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<p>This study examines the effects of partially replacing Portland cement (PC) with eucalyptus ash (E) and willow wood ash (W) on the properties of cement pastes and mortars. Wood waste ashes were incorporated at 5–20 wt% relative to cement in pastes and mortars. The cement paste specimens were evaluated for setting time, consistency, and hydration behavior. Additionally, mortars cured for 7 and 28 days underwent testing for water absorption, compressive strength, ultrasonic pulse velocity (UPV), and electrical resistivity (ER). Higher dosages of wood waste ash (&gt; 15%) increased water demand, delayed setting times, and reduced hydration rates, resulting in fewer hydration products, such as calcium hydroxide (CH) and calcium silicate hydrate (CSH). In mortars, increased ash dosages led to higher water absorption, porosity, and sorptivity, decreasing compressive strength. Using semi-quantitative analyses, the degree of hydration in cement mortars was estimated based on the portlandite (calcium hydroxide) content observed in fourier transform infrared (FTIR) spectroscopy and x-ray diffraction (XRD) analyses. Semi-quantitative analysis of FTIR and XRD using peak deconvolution revealed integrated peak ratios of portlandite to reactants as 0.376, 0.366, and 0.360 for FTIR and 0.165, 0.155, and 0.150 for XRD in C, E20, and W20 mortars, respectively. These findings indicate a reduced formation of portlandite in wood ash-based mortars, suggesting a lower degree of hydration than the control mortar sample. Compared to the control mortar, the reduced formation of portlandite in ash-based cement mortar indicates that eucalyptus and willow wood ashes slow the hydration rate. SEM and EDX analyses revealed that alumina (Al)-rich wood ashes in mortar effectively mitigate alkali-silica reaction (ASR) expansion. Thus, replacing cement with wood ash offers environmental benefits by reducing CO₂ emissions and providing a cost-effective alternative.</p>

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Assessing the influence of eucalyptus bark ash and willow wood ash on the physical, mechanical, and microstructural properties of portland cement pastes and mortars

  • 期刊论文

  • 发表日期：

    2025年1月28日

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  • Nazeef Ullah,
  • Muhammad Hanif Khan,
  • Muhammad Ali Sikandar,
  • Zhao Qiuhong,
  • Han Zhu,
  • Obaid Rauf,
  • Zaheer Farooq

摘要

This study examines the effects of partially replacing Portland cement (PC) with eucalyptus ash (E) and willow wood ash (W) on the properties of cement pastes and mortars. Wood waste ashes were incorporated at 5–20 wt% relative to cement in pastes and mortars. The cement paste specimens were evaluated for setting time, consistency, and hydration behavior. Additionally, mortars cured for 7 and 28 days underwent testing for water absorption, compressive strength, ultrasonic pulse velocity (UPV), and electrical resistivity (ER). Higher dosages of wood waste ash (> 15%) increased water demand, delayed setting times, and reduced hydration rates, resulting in fewer hydration products, such as calcium hydroxide (CH) and calcium silicate hydrate (CSH). In mortars, increased ash dosages led to higher water absorption, porosity, and sorptivity, decreasing compressive strength. Using semi-quantitative analyses, the degree of hydration in cement mortars was estimated based on the portlandite (calcium hydroxide) content observed in fourier transform infrared (FTIR) spectroscopy and x-ray diffraction (XRD) analyses. Semi-quantitative analysis of FTIR and XRD using peak deconvolution revealed integrated peak ratios of portlandite to reactants as 0.376, 0.366, and 0.360 for FTIR and 0.165, 0.155, and 0.150 for XRD in C, E20, and W20 mortars, respectively. These findings indicate a reduced formation of portlandite in wood ash-based mortars, suggesting a lower degree of hydration than the control mortar sample. Compared to the control mortar, the reduced formation of portlandite in ash-based cement mortar indicates that eucalyptus and willow wood ashes slow the hydration rate. SEM and EDX analyses revealed that alumina (Al)-rich wood ashes in mortar effectively mitigate alkali-silica reaction (ASR) expansion. Thus, replacing cement with wood ash offers environmental benefits by reducing CO₂ emissions and providing a cost-effective alternative.