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<p>The growing energy demand, rising production costs, and environmental impacts associated with ordinary Portland cement have intensified the search for sustainable, low-carbon binders. Lime–pozzolana systems incorporating agricultural waste ashes present a viable alternative; however, their development is often based primarily on strength results, limiting insight into the role of material structure and reactivity. This study comparatively evaluates sugarcane bagasse ash (SCBA) and sawdust ash (SDA) as supplementary cementitious materials in lime-based binders, with emphasis on linking physicochemical properties to performance. The ashes were produced under controlled calcination at 600–700&#xa0;°C and characterized for oxide composition, mineralogy, particle size distribution, specific surface area, and loss on ignition. SCBA exhibited a high combined content of SiO₂ + Al₂O₃ + Fe₂O₃ (86.60%) and was predominantly amorphous, whereas SDA showed a significantly lower content (23.16%), higher loss on ignition (15.33%), and a largely crystalline structure, despite possessing a higher specific surface area. Pozzolanic activity was assessed via electrical conductivity measurements. The results revealed faster early reactivity for SDA, attributed to its higher surface area, while SCBA demonstrated more sustained reactivity due to its high amorphous silica content. At 28 days, SCBA–lime mortars achieved compressive strengths of 2.98–3.72&#xa0;MPa, compared to 1.51–2.52&#xa0;MPa for SDA–lime mortars across pozzolan-to-lime ratios of 3:1 to 1:1. Similarly, SCBA mortars exhibited higher bulk density (930.6&#xa0;kg/m³) and lower water absorption (14.14%) than SDA mortars (812.4&#xa0;kg/m³ and 18.14%, respectively). All mixes exceeded the minimum strength requirement of 2&#xa0;MPa for lime–pozzolana binders, although they remained significantly lower than the OPC control (48.06&#xa0;MPa). Overall, SDA enhances early-age reactivity, whereas SCBA provides superior long-term mechanical performance. These findings establish a clear relationship between material characteristics, pozzolanic behavior, and mortar performance, offering practical guidance for the selection of locally available agricultural ashes in sustainable construction.</p>

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Pozzolanic reactivity and mortar performance of sugarcane bagasse and sawdust ashes in lime based binders

  • 期刊论文

  • 出版模式：

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  • 发表日期：

    2026年7月12日

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  • Odiwuor Vincent Onyango,
  • Enos W. Wambu,
  • Maurice O. Okoth,
  • Pius K. Kipkemboi

摘要

The growing energy demand, rising production costs, and environmental impacts associated with ordinary Portland cement have intensified the search for sustainable, low-carbon binders. Lime–pozzolana systems incorporating agricultural waste ashes present a viable alternative; however, their development is often based primarily on strength results, limiting insight into the role of material structure and reactivity. This study comparatively evaluates sugarcane bagasse ash (SCBA) and sawdust ash (SDA) as supplementary cementitious materials in lime-based binders, with emphasis on linking physicochemical properties to performance. The ashes were produced under controlled calcination at 600–700 °C and characterized for oxide composition, mineralogy, particle size distribution, specific surface area, and loss on ignition. SCBA exhibited a high combined content of SiO₂ + Al₂O₃ + Fe₂O₃ (86.60%) and was predominantly amorphous, whereas SDA showed a significantly lower content (23.16%), higher loss on ignition (15.33%), and a largely crystalline structure, despite possessing a higher specific surface area. Pozzolanic activity was assessed via electrical conductivity measurements. The results revealed faster early reactivity for SDA, attributed to its higher surface area, while SCBA demonstrated more sustained reactivity due to its high amorphous silica content. At 28 days, SCBA–lime mortars achieved compressive strengths of 2.98–3.72 MPa, compared to 1.51–2.52 MPa for SDA–lime mortars across pozzolan-to-lime ratios of 3:1 to 1:1. Similarly, SCBA mortars exhibited higher bulk density (930.6 kg/m³) and lower water absorption (14.14%) than SDA mortars (812.4 kg/m³ and 18.14%, respectively). All mixes exceeded the minimum strength requirement of 2 MPa for lime–pozzolana binders, although they remained significantly lower than the OPC control (48.06 MPa). Overall, SDA enhances early-age reactivity, whereas SCBA provides superior long-term mechanical performance. These findings establish a clear relationship between material characteristics, pozzolanic behavior, and mortar performance, offering practical guidance for the selection of locally available agricultural ashes in sustainable construction.