# Investigation of Fresh and Hardened Characteristics of Self-Compacting Concrete with the Incorporation of Ethylene Vinyl Acetate and Steel-Making Slag

Authors: Kashif Ali Khan; Hassan Nasir; Muhammad Alam; Sajjad Wali Khan; Izhar Ahmad; Zia Ur Rehman
Journal: Advances in Civil Engineering
 (2019)

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## Abstract

Advancement in the construction industry causes decline in the availability of natural resources, and this decline can be overcome by utilization of the available raw materials. This study is focused on the combined effects of ethylene vinyl acetate (EVA) and ladle furnace slag (LFS) on fresh and hardened characteristics of self-compacting concrete (SCC) by replacing some fraction of cement and sand. The characteristics of SCC in its fresh state are investigated by workability, while hardened characteristics are investigated by elastic modulus and compressive, tensile, and flexural strength. The findings showed that the workability is enhanced by the incorporation of EVA, while decreased with LFS. Furthermore, all the strength properties were enhanced at all the replacement levels of EVA and LFS except for the splitting tensile strength. The utmost gain in elastic modulus and compressive, tensile, and flexural strength was up to 18, 20, 10, and 15% more by increasing the dosage of LFS while keeping EVA constant.


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## Body

## 1. Introduction

Concrete has a significant role in building nearly all the construction plans throughout the world. Aggregates, cement, and water are the primary ingredients of concrete. The volume covered by the aggregates is approximately 70% in concrete [1]. Sometimes, admixtures are added to concrete for a certain property in demand. Almost in all construction projects, cement is the basic binding element of concrete which holds the ingredients all together in a packed mass. The manufacturing of cement demands for a huge amount of energy which is then transmitted to the environment in the form of greenhouse gases and particulate matter [2].From one point of view, humankind is facilitated with the advancement in engineering technology and industrialization, while it has severely stroked the environment from another point of view by the discharge of poisonous gases and yielding of a huge amount of solid wastes [3–8]. To avoid such problems, a lot of studies have been made till now by utilizing industrial wastes in concrete through the substitution of some portion of aggregates and binding materials for expecting better performance of concrete. For instance, one of the researchers concluded that adding recycled coarse aggregates and blast furnace as a replacement for coarse aggregates and cement, respectively, may decrease the mechanical properties [9]. Alternatively, 100% replacement of coarse aggregate by stainless steel-oxidized slag may raise the compressive strength up to 14% [10–13]. The incorporation of steel‐making slag in concrete may yield to the enhanced compressive strength up to 35% [14] and other properties such as durability, bonding to steel rebars, and others [15–22]. Compressive strength of concrete may decrease when fly ash and steel-making slag are incorporated in combination with recycled aggregates [23]. By incorporating steel-making slag as a replacement for coarse aggregates, the mechanical properties may decrease up to 50% [24]. In a similar manner, some of the studies are showing a decreasing trend of 30% in compressive strength by the inclusion of steel-making slag [25, 26]. However, 100% enhancement in compressive strength takes place by the substitution of iron slag with sand [27]. Enhancement of compressive strength was found by replacing fine and coarse aggregates with cooled slag and air-cooled slag, respectively [28]. The substitution of steel-making slag with basalt aggregates may increase the mechanical properties; even so, the reduction in the workability was observed [29]. Mechanical behavior may be enhanced by replacing sand with blast furnace slag [30].SCC is a sort of concrete representing the enhanced workability and nonsegregation properties. This kind of concrete needs little mechanical effort for the purpose of compaction as it could be pour out at ease and at any place [31]. To obtain better flow characteristics of SCC, the fine aggregate is often proportioned in greater amount compared to the coarse aggregate [32]. However, if cement is solely considered a binding material in concrete, it will make the construction more uneconomical and would lead to the hazardous impact on the environment. Because of such a rationale, the researchers started studying the effect of substituting cement by blast furnace slag, fly ash, silica fume, SBR (styrene-butadiene rubber), and EVA [33, 34]. The mentioned materials were used by researchers as a substitute for cement, and they concluded better performance concerning durability characteristics [35, 36]. Workability [37] and strength properties [38] of SCC might be enhanced by the inclusion of fly ash and blast furnace slag. Incorporating steel-making slag up to a dosage of 50% as a replacement for sand might decrease the workability of concrete [39], but other authors have obtained good results with electric arc furnace slag as coarse aggregates [40]. Strength and flow characteristics of SCC may be improved by the inclusion of marble powder and lime [41].EVA may be utilized relatively flourishing in developing concrete in various supplemental applications [42]. Globally, a lot of waste is produced, which may affect the environment; for example, EVA after utilizing as a shoe sole on the user side is more critical concerning environmental issues. In the 70th decennium, EVA was brought in as a substitution material for leather in the shoe industry [43]. Globally, the production of shoes is almost seventeen billion pairs, each year. Utilization of these shoe pairs leads to a tremendous quantity of waste which is then conveyed to the landfill sites for final disposal [44]. It would be more benefitting if such a kind of material is employed in developing concrete by such a practice, and the construction will be more economical and environmentally friendly. Polymers like EVA and SBR are used nowadays in many construction applications either in an emulsified or redistributed form [45, 46]. By the utilization of polymers in concrete, many desired characteristics may be acquired like increased elastic modulus [47], higher flexural strength [48], and improved compressive strength [49]. Nevertheless, few studies are depicting a decreasing trend in mechanical properties of concrete by the utilization of polymers [50]. However, because of the nature of experiments, former results cannot be correlated straight away [51].The necessities of utilization of EVA in construction applications are increasing each day. As per the understanding of the authors, the findings concerning the combined influences of EVA and LFS in the development of SCC are limited. Consequently, efforts have been made in this study to conclude findings concerning combined influences of EVA and LFS on SCC in its fresh and hardened states.


