Simulation of ready mixed concrete delivery from a single plant to mutiple construction sites

Abstract

A simulation program RMCSIM has been developed in this project using Visual Basic combined with a Microsoft Access database system and other Microsoft tools. It simulates a concrete plant with N mixing bays, M TMs (truckmixers) serving S sites, where sites are at variable distances D from the plant and different concrete quantities Q are required by each site on which different placing methods are used. N, M, S, D, Q and placing methods are the variables which can be input by the user. RMCSIM has been used to simulate many different situations for a batching plant as explained below. Three simulated operation days were selected which represent three different concrete quantity demands (large, medium and small) in total from sites. 450 simulations were run, 150 for each case (day). In order to assess the scale of the mismatch problem, a questionnaire survey was conducted in the first quarter of 2003 to ask for the opinions of concrete professionals in Hong Kong and 51 respondents provided useful information. To achieve a better matching of deliveries between concrete plant and sites, it is suggested that (1) the time interval required between successive TMs should be adjusted to take account of the different placing method for each pour and (2) the account should be taken of 'miscellaneous waiting time' on site. After adjusting (1) and (2) and rerunning RMCSIM, a great improvement was observed in the "Time waiting for TM arrival (% of pour time)", a measure of the interruption in concrete supply to the sites. This measure could be reduced by about 40%.