浸渍及固载法用于混凝土微生物表面处理对比研究

A Comparison Investigation on the Immersion and Immobilization Methods Applied in the Microbial Surface Treatment for Concrete

中文关键词: 混凝土 微生物 表面处理 耐久性

英文关键词: concrete, microorganism, surface treatment, durability

中文摘要:

      微生物诱导碳酸钙沉积目前已广泛用于各种多孔介质的表面处理,以提高其耐久性和使用寿命。选用了脲解型微生物,分别采用液体浸渍和琼脂固载两种方式对混凝土表面进行处理。沉积一周后,测试混凝土的毛细吸水系数、水渗透系数和氯离子电通量,以及表面接触角和沉积厚度,并综合利用扫描电镜、能谱仪以及X射线衍射仪分析了沉积产物的微观形貌和组成。结果发现,微生物沉积产物膜层厚度约为10 μm。与液体浸渍方式相比,琼脂固载所获得的沉积产物尽管较薄且表面呈亲水性,但固载可为微生物的生长提供良好的微环境,有利于形成致密的碳酸钙层,因此琼脂固载能更有效地提高混凝土的抗渗性,可使水渗透系数降低80%以上。同时,固载方式显然更具备实用价值。

英文摘要:

      Microbially-induced calcium carbonate precipitation has been widely used for the surface treatment of all sorts of porous media, for the purpose of improving the durability and extending the service life. By using ureolytic type microorganism, two methods including liquid immersion and agar immobilization were employed for the surface treatment of concrete. After treatment for one week, the capillary water absorption coefficient, water permeation coefficient, and rapid chloride permeation (RCP) of concrete were tested. The contact angle of the surfaces and the thickness of the precipitates were measured. The morphology and composition of the precipitates were comprehensively studied by scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), and X-ray diffraction (XRD) analyses. Results revealed that the thickness of the microbial precipitated coating layer was about 10 μm. Although the layer precipitated by agar immobilization showed hydrophilicity and was thinner than that by liquid immersion, much denser layer of calcium carbonate was obtained by immobilization method since agar provided favorable microenvironment for the growth of bacteria. Thus, the resistance to permeability of concrete can be effectively enhanced, in particular, the water permeation coefficient was decreased more than 80% by immobilization technique. Meanwhile, agar immobilization has significant values in practical application.