa

Compressive strength MPa

59

20 2

28th day(com) 56th day(com) 7th day(flex) 28th day(flex) 56th day(flex)

10 0

0 M1(0%)

M2(0%)

M3(0.25%) M4(0.5%) M5(0.75%) M6(0.25%) M7(0.50% M8(0.75%)

Mix ID & Steel Fibres(%) Fig. 12. Comparison between compression and flexural strength.

the failure in vertical axis. The obtained values are substituted in Eq. (6), to get tensile strength represented in Fig. 13  Percentages of steel fibres were directly proportional to the split tensile strength of the concrete. The results were similar to that of flexural strength.  There was no brittle failure found in concrete containing steel fibres.  Replacement of mineral admixtures of 40% (M8) showed improvement of 5% strength in 56 days of tensile strength.  When M8 is compared with M2, addition of steel fibres enhanced the tensile strength up to 20%.

4.4. Statistical analysis It is the traditional way of analysis of variance and linear regression equations to extract the perfect model for prediction of forecast behavior of the developed experimental model, for better research purpose in future in this field. It is one of the effective model that helps to visually interact and analysis the obtained data. It is one of the mathematical approaches to review the data’s quality and to categorize the specimens accordingly. In the study compression strength and flexural strength with respective days has been considered as responses. Varying percentage content of 0.00%, 0.25%, 0.50% and 0.75% had been considered as a variable.

6

Tensile strength MPa

5

4.459 4.395

4.618

4.618 4.522

4.777 4.713

5.191 5.159 4.777 4.459

4.936 4.682

5.318 5

4.204 3.79

4 3.408

3.981

3.471

3.408 3.185

3.121

2.93

3

7th day 28th day 56th day

2

1

0 M1 (0%)

M2 (0%)

M3 (0.25%) M4 (0.5%) M5 (0.75%) M6 (0.25%) M7 (0.50%) M8 (0.75%)

Mix ID & Steel Fibres(%) Fig. 13. Tensile strength.

9

compressive strength at 7th,28th and 56th day

Specimens containing only cement content i.e. M1, M3, M4 and M5 had been considered as a one set of model and specimen containing mineral admixtures i.e. M2, M6, M7 and M8 had been considered as a second model. Accordingly regression equations were developed using linear fitting cure. The results of the analyses were shown in Figs. 14–17. 64 62 60 58 56 54 52 50 48 46 44 42 40 38 36

7th day Linear fit of 7th day 28th day Linear fit of 28th day 56th day Linear fit of 56th day

7th day 28th da 56th da

Intercep Value 35.26 56.93 57.79

Intercep Slope Standar Value 0.83499 11.04 0.08972 8.92 0.09721 8.36

Slope Standar 1.78527 0.19183 0.20785

Statistic Adj. R-S 0.92545 0.99861 0.99815

7th day Linear fit of 7th day 28th day Linear fit of 28th day 56th day Linear fit of 56th day

2.6 2.4 2.2 2.0 1.8 1.6 1.4

7th day 28th day 56t day

Intercept Intercept Slope Slope Statistics Value Standard Err Value Standard Err Adj. R-Squar 1.025 0.20026 2 0.85391 0.59924 1.575 0.22707 2 0.96825 0.52128 1.77333 0.31503 2.73333 1.3433 0.51143

1.2 0.0

0.1

0.2

0.3

% of steel fibres Fig. 17. Flexural strength with respective to steel fibres.

0.0

0.2

0.4

0.6

4.4.1. Compression strength with respective to steel fibres (mix M1, M3, M4 and M5) Linear fitting curve was developed between compression strength of 7th day, 28th day and 56th day to varying percentage of steel fibres (0.00%, 0.25%, 0.50% and 0.75%). Here the data of 7 days, 28 days and 56 days compression strength was over lapped. From Fig. 10 it is clearly seen that all points of compression strength fall within the fitting line, showing maximum relation between the variable (independent- steel fibres %) and responses (dependent – compression strength). Considering, y¼ mx þ c a functioning model, describing, y-intercept = c and slope = m. r 2 is the co-efficient value, when the output data and the observed predictor values are interpreted. i.e. Pearson correlation coefficient between the (predicted) (y) and modeled observed xdata values of the dependent variable. Hence the best predicted responses and estimated r2 values are shown in Eqs. (7)–(9).

