FIELD PERFORMANCE OF CONCRETE AND CORRUGATED STEEL PIPE CULVERTS AND BITUMINOUS PROTECTION OF CORRUGATED STEEL PIPE CULVERTS (DISCUSSION AND CLOSURE)

In this paper information is provided regarding the durability of concrete pipe, galvanized corrugated steel pipe (6 x 2-in. and 2.67 x 0.5-in. corrugations), and bituminous protection (AASHTO M 190, Types A, B, and C) of corrugated steel pipe used for culverts in Ohio. Detailed analyses were performed to evaluate the effects of various environmental factors on the durability of these materials. None of the environmental parameters studied had a significant effect on the performance of the bituminous protection. Loss of adherence to the pipe was the major cause of deterioration of the material. The average lives of bituminous coating and coating with invert paving were 3.16 and 18.71 years, respectively. Water pH and abrasiveness of flow were the only environmental parameters to have a significant effect on the deterioration rate of corrugated steel pipe. Below a value of 7.0, water pH had a significant effect on concrete pipe performance. Predictive equations and graphs are presented that can be used to estimate service lives of concrete and corrugated steel pipe culverts. Information is provided regarding the geographic location of various ranges of environmental parameters found to have a significant effect on culvert durability. In the discussion Hirsch argues that a review of Hurd's pipe inspection data indicated that his two similar graphs for predicting concrete pipe life are based on data too sparse and too scattered to permit life prediction with any accuracy by his techniques. In the closure, Hurd replies that the fact that specific data points do not exactly fit the equation is more likely caused by the range in values of environmental variables at each sight with time rather than the exclusion of variables whose effect was not statistically significant from the predictive equations.