HASEGAWA, TAKUYA1; SENBU, OSAMU2

1) Associate Professor, Hokkaido University, Faculty of Engineering, hase-t@eng.hokudai.ac.jp

2) Professor, Hokkaido University, Faculty of Engineering, senbu@eng.hokudai.ac.jp

An effective quality control method for joint strength in concrete block (CB) construction systems is required, but at present, there are limited choices. This paper reports an estimation method for joint mortar strength in CB masonry using a scratch test for quality control. According to the test results, there is a correlation between strength and the width of the scratch. The test results also showed that the surface roughness and the moisture content in the joint affected the width of scratch. The width increased with increasing moisture content and surface roughness. Changes of the W/C of the joint mortar depended on the mortar type, CB type, and joint width, and it was found that mortar strength was reduced by increasing water absorption of the CB. Finally, we propose an estimation method for joint mortar strength using the scratch test and a quality control method on the basis of these results.

Keywords: Compressive strength of joint, Scratch, Surface roughness, Moisture content