ENGINEERING JOURNAL CHIANG MAI UNIVERSITY

Volume 26, No. 02, Month AUGUST, Year 2019, Pages 36 - 46

Appropriate proportion of dust rock in ready mix concrete by six sigma

Weerachai Areerak and Jeerapat Nagoprasertwong

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This research was aimed to search for an appropriate proportion of using dust rock as a component for ready-mixed concrete manufacturing. 5-step six sigma was applied as the research methodology. The research was started from defining a problem, that is, finding a way to combine dust rock as a component for ready-mixed concrete manufacturing in order to improve quality and reduce the concrete margin cost. Then, the data was measured and collected for evaluating the effectiveness of materials as well as material weighing system. Next, causes of the problem were analyzed through brainstorming among involved persons so as to design a cause and effect diagram. Each factor was taken for drawing a Pareto chart afterwards so that the biggest causes affecting the problem were identified. The hypotheses were statistically tested to prove whether or not those causes brought about effects indeed. The factors with statistically significant effects were improved through a full factorial experimental design for examining appropriate values of the factors. Lastly, the experiment was controlled. The post-improvement result indicated that the cement margin was diminished, with the deducted cost at 67 baht/m3. In other words, the cost was decreased 6.13% of total cost before the improvement.

Keywords

Six sigma, dust rock, ready-mixed concrete

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