2019 Volume 75 Issue 2 Pages 142-156
Requirements for concrete structures are changing to meet emerging needs such as higher earthquake resistance. Those requirements include higher densities of reinforcement, but they could lead to defective construction due to inadequate compaction. It is obvious that reinforcement patterns influence concrete compaction, but such influence is difficult to evaluate quantitatively. Constructors expect designers to develop designs that include reinforcement patterns allowing for concrete compaction and to specify concrete slump requirements that take concrete compaction into consideration. Even with the latest technology, however, it is difficult to determine reinforcing bar diameter and spacing requirements, taking concrete compaction into account. Constructors, therefore, have to make a concrete compaction plan for achieving an adequate degree of filling by an appropriate method of compaction while meeting the specified reinforcement pattern and slump requirements. Since, however, quantitative evaluation of compaction is difficult, appropriate concreting planning is no easy task. This paper introduces a newly developed measuring system designed for quantitative evaluation of compaction completion energy, which consists of the energy necessary for concrete to flow through the spaces between reinforcing bars and the energy needed to compact concrete, and proposes a method for evaluating the compactibility of concrete flowing between reinforcing bars by using the newly developed system.
