Abstract
Tunnel lining concrete is generally placed by a concrete pumping method. Since this method fills concrete while pumping, material segregation and poor compaction are easily to occur. This may lead to quality deterioration such as floating and spalling. In this study, core samples of lining concrete were collected from a road tunnel that had reached the end of its service life and examined focusing on cracks at the joint parts of the lining concrete spans and gradation of coarse aggregate as an index of material segregation. As a result, it was confirmed that quality of the concrete deteriorated. For improving that, volcanic glass powder using as a concrete additive in order to increase resistance to material segregation and improve quality of the lining concrete was proposed, and its effectiveness was verified through the model construction test and the actual construction test. As a result of the verification, it was confirmed that volcanic glass powder contributed to spreading coarse aggregate sufficiently to the joint parts of the lining concrete spans and improved quality of the lining concrete surfaces.
