1 Introduction

The phenomenon of economic globalization can be attributed to the substantial expansion of industrialization, which has concurrently led to a notable surge in the requirement for raw materials. Despite the considerable efforts of researchers and scientists involved in the development of sustainable science strategies, there is still a significant distance to cover towards achieving a more equitable and harmonious world with nature. The notion of sustainability was first introduced in 1987 by the Brundtland Commission, which proposed a strategy to meet the needs of a burgeoning population while preserving resources for future generations. The concept of industrial symbiosis is a recent development that has gained widespread acceptance in many countries. It is believed that this approach can help achieve sustainability goals without compromising economic growth. The proposed approach emphasizes the collaborative utilization of resources among multiple industries. Specifically, the waste generated during the production process of one industry is repurposed as a resource for another industry.

Concrete is the most widely utilized man-made material for building on the planet. Vibrating equipments are normally required to remove the entrapped air in concrete to make it dense and homogeneous. Skilled workers do adequate compaction of concrete, making concrete structures more durable. In the beginning of 1983, Japan's construction companies faced the problem of shortage of skilled workers which in turn lead to the reduction of quality of construction work [1]. This paved the way for the development of SCC. It is a type of concrete that can move under its own weight without the need for mechanical vibration. Therefore, SCC is a cohesive concrete that can fill every corner of a congested reinforcement region by flowing under its own weight without any mechanical vibration [2].

When it comes to SCC, the aggregates are responsible for sixty to seventy percent of the entire volume. Fine aggregate used in SCC for centuries is natural sand [3]. On the other hand, due to depletion and increased demand for natural sand, restrictions are being imposed on exploitation of natural sand, making researchers find alternative materials to natural sand [4]. This led to the production of M-sand and SFS as a replacement for natural sand in concrete [5].

Manufactured sand is produced by crushing of stones, screening and washing of sand. Compared to naturally weathered sand, manufactured sand consists of more sharp-cornered and rough surface texture. However, it is possible to produce cubical shape particles with uniform grading by using appropriate crushing technology. Since M-sand contains high fines it increases water demand compared to river sand. On the other hand, these fines present in M-sand contribute to high paste volume, which is essential for any SCC mix [6, 7].

In the United States over 3,000 foundries generate 6 to 10 million tons of SFS per year. Only 10 percent of the 6 to 10 million spent foundry sand is reused. The ‘spent foundry sand’ from the non-ferrous foundries is generally not reused. In India out of 1.71 million tons of industrial waste, 0.18 million tons of waste are generated from foundry industries per year. Foundry sand is used in engineering usages namely portland cement concrete, embankments, hot mix asphalt and flowable fill. Foundry sand is also used extensively in agriculture as topsoil. Blending spent foundry sand with fine or coarse aggregates can be used as a sub-base or road-base material [8, 9].

Although extensive studies have been accompanied on the mechanical characteristics of regular concrete, very few studies on SCC containing M-sand and spent foundry sand are now available. The current research studied the effect of spent foundry sand and M-sand on workability and strength characteristics. In addition, the quality of spent foundry sand and M-sand incorporated SCC was checked for the transport properties such as sorptivity and water absorption.

2 Materials

OPC of 53 grade conforming to BIS: 12269-1987 [10] with specific gravity, consistency, initial and final setting time of 3.13, 32%, 110 and 280 min, respectively, is used in this research. Fly ash is obtained from a local thermal power plant (i.e., RTPP, YSR district) conforming to IS:3812-2003 [11]. River sand is used as a fine aggregate with specific gravity, bulk density, fineness modulus and maximum size of 2.6, 1810 kg m⁻³, 3.15 and 4.75 mm, respectively. Coarse aggregate having an angular shape with bulk density, fineness modulus, maximum size and specific gravity of 1940 kg m⁻³, 6.5, 2.6 and 10 mm, respectively, is used [12]. Manufactured sand is purchased from local industry in Hyderabad and is utilized as a fine aggregate conforming to IS:2386-1963 [13]. Spent foundry sand acquired from local industry in Hyderabad is utilized as a fine aggregate conforming to IS:1918-1966 [14]. GLENIUM (i.e., brand name-BASF) is utilized as a superplasticizer (i.e., polycarboxylate ether).

