CHECKER BRICK

PROBLEM TO BE SOLVED: To provide a checker brick capable of preventing breakage around dowels and ABC layering.SOLUTION: In a hexagonal columnar brick body 21, thirty seven gas passageways 22 having a hexagonal cross-sectional shape are formed and the gas passageways 22 are arranged so that each side of the hexagon of the cross-section is facing each other with same intervals. Three projected dowels 23 are formed with 120 degree intervals on a top face 25 of the brick body 21, recessed dowels are formed with 120 degree intervals on an under face, and each of them is arranged with 60 degree rotation each other. The projected dowels 23 are arranged over two openings 221 of the gas passageways 22 on a line segment S from an apex P1 to a center C1 of the hexagon of the top face 25, and a lateral face of the projected dowels 23 intersects with a periphery of the opening 221 at a closer side to the apex P1 of the two openings 221 of the gas passageways 22 in an area closer to the center C1 than a pair of apexes P2 which are farthest from the line segment S.