海水环境下砂浆表面生物被膜特性及其对砂浆性能影响

Characteristics of Biofilm on Mortar Surface and Its Influence on Mortar Performance in Seawater Environment

采用傅里叶变换红外光谱(FTIR)、超景深显微镜、扫描电镜(SEM)、能谱仪(EDS)、X射线衍射(XRD)、热重分析(TG-DTG)等,研究了海水环境下砂浆表面形成的生物被膜特性及其对砂浆性能的影响.结果表明:海水环境中硫氧化细菌会在砂浆表面附着形成大量的生物被膜,该生物被膜由多糖、蛋白质和微生物构成,其中微生物多呈卵状和气泡状;生物被膜在15 d后开始快速繁殖,75 d后逐渐脱落,90 d后新的生物被膜重新附着;120 d时无生物被膜砂浆试样的抗压强度为52.5 MPa,强度增长率为0.38%,矿化产物中石膏含量较多,而有生物被膜试样的抗压强度为68.1 MPa,强度增长率为31.72%,矿化产物中石膏含量较少.这表明生物被膜的存在影响了海水中腐蚀介质的传输,对砂浆起到缓蚀作用.

By means of Fourier transform infrared spectrometer(FTIR),super deep scene microscope,scanning electron microscope(SEM),energy dispersive spectrometer(EDS),X-ray diffraction(XRD)and thermal gravimetric analyzer(TG-DTG),the characteristics of biofilm formed on mortar surface in seawater environment and its influence on mortar performance were studied.The results showed that sulfur oxidizing bacteria in seawater would adhere to the mortar surface and form a large number of biofilms,which were composed of polysaccharides,proteins and microorganisms.After 15 d,the biofilm began to reproduce rapidly.After 75 d,the biofilm gradually fell off,and after 90 d,the new biofilm reattached.In the process of reproduction and evolution,the biofilm would consume a large amount of oxygen in seawater.By studying the effect of the presence or absence of biofilm on mortar performance,it was found that at 120 d,the compressive strength of the biofilm free samples was 52.5 MPa,with a strength growth rate of 0.38%,and the mineralized products contained a large amount of gypsum.However,the compressive strength of the biofilm free samples was 68.1 MPa,with a strength growth rate of 31.72%,and the mineralized products contained a small amount of gypsum.This indicates that the presence of biofilm affects the transmission of corrosive medium in seawater and has a moderating effect on the corrosion of mortar.