Theoretical Model and Experimental Research on Mortar Corrosion by Sulfuric Acid in Laminar Flow

Abstract

Surfaces of concrete structure could suffer the corrosion of flowing sulfuric acid coming from acid rain or sewage water. This paper establishes an analytical corrosion model and carries out experimental studies to investigate the corrosion rate of mortar in laminar flow of sulfuric acid with different flow velocities. The analytical model was deduced from the relationship between Flow Boundary Layer and Concentration Boundary Layer, connected by Schmidt number, and the dissolution diffusion process of mortar. The analytical model indicates that the corrosion rate will increase with flow velocity, but the increment effect will decrease with flow velocity in an exponential relationship. Nine groups of cement mortar specimens were tested in flow-corrosion devices for 1440 hours. The corrosion rate was obtained for the cases of the water cement ratio of mortar 0.5, the pH value of sulfuric acid 3.4 and the flow velocities ranging from 0.13 m/s to 1.57 m/s.

Keywords

• cement mortar
• flow-corrosion model
• laminar flow
• sulfuric acid