Characteristics of the Surface Air Permeability Test and the Evaluation of Quality Variation in Cover Concrete due to Segregation of Concrete

Abstract

The durability of concrete structures depends on the mass transfer resistance of cover concrete, which is a primary factor controlling the deterioration caused by carbon dioxide and other penetrants. Therefore, the quality of cover concrete is very important for ensuring the durability of concrete structures. This research examined the influences of mix proportions and construction work conditions on the variation in quality of cover concrete using the on-site air permeability test. However, the influence of concrete water content on the measurement results and the measurable depth of the test are not yet clearly understood, so this effect also needs to be clarified first. Our experimental results showed that the relationship between water content and air permeability is mostly the same regardless of the W/C and concrete thickness, and the measurable depth is between 15 to 40 mm depending on the air permeability. In addition, the air permeability can be formulated as a function of the W/C and the amount of bleeding water, and the change in air permeability over the height of a concrete structure can be expressed by the amount of bleeding water and the height.