0.8

% of steel fibres Fig. 14. Compression strength with respective to steel fibres.

Flexural strength at 7th, 28th and 56th day

Flexural strength at 7th,28th and 56th day

V. Athiyamaan, G. Mohan Ganesh / Construction and Building Materials 246 (2020) 118450

7th day Linear fitting of 7th day 28th day Linear fitting of 28th day 56th day Linear fitting of 56th day

2.6 2.4 2.2 2.0 1.8 1.6

7th day 28h day 56th day

Intercept Intercept Slope Slope Statistics Value Standard E Value Standard E Adj. R-Squ 1.24 0.12124 1.16 0.25923 0.86378 1.65 0.10869 1.1 0.23238 0.87709 1.71 0.10374 1.14 0.22181 0.89442

1.4 0.0

0.2

0.4

0.6

0.8

For7thday; y ¼ 11:04x þ 35:26; r 2 ¼ 0:925

ð7Þ

For28thdayy ¼ 8:92x þ 56:93; r 2 ¼ 0:99

ð8Þ

For56thdayy ¼ 8:36x þ 57:79; r 2 ¼ 0:99

ð9Þ

% of steel fibres

compressive strength at 7th,28th and 56th day

Fig. 15. Flexural strength with respective to steel fibres.

65 60 7th day Linear fitting for 7th day 28th day Linear fitting for 28th day 56th day Linear fitting for 56th day

55 50 45 40

7th day 28th day 56th day

Intercept Intercept Slope Slope Statistics Value Standard E Value Standard E Adj. R-Squ 24.67 1.07194 14.28 2.2919 0.92651 55.86 0.17944 6.64 0.38367 0.99005 58.84 0.31694 8.76 0.67764 0.98226

4.4.2. Flexural strength with respective to steel fibres, (mix M1, M3, M4 and M5) Similarly, the regression equations are derived with respective to responses (flexural strength of various days) (y) and the variablex. The correlation between y and x is almost significant, that be verified through r2 value. The best predicted responses and estimated r2 values are shown in Eqs. (10)–(12),

For7thday; y ¼ 1:16x þ 1:24; r 2 ¼ 0:863

ð10Þ

For28thdayy ¼ 1:1x þ 1:65; r 2 ¼ 0:877

ð11Þ

For56thdayy ¼ 1:14x þ 1:71; r2 ¼ 0:894

ð12Þ

35 30 0.0

0.2

0.4

0.6

0.8

% of steel fibres Fig. 16. Compression strength with respective to steel fibres.

4.4.3. Compression strength with respective to steel fibres (containing admixtures) (M2, M6, M7 and M8) Linear regression equations had been developed between the compressive strength and flexural strength containing admixtures vs percentage of micro steel fibres. The best predicted responses and estimated r 2 values are shown in Eqs. (14)–(18)

