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<p>A significant source of global carbon dioxide (CO₂) emissions is the large-scale production of Ordinary Portland Cement (OPC), which accounts for nearly 8% of total emissions through the energy-intensive clinker formation process. The present study examines the application of magnesium chloride (MgCl<sub>2</sub>) as a chemical accelerator/additive in GGBS-blended concrete, rather than as a supplementary cementitious material, to overcome the limitations of traditional binders. The six M30-grade concrete mixes that were prepared included a mix of 5 blended mixes of GGBS with a partial substitution of the mass, which was replaced by MgCl2 at 5–20% binder mass, and one control mix of 100% OPC. The total binder content was kept constant while MgCl₂ dosage varied from 5 to 20% of binder mass. A constant water-to-binder ratio of 0.42 was maintained. Fresh and hardened properties were studied in terms of consistency, setting time, slump, compressive, split tensile, and flexural strengths, along with the non-destructive testing methods. Among all the mixtures tested, mix 4 performed best at a 10% MgCl2 dosage, achieving compressive strength of 51.28&#xa0;MPa, split tensile strength of 4.50&#xa0;MPa, and flexural strength of 4.60&#xa0;MPa after 28&#xa0;days. Non-destructive tests confirmed its superior quality (UPV = 4700&#xa0;m/s; rebound value = 45). Microstructural examination under SEM and XRD showed localized densification of the matrix and localized microstructural modification with a partial refinement of the pore structure instead of structural refinement and pore connectivity and durability were successfully assessed by electrical impedance spectroscopy (EIS), which showed improved current conductivity (~ 1.0 × 10⁻<sup>4</sup> Ω⁻<sup>1</sup>) after 16&#xa0;days. The findings indicate that the controlled addition of MgCl2 facilitates early hydration and microstructure refinements, but also that the workability declines gradually with an increasing MgCl<sub>2</sub> dosage. This synergistic mix, together with reduced OPC consumption, helps create sustainable blended concrete with improved early-age and microstructural performance.</p>

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Holistic performance and pore structure evaluation of low-cement blended concrete incorporating magnesium chloride as a chemical accelerator

  • 期刊论文

  • 出版模式：

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  • 发表日期：

    2026年6月3日

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  • B. Narendra Kumar,
  • P. Sai Vineela,
  • Dhanalakshmi Kiran Bhat

摘要

A significant source of global carbon dioxide (CO₂) emissions is the large-scale production of Ordinary Portland Cement (OPC), which accounts for nearly 8% of total emissions through the energy-intensive clinker formation process. The present study examines the application of magnesium chloride (MgCl2) as a chemical accelerator/additive in GGBS-blended concrete, rather than as a supplementary cementitious material, to overcome the limitations of traditional binders. The six M30-grade concrete mixes that were prepared included a mix of 5 blended mixes of GGBS with a partial substitution of the mass, which was replaced by MgCl2 at 5–20% binder mass, and one control mix of 100% OPC. The total binder content was kept constant while MgCl₂ dosage varied from 5 to 20% of binder mass. A constant water-to-binder ratio of 0.42 was maintained. Fresh and hardened properties were studied in terms of consistency, setting time, slump, compressive, split tensile, and flexural strengths, along with the non-destructive testing methods. Among all the mixtures tested, mix 4 performed best at a 10% MgCl2 dosage, achieving compressive strength of 51.28 MPa, split tensile strength of 4.50 MPa, and flexural strength of 4.60 MPa after 28 days. Non-destructive tests confirmed its superior quality (UPV = 4700 m/s; rebound value = 45). Microstructural examination under SEM and XRD showed localized densification of the matrix and localized microstructural modification with a partial refinement of the pore structure instead of structural refinement and pore connectivity and durability were successfully assessed by electrical impedance spectroscopy (EIS), which showed improved current conductivity (~ 1.0 × 10⁻4 Ω⁻1) after 16 days. The findings indicate that the controlled addition of MgCl2 facilitates early hydration and microstructure refinements, but also that the workability declines gradually with an increasing MgCl2 dosage. This synergistic mix, together with reduced OPC consumption, helps create sustainable blended concrete with improved early-age and microstructural performance.