Experimental Study on Utilization of Blast Furnace Slag in Concrete

Abstract

Slag is one of the non metallic product which is formed in the manufacture of pigiron and steel in blast furnace. The constituents of slag are silicates of calcium,manganese and aluminium in different compositions. The molten slag is insoluble havinglower density and floats on the pig iron. Slag is one of the essential by product obtainedin the manufacture of iron, which is considered as the industrial waste product. But thiswaste product will be considered as one of the useful product in the construction industry.Hence this slag can be used as alternative material for coarser aggregates and fineraggregates in construction activities. The study can be carried out by partial replacementsof steel slag for fine aggregates to know the concrete strength parameters.The different types of steel slag are listed below:Blast furnace slag (BFS) and steel furnace slag (SFS) are being use as an industrial byproduct.For the cement composites and cementitious components of concrete, Groundgranulated blast furnace slag (GGBS) has been used.BFS and SFS have distinctive chemical and physical properties hence they are wellsuited for use in various construction and civil engineering projectsAir-cooled BFS provides a strong aggregate that can be used in the production ofconcrete, Portland cement as well as asphalt-concrete. Water Cooled slag with giveslightweight aggregates which can be uses in the production of masonry blocks andlightweight concrete. Pelletized & granulated BFS are grouted and used in productionslag cement. Slag cement shows low heat of hydration and better resistance to alkali-silicareaction, chloride penetration, and sulphate attack when compared to ordinary Portlandcement. It shows reduced risk of thermal cracking and highly electrolytic resistant.The chief applications of SFS and BFS are listed belowAir-cooled BFS

Introduction

The experimental study investigates the feasibility of partially replacing natural river sand with LD slag in concrete mixes, aiming to assess the impact on concrete strength parameters such as compressive strength, split tensile strength, and bond strength.

I. Experimental Overview

• Objective: To evaluate the effects of replacing 0% and 20% of natural sand with LD slag on concrete's mechanical properties.

• Tests Conducted:

  • Compressive strength (cylinder compression)

  • Split tensile strength

  • Bond strength between steel reinforcement and concrete

• Materials Used:

  • Ordinary Portland Cement (OPC) 53 Grade

  • Natural river sand (Zone II)

  • LD slag

  • Coarse aggregates (20mm and 12mm)

  • Plasticizer as chemical admixture

• Mix Design:

  • Water-to-cement ratio: 0.48

  • Target slump: 60 mm

  • Exposure condition: Severe

II. Literature Review Highlights

• P. Sathish Kumar et al. (2015): Found that replacing fine aggregates with steel slag increased compressive strength, tensile strength, and flexural strength.

• Dr. B. Krishna Rao et al. (2015): Observed that 25% replacement of natural fine aggregate with air-cooled furnace slag achieved target strength in M30 grade concrete.

• M. C. Nataraja et al. (2013): Noted that replacing fine aggregates with Ground Granulated Blast Furnace Slag (GGBS) improved compressive strength and flow characteristics in cement mortar.ijraset.com+1link.springer.com+1

• Juan Murcia-Delso et al. (2013): Indicated that bond strength decreased with increasing bar diameter but increased with higher concrete strength.

• Mohammad Nadeem et al. (2012): Reported that replacing aggregates with steel slag in M20, M30, and M40 grades resulted in a 4–7% increase in compressive strength.

• G. Apparao et al. (2010): Found good bond strength in concrete with 16mm and 20mm bars, with ultimate strengths of 10.8 MPa and 11 MPa, respectively.

III. Concrete Proportioning

• Trial Mix Design:

  • Cement content: 300 kg/m³

  • Coarse aggregate: 60% (20mm), 40% (12mm)

  • Fine aggregate (natural sand): 765 kg/m³

  • LD slag (for 20% replacement): 597.51 kg/m³

  • Water: 156.23 kg/m³

• Mixing Process:

  • Dry mixing of all ingredients in a drum mixer for 10 minutes.

  • Addition of water and admixture, followed by mixing until uniform consistency.

  • Concrete poured into cast iron molds and compacted for optimum compaction.

• Curing:

  • Specimens cured in a tank with clean potable water for 28 days.

IV. Testing of Concrete Specimens

• Compressive Strength:

  • Specimens tested after 28 days of curing.

  • Results:

    • Control mix (K0): 25.08 MPa

    • 20% slag replacement (K20): 31.14 MPa

  • Conclusion: 20% slag replacement increased compressive strength by approximately 24%.link.springer.com+5ijraset.com+5link.springer.com+5

• Split Tensile Strength:

  • Specimens tested after 28 days of curing.

  • Results:

    • Control mix (K0): 2.9 N/mm²

    • 20% slag replacement (K20): 3.72 N/mm²

  • Conclusion: 20% slag replacement increased split tensile strength by approximately 28%.icjonline.com+1ijert.org+1

• Bond Strength:

  • Specimens tested after 28 days of curing.

  • Results:

    • Control mix (K0): 10.8 MPa

    • 20% slag replacement (K20): 11.0 MPa

  • Conclusion: 20% slag replacement resulted in a slight increase in bond strength.

Conclusion

1) Cylindrical Compressive strength of increased with increase in replacement offine aggregates with steel slag. 2) Split tensile strength increased with increase in replacement of fine aggregateswith steel slag.

References

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Copyright

Copyright © 2025 Aparna B P, Roopakala C G, Vikram M K. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.