10

V. Athiyamaan, G. Mohan Ganesh / Construction and Building Materials 246 (2020) 118450

evaluate the impact of micro steel fibres in reinforced prism containing admixtures and to assess the alignment of micro steel fibres, while pouring the concrete in the prism mould. The properties and the details of the working model are explained in Table 7. Control prism (C-1) consists of cement as binder content. In Prism 2 (C-2) cement is partially replaced with fly ash (30%) and micro silica fume (MSF) (10%). In prism 3 (C-3) along with partial replacement of mineral admixtures (40%) 0.5% of micro steel fibres (aspect ratio 60) is added to the total volume of prism. Prism-4 (C-4) contains exact material content of C-3 but concrete was poured in the unidirectional with slope of 1/7 as shown in Fig. 14. All beams were having length of 1000 mm, width of 100 mm and the depth of 150 mm. The cover of 20 mm was provided [37]. Two 8 mm diameter Steel bars of Fe250 were used as the bottom reinforcement. In order to use the area of bars efficiently the reinforcement was adopted according to BS 8666: 2005 as shown in Fig. 18, the bottom bars was bend in C-shape at the distance of 60 mm and 200 mm, and used as top reinforcement. Stirrups (shear reinforcement) of diameter 6 mm were placed at the spacing of 100 mm till 200 mm form both ends of the prism, as show in Fig. 19.

Regression equation on compression strength,

For7thday; y ¼ 14:28x þ 24:67; r ¼ 0:926

ð13Þ

For28thdayy ¼ 6:64x þ 55:86; r2 ¼ 0:99

ð14Þ

For56thdayy ¼ 8:76x þ 58:84; r2 ¼ 0:98

ð15Þ

2

Regression equation on Flexural strength,

For7thday; y ¼ 2x þ 1:025; r 2 ¼ 0:599

ð16Þ

For28thdayy ¼ 2x þ 1:575; r 2 ¼ 0:521

ð17Þ

For56thdayy ¼ 2:73x þ 1:777; r2 ¼ 0:511

ð18Þ

4.5. Experimental setup and text procedure The experimental module consists of four identical reinforced prism of span-depth ratio (6.6) was designed to study the influence of mineral admixture (40% replacement with cement), to Table 7 Property descriptions. Prism ID

Admixture (FA-30% & MSF-10%)

Steel fibre %

Compressive strength MPa

Flexural strength MPa

Flow direction

C-1 C-2 C-3 CA-4

0 40% 40% 40%

0 0 0.5% 0.5%

59 55 65 65

7 6.4 8.4 –

random random random uniform

Fig. 18. Bending stress and C-shape bent reinforcement.

Fig. 19. Reinforcement details of prism.

11

V. Athiyamaan, G. Mohan Ganesh / Construction and Building Materials 246 (2020) 118450

Xu ¼

0:87f y Ast 0:36f ck b

standard room temperature. As per the aim of the study, the deflectometer was placed exactly at the mid span of the prism, to determine the deflection at mid span and the stress–strain of each prism. The experimental set-up was clearly shown in Fig. 20. The experiment was conducted at the force rate of 2kN/ min. The values of force (kN), deflection (mm) and cracks were recorded during the test. The test was carried out up till the specimen failed beyond its ultimate bearing capacity.

X u ;lim ¼ 0:53d where d is the diameter of the bar.

X u < X u;lim Hence the designed prism is a under reinforced section.

4.5.2. Result and discussion The collected values of load and deflection at the mid span of every prism are shown in Table 8. The stress and strain were calculated by the formula load/area anddl=l respectively. As shown in Fig. 21 it was clearly seen that all specimens(C-1 to CA-4) were failed under bending; there was no shear failure occurred. This

4.5.1. Test set-up and procedure Static flexural method for flexural performance of fiberreinforced concrete tests were conducted for all four prism using standard universal testing machine (UTM) as per ASTM standards [38,39]. The test was conducted after 28 days of curing under

Fig. 20. Experimental set-up.

Table 8 Recorded data of load and deflection of each prism. C-1

C-2

C-3

CA-4

Load (kN)

Def mm

Stress MPa

strain

Load (kN)

Def mm

Stress MPa

strain

Load (kN)

Def (mm)

Stress MPa

strain

Load (kN)

Def (mm)

Stress MPa

Strain

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 25 25 25 26 27 27 27 27

0.4 0.9 1 1.04 1.1 1.16 1.26 1.5 1.6 1.66 1.76 1.9 2.08 2.24 2.5 2.76 3 3.3 3.5 3.7 4 4.2 4.4 4.7 5 5.2 5.4 5.6 5.6 6.4 7 7.6 8.4

