Augmented balance point diagrams for matching site and concrete-supply resources

Matching site concrete-placing resources with the appropriate number of concrete-delivery truckmixers depends upon good site and concrete plant coordination if good concreting productivity is to be achieved. In general practice, however, the placing crew usually is idle for some of the pour time waiting for deliveries, and at other times, truckmixers are idle on site waiting to be emptied. In the case of concrete supplied by a circulating fleet of truckmixers, which is a balance point process, two new diagram models were developed relating fleet size to the parameters of placing-crew idle time, truckmixer idle time, truckmixer unloading time, round-trip time, and concrete-placing production rate. The new models augment classical balance point theory. To illustrate practical application: (1) the diagrams were developed and used to reveal system behavior insights for the case of three circulating truckmixers, and (2) the relevance of the new model to a real pour of 46 deliveries was examined in relation to the balancing of site and plant resources for better coordination and system productivity.