评估使用碳化残留物用于粘土稳定的可持续性:整合机械行为和生命周期评估
Sharanya Anandan Govindan1,2, Heeralal Mudavath3, Guru Prathap Reddy Vaddemani4
1Department of Civil Engineering, National Institute of Technology Warangal, Warangal, Telangana, 506004, India. sharanyaag@student.nitw.ac.in.
概括
碳化残留物 (CCR) 为稳定广的粘土提供了一种可持续的替代石灰. 经CCR稳定的土壤表现出优越的强度和耐用性,大大降低了建筑对环境的影响.
科学领域:
- 地质技术工程 地质技术工程
- 可持续的建筑材料 可持续的建筑材料
- 环境科学 环境科学
背景情况:
- 膨胀性粘土由于其体积变化潜力,在建筑中带来了重大挑战.
- 传统的土壤稳定剂,如水合石灰具有环境缺点,包括高碳排放.
- 在建筑材料中,迫切需要可持续的替代品来减轻对环境的影响.
研究的目的:
- 评估碳化残留物 (CCR) 作为扩张性粘土的可持续稳定剂的有效性.
- 为了比较CCR稳定膨胀粘土的性能与用水合石灰稳定的性能.
- 评估使用CCR作为土壤稳定剂对环境的影响,包括碳排放和体现的能量.
主要方法:
- 用CCR和水合石灰稳定膨胀粘土的机械特征.
- 通过多个湿干周期进行耐用性测试.
- 生命周期评估 (LCA) 用于量化碳排放 (CE) 和体内能量 (EE).
主要成果:
- 用9%的CCR稳定土壤在经过三次湿干循环后保留了51%的不受限制的压力强度,而用6%的石灰稳定土壤则保持了23%.
- 在CCR稳定土壤中的天然碳化随着固化时间的增加而增加,增强强度,特别是在干燥阶段.
- 生命周期评估表明,超过80%的环境影响来自稳定剂生产.
结论:
- 碳化残留物 (CCR) 是扩张性粘土的可行和有效稳定剂,在强度和耐久性方面表现优于水合石灰.
- 使用CCR显著减少了土壤稳定对环境的影响,提供了一个可持续的替代方案.
- 对CCR稳定土壤中碳化机制和键形成 (例如,C-S-H) 的进一步研究可以优化其应用.
相关概念视频
01:24Hydration of Cement
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Hydration of cement is a chemical reaction between cement particles and water. This process occurs primarily through two mechanisms: through-solution and topochemical. In the through-solution process, anhydrous compounds dissolve into their constituents, hydrates form in the solution, and then precipitate from the supersaturated solution. The topochemical process involves solid-state reactions at the cement particle surface. The through-solution process dominates the topochemical process at the...
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01:17Soundness of Cement
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The soundness of cement refers to the ability of cement paste to retain its volume after setting. Unsound cement can lead to expansion and structural damage due to the presence of free lime, magnesia, and calcium sulfate. Free lime hydrates very slowly, expanding and causing unsoundness, which is difficult to detect because it intercrystallizes with other compounds. Magnesia also reacts with water, forming crystals that can disrupt the cement's structure. Calcium sulfate can create...
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01:24Carbonation Shrinkage
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Atmospheric CO2 penetrates the concrete's pores and, in the presence of moisture, forms carbonic acid, which then reacts with calcium hydroxide in the hydrated cement, forming calcium carbonate. This process reduces the concrete's volume and is termed carbonation shrinkage.
The concrete's permeability is slightly reduced as calcium carbonate produced during the reaction fills its pores. Furthermore, its strength is slightly enhanced as the water released during the reaction...
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01:29Strength and Heat of Hydration
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The hydration of cement is an exothermic reaction in which heat is generated as cement hydrates. This heat of hydration is critical to cement's strength development. The rate at which this heat is generated affects the temperature rise, with a majority of the heat being released early in the hydration process, half within the first three days, and about 75% within the first week.
The heat of hydration for each cement compound is significant; for instance, tricalcium aluminate (C3A) and...
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01:25Deleterious Substances in Aggregate
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Deleterious substances in aggregates can be detrimental to the quality and durability of concrete. These substances include organic impurities like loam, which interfere with cement hydration and are usually present in the sand. These prevent a good bond between aggregate and cement paste. Organic impurities can be detected using the colorimetric test, where the darkness of a solution after agitation indicates the level of organic content.
Another type of impurity is clay and fine material that...
Another type of impurity is clay and fine material that...
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01:21Pozzolans
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Pozzolans are siliceous or aluminous materials blended with Portland cement. They interact with the calcium hydroxide produced during the hydration of Portland cement and contribute to improved strength and durability of concrete. The pozzolanic activity, a measure of a pozzolan's effectiveness, is typically assessed using the strength activity index, as defined in ASTM C 618-93, which calculates the ratio of the compressive strength of cement mixtures with and without pozzolan.
Fly ash is...
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