0.67 1.33 2.00 2.67 3.34 4.00 4.67 5.34 6.00 6.67 7.34 8.00 8.67 9.32 10.01 10.67 11.34 12.01 12.67 13.34 14.01 14.67 15.34 16.01 16.68 16.68 16.68 16.67 17.34 18.01 18.01 18.01 18.01

0.02 0.045 0.05 0.052 0.055 0.058 0.063 0.075 0.08 0.083 0.088 0.095 0.104 0.112 0.125 0.138 0.15 0.165 0.175 0.185 0.2 0.21 0.22 0.235 0.25 0.26 0.27 0.28 0.28 0.32 0.35 0.38 0.42

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 23 23 23 23 23 24 25 25 25 25

0.04 0.12 0.2 0.26 0.32 0.42 0.5 0.6 0.7 0.76 0.9 1.04 1.24 1.48 1.7 1.9 2.1 2.4 2.6 2.9 3.16 3.44 4.8 5.2 5.4 5.6 5.8 6 6.8 7.4 8 9 10

0.667 1.334 2.001 2.668 3.335 4.002 4.669 5.336 6.003 6.67 7.337 8.004 8.671 9.338 10.005 10.672 11.339 12.006 12.673 13.34 14.007 14.674 15.341 15.341 15.341 15.341 15.341 15.341 16.008 16.675 16.675 16.675 16.675

0.002 0.006 0.01 0.013 0.016 0.021 0.025 0.03 0.035 0.038 0.045 0.052 0.062 0.074 0.085 0.095 0.105 0.12 0.13 0.145 0.158 0.172 0.24 0.26 0.27 0.28 0.29 0.3 0.34 0.37 0.4 0.45 0.5

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 29 29 29 29

0.02 0.04 0.1 0.13 0.18 0.24 0.3 0.4 0.48 0.57 0.66 0.82 1 1.16 1.4 1.64 1.9 2.1 2.34 2.56 2.78 3.1 3.34 3.6 3.8 4.2 4.8 5.5 6 6.4 6.8 7.2 8

0.667 1.334 2.001 2.668 3.335 4.002 4.669 5.336 6.003 6.67 7.337 8.004 8.671 9.338 10.005 10.672 11.339 12.006 12.673 13.34 14.007 14.674 15.341 16.008 16.675 17.342 18.009 18.676 19.343 19.343 19.343 19.343 19.343

0.001 0.002 0.005 0.0065 0.009 0.012 0.015 0.02 0.024 0.0285 0.033 0.041 0.05 0.058 0.07 0.082 0.095 0.105 0.117 0.128 0.139 0.155 0.167 0.18 0.19 0.21 0.24 0.275 0.3 0.32 0.34 0.36 0.4

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 26 27 28 29 30 31 31 31 31

0.04 0.1 0.16 0.22 0.28 0.34 0.38 0.44 0.52 0.58 0.64 0.72 0.86 1 1.12 1.24 1.26 1.5 1.72 1.98 2.34 2.48 2.82 3.18 3.56 3.76 3.9 4.2 4.8 5.2 5.6 6 7

0.667 1.334 2.001 2.668 3.335 4.002 4.669 5.336 6.003 6.67 7.337 8.004 8.671 9.338 10.005 10.672 11.339 12.006 12.673 13.34 14.007 14.674 15.341 16.008 17.342 18.009 18.676 19.343 20.01 20.677 20.677 20.677 20.677

0.002 0.005 0.008 0.011 0.014 0.017 0.019 0.022 0.026 0.029 0.032 0.036 0.043 0.05 0.056 0.062 0.063 0.075 0.086 0.099 0.117 0.124 0.141 0.159 0.178 0.188 0.195 0.21 0.24 0.26 0.28 0.3 0.35

The bold, italics were indicates the development of initial crack for each specimens.