## 2. Scope of the Study

Most often, compressive strength is compromised while improving the workability by adding extra water to the concrete mix, while in this research, it is determined adding EVA to concrete mix improves workability without compromising the compressive strength. According to few researchers, as mentioned in the literature, the mechanical properties may decrease up to 50% by incorporating steel-making slag as a replacement for coarse aggregates [24]. In a similar manner, some of the studies are showing a decreasing trend of 30% in compressive strength by the inclusion of steel-making slag [25, 26]. The compressive strength of the concrete in the present study is enhanced by the incorporation of LFS as a fine aggregate, which also improves concrete’s mechanical properties. Cement is a basic binding element of concrete utilized almost in each construction which holds the ingredients all together in a packed mass, while the manufacturing of cement demands for a huge amount of energy which is then transmitted to the environment, leading to the formation of a tremendous amount of carbon dioxide [2]. For acquiring improved characteristics of SCC, the necessities for cement increase which could make the construction more expensive. So, this necessitates a substitution material to get over such issues in construction practices; therefore, an effort is made in this study for using EVA as a partial replacement for cement, and the workability and other mechanical properties are enhanced.


## 3. Properties of Materials

Locally available cement with a trade mark Askari was utilized in this study, whose properties are listed in Table1. The surface area of the cement was found to be 337 m2/kg. Materials like fine aggregates (locally named Lawrencepur sand) and coarse aggregates (locally named Margalla crush) were conveyed from nearby available sources. The nominal size of coarse aggregates was found to be 19 mm. A huge amount of LFS may be found near the regional steel manufactory plant as a waste material, so it was carried from the local steel manufactory plant. The large sizes of the LFS were ground to an average of 3 mm grains. The physical and chemical characteristics of LFS are tabulated in Table 2, whereas the characteristics of aggregates are tabulated in Table 3. EVA was acquired by chopping down the shoe soles to powdered form of sizes equal to or less than cement sizes. The physical characteristics of EVA are shown in Table 4, while its Vicat softening data are shown in Table 5. Heat resistance of polymers is a critical parameter in construction, and it can be evaluated based on the capability of polymers used to maintain their performances under elevated temperatures. Heat resistance of the polymers can be found out through Vicat softening temperature. Ultra plastic 470 is employed as a water-reducing admixture.Table 1
Proportions of cement ingredients.
Compounds (%)
Mineral compounds (%)
SiO2
Al2O3
Fe2O3
CaO
MgO
SO3
K2O
Na2O
LOI
C2S
C3S
C3A
C4AF
21.3
7.2
2.3
61.1
1.9
2.9
0.5
0.3
2.5
27.9
48.6
11.3
7.8Table 2
Physical and chemical characteristics of LFS.
Name of the compound
Oxide composition (%)
Chemical properties
CaO
43.41
SiO2
14.67
Fe2O3
23.72
Al2O3
3.84
MgO
7.60
MnO
2.93
SO3
0.29
Cr2O3
0.46
P2O5
0.91
TiO2
0.53
K2O
0.06
CaOfree
—
Loss on ignition
1.58
Physical properties
Average porosity (%)
7.62
Specific gravity
3.10
Specific weight (kg/m3)
1858
Water absorption (%)
1.08Table 3
Physical characteristics of fine and coarse aggregates.
Materials used
Characteristics
Size (mm)
Relative density
Specific weight (kg/m3)
Percentage
Water absorption
Water content
Contaminants
Sand
4
2.29
1971
0.21
0.51
0.00
Gravel
19
2.67
1582
0.69
0.32
0.00Table 4
Characteristics of EVA.
Materials
Appearance
pH (20°C)
Grain size (μm)
Transition temp. (°C)
Viscosity at 20°C (mPa·s)
Relative density (60°F)
Surface area (m2/kg)
EVA
Half white
9.3
Less than 50
−9.1
2204
0.94–0.98
329Table 5
Softening of EVA through the Vicat apparatus.
Sample
Rise of temperature at respective penetration (°C)
1 mm
2 mm
3 mm
4 mm
1
69.89
71.23
72.56
74.11
2
70.21
71.93
72.10
73.54
Average
70.05
71.58
72.33
73.82


