摘要
为寻找一种低能耗、绿色环保的特殊土改良剂,以NaOH为碱激发剂、粉煤灰为前驱体制备地聚物试样,通过无侧限抗压强度试验与微观试验相结合的手段,研究碱激发剂浓度及含水率对试样强度及破坏形式的影响。结果表明:NaOH碱激发剂对粉煤灰活性激发效果明显,碱激发试样无侧限抗压峰值强度随NaOH浓度增加整体呈现先增加后减小的趋势,当NaOH浓度为8 mol/L、含水率为22.5%时,地聚物强度最大(4.21 MPa);当NaOH浓度保持不变时,地聚物强度随含水率增加呈先增加后减小趋势,所有浓度下的地聚物强度均在含水率22.5%时出现峰值;在NaOH浓度及含水率两个因素共同作用下,地聚物应力-应变曲线与抗压破坏形式出现明显差异。结合SEM图像可知,NaOH溶液促使聚合反应发生,适当范围内提高浓度可使地聚物结构变得密实,继续增大浓度则会使地聚物微观结构产生不良形态,同样过高的含水率会使地聚物黏性降低,颗粒之间无法较好胶结,导致结构松散,而应力-应变曲线与抗压破坏形式出现差异可能与试样微观结构中颗粒排布相关。
To develop an energy-efficient,green,and environmentally friendly special soil stabilizer,NaOH was used as alkaline activator and fly ash as precursor to prepare geopolymer specimens.By combining unconfined compressive strength tests with microscopic tests,the effects of alkaline activator concentration and moisture content on the strength and failure modes of the specimens were investigated.The results showed that NaOH alkaline activator significantly enhanced the activity of fly ash.The peak value of unconfined compressive strength of the alkaline-activated specimens first increased and then decreased with increasing NaOH concentration.When the NaOH concentration was 8 mol/L and the moisture content was 22.5%,the geopolymer strength reached its maximum(4.21 MPa).When the NaOH concentration remained constant,the strength of the geopolymer first increased and then decreased with increasing moisture content.At all concentrations,the strength peaked at a moisture content of 22.5%.Under the combined influence of NaOH concentration and moisture content,the stress-strain curve and compressive failure mode of the geopolymers exhibited significant differences.SEM images revealed that NaOH solution promoted polymerization reaction,and increasing the concentration within a certain range could make the geopolymer structure denser.However,further increase in concentration could lead to adverse morphological changes in the geopolymer microstructure.Similarly,excessively high moisture content reduced geopolymer viscosity,causing inadequate bonding between particles and resulting in loose structure.The differences in the stress-strain curves and the compressive failure modes may be related to the particle arrangement in the microstructure of the specimens.
作者
刘玉琳
袁胜洋
邓开元
程学兵
郑亦轩
刘先峰
LIU Yulin;YUAN Shengyang;DENG Kaiyuan;CHENG Xuebing;ZHENG Yixuan;LIU Xianfeng(School of Civil Engineering,Southwest Jiaotong University,Chengdu 610031,China;Key Laboratory of High-speed Railway Engineering of Ministry of Education,Southwest Jiaotong University,Chengdu 610031,China;Southwest Electric Power Design Institute Co.,Ltd.of China Power Engineering Consulting Group,Chengdu 610056,China;School of Civil Engineering,Xinjiang Institute of Engineering,Urumqi 830023,China)
出处
《铁道标准设计》
北大核心
2025年第7期79-86,共8页
Railway Standard Design
基金
国家自然科学基金项目(52008355)。
关键词
地聚物
碱激发剂
无侧限抗压强度
应力-应变曲线
扫描电镜
geopolymer
alkaline activator
unconfined compressive strength
stress-strain curve
scanning electron microscope
