Evaluating the carbonation damage to concrete bridges using a grey forecasting model combined with a statistical method

Traditionally, the statistical method of standard normal distribution is used to evaluate the durability of concrete bridges with carbonation damage. However, the predicted results obtained by applying the statistical method to analyze a small number of specimens are always larger than those results of natural and accelerated tests. In this paper. an improved grey model GM(1, 1)combined with a statistical method is developed to evaluate the durability of concrete bridges due to carbonation damage, The grey model of CM(1, 1) is a method of evaluating the regularity, with exponential variation, of original data sequence, Using the improved model we evaluated the carbonation depth of some concrete bridges in Taipei city with service lives of 50 years. These results are compared with those obtained from empirical formulas of natural and accelerated carbonation tests. It is found that the improved model raises the predicted accuracy to some extent.