## 4. Proportioning of the Mixes

For mix proportioning, 10 mixes were prepared in accordance with ACI 237R-07. Of these 10 mixes, 9 were blended mixes which were prepared by the addition of EVA and LFS as a substitute for cement and fine aggregates, while the remaining mix was the reference mix which was prepared without the addition of EVA or LFS. The substitution level for EVA and LFS was kept up to 6, 12, and 18% and 40, 60, and 80%, respectively. The desired strength was targeted at the 28th day with a slump of 580 mm. The reference mix was decided on the basis of trails accompanied by the inclusion of EVA and LFS in different fractions. The symbols used for various blended mixes are shown in Table6, while the details of mix proportioning are tabulated in Table 7. The fine aggregate used in this study was natural siliceous sand with some percentages of LFS, with the finer contents of siliceous sand lying in the range of 0.075 mm to 4.75 mm, while the crushed LFS ranged from 0 to 9.5 mm, and the gradation curves for component fractions are shown in Figure 1, whereas the gradation curves for all the mixes are shown in Figure 2.Table 6
Notations used for various blended mixes.
Materials
E0
E1
E2
E3
E4
E5
E6
E7
E8
E9
% of EVA
0
6
6
6
12
12
12
18
18
18
% of LFS
0
40
60
80
40
60
80
40
60
80Table 7
Mix design data.
Mix ID
W/B
Materials (kg/m3)
Cement content
EVA content
Water content
Fine aggregates
LFS
Coarse aggregates
Superplasticizer
E0
0.52
440.0
0.00
226
965
0.00
695
11
E1
0.52
413.6
26.4
214
579
386
695
11
E2
0.52
413.6
26.4
214
386
579
695
11
E3
0.52
413.6
26.4
214
193
772
695
11
E4
0.52
387.2
52.8
200
579
386
695
11
E5
0.52
387.2
52.8
200
386
579
695
11
E6
0.52
387.2
52.8
200
193
772
695
11
E7
0.52
360.8
79.2
190
579
386
695
11
E8
0.52
360.8
79.2
190
386
579
695
11
E9
0.52
360.8
79.2
190
193
772
695
11Figure 1
Gradation of aggregate fractions.Figure 2
Aggregate gradation of mixtures.


## 5. Experimentation

For the purpose of intended functioning of SCC, various levels of replacements EVA and LFS were employed in concrete with cement and sand, respectively. SCC was studied in its fresh state as well as in the hardened state, and the details are given as follows.


### 5.1. Characteristics of Fresh SCC

Characteristics of fresh SCC were examined by a series of tests, involving the determination of air content, density, and workability. Air content and workability tests were investigated complying with ASTM C138. Workability tests were conducted by L-box, J-ring V-funnel, and slump flow tests complying with BS EN 12350-10:2010, BS EN 12350-12:2010, BS EN 12350-9:2010, and BS EN 12350-8:2010, respectively. The flow experiments are conducted in the laboratory, as depicted in Figure3.Figure 3
Laboratory testing of slump flow (a) and J-ring (b).
(a)
(b)


### 5.2. Characteristics of Hardened SCC

SCC in the hardened state was investigated by compressive, flexural, and splitting tensile strength tests. These tests were carried out using cylindrical moulds. The moulds used for the splitting tensile strength test were 200 mm in length and 100 mm in diameter. The flexural strength test was performed with the help of prismatic beams having 100 × 100 × 350 mm dimensions. A four-point loading system was used for the flexural strength test. Immersed curing was followed for 28 days complying with ASTM C192. A total of ten mixes were prepared, in which one was the reference mix and the other nine were blended mixes. Out of these nine mixes, three mixes were prepared for each of the desired strength, for instance, three mixes for compressive strength, three mixes for tensile strength, and three mixes for flexural strength. The strengths were determined according to ASTM specifications; that is, compressive strength was determined according to ASTM C39, flexural strength according to ASTM C192, splitting tensile strength according to ASTM C496, and elastic modulus according to ASTM C469.


## 5.1. Characteristics of Fresh SCC

Characteristics of fresh SCC were examined by a series of tests, involving the determination of air content, density, and workability. Air content and workability tests were investigated complying with ASTM C138. Workability tests were conducted by L-box, J-ring V-funnel, and slump flow tests complying with BS EN 12350-10:2010, BS EN 12350-12:2010, BS EN 12350-9:2010, and BS EN 12350-8:2010, respectively. The flow experiments are conducted in the laboratory, as depicted in Figure3.Figure 3
Laboratory testing of slump flow (a) and J-ring (b).
(a)
(b)


## 5.2. Characteristics of Hardened SCC

SCC in the hardened state was investigated by compressive, flexural, and splitting tensile strength tests. These tests were carried out using cylindrical moulds. The moulds used for the splitting tensile strength test were 200 mm in length and 100 mm in diameter. The flexural strength test was performed with the help of prismatic beams having 100 × 100 × 350 mm dimensions. A four-point loading system was used for the flexural strength test. Immersed curing was followed for 28 days complying with ASTM C192. A total of ten mixes were prepared, in which one was the reference mix and the other nine were blended mixes. Out of these nine mixes, three mixes were prepared for each of the desired strength, for instance, three mixes for compressive strength, three mixes for tensile strength, and three mixes for flexural strength. The strengths were determined according to ASTM specifications; that is, compressive strength was determined according to ASTM C39, flexural strength according to ASTM C192, splitting tensile strength according to ASTM C496, and elastic modulus according to ASTM C469.


