Main Priority Factors Causing Nonconforming Product (NCP) On Readymix Concrete Product

American Concrete Institute (ACI) Manual of Concrete Practice Part-1 defines ready-mix concrete (RMC) as concrete made for customer or purchaser in plastic and unhardened state. Many complaints from customers in relation with nonconforming products (NCP) requires RMC producers to improve the quality of RMC. One of its efforts is to find out the main problems of nonconforming products.

An investigation was carried out main problems on five dry-mix plants of a RMC company. This research was identified factors causing fourteen types of NCP using cause-effect analysis. In order to determine the scores of importance and cause effects of the fourteen NCP types, a preliminary questionnaire was carried out. The result of this questionnaire indicated that only five out of fourteen types of NCP have significant financial effects on the company, namely; unspecified compressive strength, late product delivery , unspecified slump, less volume than ordered, and too fast or too late setting time. Further investigation was carried out by conducting pairwise comparison between two factors of the many factors causing each NCP. Matrix analysis of pairwise comparison was used to obtain priority scores of the factors causing the five NCP types.
It was found in this research, that the main priority factors causing the five types of NCP on the entire plant, were non-standard quality control equipment, low quality of fine aggregate, quality of chemical admixtorure, skill of quality control technician, inaccurate weighting by operators, skill of scheduling and delivering operators, accuracy of weighting tool, communications system between plant and site, accuracy of aggregate moisture content, fetch of delivery and traffic problems and influence of hot weather. There was no difference of main priority factors causing each NCP between the five plants; the difference occurred only on the sequence of the priorities.

Key Words: readymix concrete, nonconforming product, pairwise comparison.

For management topic http://www.holikbisnis.com