Keywords

1 Introduction

Self-compacting concrete (SCC) is a highly fluid and stable concrete that can flow consistently under its own weight, pass between the bars and fill in the formwork without the need of compaction. The self-compact ability is achieved by adding a superplasticizer to the mixture and by increasing the amount of fine materials. From different types of studies, it has been shown that fibre reinforcement materials are proved to be efficient as compared to other materials. These types of fibre component are used to improve cracking and fracture toughness of the structure. The local structure has deboning, pulling out and sliding of the fibres which provide the bridging action. The fibres reduce the starting of macrocracking and avoid opening as well as growth of cracks in the structure. Due to these types of components, high demand of energy is required for remarkable crack propagation. Use of low volumetric fibre demand does not affect the elastic performance of the structure.

The glass fibres are two types: (1) continues, (2) discontinues or chopped fibres. Principal choices are below cost, huge capacity, easy and safely functioning and rapid and orderly diffusion expedite comparable mixes [ShahanaSheril, P.T, 2013].

In the current work, SCC having 12 mm chopped glass fibre added in various proportions like 0.05, 0.1, 0.15, 0.20, 0.25 and 0.39%, respectively, have been used.

2 Experimental Programme

2.1 Materials

In this project, Portland slag cement is used according to IS 455:1989. The physical properties are referred from IS 12089:1987 presented in Table 1. In this experiment, 10 mm size of coarse aggregates are used. The required physical properties are referred from IS: 383-1970 (Table 2). Zone III sand is used according to IS: 383-1970 and the properties are in Table 2. Alkali-resistant glass fibre (ARGF) of Young’s modulus of 72 GPA and 12 mm long is utilized and the physical properties are given in Table 3. Advantages of this type of glass fibres are little price, better strength, easy and safe behaviour, and then quick and unchanging dispersion simplifying same mixes which in word produce durable concrete. In this research, the SIKA VISCOCRETE 2004 NS superplasticizer is used.

Table 1 Physical properties of Portland slag cement
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Table 2 Physical properties of coarse aggregate
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Table 3 Physical properties of glass fibre
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2.2 Mixture Proportion

The experiment of the ordinary concrete and GFRC mix concrete, M30 grade of concrete mix for SCC using subsequent EFNARC code 2005 is prepared. Table 4 shows the mix proportion for both mix. Sika Viscocrete 2004 NS was used to improve the workability. To satisfy SCC, the workability was measured by T500 test, L-box test and V-funnel test. Glass fibre percentages of 0.05, 0.10, 0.15, 0.20, 0.25 and 0.30% are added to concrete to make composite concrete.

Table 4 Approve mix proportion of SCC
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2.3 Testing of Fresh Concrete

T500 and L-box test were conducted to measure the degree of workability. If the concrete can flow above 500 to 700 mm then the slump test value satisfies SCC. Like flow value, in L-box test, concrete can flow in between 8 s. To control the flow ability of self-compacting concrete, V-funnel test is analysed. The test result of workability is shown in Table 5.

Table 5 Result of fresh concrete
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2.4 Preparation of Test Specimens

Cube of size 150 × 150 × 150 mm, cylinder of size 150 × 300 mm and prisms of size 100 × 100 × 500 mm were taken for conducting mechanical properties. After demoulding, all the samples are cured for 28 days in normal tap water.

2.5 Sorptivity Test

Sorptivity test measure for capillary force which utilizes the outlet structure produces liquids to be peaked into the body of the structure. Here, the capillary rice is calculated in concrete cube by putting the cube in water to a depth of 2 to 5 mm deep. The relation among absorption and sorptivity is

$$K\; = \;\frac{W}{A\sqrt t }$$

where K = sorptivity,

W/A = water absorption per unit area cumulatively,

t = time elapsed.

This was accompanied in laboratory. The time interval selected is 30 min, 1, 2, 6, 24 and 48 h and then remove the sample from the water and weigh it. Weigh the cube till the weight increased, when the weight stays constant and the cube is not gaining the weight at that time, then stop the check.

3 Result and Discussion

3.1 Workability

Different mix proportions are made by adding glass fibre at different percentages. The name of the mixes is described in Table 6. All the mixes are tested through slump flow, T50 flow, L-box and V-funnel to satisfy the SCC criteria. Respective values are presented in Table 7. Figures 1, 2, 3 and 4 show the graphical presentation of workability in different forms.

Table 6 Characterization of mixes
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Table 7 Test result of workability
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Fig. 1
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Slump test

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Fig. 2
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T50 flow test

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Fig. 3
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L-box test

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Fig. 4
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V-funnel test

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4 Mechanical Properties

After successive curing, all the samples at 7 days and 28 days are tested to quantify the difference between SCC and fibre SCC. Table 8 shows all the values at different days, respectively.

Table 8 Test results at 7 and 28 days
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In control mix, 7 days value was 34.25 MPa and the FRSCC value was 36.39 MPa. There is an increase in between them around 5.88% which shows no significant improvement. The peak value of FRSCC shows 0.20% of glass fibre. At 28 days, control mix shows 40.78 MPa and the FRSCC shows 48.95 MPa. Here the glass fibre shows 16.69% of increase at 0.20% of glass fibre. Deviation in the compressive strength in both types of SCC is presented in Figs. 5 and 6.

Fig. 5
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Deviation of 7 days compressive strength

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Fig. 6
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Deviation of 28 days compressive strength

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The percentage improvement of flexural strength for glass fibre over control mix is 5.91% when 0.20% of glass fibre is added in concrete. In control mix, it shows 9.06 MPa and in 0.20% of glass fibre, it shows 9.63 MPa. Figure 7 shows the deviation in the flexural strength for PSC and different fibre SCCs.

Fig. 7
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Deviation of 28 days flexural strength

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Experimental investigation shows control mix having 4.15 MPa and 0.20% of glass fibre shows 4.35 MPa. The glass fibre mixed SCC shows 4.59% of increase at 0.20% of glass fibre. Figure 8 describes about the deviation of split tensile strength.

Fig. 8
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Deviation of 28 days split tensile strength

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5 Sorptivity

Figure 9 shows the capillary absorption of water at different time intervals. Here the water absorption through capillary in GFC sample is higher than PSC samples, which indicates the fibres absorbed the water for which the weight of the sample is higher than PSC sample. Figure 9 and Table 9 shows the trend of capillary action for both concretes.

Fig. 9
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Sorptivity at different time intervals

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Table 9 Sorptivity test results
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6 Conclusion

  1. 1.

    As glass fibre absorbed more water, it shows the value of slump.

  2. 2.

    Addition of glass fibre in self-compacted concrete enhances the mechanical properties.

  3. 3.

    0.20% of glass fibre was recognized as optimum doses to increase all the mechanical properties of SSC.

  4. 4.

    At 0.20% of glass fibre, it was observed that compressive strength increased by 5.88% (7 days), and 16.69% (28 days), flexure strength increased by 5.91% (28 days), split tensile strength increased by 4.59% (days), respectively.

  5. 5.

    The GFR concrete is in the state of increased mechanical properties with higher quantity fraction. In fresh state, it showed good performance.

  6. 6.

    In case of sorptivity test, the capillary water absorption of GFC is more than PSC because GFC observed more water due to the glass fibre.