## 6. Results and Discussion

The findings of this study are presented as follows.


### 6.1. Findings of Fresh SCC

The findings associated with the SCC in its fresh state are shown in Table8. The findings revealed that, by increasing the content of LFS at a fixed level of EVA, the air content is enhanced although the drift of density is nearly the same as the negligible increase or reduction drift is seen. One of the reasons for enhancing the air content may be the porous nature of the LFS itself. While concerning the workability, Figure 4 depicts that all the flow properties were reduced except for the V-funnel flow test which showed enhancement in its flow properties with the increase of LFS at a fixed rate of EVA inclusion.Table 8
Findings of SCC in its fresh state.
Mix ID
Fresh SCC characteristics
Slump flow (mm)
J-ring (mm)
L-box data
V-funnel (s)
Air content (%)
Relative density (kg/m3)
E0
741
721
1.20
8.6
3.45
2503
E1
730
693
1.08
9.23
3.46
2513
E2
716
679
1.04
10.13
3.47
2516
E3
690
662
0.97
10.87
3.47
2517
E4
739
715
1.20
9.52
3.47
2515
E5
728
695
1.13
9.77
3.46
2513
E6
705
673
1.03
9.86
3.46
2509
E7
751
729
1.20
9.01
3.45
2506
E8
738
717
1.20
9.31
3.44
2496
E9
727
699
1.13
9.42
3.43
2489Figure 4
Comparative analysis of slump flow at a fixed rate of (a) EVA inclusion and (b) LFS inclusion.
(a)
(b)Since the relative density of the steel-making slag is more than that of sand, the prediction was to enhance the workability of SCC rather than to reduce by the inclusion of the steel-making slag [40]. The reduction in workability is possibly due to either the rough texture of LFS or the extra water absorption of LFS. The findings of the present study concerning fresh SCC show similarity to the past results [29, 31, 40, 45], where reduction in workability was concluded in SCC with the substitution of sand by steel-making slag.From another point of view, the inclusion of EVA at a fixed level of LFS enhanced all the flow characteristics with the exception of the V-funnel test, which showed reduction in the flow characteristics, as shown in Figure4. The results obtained in this study are in line with those of previous research [45], where same results were concluded by the inclusion of polymers in concrete at various levels.


### 6.2. Findings of Hardened SCC

All the mechanical testing results of SCC in its hardened state are listed in Table9. For each value of mechanical testing, three samples were tested, and subsequently, an average or mean value was determined. The coefficient of variation (COV) for all results has also been found out as it is a significant indicator of the dataset dispersion. The COV is defined as the ratio of the standard deviation to the mean value. The percentage of COV is nearly similar for compressive, flexural, and splitting tensile strength, around 2.5%. However, the variability observed for elastic modulus is significantly lowered (between 0.7 and 1.2).Table 9
Hardened properties of SCC.
Concrete Mix
No. of samples tested
Strength (N/mm2)
Compressive
Split tensile
Flexural
Elastic modulus
Mean
COV (%)
Mean
COV (%)
Mean
COV (%)
Mean
COV (%)
E0
3
22.6
3.2
2.37
1.5
2.58
1.2
24012
0.9
E1
3
23.2
2.8
2.43
1.9
2.65
1.8
24842
1.2
E2
3
24.1
1.9
2.54
1.9
2.69
1.7
25356
0.7
E3
3
24.5
2.7
2.60
2.3
2.71
2.3
25804
0.7
E4
3
24.9
2.8
2.33
2.5
2.78
1.7
26112
0.8
E5
3
25.3
1.4
2.46
1.8
2.81
1.6
26612
1.1
E6
3
25.8
1.8
2.53
1.7
2.86
1.7
27109
0.9
E7
3
26.6
1.3
2.14
1.7
2.89
1.4
27625
0.8
E8
3
26.9
1.6
2.22
1.2
2.92
2.4
27980
1.1
E9
3
27.1
2.1
2.31
1.1
2.96
1.1
28219
0.8


