摘要
目的 探究硫氧化细菌及其生物膜对混凝土宏观性能和微观结构的作用效果以明确硫氧化细菌对混凝土性能的影响规律。方法 将混凝土试样半浸泡于含有微生物的海水中,利用光学显微镜和紫外光密度(OD)分析不同龄期生物膜厚度、膜内微生物数量变化,观察测定混凝土不同龄期的外观形貌、抗压强度、质量以及通过电通量法分析混凝土抗氯离子渗透能力表征混凝土宏观性能,利用热分析仪、X射线衍射仪、压汞仪分析混凝土微观结构。结果 生物膜的生长、发育和脱落具有周期性规律,且膜内微生物数量与生物膜厚度呈正相关。120 d时无菌组混凝土电通量达到793.1 C,有菌组混凝土电通量仅为173.4 C,180 d时仅无菌对照组的混凝土出现开裂,240 d时有菌混凝土和无菌混凝土的质量损失率分别为0.79%、1.20%,有菌混凝土的抗压强度增加了6.9%,而无菌混凝土的抗压强度降低了7.1%;有菌组混凝土石膏生成量和C-S-H凝胶损失量均小于无菌混凝土,使得有菌组混凝土孔隙率比无菌组混凝土低了1.193 5%。结论 附着在混凝土的气液固界面的硫氧化细菌逐渐形成生物膜,膜厚度以及膜内微生物数量发生周期性变化,生物膜会降低SO42-的传质效率从而减缓混凝土的劣化。
Microbial corrosion is a widespread problem in nature,and the construction industry is included,particularly in microbial-rich areas such as sewage treatment facilities and marine buildings.Microbial growth in different environments will have different significant effects on the microstructure and macroscopic properties of concrete,but there appears to be no published literature on the effects of sulfur-oxidizing bacteria on concrete properties in a seawater environment.In this study,concrete specimens were semi-submerged in seawater containing microorganisms,and the changes in biofilm thickness and the number of microorganisms within the film at the gas-liquid-solid interface of concrete at different corrosion ages was analyzed with an optical microscopy and ultraviolet optical density (OD). The evolution of the surface morphology of concrete was recorded with a general video camera, a VHX-600e ultra-deep field microscope, a YAW-2000J pressure tester and scales to test the changes in compressive strength and mass of concrete specimens, and a NJ-DTL-6 concrete chloride ion electric flux tester was used to measure the electric flux of concrete specimens. Samples were also taken at the gas-liquid-solid interface of the concrete specimens and the microstructure of the concrete was analyzed and tested with a Q600 simultaneous thermal analyzer, a Rigaku ultima-V1 X-ray diffractometer, a Tensor 27 Fourier transform infrared spectrometer (FTIR) and an Auto Pore V 9600 mercury compression meter. A cyclical pattern of growth, development and shedding of biofilms could be found, starting at around 30 days, entering a rapid development phase after 60 days, maturing to a peak thickness of 2 200 μm at 120 days and then starting to shed until the next growth cycle at 150 days, with a positive correlation between the number of microorganisms in the membrane and the thickness of the biofilm. The results of the macroscopic properties of the concrete showed that the electric flux of the concrete in the sterile group reached 793.1 C at 120 days, while the electric flux of the concrete in the bacterial group was only 173.4 C. At 180 days, the concrete in the sterile control group cracked with a crack width of 0.11 mm, while no cracks were produced in the concrete in the bacterial test group. The compressive strength of the bacterial concrete increased by 6.9% while that of the aseptic concrete decreased by 7.1%. The results of the micro-structural tests on the concrete showed that the gypsum production and C-S-H gel loss of the concrete in the bacterial group were less than that of the aseptic concrete, and the porosity of the concrete in the bacterial group was 1.193 5% lower than that of the aseptic concrete. It can be concluded that sulfur-oxidizing bacteria attached to the gas-liquid-solid interface of the concrete gradually form biofilms, with periodic changes in the thickness of the film and the number of microorganisms within it. Sulfur-oxidizing bacteria and their biofilm have a protective effect on the microstructure of the concrete. The negatively charged nature of the sulfur-oxidizing bacteria repels the migration of SO42‒ from the medium to the concrete and the dense nature of the biofilm also leads to a reduction in the mass transfer efficiency of SO42‒, thus slowing down the erosion of SO42‒ into the concrete.
作者
刘志华
甘立钦
刘德娥
荣辉
LIU Zhi-hua;GAN Li-qin;LIU De-e;RONG-hui(School of Materials Science and Engineering,Tianjin Chengjian University,Tianjin 300384,China;Tianjin Key Laboratory of Building Green Functional Materials,Tianjin Chengjian University,Tianjin 300384,China)
出处
《表面技术》
EI
CAS
CSCD
北大核心
2023年第11期280-290,317,共12页
Surface Technology
基金
国家自然科学基金资助项目(51978439)
天津市杰出青年科学基金项目(22JCJQJC00020)。
关键词
硫氧化细菌
生物膜
混凝土
微观结构
宏观性能
sulfur-oxidizing bacteria
biofilm
concrete
microstructure
macroscopic properties
