摘要
生物炭具有疏松多孔、高比表面积和强吸附等特性,在土体改良以及修复受污染土体方面展现出应用潜力。添加生物炭可改善土体结构,进而增强土体持水特性等,其中,生物炭掺量和粒径对改良效果有较大的影响。为了研究生物炭掺量和粒径对生物炭-黏土混合土持水特性的影响,通过蒸汽平衡法控制土样的吸力,确定吸力平衡后土样的含水率和体积等,得到吸湿过程中不同生物炭掺量(0%、5%、10%和15%)、不同粒径范围(>74、40~74、20~40μm和<74μm)生物炭-黏土混合土在高吸力(3.29~286.7MPa)范围的土-水特征曲线,并结合扫描电镜(SEM)和压汞(MIP)试验结果分析其微观孔隙结构。试验结果表明:(1)当掺入生物炭的粒径较小时,随着生物炭掺量的增加,土样的持水特性有较明显的提高,随着掺入生物炭粒径的增大,生物炭掺量对土样的持水特性影响不大。(2)当生物炭的掺量较少时,不同粒径生物炭-黏土混合土的土-水特征曲线基本相同,随着生物炭掺量提高,小粒径生物炭对混合土持水特性的影响逐渐显现。(3)由生物炭-黏土混合土微观孔隙结构的演变规律进一步阐释生物炭掺量、粒径对生物炭-黏土混合土持水特性的影响机制。
Biochar is increasingly used in soil improvement, pollutant remediation and other fields for its porosity, high specific surface area and strong adsorption properties. The addition of biochar can alter the pore structure of the soil, and subsequently change the water retention behaviour. Among many influencing factors, the biochar content and particle size have a great influence on the improvement effect. In order to study the effect of biochar content and particle size on water retention behavior of biochar-clay mixture, the soil-water characteristic curve in the wetting process was obtained for biochar-clay mixture with different biochar contents(0%, 5%, 10% and 15%) and particle sizes(>74, 40-74, 20-40 μm and <74 μm) at high suction range(3.29-286.7 MPa) by using the vapour equilibrium technique for controlled suction. The micro-pore structures were analyzed by scanning electron microscopy(SEM) and mercury intrusion porosimetry(MIP) tests. The results show that: 1) When the particle size of biochar is small, the water retention capacity of biochar-clay mixture improved obviously with the increase of biochar content;With the increase of biochar particle size, the water retention capacity of mixture is slightly affected by the amount of biochar. 2) When the content of biochar is small, the soil-water characteristic curves of biochar-clay mixtures with different particle sizes are basically the same, with the increase of biochar content, the influence of biochar with small particle size on the water retention capacity of biochar-clay mixtures has appeared out gradually. 3) The evolution of microscopic pore structure of biochar-clay mixtures further explains the influence mechanism of biochar content and particle size on its water retention capacity.
作者
李明玉
孙文静
LI Ming-yu;SUN Wen-jing(Department of Civil Engineering,Shanghai University,Shanghai 200444,China)
出处
《岩土力学》
EI
CAS
CSCD
北大核心
2019年第12期4722-4730,4739,共10页
Rock and Soil Mechanics
基金
国家自然科学基金（No.41572284,41977214）~~
关键词
生物炭
微观结构
粒径
掺量
蒸汽平衡法
土-水特征曲线
biochar
microstructure
particle size
content
vapor equilibrium technique
soil-water characteristic curve