#### 6.2.1. Compressive Strength

The findings concerning compressive strength revealed that increasing the dosage of both EVA and LFS enhanced the compressive strength. For instance, the compressive strength is enhanced when cement is substituted by EVA at a fixed level of LFS. Likewise, it is enhanced when sand is substituted by LFS at a fixed level of EVA, as listed in Table9 and Figure 5.Figure 5
Comparative analysis of compressive strength at a fixed rate of (a) EVA inclusion and (b) LFS inclusion.
(a)
(b)The maximum compressive strength was 20% more than that of the reference mix while substituting 18% of cement and 80% of sand by EVA and LFS, respectively, at all replacement levels, as depicted in Figures5(a) and 5(b), whereas the minimum compressive strength was 2.6% more than that of the reference mix while substituting 6% of cement and 40% of sand by EVA and LFS, respectively, at all the replacement levels. The results of the previous findings depict that when LFS is used up to a replacement level of 30% with fine aggregates, the compressive strength is enhanced [25, 27, 31]. Furthermore, according to one of the researchers [32], the compressive strength is enhanced by the inclusion of EVA in concrete which is in line with the present findings. The enhancement in the compressive strength behavior of SCC is possibly due to the fact that EVA has the property of reducing the water content as a result of which the hydrated cement particles create strong bonds with the aggregates [52]. The enhancement in compressive strength by the use of polymers may be either due to the creation of binding forces or due to the filling potentiality of the polymers [53]. One of the studies [48] concluded that the free radical on the boundaries of aggregates establishes hydrogen bonds with the polymers, thus developing the concrete of enhanced compressive strength. The tremendous retention of water by the polymer led to the higher compressive strength of concrete [54].


#### 6.2.2. Flexural Strength

The findings concerning flexural strength are shown in Table9 and Figure 6. The data of flexural strength revealed that increasing the amount of both EVA and LFS enhanced the flexural strength at all substitution levels. Such a variation was also seen in case of compressive strength findings in a similar fashion.Figure 6
Comparative analysis of flexural strength at a fixed rate of (a) EVA inclusion and (b) LFS inclusion.
(a)
(b)The maximum flexural strength was 17.4% more than that of the reference mix, while substituting 12% of cement and 80% of sand by EVA and LFS, respectively, at all replacement levels, as depicted in Figures6(a) and 6(b), whereas the minimum flexural strength was 2.7% more than that of the reference mix, while substituting 6% of cement and 40% of sand by EVA and LFS, respectively, at all the replacement levels.According to one of the studies [55], by replacing sand up to 60% by steel-making slag, the maximum enhancement in the flexural strength is up to 9.3% which is indicating a similar trend as presented in this study. A similar increasing behavior of flexural strength was noted with the incorporation of polymers in concrete by another researcher [47]. Likewise, the flexural strength might increase up to 20% if polymers are blended in concrete at various replacement levels [45]. The flexural strength of concrete may be 3 times that of the controlled mix when polymers are incorporated in concrete [56].


#### 6.2.3. Splitting Tensile Strength

The findings concerning splitting tensile strength are shown in Table9 and depicted in Figure 7. The data revealed that splitting tensile strength of SCC is enhanced by increasing the dosage of LFS at the constant level of EVA content. In the meantime, it was reduced by increasing the dosage of EVA at the constant level of LFS. The maximum splitting tensile strength was 13.2% more than that of the reference mix, while substituting 6% of cement and 40% of sand by EVA and LFS, respectively, as depicted in Figures 7(a) and 7(b), whereas the minimum splitting tensile strength was 5.6% more than that of the reference mix, while substituting 18% of cement and 80% of sand by EVA and LFS, respectively.Figure 7
Comparative analysis of splitting tensile strength at a fixed rate of (a) EVA inclusion and (b) LFS inclusion.
(a)
(b)The decline in splitting tensile strength might be due to the fact that the particles of EVA promote hydration; consequently, the density of the cement grains decreased [54].From another point of view, when sand is substituted by iron slag at a replacement level up to 40%, the splitting tensile strength may be enhanced [30]. Splitting tensile strength may also increase if sand is replaced by granular blast furnace slag up to 60% [55]. Similar findings were ensued by utilizing blast furnace slag as a replacement for sand up to 30% [29].


#### 6.2.4. Modulus of Elasticity

The findings concerning modulus of elasticity are shown in Table9 and depicted in Figure 8. Elastic modulus is behaving in a same manner as compressive strength. The maximum rise in modulus of elasticity was up to 17.5% more than that of the reference mix, while substituting 12% of cement and 80% of sand by EVA and LFS, respectively, at all replacement levels, as depicted in Figures 8(a) and 8(b), whereas the minimum rise in modulus of elasticity was 3.5% more than that of the reference mix, while substituting 6% of cement and 40% of sand by EVA and LFS, respectively, at all the replacement levels. One of the researchers concluded that the inclusion of polymers in concrete enhanced the modulus of elasticity [48].Figure 8
Comparative analysis of elastic modulus at a fixed rate of (a) EVA inclusion and (b) LFS inclusion.
(a)
(b)


