含两步热化学活化生物炭的胶凝复合材料中的碳固存

IF 13.1 1区 工程技术 Q1 CONSTRUCTION & BUILDING TECHNOLOGY
Sahana C. M, Souradeep Gupta
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引用次数: 0

摘要

生物炭(BC)活化可以引起结构变化,从而提高生物炭基胶凝材料的CO2固存能力和工程性能。本研究考察了生物炭在550℃、650℃和750℃条件下的热处理(TTBC),以及在上述温度下的KOH活化(KBC: KOH为1:2、1:3和1:4)对生物炭-水泥复合材料水化动力学、CO2固相、结构变化、强度和收缩率的影响。KBC具有较高的宏观孔隙(>;而TTBC主要是芳香族和微孔(<;2 nm孔隙)。750℃活化的KBC具有高表面积(190 ~ 237 m2/g)、结构紊乱和富氧官能团的存在,与550℃和650℃下制备的TTBC和KBC相比,加速了水泥浆体的水化动力学,使水泥浆体的总水化率提高了30 ~ 51%。KOH活化促进了碳的燃烧,增加了生物炭的中观和宏观孔隙度,从而为二氧化碳的扩散创造了额外的渠道。与TTBC相比,生物炭水泥的二氧化碳固存能力提高了17 - 45%。随着BC: KOH比例从1:2变为1:4,生物炭水泥的CO2固存量增加,中小毛细管孔隙体积减少40 ~ 71%。这将使1天的强度提高16 - 37%,长期强度(1年后)提高22 - 45%。此外,由于残余钾(来自KOH活化)形成了扩大的波特兰石晶体,这减轻了15 - 38%的总收缩,增强了活化的生物炭基胶凝材料的稳定性。
本文章由计算机程序翻译,如有差异,请以英文原文为准。
Carbon sequestration in cementitious composites containing two-step thermochemically activated biochar
Biochar (BC) activation can induce structural changes, which may enhance CO2 sequestration and the engineering performance of biochar-based cementitious materials. In this research, the effect of biochar engineered under two conditions – (i) thermal treatment (TTBC) at 550 °C, 650 °C, and 750 °C respectively, and (ii) KOH- activation (KBC) at the mentioned temperatures and BC: KOH of 1:2, 1:3, and 1:4, on the hydration kinetics, CO2 sequestration, structural changes, strength and shrinkage of biochar-cement composites is examined. KBC has a high macro-pore (>50 nm pores) volume and contains oxygenated groups, while TTBC is primarily aromatic and micro-porous (<2 nm pores). High surface area (190–237 m2/g), structural disorder, and the presence of oxygen-rich functional groups in KBC activated at 750 °C accelerate the hydration kinetics and enhance the total hydration of cement pastes by 30–51 % compared to pastes with TTBC and KBC prepared at 550 °C and 650 °C. KOH activation promotes carbon burn-off and increases meso- and macro-porosity of biochar, thus creating additional diffusion channels for CO2. This enhances the CO2-sequestration of biochar-cement by 17–45 % compared to TTBC. CO2 sequestration in biochar-cement increases with a change in BC: KOH from 1:2 to 1:4, reducing the small and medium capillary pore volume by 40–71 %. This enhances the 1-day strength by 16–37 % and longer-term strength (after 1 year) by 22–45 %. Further, enlarged portlandite crystals are formed due to residual potassium (from KOH activation), which mitigates the total shrinkage by 15–38 %, enhancing the stability of activated biochar-based cementitious materials.
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来源期刊
Cement & concrete composites
Cement & concrete composites 工程技术-材料科学:复合
CiteScore
18.70
自引率
11.40%
发文量
459
审稿时长
65 days
期刊介绍: Cement & concrete composites focuses on advancements in cement-concrete composite technology and the production, use, and performance of cement-based construction materials. It covers a wide range of materials, including fiber-reinforced composites, polymer composites, ferrocement, and those incorporating special aggregates or waste materials. Major themes include microstructure, material properties, testing, durability, mechanics, modeling, design, fabrication, and practical applications. The journal welcomes papers on structural behavior, field studies, repair and maintenance, serviceability, and sustainability. It aims to enhance understanding, provide a platform for unconventional materials, promote low-cost energy-saving materials, and bridge the gap between materials science, engineering, and construction. Special issues on emerging topics are also published to encourage collaboration between materials scientists, engineers, designers, and fabricators.
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