33 / 2022-03-13 06:17:54

Fire spalling behavior of heat-resistant repair materials with ring restrained heating test

heat-resistant repair materials, ring restrained specimen, fire spalling, jute fiber, vapor pressure, restrained stress

When repaired RC structures are exposed to fire, there is a risk of fire spalling, as in the case of concrete. Japan Concrete Institute has standardized a fire spalling test method using a ring restrained specimen. In our group, we investigated fire spalling behavior of cement material using the ring-restrained heating test. On the other hand,  heat-resistant repair materials (HRM) that can be used within the application range of 300℃ lower are developed in our group.

However, we have not yet examined whether it can be applied at temperatures above 300℃.

Therefore, we evaluated fire spalling behavior of HRM using a ring-restrained heating test in this study. A small cylindrical electric furnace was used. In addition, the effect of Jute fiber on the fire spalling prevention of repair mortar was also examined. Three types of ring-constrained specimens were prepared without fiber and with 0.1 and 0.2 vol% Jute fiber.  The heating test was conducted at a constant 850℃ for 15 minutes. The internal temperature, vapor pressure, and restrained stress were measured. And a grading evaluation of the fire spalling was conducted. As a result, the Maximum fire spalling depth of the control specimen was 12mm. fire spalling suppression effect on HRM was confirmed by mixing more than 0.1 vol% of Jute fiber.