我国首例海工混凝土碱集料反应

STUDIES ON THE FIRST AAR CASE OF THE OCEAN CONCRETE PROJECT IN CHINA

对浙江省宁波北仑港海工混凝土构件，用岩相法、扫描电镜／能谱分析、快速压蒸测长法，Ｘ－射线衍射分析等方法进行研究，发现在浪溅区凡表面开裂剥落的混凝土构件中都含有大量的活性集料，并发生了碱集料反应，而表面完整没有裂纹的混凝土构件中活性集料较少；结果表明，海工混凝土如使用碱活性集料，它与来自海水中的碱将会发生反应造成混凝土开裂；碱集料反应和钢筋锈蚀等破坏作用的相互促进，使海工混凝土构件的耐久性大大下降。

The alkali-aggregate reaction (AAR) occurred in the ocean concrete project of Beilun seaport harbor in Ningbo, Zhejiang Province, was studied by means of the petrography analysis, the autoclave rapid test method, SEM/EDAX, XRDA and other techniques. It was found that there are a lot of reactive aggregates in the cracking concrete projects, located at the sea water spray zone but there are few reactive aggregates in the intact crack-free concrete projects. Although alkali content in the cement is very low, the reaction of the active aggregates in the ocean concrete with alkali from seawater could result in cracking of the concrete projects. AAR may promote rusting of steel bars and other harmful actions , and then the durability of the ocean concrete will be greatly decreased.