| 摘要 |
PURPOSE:To obtain an expansion and contraction meter for concrete which is unaffected by the change in temp. by using quartz glass bars having a small coefft. of thermal expansion which are connected to each other as base bodies, and negating the thermal expansion or contraction of the base bodies by the thermal expansion or contraction of steel materials used in the connecting part. CONSTITUTION:A measuring bar 5 of an expansion and contraction meter for concrete consists of a quartz glass bar 6 of the length coinciding with the positions of the two gage marks of a concrete floor surface 2, which glass bar is covered with an acrylic pipe 7 and is supported with a stationary fitting 1 and a measuring part 2 provided with a dial gage 4. The bar 5 is provided by bisecting the bar 6 and the pipe 7 respecitively, the dividing the same to the bars 6A, 6B having stationary pieces 9A, 9B at the inside ends and the pipes 7A, 7B interposed with rubber vibration isolators 12A, 12B. Two auxiliary glass bars 6C in parallel with the bars 6A, 6B are provided with supporting pieces 8A, 8B at the outside ends thereof and are supported to the acrylic pipes 7A, 7B respectively. Also, stationary pieces 10A, 10B are coupled thereto. The pieces 9A and 10A and 9B and 10A are connected respectively to steel wires 11A, 11B. Thus the expansion and contraction of concrete are measured accurately by selecting the materials and sizes of the steel wires and offsetting the rates of thermal expansion or contraction of the bars 6A, 6B, 6C with the rates of thermal expansion or contraction of the steel wires. |