3 SCC mix design

The primary goal of this research is to examine the fresh and strength properties of M-sand concrete without and with spent foundry sand. The mix proportions were determined by testing numerous mixes developed according to IS10262-2009 [15] recommendations for grades M30 with a water-to-cement ratio of 0.45, as shown in Table 1. In all SCC mixes, the quantities of fly ash and alccofine were kept constant at 30% and 20% by weight of whole powder content, respectively. SCC1 mix was prepared by replacing 100% of fine aggregate with manufactured sand without any addition of spent foundry sand. Further mixes SCC2 to SCC4, manufactured sand was replaced with SFS in proportions of 10%, 20% and 30%, respectively. Further mixes SCC2 to SCC4 were prepared by keeping fly ash and alccofine as 30% and 20% of cement as in SCC0 and SCC1 with varying quantities of spent foundry sand (i.e., 10%, 20% and 30%) by weight of manufactured sand. In all mixes, the W/B ratio is kept at 0.45.

4 Methods

5 Results and discussion

5.2 Compressive strength

Figure 1 shows the compressive strengths of SCC mixes at the curing period of 3, 7 and 28 days. It is observed that a slight enhancement in compressive strength is accomplished with a 100% percentage substitution of natural sand by manufactured (i.e., SCC1 mix) sand at all curing days as shown in Fig. 1. The compressive strength of SCC 2 and SCC3 mixes containing 10% and 20% SFS is enhanced by 5.4%, 5.9%, 3.87% and 11.48%, 7.9%, 5.8%, for the curing age of 3, 7 and 28 days, respectively, in compression to the SCC1 mix. However, the compressive strength is enhanced in the range of 1.9%–2.7% with the addition of 30% SFS. With the addition of SFS, the compressive strength is greatly increased, which can be attributed to the densification of the concrete matrix caused by the filling of pores by SFS particles. Possible causes of a loss in strength include disruption of aggregate particle packing or an increase in finer material at high replacement levels. Additionally, the inclusion of fine binder particles in SFS might result in a loss in strength. The binder type and contaminants present in SFS can also substantially impact its strength.

View Full Size

CS of SCC mixes at curing period of 3, 7 and 28 days

Citation: International Review of Applied Sciences and Engineering 14, 3; 10.1556/1848.2023.00648

• Download Figure
• Download figure as PowerPoint slide

5.3 Split tensile strength

Figure 2 illustrates the SPT of SCC mixes measured at the curing period of 7 and 28 days. The outcomes exhibited that the SCC1 mix (i.e., 100% M-sand) had somewhat higher tensile strength values than the SCC0 mix (i.e., Conventional SCC mix). At 7 days, SPT of SCC2, SCC3 and SCC4 mixes improved by 6.25%, 12.5% and 3.125%, respectively, compared to the SCC1 mix. The SPT of concrete at 28th age for mixes SCC2, SCC3 and SCC4 also increased by 4.76%, 11.9% and 2.38%, compared to SCC1 mix. Because of its greater surface area and chemical composition, SFS improves the STS of concrete by reducing the binder paste aggregate transition zone. Because SFS is a very fine substance, it reduced the porosity of concrete, which in turn increased the density and resulted in the achievement of a greater split tensile strength.

View Full Size

STS of SCC mixes at curing period of 7 and 28 days

Citation: International Review of Applied Sciences and Engineering 14, 3; 10.1556/1848.2023.00648

• Download Figure
• Download figure as PowerPoint slide

Table 3 illustrates the predicted equations for the STS of SCC mixes from CEB-FIP (1990) and ACI 363R (ACI, 1992). The obtained split tensile strength of SCC mixes after curing period of 7 and 28 days was compared with the CEB-FIP (1990) and ACI 363R (ACI, 1992) predicted equations and is displayed in Table 4.

Table 3.

Split tensile strength equations as per codes

Code	Expression for STS (MPa)	Range of compressive strength
CEB-FIP	$1.56\hspace{0.17em}{\left[\frac{f_c^{\prime }-8}{10}\right]}^{\raisebox{1ex}{$2$}\!\left/ \!\raisebox{-1ex}{$3$}\right.}$	$f_c^{\prime }$ < 80 MPa
ACI 363R	$0.59\hspace{0.17em}{\left(f_c^{\prime }\right)}^{\raisebox{1ex}{$1$}\!\left/ \!\raisebox{-1ex}{$2$}\right.}$	21 MPa < $f_c^{\prime }$ < 83 MPa

Table 4.

