Evaluation performance of constructors in concrete producing based on cost and quality parameters

Abstract

Some extensive researches have been undertaken on raw concrete, structural use of concrete and concrete production although a less concern has been given on the aspects of optimizing cost, quality and time (CTQ) objectives in concrete production. The degree of control over cost, quality and time overruns by client is limited to a certain extent during implementation stage of a project associated with more concrete based works due to various reasons. However, during the initial stage of a project (i.e. in initial procurement stage) the client has a sound control over cost and quality aspects of producing concrete. In this study the main objective was to develop a methodology to evaluate the performance of constructors in producing concrete introducing a scoring system in technical bid evaluation since concrete production is an essential and an expensive item in construction projects. First relationships of cost and quality parameters (Unit production cost-U, Wastage- Ws, Concrete strength-S, and Workability- W) were developed against the Rate of concrete production (R - Time parameter) using regression analysis using collected data from few national construction projects. Then a range of R was generated from 5 to 25 (m3/Hour) for different 81 constructors, fitting the best curves for above four relationships. The collected data were also analyzed statistically and descriptive statistic results were reviewed including mean, standard deviations, confidential intervals (Cl) at different confidence levels. Then the calculated S, W, U and Ws for above range of R were contrasted separately within their CI at 90%, 95%, 99%, 99.99% confidence levels for 81 constructors. The evaluating constructors for each parameter were done giving scores based on the CI within which the calculated parameter lays on for the range of R from 5 to 25 (m3/Hour). Finally total score obtained by each constructor (bidder) was determined and reviewed by adding individual scores of S, W, U and Ws with different weightings. The final out put was