12

V. Athiyamaan, G. Mohan Ganesh / Construction and Building Materials 246 (2020) 118450

Fig. 21. Tested specimens.

was due to presence of shear reinforcement [40]. There was no failure due to crushing showing that the beams were under reinforced structure; the failure occurs slowly which is also called as ductile failure, where it satisfies the condition Mu < Mu,lim. The ultimate load C-2 was lesser than C-1 this was due to the incomplete pozzolanic reaction. C-2 shows better results against stress. This was due to the presence of finer particle, which increases the surface area of the specimen. The same results were observed in split tensile study. Addition of hooked ended micro steel fibres showed better ultimate strength. C-3 showed increment in ultimate strength of 2kN (7.41%) and 4kN (16%) when compared C-1 and C-2 respectively. The occurring of initial crack was in linear pattern from C-1 to CA-4. The deflection and load bearing capacity was predominantly influenced by steel fibres. C-4 showed 24% increase in ultimate strength compared to C-1. This due to presence of steel fibres but there was increase in 6.9% of ultimate strength when compared to C-3 shows that the fibres are tend to align in the unidirectional

along the direction of flow. The increase in strength was due to the alignment of fibres along the axial direction of flow and normal to the direction to load, whereas in C-3 the fibres are randomly oriented. The initial crack for all the specimens occurred only after the pffiffiffiffiffiffiffi load of 0.7 fck (5.53kN) and is shown in Fig. 22. Since, the dimension of all specimens were same, the stress–strain will also identical as load–deflection graph. 5. Simulation of 1 m reinforced beam 5.1. Modeling procedure ABAQUS/CAE tool was used to develop the 3D finite element mesh of concrete and incorporated rebars, to analysis the beam under 3-point loading condition, like the beam tested early as shown in Figs. 15 and 16. Totally two models were designed to study the impact of micro steel fibres over the concrete beam and reinforced bar. Initially, parts of the design were created, show in Fig. 23. First a concrete beam of cross section 100mm
150mm was created along X and Y axis then extruded along Z-axis about 1000 mm, next main bars of length 960 mm and stirrups of 60mm
110mm were created, with clear cover of 20 mm for model-1. Steel fibres was created and embedded in model-2 5.2. Algorithm for simulation

Fig. 22. Load vs deflection.

The material properties were defined for concrete, rebars, micro steel fibres and stirrups. It is important to define the physical properties of materials to get the accurate result. From the experimental study, references and IS standards, the material properties for stimulation of the model was defined, as shown in Table 9. Section was created for concrete M50, steel rebar, stirrups for first model then micro steel fibres were added with the same specification for model 2. Later the created sections were assigned to the respected parts and assembled together as shown in Fig. 24 (a) with the clear cover of 20 mm in all direction. The ultimate

Fig. 23. (a) Concrete beam (b) 8 mm Bar (c) Stirrups 6 mm.

13

V. Athiyamaan, G. Mohan Ganesh / Construction and Building Materials 246 (2020) 118450 Table 9 Physical properties. Descriptions

Reinforced Bar

Dimension (mm)

Main Bar 960 mm (length)

Spacing (mm) Diameter (mm) Modulus of Elasticity (MPa) Yield Stress (MPa) Density (kg/m3) Aspect Ratio (l/d) Cross sectional area (mm2) Poission’s Ratio

60 mm 8 mm 200,000 278 7800 – 50.24 0.3

Micro steel fibres

M50 concrete

Stirrup 60mm
110mm (width
depth)

30 mm (length)

100 mm 6 mm 200,000 500 7800 60 28.27 0.3

unidirectional 0.5 mm 35,000 50 2400 – 0.20 0.2

1000 mm (Total Length of the beam including clear cover) – 100mm
150mm

15,000

Fig. 24. Assembled parts of reinforced beam.

