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<p>The durability of reinforced concrete structures constructed in Iraq is affected by different environmental factors, where the two most common and harmful factors on the durability of concrete are the presence of chloride and sulfate salts in the surrounding environment. Therefore, the main objective of the research is to study the combined effect of these salts on the properties of green concrete, knowing that the individual impact of these salts has been widely studied. Still, there is a lack of understanding regarding how they interact and how their combined presence affects the durability and service life of concrete. In addition, its durability can be improved by replacing cement with supplementary cementitious materials thus reducing carbon dioxide emissions. To achieve this goal, seven mixtures were prepared, one of which was a reference without any substitute and six mixtures that included silica fume (SF) and ground granulated blast furnace slag (GGBS) independently and in varying amounts (3, 5, 7% SF) and (30, 40, 50% GGBS). After adequate curing, they were exposed to aggressive chemicals: (5% sodium chloride + 2% calcium chloride), (5% sodium sulfate), and combined (5% sodium chloride + 2% calcium chloride + 5% sodium sulfate), in addition to tap water (i.e. reference). Strength and durability were evaluated using tests including compressive strength, electrical resistivity, porosity, total absorption and length change, along with repeated visual inspections. In addition, the intensity of chlorine and sulfur components in the concrete was evaluated using X-ray diffraction. The results indicated less deterioration in concrete samples with silica fume and GGBS compared to the reference mixture (without replacing) exposed to the above solutions. Chloride ions do not cause deteriorated effects on concrete and enhance its physical and mechanical properties, which is essential for their role in mitigating sulfate attacks on concrete. In the combined solutions, the deterioration is less severe than in the sulfate solutions. The inhibitory mechanism of chloride ions on concrete sulfate attack indicates that while they cannot completely prevent sulfate attack, they can somewhat mitigate the associated risk. Mixtures with the highest replacement ratio (7% SF and 50% GGBS) showed the highest resistance to aggressive environments and the highest durability.</p>

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Investigation of the properties of green concrete exposed to different aggressive environments

  • 期刊论文

  • 发表日期：

    2025年3月24日

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  • Akram O. Kadhum,
  • Abbas S. AL-Ameeri,
  • Shaker J. Edrees

摘要

The durability of reinforced concrete structures constructed in Iraq is affected by different environmental factors, where the two most common and harmful factors on the durability of concrete are the presence of chloride and sulfate salts in the surrounding environment. Therefore, the main objective of the research is to study the combined effect of these salts on the properties of green concrete, knowing that the individual impact of these salts has been widely studied. Still, there is a lack of understanding regarding how they interact and how their combined presence affects the durability and service life of concrete. In addition, its durability can be improved by replacing cement with supplementary cementitious materials thus reducing carbon dioxide emissions. To achieve this goal, seven mixtures were prepared, one of which was a reference without any substitute and six mixtures that included silica fume (SF) and ground granulated blast furnace slag (GGBS) independently and in varying amounts (3, 5, 7% SF) and (30, 40, 50% GGBS). After adequate curing, they were exposed to aggressive chemicals: (5% sodium chloride + 2% calcium chloride), (5% sodium sulfate), and combined (5% sodium chloride + 2% calcium chloride + 5% sodium sulfate), in addition to tap water (i.e. reference). Strength and durability were evaluated using tests including compressive strength, electrical resistivity, porosity, total absorption and length change, along with repeated visual inspections. In addition, the intensity of chlorine and sulfur components in the concrete was evaluated using X-ray diffraction. The results indicated less deterioration in concrete samples with silica fume and GGBS compared to the reference mixture (without replacing) exposed to the above solutions. Chloride ions do not cause deteriorated effects on concrete and enhance its physical and mechanical properties, which is essential for their role in mitigating sulfate attacks on concrete. In the combined solutions, the deterioration is less severe than in the sulfate solutions. The inhibitory mechanism of chloride ions on concrete sulfate attack indicates that while they cannot completely prevent sulfate attack, they can somewhat mitigate the associated risk. Mixtures with the highest replacement ratio (7% SF and 50% GGBS) showed the highest resistance to aggressive environments and the highest durability.