Technological control of concrete: a case study of process capability with non-normal data

Abstract

The evaluation of the capability of a certain process verifies whether customers are receiving products that meet the specifications or not. Such evaluation assumes this process has normal distribution If this doesn’t occur the analysis can be compromised.. In this case, some specific alternatives to evaluate capability should be taken. This work aimed to present processes capability evaluation of non-normal distribution data and its application in a real case related to unconfined compression strength of concrete. Therefore, modifications were performed on the data in order to present normal distribution and thus to calculate the traditional indices. The capacity indices pertinent to non--normal processes were also obtained. The analyzed data originate from the process of technological control of concrete on a construction site located at Joinville-SC. The data collected corresponded to the concrete strength at 7 days of curing whose specification for the situation evaluated was that the resistance should reach at least 70% of the specified fck at 28 days. It was found that the process was not capable, whether through modifications or by non-normal capacity indices. In the end, a comparison between the methods used is established, and all indicate the lack of the ability of the process to perform within the specifications.

Keywords

• Process capability
• Non-normal distribution
• Technological control of concrete