摘要
建筑垃圾的大量堆积和冻融破坏作用导致的混凝土耐久性衰减是目前土木建筑工程领域面临的两大严峻挑战。为提高建筑垃圾再生利用率,并从本质上揭示掺建筑垃圾(废砖粉)复合粉体材料(CWCPM)混凝土的冻融损伤演化机理,采用室内加速试验和理论分析相结合的研究方法,分析不同因素对混凝土宏观抗冻性能劣化规律的影响,并采用多因素分析方法建立掺CWCPM混凝土的冻融损伤演化模型。借助微细观测试手段,分析冻融过程中掺CWCPM混凝土微观形貌及孔结构的损伤演化规律,揭示混凝土冻融损伤演化机理。结果表明:随水灰比、冻融循环次数的增加和盐溶液的加入,混凝土冻融损伤破坏程度增加;CWCPM的掺入提高了混凝土的抗冻性能,与基准试件相比,50次冻融循环后,掺30%CWCPM混凝土的单位面积剥蚀量降低27.1%,抗压强度提高6.2%;基于宏观试验结果建立的冻融损伤演化模型可较好地预测混凝土抗冻性能。由混凝土微细观试验结果可知,掺CWCPM混凝土的冻融损伤的实质是其内部微观结构逐渐松散、孔结构逐渐劣化的物理变化过程,是试件内部裂纹、孔隙等缺陷产生、扩展直至破坏的损伤积累过程。
The pile-up of significant amount of construction waste and the deterioration of the durability of cement concrete under freezing-thawing cycling are two major challenges in civil engineering.In order to improve the reuse rate of the construction waste and to have better understanding of the deterioration mechanism of concrete mixed with construction waste(brick powder)composite powder materials(CWCPM)under freezing-thawing condition,laboratory experiment and theoretical analysis were carried out.The effect of different factors on the macroscopic performance deterioration of concrete was investigated and the freezing-thawing damage evolution model of concrete mixed with CWCPM was established by multifactor analysis.The microscopic structure and appearance and pore structure of the concrete were also analyzed,and the deterioration mechanism was revealed.The results show that the degree of freezing-thawing damage increased with the increase of water cement ratio,the number of freezing-thawing cycles and the concentration of the salt solution.The anti-frost performance of the concrete was improved by the CWCPM.Compared with the control specimen,the amount of stripping per unit area and the compressive strength of the concrete specimen with 30%CWCPM decreased by 27.1%and increased by 6.2%respectively,after 50 cycles of freezing-thawing.The freezing-thawing damage evolution model based on macroscopic test results can predict the frost resistance of concrete accurately.In essence,the deterioration of the concrete under freezing-thawing condition is a physical process during which its microscopic structure gradually become loose and its pore structure become worse.
作者
薛翠真
申爱琴
乔宏霞
XUE Cuizhen;SHEN Aiqin;QIAO Hongxia(School of Civil Engineering,Lanzhou University of Technology,Lanzhou 730050,Gansu,China;School of Highway,Chang an University,Xi an 710064,Shaanxi,China)
出处
《华南理工大学学报（自然科学版）》
EI
CAS
CSCD
北大核心
2020年第3期136-144,共9页
Journal of South China University of Technology(Natural Science Edition)
基金
国家自然科学基金资助项目(51868044)
公路建设与养护技术、材料及装备交通运输行业研发中心(甘肃路桥建设集团有限公司)开放基金课题(GLKF201813)。
关键词
建筑垃圾复合粉体材料
抗冻性能
预测模型
损伤机理
孔结构
construction waste composite powder materials
anti-frost performance
prediction model
deterioration mechanism
pore structure
