A methodology for comparing the productivities of the ready mixed concrete industries in major cities

"There are many indexes representing different aspects of the productivity of a ready mixed concrete (RMC) industry in any city. A comparison of productivities between two places and a verdict on which is better is thus a complicated multi-criteria decision-making problem. This thesis has proposed a methodology for this kind of comparison, based on a detailed study and comparison of the RMC industries in Hong Kong and Beijing. The methodology consists of the compilation of the appropriate data followed by two analysis steps, i.e. the Consumption Comparison which compares the consumptions of major resources in the production, transporting and placing of each 1 m3 of RMC finally in place, and the Profile Comparison which lists values for many relevant parameters so that the data profiles relating to the RMC industry can be seen side by side. The thesis points out that a correct comparison conclusion can be gauged by comparing the various measures in the three categories of the nature of the demand on the RMC industry by construction sites, the total resources available in the RMC industry to meet the demand and the utilization of those resources. Each category should also be divided into the three phases making up the whole concreting processes, i.e. the batching, the transporting and the placing of RMC. An important part of a viable methodology is an ordered classification of the categories of data needed. The first comparison step is simple and more suitable for global comparisons. In addition, it is especially meaningful and practical for international comparisons, because the resources themselves are of the same importance and meaning to humankind throughout the world. The concept introduced of the conversion of all resources used to units of one common resource in this step is practical and would give a realistic comparison. Based on Consumption Comparison, cost comparison can also be made and this is very easy. If a better and deeper understanding of the factors affecting the consumption of those resources is needed, the more detailed, second step of comparison is necessary. The proposed methodology is useful not only for systematically comparing RMC industries in different cities but also for studying how an industry in one city changes over time. The thesis also points out that matching concrete supply to site requirement is just as important as improving the productivity of batching or placing separately. A concept of a Cost Efficient Zone has been introduced in relation to matching, a good way to reflect the extent of the efficiency being achieved. As for the sample cities concerned, the productivity of the RMC industry in Hong Kong, especially of the concrete placing phase, is in general better than that in Beijing. It is found that the ability of the RMC industry to supply the concrete to site when needed is good in both Hong Kong and Beijing. But in achieving this truckmixers do spend a considerable amount of time queuing when they are present on site and, in addition, the utilization of batching plants and truckmixers is low in both Hong Kong and Beijing. As a by-product of the study, various factors affecting the productivity of concrete placing have been studied. A model of this and detailed performance yardsticks of concrete placing for Hong Kong and Beijing have also been established which are useful not only for comparison purposes but also for planning concrete supply and placing and other purposes."