Abstract
Recently it is often reported that broken pieces of concrete happened to fall from tunnel linings or concrete walls, and its cause is supposed to be improper construction joints called ' cold joint. Consequently the durability of concrete structure has become a social problem.
In this report, the influence of the construction joints upon flexural strength of concrete is measured. Some simple and effective methods which may be able to estimate the setting of concrete in order to prevent an occurrence of the cold joint is discussed experimentally.