failure; that was determined in experimental study, was described with initial increment of 0.1. Then an embedded region of concrete to steel was created under interaction section. The datum plane was created along the principle plane to specify the load and boundary conditions. As shown in Fig. 16 the boundary condition of pinned connection was given; assuming U1 = U2 = U3 = 0. Then the ultimate failure load of 25kN was defined exactly at the mid span of the beam to determine the displacement at the mid span of the structure. Meshing was done for all the parts that was created initially, with the approximate global of 10, 5 and 5 for concrete beam, rebars and stirrups respectively as shown in Fig. 19. Finally the job was created to analyse displacement of the beam under ultimate failure load and pinned boundary condition. 5.3. Visualization of output The stressed regions of the model-1 and model-2 can be clearly seen in Figs. 25 and 26. The highly stressed part was displayed in

red color and dark blue region shows the minimum exposure to stress. From Fig. 20 it is seen that the provided stirrups prevented the beam from shear failure that was tend to develop at the crack at the angle of 45° from the support condition and it is indicated in light green color. Fig. 25 clearly shows the influence of aligned micro steel fibres in reducing the impact of load and distributing the load evenly. The micro steel fibres in the concrete prevented the propagation of micro cracks that resulted in reduction of deflection. The nodal point that was located exactly below the mid span was picked up to determine the deflection over time for both the developed model-1 and model-2. The impact of micro steel fibres over deflection is shown in Fig. 26. The MSF not only enhances the flexural strength but also reduced the development of strain. From Fig. 27 it is clearly seen that over time and displacement the model that contains steel fibres showed better performance over the model without micro steel fibres. Model-2 showed nearly 8% improvement in displacement over model-2. This shows that the micro steel fibre model plays eminent role in flexural properties of a concrete structure.

Fig. 25. Stress development in prism and reinforced bar.

14

V. Athiyamaan, G. Mohan Ganesh / Construction and Building Materials 246 (2020) 118450

Fig. 26. Stress development in prism, reinforced bar and micro steel fibres.

 In the experiment study of 1 m beam, the beam with aligned fibres (CA-4) showed better performance followed by the beam with random distribution of fibres (C-3), control beam (C-1) and the beam containing mineral admixtures (C-2); hence the order of the flexural strength for 28 days varies like CA-4 > C-3 > C1 > C-2.  In FEM modeling also similar behaviour was observed as in the experimental study, i.e., Model-2 shows better results than model-1. The performance of mixes through experimental study and simulation through the developed models were almost similar. CRediT authorship contribution statement V. Athiyamaan: Formal analysis, Investigation, Writing - original draft. G. Mohan Ganesh: Supervision, Conceptualization. Fig. 27. Displacement of model-1 and model-2.

6. Conclusion From the above results and discussion following conclusions were made,

Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper. References

 The fresh and hardened properties of SCC containing micro steel fibres and mineral admixtures assessed with their respective control mixes.  A combined use of mineral admixture (fly ash-30% & micro silica 10%) enhances the rheological properties by 7%.  Increase in Micro Steel Fibres affects the flow, filling and passing ability of Micro Steel Fibre Reinforced SCC (MS-FR-SCC) up to 6%.  Addition of 0.50% (M4 and M7) of steel fibres showed the better compressive strength when compared with other mixes (M1, M2, M3, M5, M6 and M8). Also it (M4 and M7) showed better rheological properties with compared with M5 and M8.  Increase in micro steel fibres increases the flexural strength of the concrete, up to 50%-60% and preventing concrete from brittle failure.  From the morphological behavior of concrete, the hydration process continues of mix containing mineral admixtures even after 28 days curing. This can be seen in strength gaining of M2, M6, M7 and M8 at 56 days when compared with M1, M3, M4 and M5.  The statistical study was carried out and the regression equations were proposed. Even though the behavior of concrete under loading is highly non-linear due to the heterogeneous mix, each regression model was developed to predict either compressive or flexural strength of Micro Steel fibre SCC only by varying the fibre content (upto 0.75%).