## 6.1. Findings of Fresh SCC

The findings associated with the SCC in its fresh state are shown in Table8. The findings revealed that, by increasing the content of LFS at a fixed level of EVA, the air content is enhanced although the drift of density is nearly the same as the negligible increase or reduction drift is seen. One of the reasons for enhancing the air content may be the porous nature of the LFS itself. While concerning the workability, Figure 4 depicts that all the flow properties were reduced except for the V-funnel flow test which showed enhancement in its flow properties with the increase of LFS at a fixed rate of EVA inclusion.Table 8
Findings of SCC in its fresh state.
Mix ID
Fresh SCC characteristics
Slump flow (mm)
J-ring (mm)
L-box data
V-funnel (s)
Air content (%)
Relative density (kg/m3)
E0
741
721
1.20
8.6
3.45
2503
E1
730
693
1.08
9.23
3.46
2513
E2
716
679
1.04
10.13
3.47
2516
E3
690
662
0.97
10.87
3.47
2517
E4
739
715
1.20
9.52
3.47
2515
E5
728
695
1.13
9.77
3.46
2513
E6
705
673
1.03
9.86
3.46
2509
E7
751
729
1.20
9.01
3.45
2506
E8
738
717
1.20
9.31
3.44
2496
E9
727
699
1.13
9.42
3.43
2489Figure 4
Comparative analysis of slump flow at a fixed rate of (a) EVA inclusion and (b) LFS inclusion.
(a)
(b)Since the relative density of the steel-making slag is more than that of sand, the prediction was to enhance the workability of SCC rather than to reduce by the inclusion of the steel-making slag [40]. The reduction in workability is possibly due to either the rough texture of LFS or the extra water absorption of LFS. The findings of the present study concerning fresh SCC show similarity to the past results [29, 31, 40, 45], where reduction in workability was concluded in SCC with the substitution of sand by steel-making slag.From another point of view, the inclusion of EVA at a fixed level of LFS enhanced all the flow characteristics with the exception of the V-funnel test, which showed reduction in the flow characteristics, as shown in Figure4. The results obtained in this study are in line with those of previous research [45], where same results were concluded by the inclusion of polymers in concrete at various levels.


## 6.2. Findings of Hardened SCC

All the mechanical testing results of SCC in its hardened state are listed in Table9. For each value of mechanical testing, three samples were tested, and subsequently, an average or mean value was determined. The coefficient of variation (COV) for all results has also been found out as it is a significant indicator of the dataset dispersion. The COV is defined as the ratio of the standard deviation to the mean value. The percentage of COV is nearly similar for compressive, flexural, and splitting tensile strength, around 2.5%. However, the variability observed for elastic modulus is significantly lowered (between 0.7 and 1.2).Table 9
Hardened properties of SCC.
Concrete Mix
No. of samples tested
Strength (N/mm2)
Compressive
Split tensile
Flexural
Elastic modulus
Mean
COV (%)
Mean
COV (%)
Mean
COV (%)
Mean
COV (%)
E0
3
22.6
3.2
2.37
1.5
2.58
1.2
24012
0.9
E1
3
23.2
2.8
2.43
1.9
2.65
1.8
24842
1.2
E2
3
24.1
1.9
2.54
1.9
2.69
1.7
25356
0.7
E3
3
24.5
2.7
2.60
2.3
2.71
2.3
25804
0.7
E4
3
24.9
2.8
2.33
2.5
2.78
1.7
26112
0.8
E5
3
25.3
1.4
2.46
1.8
2.81
1.6
26612
1.1
E6
3
25.8
1.8
2.53
1.7
2.86
1.7
27109
0.9
E7
3
26.6
1.3
2.14
1.7
2.89
1.4
27625
0.8
E8
3
26.9
1.6
2.22
1.2
2.92
2.4
27980
1.1
E9
3
27.1
2.1
2.31
1.1
2.96
1.1
28219
0.8


### 6.2.1. Compressive Strength

The findings concerning compressive strength revealed that increasing the dosage of both EVA and LFS enhanced the compressive strength. For instance, the compressive strength is enhanced when cement is substituted by EVA at a fixed level of LFS. Likewise, it is enhanced when sand is substituted by LFS at a fixed level of EVA, as listed in Table9 and Figure 5.Figure 5
Comparative analysis of compressive strength at a fixed rate of (a) EVA inclusion and (b) LFS inclusion.
(a)
(b)The maximum compressive strength was 20% more than that of the reference mix while substituting 18% of cement and 80% of sand by EVA and LFS, respectively, at all replacement levels, as depicted in Figures5(a) and 5(b), whereas the minimum compressive strength was 2.6% more than that of the reference mix while substituting 6% of cement and 40% of sand by EVA and LFS, respectively, at all the replacement levels. The results of the previous findings depict that when LFS is used up to a replacement level of 30% with fine aggregates, the compressive strength is enhanced [25, 27, 31]. Furthermore, according to one of the researchers [32], the compressive strength is enhanced by the inclusion of EVA in concrete which is in line with the present findings. The enhancement in the compressive strength behavior of SCC is possibly due to the fact that EVA has the property of reducing the water content as a result of which the hydrated cement particles create strong bonds with the aggregates [52]. The enhancement in compressive strength by the use of polymers may be either due to the creation of binding forces or due to the filling potentiality of the polymers [53]. One of the studies [48] concluded that the free radical on the boundaries of aggregates establishes hydrogen bonds with the polymers, thus developing the concrete of enhanced compressive strength. The tremendous retention of water by the polymer led to the higher compressive strength of concrete [54].


