加速溶蚀条件下铸铁管内衬水泥砂浆的孔结构演变规律

Evolution of Pore Structure of Cement Mortar Lined in Ductile Iron Pipe under Accelerated Leaching

摘要:

设计了一种用离心工艺制作的内衬水泥砂浆铸铁管试件，采用流动的6mol/L氯化铵溶液对水泥砂浆内衬进行加速溶蚀试验，并利用压汞(MIP)法和X射线断层扫描(XCT)方法分析了水泥砂浆内衬孔结构的变化.结果表明：加速溶蚀过程中水泥砂浆内衬的孔结构变化明显，溶蚀150d时水泥砂浆内衬中的净浆层孔隙率(体积分数，下同)从溶蚀前的957%增加至3549%，最可几孔径从1711nm增加到2630nm，并有少量危害孔(单孔体积大于4×10-6mm3)出现；溶蚀450d时水泥砂浆内衬中的净浆层孔隙率达到6154%，并出现大量危害孔；水泥砂浆内衬中的砂浆层孔隙率和危害孔数量随溶蚀时间的增加而增加.

Abstract:

The accelerated calcium leaching experiments of cement mortar lining of ductile iron pipe specimen, which is designed and performed under centrifugal casting, were carried out under flowing 6mol/L ammonium chloride solution. The pore structure of cement mortar lining in the process of calcium leaching was investigated by means of mercury intrusion porosimetry(MIP) and X ray computed tomography imaging technology(X CT) for analyzing the evolution of pore structure of cement mortar lining caused by the flowing solution. The results show that the pore structure of cement mortar lining has a great change in the process of the accelerated leaching. After leaching for 150 d, the porosity(by volume) of cement pastes in cement mortar lining increases from 957% to 3549%, and the most probable pore diameter increases from 1711nm to 2630nm, which results in a small amount of damage pore. While the leaching time is 450 d, the porosity of cement pastes in cement mortar lining reaches 6154%, and thus produces a lot of damage pore(single pore size greater than 4×10-6mm3), and the porosity and the number of damage pore of cement mortars in cement mortar lining increase with the leaching time.