[1] V. Athiyamaan, G.M. Ganesh, Statistical and detailed analysis on fiber reinforced self-compacting concrete containing admixtures- a state of art of review, IOP Conf. Ser. Mater. Sci. Eng. 263 (2017) 032037. [2] H. Okamura, M. Ouchi, Self-compacting concrete, 1 (1) (2003) 5–15.. [3] A. Khaloo, E.M. Raisi, P. Hosseini, H. Tahsiri, Mechanical performance of selfcompacting concrete reinforced with steel fibers, Constr. Build. Mater. 51 (2014) 179–186. [4] T.E. Guidelines, S. Concrete, ERMCO the European guidelines for selfcompacting concrete, (May) (2005).. [5] N. Su, K. Hsu, H. Chai, A simple mix design method for self-compacting concrete, 31 (2001) 1799–1807.. [6] V. Athiyamaan, G.M. Ganesh, Optimization of SCC mix design using nan-su theory embodying DOE method, (2018) 1–11.. [7] Cristina Frazão, Aires Camões, Joaquim Barros, Delfina Gonçalves, Durability of steel fiber reinforced self-compacting concrete, Constr. Build. Mater. 80 (2015) 155–166. [8] E. Güneyisi, M. Gesoglu, Z. Algin, H. Yazici, Rheological and fresh properties of self-compacting concretes containing coarse and fine recycled concrete aggregates, Constr. Build. Mater. 113 (2016) 622–630. [9] M.I. Abukhashaba, M.A. Mostafa, I.A. Adam, Behavior of self-compacting fiber reinforced concrete containing cement kiln dust, Alexandria Eng. J. 53 (2) (2014) 341–354. [10] S.U. Khan, M.F. Nuruddin, T. Ayub, N. Shafiq, Effects of different mineral admixtures on the properties of fresh concrete, 2014 (2014).. [11] R. Siddique, G. Kaur, Kunal, Strength and permeation properties of selfcompacting concrete containing fly ash and hooked steel fibres, Constr. Build. Mater. 103 (2016) 15–22. [12] E. Güneyisi, M. Gesoglu, O.A. Azez, H.Ö Öz, Effect of nano silica on the workability of self-compacting concretes having untreated and surface treated lightweight aggregates, Constr. Build. Mater. 115 (2016) 371–380. [13] R. Vignjevic, N. Djordjevic, T. De Vuyst, S. Gemkow, ScienceDirect modelling of strain softening materials based on equivalent damage force, Comput. Methods Appl. Mech. Eng. 335 (2018) 52–68.

V. Athiyamaan, G. Mohan Ganesh / Construction and Building Materials 246 (2020) 118450 [14] A. Mohan, K.M. Mini, Strength and durability studies of SCC incorporating silica fume and ultra fine GGBS, Constr. Build. Mater. 171 (2018) 919–928. [15] B. Akcay, M. Ali, Mechanical behaviour and fibre dispersion of hybrid steel fibre reinforced self-compacting concrete, Constr. Build. Mater. 28 (1) (2012) 287–293. [16] E.T. Dawood, M. Ramli, Mechanical properties of high strength flowing concrete with hybrid fibers, Constr. Build. Mater. 28 (1) (2012) 193–200. [17] G. Jen, W. Trono, C.P. Ostertag, Self-consolidating hybrid fiber reinforced concrete: development, properties and composite behavior, Constr. Build. Mater. 104 (2016) 63–71. [18] B.S.E.N. Iso, Construction drawings — simplified representation of concrete reinforcement, 3 (1) (2003).. [19] A. Ahmed, Modeling of a reinforced concrete beam subjected to impact vibration using ABAQUS, 4 (3) (2014) 227–236.. [20] J.E. Bolander, H. Stang, Z. Giedrius, Influence of formwork surface on the orientation of steel fibres within self-compacting concrete and on the mechanical properties of cast structural elements, Cem. Concr. Compos. 50 (2014) 60–72. [21] A. Alsalman, C.N. Dang, W.M. Hale, Development of ultra-high performance concrete with locally available materials, Constr. Build. Mater. 133 (February) (2017) 135–145. [22] D. Yoo, Y. Yoon, N. Banthia, Flexural response of steel-fiber-reinforced concrete beams: effects of strength, fiber content, and strain-rate, Cem. Concr. Compos. 64 (2015) 84–92. [23] D. Yoo, N. Banthia, S. Kang, Y. Yoon, Size effect in ultra-high-performance concrete beams, Eng. Fract. Mech. 157 (2016) 86–106. [24] W. Abbass, M.I. Khan, S. Mourad, Evaluation of mechanical properties of steel fiber reinforced concrete with different strengths of concrete, Constr. Build. Mater. 168 (2018) 556–569. [25] Q. Song, R. Yu, Z. Shui, X. Wang, S. Rao, Z. Lin, Optimization of fibre orientation and distribution for a sustainable Ultra-High Performance Fibre Reinforced Concrete (UHPFRC): experiments and mechanism analysis, Constr. Build. Mater. 169 (2018) 8–19. [26] A. Pineaud, P. Pimienta, S. Rémond, H. Carré, Mechanical properties of high performance self-compacting concretes at room and high temperature, Constr. Build. Mater. 112 (2016) 747–755.