### 6.2.2. Flexural Strength

The findings concerning flexural strength are shown in Table9 and Figure 6. The data of flexural strength revealed that increasing the amount of both EVA and LFS enhanced the flexural strength at all substitution levels. Such a variation was also seen in case of compressive strength findings in a similar fashion.Figure 6
Comparative analysis of flexural strength at a fixed rate of (a) EVA inclusion and (b) LFS inclusion.
(a)
(b)The maximum flexural strength was 17.4% more than that of the reference mix, while substituting 12% of cement and 80% of sand by EVA and LFS, respectively, at all replacement levels, as depicted in Figures6(a) and 6(b), whereas the minimum flexural strength was 2.7% more than that of the reference mix, while substituting 6% of cement and 40% of sand by EVA and LFS, respectively, at all the replacement levels.According to one of the studies [55], by replacing sand up to 60% by steel-making slag, the maximum enhancement in the flexural strength is up to 9.3% which is indicating a similar trend as presented in this study. A similar increasing behavior of flexural strength was noted with the incorporation of polymers in concrete by another researcher [47]. Likewise, the flexural strength might increase up to 20% if polymers are blended in concrete at various replacement levels [45]. The flexural strength of concrete may be 3 times that of the controlled mix when polymers are incorporated in concrete [56].


### 6.2.3. Splitting Tensile Strength

The findings concerning splitting tensile strength are shown in Table9 and depicted in Figure 7. The data revealed that splitting tensile strength of SCC is enhanced by increasing the dosage of LFS at the constant level of EVA content. In the meantime, it was reduced by increasing the dosage of EVA at the constant level of LFS. The maximum splitting tensile strength was 13.2% more than that of the reference mix, while substituting 6% of cement and 40% of sand by EVA and LFS, respectively, as depicted in Figures 7(a) and 7(b), whereas the minimum splitting tensile strength was 5.6% more than that of the reference mix, while substituting 18% of cement and 80% of sand by EVA and LFS, respectively.Figure 7
Comparative analysis of splitting tensile strength at a fixed rate of (a) EVA inclusion and (b) LFS inclusion.
(a)
(b)The decline in splitting tensile strength might be due to the fact that the particles of EVA promote hydration; consequently, the density of the cement grains decreased [54].From another point of view, when sand is substituted by iron slag at a replacement level up to 40%, the splitting tensile strength may be enhanced [30]. Splitting tensile strength may also increase if sand is replaced by granular blast furnace slag up to 60% [55]. Similar findings were ensued by utilizing blast furnace slag as a replacement for sand up to 30% [29].


### 6.2.4. Modulus of Elasticity

The findings concerning modulus of elasticity are shown in Table9 and depicted in Figure 8. Elastic modulus is behaving in a same manner as compressive strength. The maximum rise in modulus of elasticity was up to 17.5% more than that of the reference mix, while substituting 12% of cement and 80% of sand by EVA and LFS, respectively, at all replacement levels, as depicted in Figures 8(a) and 8(b), whereas the minimum rise in modulus of elasticity was 3.5% more than that of the reference mix, while substituting 6% of cement and 40% of sand by EVA and LFS, respectively, at all the replacement levels. One of the researchers concluded that the inclusion of polymers in concrete enhanced the modulus of elasticity [48].Figure 8
Comparative analysis of elastic modulus at a fixed rate of (a) EVA inclusion and (b) LFS inclusion.
(a)
(b)


## 6.2.1. Compressive Strength

The findings concerning compressive strength revealed that increasing the dosage of both EVA and LFS enhanced the compressive strength. For instance, the compressive strength is enhanced when cement is substituted by EVA at a fixed level of LFS. Likewise, it is enhanced when sand is substituted by LFS at a fixed level of EVA, as listed in Table9 and Figure 5.Figure 5
Comparative analysis of compressive strength at a fixed rate of (a) EVA inclusion and (b) LFS inclusion.
(a)
(b)The maximum compressive strength was 20% more than that of the reference mix while substituting 18% of cement and 80% of sand by EVA and LFS, respectively, at all replacement levels, as depicted in Figures5(a) and 5(b), whereas the minimum compressive strength was 2.6% more than that of the reference mix while substituting 6% of cement and 40% of sand by EVA and LFS, respectively, at all the replacement levels. The results of the previous findings depict that when LFS is used up to a replacement level of 30% with fine aggregates, the compressive strength is enhanced [25, 27, 31]. Furthermore, according to one of the researchers [32], the compressive strength is enhanced by the inclusion of EVA in concrete which is in line with the present findings. The enhancement in the compressive strength behavior of SCC is possibly due to the fact that EVA has the property of reducing the water content as a result of which the hydrated cement particles create strong bonds with the aggregates [52]. The enhancement in compressive strength by the use of polymers may be either due to the creation of binding forces or due to the filling potentiality of the polymers [53]. One of the studies [48] concluded that the free radical on the boundaries of aggregates establishes hydrogen bonds with the polymers, thus developing the concrete of enhanced compressive strength. The tremendous retention of water by the polymer led to the higher compressive strength of concrete [54].


