摘要
早龄期水工混凝土结构在不利荷载工况下常易产生损伤开裂,如果及时加强对早龄期损伤水工混凝土的养护,后期水工混凝土自然自愈合效果对结构服役寿命具有重要影响。为此,本文设计并开展了3种预损伤龄期(1 d、2 d、3 d)和3种粉煤灰掺量(0%、15%、35%)下的早龄期水工混凝土抗压强度预损伤试验,以损伤试件标准养护至28 d龄期后的不同受压面抗压强度增长率R 1和恢复率R_(2)作为评价指标,同时结合损伤混凝土试件的微观孔结构测试结果,共同探究早龄期损伤混凝土的自然自愈合效果。研究结果表明,在相同粉煤灰掺量下,损伤试件的强度恢复率R_(2)均随着预损伤龄期的增加而增大,且在3 d预损伤龄期下A组损伤试件的R_(2)均大于95%,表明损伤试件得到了较好的恢复;在同一预损伤龄期下,不同受压面二次强度测试结果表现为F_(2,A)>F_(2,B),平均孔径、最可及孔径和分形维数均表现为A组检测样品<B组检测样品,这表明裂缝平行于二次受压方向的损伤混凝土试件的自愈合情况较好;掺入粉煤灰能够使损伤试件强度增长率R 1和恢复率R_(2)得到提升,并降低总体积、最可及孔径和分形维数,增加无害孔和少害孔的占比。上述结果表明,及时加强对早龄期损伤混凝土的养护,其后期的自愈合效果较好,且适量掺入粉煤灰能提升损伤混凝土的自愈合效果。
The early-age hydraulic concrete structure is often prone to damage and cracking under adverse load conditions.If the maintenance of damaged hydraulic concrete is strengthened in time,the natural self-healing effect of the later hydraulic concrete has an important impact on the service life of the structure.For this reason,this paper designed and carried out the pre-damage test of compressive strength of early-age hydraulic concrete at three pre-damage ages(1 d,2 d,3 d)and three fly ash contents(0%,15%,35%),taking the growth rate R 1 and recovery rate R_(2)of compressive strength of different compression surfaces of the damaged concrete specimen after the standard curing to 28 d as the evaluation index,and combining the microscopic pore structure test results of the damaged concrete specimen,to jointly explore the natural self-healing effect of early-age damaged concrete.The results show that under the same fly ash content,the strength recovery rate R_(2)of the damaged concrete specimens increase with the increase of the pre-damage age and R_(2)of the damaged specimens in Group A is greater than 95%at the 3 d of pre-damage age,indicating that the damaged specimens achieve good recovery.Under the same pre-damage age,the strength test results of different compression surfaces show the F_(2,A)﹥F_(2,B)and the average pore size,maximum bore size and fractal dimension are both shown as group A test specimens<group B test specimens,indicating that the self-healing of damaged concrete specimens with cracks parallel to the direction of secondary compression is better.The incorporation of fly ash can improve the strength growth rate R 1 and recovery rate R_(2)of the damaged specimen,reduce the total pore volume,maximum bore size and fractal dimension,as well as increase the proportion of harmless and less harmful pores.The above results show that the self-healing effect of early-age damaged concrete is better if the curing of early-age damaged concrete is strengthened in time,and the self-healing effect of damaged concre
作者
李泽鹏
黄耀英
余正源
张耀
LI Zepeng;HUANG Yaoying;YU Zhengyuan;ZHANG Yao(College of Hydraulic and Environmental Engineering,China Three Gorges Univ.,Yichang 443002,China)
出处
《中国水利水电科学研究院学报（中英文）》
北大核心
2023年第6期511-518,共8页
Journal of China Institute of Water Resources and Hydropower Research
基金
国家自然科学基金项目(52239009,52179135)。
关键词
早龄期
水工混凝土
自然自愈合
不同受压面
抗压强度
微观孔结构测试
early-age
hydraulic concrete
natural self-healing
different compression surfaces
compressive strength
microscopic pore structure test
