2019 Volume 57 Issue 6 Pages 433-440
Based on the assumption that workers can be made to learn correct test methods by having them understand the importance of adhering to the work items specified in the Japanese Industrial Standards (JIS) and properly understand ing the mechanism of measuring equipment, workers were made to conduct the slump test, air content test, and compressive strength test under conditions deviating from those specified by JIS. Two types of concrete were used, with respective slump of 21 cm and 12 cm. The findings included the facts that the timing of lifting of the slump cone can decrease the measured slump value of fresh concrete by up to 3.0 cm, that the finishing method of the samples placed in the air content tester can cause the measured air content value to vary by up to 1.5％, and that tumbling of specimens prior to concrete hardening can cause reduction in compressive strength by approximately 7％ by the material age of 28 days.
