涂层钢筋镁水泥混凝土防护试验研究

An Experimental Study on Protection of Coated Steel Bar in Magnesium Cement Concrete

我国西部盐渍土地区普通钢筋混凝土腐蚀较为严重,镁水泥混凝土可以抵抗盐卤腐蚀,但其自身所含有的氯离子对钢筋的腐蚀作用却会缩短其服役寿命,因此提出利用涂层来缓解钢筋的腐蚀问题。采用电化学方法测试分析自然和氯盐2种不同环境下涂层和裸露钢筋的极化曲线,并通过扫描电镜(SEM)和X射线衍射(XRD)微观试验对钢筋表面的锈蚀产物进行测试分析,讨论腐蚀机理和腐蚀形貌。结果表明:涂层钢筋在自然和氯盐溶液中的腐蚀电流密度分别是裸露钢筋的15%和1%,腐蚀速率远小于裸露钢筋,裸露钢筋上的块状腐蚀产物是Fe2O3;涂层钢筋表面的腐蚀产物则主要是水泥胶凝体和锌铁复合物,说明涂层能够防护钢筋使其免受严重腐蚀,因而钢筋镁水泥混凝土可以更加广泛地应用到盐渍土地区。

Due to the serious corrosion of ordinary reinforced concrete in the saline soil area of western China,magnesium cement concrete is used in this area to resist the corrosion of brine. However,the service life of the reinforced concrete is shortened due to the corrosion effect of chloride ion in the concrete on steel bars. Thus,an approach to prepare coatings was proposed to overcome the corrosion of rebar. The polarization curves of coated and bare steel bars in different environments of nature and chloride salt were measured and analyzed by electrochemical method. Furthermore,the corrosion products on steel bar surface were analyzed via scanning electron microscope( SEM) and X-ray diffraction( XRD),and the mechanism and corrosion morphology were further discussed. Results showed that the corrosion current densities of coated rebar in natural solution and chloride salt solution were 15% and 1%,respectively,and the corrosion rate of coated rebar was much lower than that of bare rebar. Moreover,the massive corrosion product on bare rebar was Fe2 O3,while the corrosion products on coated rebar surface were mainly cement cementite and zinc-iron composite. The above results revealed that the coating could protect the steel bar from serious corrosion,and so the reinforced magnesium cement concrete could be more widely used in the saline soil area.