氯氧镁水泥混凝土中钢筋的腐蚀与防护试验研究

结合氯氧镁水泥混凝土耐水性,研究氯氧镁水泥混凝土中钢筋的腐蚀与防护,试验变量包括钢筋种类、混凝土保护层厚度和腐蚀龄期等。钢筋种类包括裸露钢筋和美加力涂层钢筋;混凝土保护层厚度包括25、50mm;腐蚀龄期包括60、120、180、240、300、360d。试验采用自来水长期浸泡至试块2/3处,并采用扫描电子显微镜(SEM)和能谱仪(EDS)对腐蚀后的钢筋微观结构和化学元素组成进行分析,研究钢筋的腐蚀机理。结果表明,通过软化系数分析,氯氧镁水泥混凝土的软化系数处于0.78~0.87,说明试验设计的氯氧镁水泥混凝土可用于干燥地区、受潮较轻地区或次要建筑结构。通过极化曲线及其电化学参数分析,裸露钢筋腐蚀速率为美加力涂层钢筋腐蚀速率的40~80倍,说明涂层防腐效果明显。

Experimental analysis of corrosion and protection for steel bar in magnesium oxychloride cement concrete

Combined with water resistance of magnesium oxychloride cement concrete, the corrosion and protection for steel bar in magnesium oxychloride cement concrete were experimentally investigated, and the influencing factors included: the type of steel bar, thickness of the concrete protective layer and the corrosion duration. The two types of steel bar were bare steel bar and MAGNI coated steel bar. The two types of thickness of the concrete protective layer were 25 mm and 50 mm. The six types of the corrosion duration were 60 d, 120 d, 180 d, 240 d, 300 d and 360 d. 2/3 height of test block was prolonged soaked in water. By SEM and EDS, microstructure and chemical elements of steel bar with corrosion were analyzed to study corrosion mechanism. Result showed that by softening coefficient, the softening coefficient of magnesium oxychloride cement concrete was from 0.78 to 0.87, and the magnesium chloride cement concrete designed by this experiment could be used as a dry area, damp lighter area or secondary structure. By polarization curves and its electrochemical parameters, corrosion rate of bare steel bar was from 40 to 80 times as large as corrosion rate of MAGNI coated steel bar.