Testing Concrete Sewer Maintenance Holes Using an Angular Modulated Penetrometer.

Around the world, a significant proportion of sewers and sewer maintenance holes are constructed from concrete. Unfortunately, one major problem with concrete sewer infrastructure is corrosion caused by biogenic hydrogen sulphide, which causes major issues for concrete structural integrity. Furthermore, concrete may be significantly corroded and softened but still pass a visual inspection. The novel system presented in this paper uses a penetrometer mounted on a robotic platform to measure the depth of penetration through a corroded concrete surface. An angular mechanism is used to rotate the penetrometer to new positions as striking aggregate may result in false readings. Based on laboratory analysis, this design is capable of providing consistent and precise multiple observations for both smooth and rough surfaces, as well as for flat and curved surfaces, with 0.1 mm accuracy. The use of a remote robotic platform eliminates the hazards of confined space entry whilst providing a repeatable analysis platform.