Abstract
Given the growing scarcity of traditional supplementary cementitious materials (SCMs), interest in non-traditional and natural pozzolans (NNPs) is increasing. While much of prior research has focused on fundamental physical properties and mechanical performance, durability - particularly scaling resistance - remains a concern for concrete exposed to deicing salts. This study evaluated the matrix-deicer interactions of paste samples containing 25% of 11 different NNPs - including three calcined clays (CCs), three volcanic ashes (VAs), two fluidized bed combustion ashes (FBCs) and three ground bottom ashes (GBAs). Paste samples were exposed to CaCl2, MgCl2 and NaCl solutions and subjected to 50 freeze-thaw cycles per ASTM C672. At the end of the exposure period, differential scanning calorimetry (DSC) and quantitative X-ray diffraction (QXRD) were used to assess changes in the amounts of originally formed phases, such as Ca(OH)2 and AFm/AFt content, and identify new phases such as Friedel’s salt and brucite. The findings were correlated with chemical composition of the NNPs, particularly their alumina content. Additionally, concrete slabs containing the least reactive NNP from each group were tested per ASTM C672 using a 4% CaCl2 solution. Results from paste and slab tests were consistent, showing that low chloride-binding capacity is associated with poor salt scaling resistance.
Keywords
SCMs, salt scaling, deicing chloride salts, chloride binding capacity.
DOI
10.5703/1288284318138
Recommended Citation
Tokpatayeva, Raikhan; Castillo, Alberto; and Olek, Jan, "Interaction of Cementitious Systems Containing Nontraditional and Natural Pozzolans (NNPs) with Chloride-based Deicers" (2025). International Conference on Durability of Concrete Structures. 9.
https://docs.lib.purdue.edu/icdcs/2025/keynote/9
Interaction of Cementitious Systems Containing Nontraditional and Natural Pozzolans (NNPs) with Chloride-based Deicers
Given the growing scarcity of traditional supplementary cementitious materials (SCMs), interest in non-traditional and natural pozzolans (NNPs) is increasing. While much of prior research has focused on fundamental physical properties and mechanical performance, durability - particularly scaling resistance - remains a concern for concrete exposed to deicing salts. This study evaluated the matrix-deicer interactions of paste samples containing 25% of 11 different NNPs - including three calcined clays (CCs), three volcanic ashes (VAs), two fluidized bed combustion ashes (FBCs) and three ground bottom ashes (GBAs). Paste samples were exposed to CaCl2, MgCl2 and NaCl solutions and subjected to 50 freeze-thaw cycles per ASTM C672. At the end of the exposure period, differential scanning calorimetry (DSC) and quantitative X-ray diffraction (QXRD) were used to assess changes in the amounts of originally formed phases, such as Ca(OH)2 and AFm/AFt content, and identify new phases such as Friedel’s salt and brucite. The findings were correlated with chemical composition of the NNPs, particularly their alumina content. Additionally, concrete slabs containing the least reactive NNP from each group were tested per ASTM C672 using a 4% CaCl2 solution. Results from paste and slab tests were consistent, showing that low chloride-binding capacity is associated with poor salt scaling resistance.