15

[27] M.M. Kamal, M.A. Safan, A.A. Bashandy, A.M. Khalil, Experimental investigation on the behavior of normal strength and high strength selfcuring self-compacting concrete, J. Build. Eng. 16 (July) (2017, 2018,) 79–93. [28] M. Sonebi, Medium strength self-compacting concrete containing fly ash: Modelling using factorial experimental plans, Cem. Concr. Res. 34 (7) (2004) 1199–1208. [29] K. Aarthi, K. Arunachalam, Durability studies on fi bre reinforced self compacting concrete with sustainable wastes, J. Clean. Prod. 174 (2018) 247–255. [30] M. Kisan, S. Sangathan, J. Nehru, S.G. Pitroda, ‘‘म ा नक,” (1992).. [31] C. Ag-, Standard specification for coal fly ash and raw or calcined natural pozzolan for use, (2017) 1–5.. [32] S. Saxena, A.R. Tembhurkar, Impact of use of steel slag as coarse aggregate and wastewater on fresh and hardened properties of concrete, Constr. Build. Mater. 165 (2018) 126–137. [33] S. Aparicio, S. Martínez-Ramírez, M. Molero-Armenta, J.V. Fuente, M.G. Hernández, The effect of curing relative humidity on the microstructure of self-compacting concrete, Constr. Build. Mater. 104 (2016) 154–159. [34] S. Samad, A. Shah, Role of binary cement including Supplementary Cementitious Material (SCM), in production of environmentally sustainable concrete: a critical review, Int. J. Sustain. Built Environ. 6 (2) (2017) 663–674. [35] a. L. a. Fraay, J. M. Bijen, and Y. M. de Haan, The reaction of fly ash in concrete a critical examination, Cem. Concr. Res. 19 (2) (1989) 235–246. [36] Q. Zeng, K. Li, T. Fen-Chong, P. Dangla, Determination of cement hydration and pozzolanic reaction extents for fly-ash cement pastes, Constr. Build. Mater. 27 (1) (2012) 560–569. [37] Concrete Frame Design Manual Concrete Frame Design Manual.. [38] C.C. Test, T. Drilled, C. Ag-, C.C. Test, S.T. Panels, Standard test method for flexural performance of fiber-reinforced concrete (using beam with thirdpoint loading), 1 (2018).. [39] A.T. Cl, Standard specification for deformed and plain, low-carbon, chromium, steel bars for, (2018) 1–7.. [40] J. Lee, H. Shin, D. Yoo, Y. Yoon, Structural response of steel-fiber-reinforced concrete beams under various loading rates, Eng. Struct. 156 (August 2017) (2018) 271–283.