ABSTRACT
The present study is a fundamental investigation necessary for the development of a non-destructive method to measure the distribution of chloride ion concentration in cover concrete via prompt gammaray analysis (PGA). PGA is a multi-elemental, nondestructive analysis technique. A nondestructive method for measuring the distribution of chloride ion concentrations in surface layers of concrete using PGA has been reported (Ujike et al., 2010). Using this method, the estimation of chloride concentration distribution in concrete is accurately determined when the chloride concentration gradually decreases from the surface. However, the estimation is poor when the chloride concentration is arbitrary and does not follow a decreasing trend. This study proposes a method of varying
1 INTRODUCTION
Japan has seen significant growth in the last fifty years in the construction industry. It has been reported that within the next several decades, 50% of residential buildings will be fifty years old or more (MLIT 2009). Considering such a forecast, efficient maintenance within the budget limits are needed, and the infrastructure management is shifting from corrective preservation to preventive preservation. Preventive maintenance is advantageous because detailed inspections are performed before the manifestation of deterioration, and appropriate measures are taken for maintaining the structure.
