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<p>Soil stabilization in highly acidic environments poses significant challenges in deep mixing method (DMM) applications, particularly due to the corrosive effects of low pH on cementitious materials. This study evaluates the performance of Hydraulic Cement (HC) compared to Ordinary Portland Cement (OPC) for stabilizing highly acidic soils by investigating strength development, pH stabilization, microstructural evolution, and environmental impact. Unconfined compressive strength (<i>q</i><sub><i>u</i></sub>) tests demonstrated that HC-treated soils exhibited superior strength development, particularly over extended curing periods, due to efficient hydration reactions and the formation of stable cementitious compounds. In contrast, OPC-treated soils exhibited poorer long-term performance due to excessive ettringite formation, which increased porosity and weakened the stabilized matrix. The impact of pH pre-treatment was also examined, revealing that adjusting acidic soils to pH levels of 4.0 and 6.0 significantly improved <i>q</i><sub><i>u</i></sub> values (25–38% higher than untreated soils at pH 2.3). Scanning Electron Microscopy (SEM) analysis confirmed that HC-treated soils developed a denser, more cohesive microstructure, with well-distributed hydration products and minimal ettringite-induced expansion. Conversely, OPC-treated soils showed extensive ettringite crystal formation, leading to structural instability, increased porosity, and reduced durability. HC also demonstrated superior pH stabilization, reducing cement consumption for acid neutralization and optimizing binder efficiency. A CO₂ emissions assessment revealed that HC has a lower carbon footprint than OPC, attributed to its lower clinker content and the incorporation of supplementary cementitious materials (SCMs). This sustainability advantage supports HC’s feasibility for large-scale DMM applications. Overall, the findings highlight HC’s advantages in strength performance, pH stabilization, microstructural integrity, and environmental sustainability, positioning it as a viable alternative to OPC for deep mixing stabilization in highly acidic soils.</p>

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Hydraulic Cement as a Sustainable Ground Improvement Solution for Highly Acidic Soils: Advancing Environmental Sustainability in the Deep Mixing Method

  • 期刊论文

  • 发表日期：

    2025年7月8日

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  • Warapot Petchgate,
  • Supasit Pongsivasathit,
  • Khathapon Pinpatthanapong,
  • Kamtornkiat Musiket

摘要

Soil stabilization in highly acidic environments poses significant challenges in deep mixing method (DMM) applications, particularly due to the corrosive effects of low pH on cementitious materials. This study evaluates the performance of Hydraulic Cement (HC) compared to Ordinary Portland Cement (OPC) for stabilizing highly acidic soils by investigating strength development, pH stabilization, microstructural evolution, and environmental impact. Unconfined compressive strength (qu) tests demonstrated that HC-treated soils exhibited superior strength development, particularly over extended curing periods, due to efficient hydration reactions and the formation of stable cementitious compounds. In contrast, OPC-treated soils exhibited poorer long-term performance due to excessive ettringite formation, which increased porosity and weakened the stabilized matrix. The impact of pH pre-treatment was also examined, revealing that adjusting acidic soils to pH levels of 4.0 and 6.0 significantly improved qu values (25–38% higher than untreated soils at pH 2.3). Scanning Electron Microscopy (SEM) analysis confirmed that HC-treated soils developed a denser, more cohesive microstructure, with well-distributed hydration products and minimal ettringite-induced expansion. Conversely, OPC-treated soils showed extensive ettringite crystal formation, leading to structural instability, increased porosity, and reduced durability. HC also demonstrated superior pH stabilization, reducing cement consumption for acid neutralization and optimizing binder efficiency. A CO₂ emissions assessment revealed that HC has a lower carbon footprint than OPC, attributed to its lower clinker content and the incorporation of supplementary cementitious materials (SCMs). This sustainability advantage supports HC’s feasibility for large-scale DMM applications. Overall, the findings highlight HC’s advantages in strength performance, pH stabilization, microstructural integrity, and environmental sustainability, positioning it as a viable alternative to OPC for deep mixing stabilization in highly acidic soils.