## 6.2.2. Flexural Strength

The findings concerning flexural strength are shown in Table9 and Figure 6. The data of flexural strength revealed that increasing the amount of both EVA and LFS enhanced the flexural strength at all substitution levels. Such a variation was also seen in case of compressive strength findings in a similar fashion.Figure 6
Comparative analysis of flexural strength at a fixed rate of (a) EVA inclusion and (b) LFS inclusion.
(a)
(b)The maximum flexural strength was 17.4% more than that of the reference mix, while substituting 12% of cement and 80% of sand by EVA and LFS, respectively, at all replacement levels, as depicted in Figures6(a) and 6(b), whereas the minimum flexural strength was 2.7% more than that of the reference mix, while substituting 6% of cement and 40% of sand by EVA and LFS, respectively, at all the replacement levels.According to one of the studies [55], by replacing sand up to 60% by steel-making slag, the maximum enhancement in the flexural strength is up to 9.3% which is indicating a similar trend as presented in this study. A similar increasing behavior of flexural strength was noted with the incorporation of polymers in concrete by another researcher [47]. Likewise, the flexural strength might increase up to 20% if polymers are blended in concrete at various replacement levels [45]. The flexural strength of concrete may be 3 times that of the controlled mix when polymers are incorporated in concrete [56].


## 6.2.3. Splitting Tensile Strength

The findings concerning splitting tensile strength are shown in Table9 and depicted in Figure 7. The data revealed that splitting tensile strength of SCC is enhanced by increasing the dosage of LFS at the constant level of EVA content. In the meantime, it was reduced by increasing the dosage of EVA at the constant level of LFS. The maximum splitting tensile strength was 13.2% more than that of the reference mix, while substituting 6% of cement and 40% of sand by EVA and LFS, respectively, as depicted in Figures 7(a) and 7(b), whereas the minimum splitting tensile strength was 5.6% more than that of the reference mix, while substituting 18% of cement and 80% of sand by EVA and LFS, respectively.Figure 7
Comparative analysis of splitting tensile strength at a fixed rate of (a) EVA inclusion and (b) LFS inclusion.
(a)
(b)The decline in splitting tensile strength might be due to the fact that the particles of EVA promote hydration; consequently, the density of the cement grains decreased [54].From another point of view, when sand is substituted by iron slag at a replacement level up to 40%, the splitting tensile strength may be enhanced [30]. Splitting tensile strength may also increase if sand is replaced by granular blast furnace slag up to 60% [55]. Similar findings were ensued by utilizing blast furnace slag as a replacement for sand up to 30% [29].


## 6.2.4. Modulus of Elasticity

The findings concerning modulus of elasticity are shown in Table9 and depicted in Figure 8. Elastic modulus is behaving in a same manner as compressive strength. The maximum rise in modulus of elasticity was up to 17.5% more than that of the reference mix, while substituting 12% of cement and 80% of sand by EVA and LFS, respectively, at all replacement levels, as depicted in Figures 8(a) and 8(b), whereas the minimum rise in modulus of elasticity was 3.5% more than that of the reference mix, while substituting 6% of cement and 40% of sand by EVA and LFS, respectively, at all the replacement levels. One of the researchers concluded that the inclusion of polymers in concrete enhanced the modulus of elasticity [48].Figure 8
Comparative analysis of elastic modulus at a fixed rate of (a) EVA inclusion and (b) LFS inclusion.
(a)
(b)


## 7. Conclusions

This study is presented to look into the combined influences of EVA and LFS on SCC by the partial substitutions with cement and sand, respectively. SCC in its fresh and hardened states was studied, and their findings are summarized as follows:(i)
The flow characteristics of SCC are improved with the inclusion of EVA itself. The improvement in workability is possibly due to the fact that EVA has enhanced the relative packing density of the particles.(ii)
By the addition of LFS, the workability characteristics are decreased. The reduction in workability is possibly due to either the rough texture of the slag or the extra water absorption of the LFS.(iii)
Furthermore, at a fixed level of EVA, the entire mechanical behavior is improved. The improvement may possibly due to either the pozzolanic processes or the variations in the stiffness of sand and LFS.(iv)
Meanwhile, at a fixed level of LFS, all the mechanical properties are improved except the splitting tensile strength which decreased. The reduction might be due to the fact that the particles of EVA promote untimely hydration on the boundaries of cement grains, which results in the decreased density of cement grains.(v)
The inclusion of EVA combined with LFS might be efficiently employed in construction concerning the manufacturing of cement that may be helpful in compensating the use of a huge quantity of cement by avoiding the utilization of natural resources. Following this, all the issues concerning the environment and landfill sites might be resolved. In constructions where moderate strength is demanded, using such concrete is more appropriate. Nevertheless, relevance of the findings by the authors encourages further investigations regarding the durability properties of SCC using EVA and LFS to clearly summarize it before its applications.



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*Source: 9146343-2019-07-10.xml*