摘要
为提升土木工程材料实验教学的前沿性及与工程实践的契合度,该研究将超高性能混凝土(ultra-high performance concrete,UHPC)高温极端工况力学性能测试纳入教学体系,构建融合常规实验与高温力学性能研究的多维度教学模块。通过火灾作用模拟与高温后抗压性能测试的耦合实验设计,系统阐释材料微观结构演变与宏观力学响应的内在关联机制。教学实践表明,该改革方案通过高温实验流程标准化设计,可有效促进学生系统构建极端环境下材料性能演化理论认知,同时强化理论解析能力与工程问题诊断水平。研究成果为土木工程新工科人才培养体系中的实验教学创新提供了可迁移的实施范式。
[Objective]To enhance the cutting-edge nature of experimental teaching in civil engineering materials and its integration with engineering practice,this study incorporates the mechanical property testing of ultra-high performance concrete(UHPC)under high-temperature extreme working conditions into a teaching system.A multidimensional teaching module is developed,integrating conventional tests with research on high-temperature mechanical properties.This approach promotes the transformation of experimental teaching from“phenomenon observation”to“mechanism exploration,”helping students cope with challenges in complex engineering environments and addressing the development needs of new engineering disciplines.[Methods]This paper combines the standard temperature-rise fire test with traditional concrete mechanics experiments to comparatively analyze differences in the compressive performance of UHPC cubes following high-temperature exposure.According to the temperature threshold for building fires specified in the ISO-834 standard,three typical exposure temperatures—200℃,400℃,and 600℃—were selected.Each specimen was held at the target temperature for a constant duration of 60 min.Before compressive testing,physical phenomena in the UHPC specimens after high-temperature exposure were observed,and the mass loss rate was analyzed.The UHPC cube compression test utilized 100-mm×100-mm×100-mm cube specimens.During testing,the load was applied continuously and uniformly at a rate of 1.4 MPa/s.This research achieved two objectives:(1)the introduction of new instruments and technologies to establish correlations and understanding between the conventional properties of civil engineering materials and their performance in extreme environments;(2)the explanation of the experimental results through a multiscale damage mechanism.[Results]The experimental results show the following.1)At 400℃,the UHPC color deepened to brownish gray.At this point,polypropylene fibers completely melted and decomposed,leaving distinct evaporation traces.2)At exposure temperatures up to 200℃,the mass loss rate of the UHPC specimens was relatively low.However,when the temperature exceeded 400℃,the specimen mass loss increased significantly.3)Following exposure to 200℃,the axial compressive failure mode of the UHPC specimens resembled that observed at room temperature.The primary manifestation was the formation of several fine,longitudinal cracks propagating along the specimen sides,connecting the upper and lower surfaces.At this stage,the cracks were relatively fine and few.4)At an exposure temperature of 200℃,the compressive strength of the UHPC cube increased by 2.30%compared with that at room temperature.At 400℃,the strength increased by 6.34%compared with that at room temperature.5)Although the cubic compressive strength of the specimens exposed to 600℃decreased compared with those exposed to 400℃,it remained slightly higher than the strength at room temperature.[Conclusions]The coupled experimental design,simulating fire effects and testing compressive performance post-high-temperature exposure,systematically elucidated the intrinsic correlation mechanism between material microstructure evolution and macroscopic mechanical response.The results indicated that the nonlinear attenuation characteristics of UHPC compressive strength with increasing temperature correlated significantly with the reconstruction process of its microscopic phase composition.At 600℃,the compressive performance of UHPC diminished significantly compared with that at 400℃.Although microstructural damage occurred at 600℃,the combined effects of water evaporation and structural optimization enabled the material to retain compressive strength marginally higher than under normal temperature conditions.Furthermore,the high density and low water-binder ratio of UHPC endowed it with excellent high-temperature damage resistance,contributing to the maintenance of its relatively high compressive strength.Teaching practice demonstrated that this reform,through standardized high-temperature experimental procedures,effectively promoted students’systematic understanding of material property evolution in extreme environments while enhancing their theoretical analysis capabilities and engineering problem diagnosis skills.
作者
何康
刘崇阳
雷斌
HE Kang;LIU Chongyang;LEI Bin(School of Infrastructure Engineering,Nanchang University,Nanchang 330031,China)
出处
《实验技术与管理》
北大核心
2025年第9期240-246,共7页
Experimental Technology and Management
基金
国家自然科学基金项目(52308172)
江西省自然科学基金项目(20242BAB25291,20232BAB214075)
教育部产学合作协同育人项目(202002157007)。
关键词
土木工程材料
实验教学
UHPC
力学性能
极端环境
civil engineering materials
experimental teaching
UHPC
mechanical properties
extreme environments
作者简介
何康(1989-),男,湖北黄冈,博士,讲师,主要从事土木工程新材料新结构教学与研究,he_kang16@ncu.edu.cn;通信作者:雷斌(1980-),男,湖南永州,博士,教授,主要从事建筑垃圾资源化高效利用教学与研究,blei@ncu.edu.cn。
