混凝土中钢筋锈蚀层发展和细观结构分析

Research on development and submicroscopic structure of steel rust layer in concrete

氯盐引起的钢筋腐蚀问题在钢筋混凝土耐久性研究中占有重要的地位。通过扫描电镜观察、电子探针微区分析及X射线衍射分析等微观分析手段,研究了混凝土中钢筋的锈蚀层细观结构特征和锈蚀层元素组成与物相组成。研究表明钢筋和混凝土之间存在明显的过渡区,过渡区为铁锈层所充满,锈层为多孔的连续网络结构。随腐蚀龄期的增长,锈蚀产物不断增多,锈蚀层逐渐增厚和密实,锈蚀层在周围混凝土的约束下逐渐呈压密的层状结构。锈蚀层中不仅含有钢筋的锈蚀产物Fe元素,而且含有混凝土中水泥的水化产物Ca、Si等元素,是钢筋锈蚀产物和水泥凝胶体的混合体,是锈蚀产物和水泥水化产物相互渗透的结果。

The chloride-induced corrosion of steel reinforcement is one of the major deterioration problems of reinforced concrete structures.Several experimental techniques such as x-ray diffraction,SEM and EDXA were used to study the corrosion products and the submicroscopic structure forming on steel rebars embedded in concrete.The SEM graphs of steel/concrete interface show: the corrosion layer between steel and concrete is composed of concrete and rust composition due to concrete restriction and rust expansion;the corrosion layer produces a dense mix layer of concrete and rust before concrete cover cracks.The results of EDXA and X-ray diffraction tests indicate: the corrosion layer composition is the mixture of corrosion products and cement hydration products due to their penetration into each other.