2003 年 68 巻 572 号 p. 173-178
We made the arches of rectangular bricks by using lime mortar for the joints. Lime mortar works as joint adjustment between rectangular bricks. For making strong arch as a kind of shell we removed the centering of arch as soon as bricks were finished to lay and did compression. This way is called a freehand applied construction method. Here this experiment causes questions about the strength of the fresh mortar. This paper concerns to the experiment about strength of the compressive plasticity of lime mortar. Strength proves to get weak when the centering remains to be fixed. So the centering is to be removed for making the strong arch during the fresh and soft condition of mortar. Lime mortar is air-hardening and hardening is very slow. Using lime mortar as compression plasticity, which is called freehand construction method as above mentioned, proves to be very important to making arch. So this way is seemed to be used as a traditional construction method.