Measured and expected STS of SCC mixes

Mixes	Curing ages	Split tensile strength
		Experimental	ACI 363R	CEB-FIP
SCC0	7 days	2.9	2.8	2.0
SCC1		3.2	2.97	2.25
SCC2		3.4	3.05	2.38
SCC3		3.6	3.08	2.42
SCC4		3.3	3	2.30
SCC0	28 days	4.1	3.35	2.8
SCC1		4.2	3.54	3.10
SCC2		4.4	3.61	3.21
SCC3		4.7	3.65	3.26
SCC4		4.3	3.58	3.16

5.4 Modulus of rupture

Figure 3 depicts the modulus of rupture with and without M-sand and spent foundry sand for SCC mixtures at 7 and 28 days after curing. It is observed that a slight enhancement in MOR is accomplished with a 100% percentage substitution of natural sand by manufactured (i.e., SCC1 mix) sand at all curing days as shown in Fig. 3. At 7 days of curing, the MOR for SCC mixes was improved by 6.12%, 12.24% and 8.16% compared to the SCC1 mix. The MOR of SCC at 28th curing age was also enhanced by 3.12%, 7.81% and 4.68% compared to the SCC1 mix. The same pattern was observed in STS and CS at early and later ages. Because of its greater surface area and chemical composition, SFS improves the modulus of rupture of concrete by reducing the binder paste aggregate transition zone. Because SFS is a very fine substance, it reduced the porosity of concrete, which in turn increased the density and resulted in the achievement of a greater modulus of rupture.

The estimated equations for the concrete's modulus of rupture from ACI 318R and ACI 363R are shown in Table 5. Table 6 compares the measured modulus of rupture of SCC mixes after curing period of 7 and 28 days with the ACI 318R and ACI 363R predicted equations.

View Full Size

MOR of SCC mixes at 7 and 28 days of curing

Citation: International Review of Applied Sciences and Engineering 14, 3; 10.1556/1848.2023.00648

• Download Figure
• Download figure as PowerPoint slide

Table 5.

Expressions for modulus of rupture

Code	Expression for STS (MPa)	Range of compressive strength
ACI 363R	$0.94\hspace{0.17em}{\left(f_c^{\prime }\right)}^{\raisebox{1ex}{$1$}\!\left/ \!\raisebox{-1ex}{$2$}\right.}$	Not Specified
ACI 318R	$0.62\hspace{0.17em}{\left(f_c^{\prime }\right)}^{\raisebox{1ex}{$1$}\!\left/ \!\raisebox{-1ex}{$2$}\right.}$	Not specified

Table 6.

Measured and predicted modulus of rupture of SCC mixes

Mixes	Curing ages	Modulus of rupture
		Experimental	ACI 363R	CEB-FIP
SCC0	7 days	4.7	4.47	2.95
SCC1		4.9	4.73	3.12
SCC2		5.2	4.87	3.21
SCC3		5.5	4.91	3.24
SCC4		5.3	4.78	3.16
SCC0	28 days	6.2	5.35	3.53
SCC1		6.4	5.65	3.73
SCC2		6.6	5.76	3.80
SCC3		6.9	5.81	3.83
SCC4		6.7	5.70	3.76

6 Conclusion

The following are the key findings of this study:

• It was observed that while replacing M-sand with spent foundry slag reduced the flow of concrete, it significantly improved its cohesiveness.

• A number of tests were conducted to see what effect spent foundry slag had on strength and durability. All concrete mixtures reached their target compressive strength in 3, 7 and 28 days, and most importantly, reference concrete and 20 SFS concrete reached their goals in 3 and 7 days. Up to 20% of M-sand being replaced with SFS, no loss of strength was seen. The SFS concrete demonstrated acceptable flexural and tensile strength results, with the latter displaying a comparable proclivity to compressive strength.

• The sorptivity test showed better results with adding SFS into the concrete; maximum and minimum absorption values were observed for the SCC0 mix and SCC3 mix, respectively.