Statistical Methods for the Quality Control of Steam Cured Concrete: Final Report

About the report:

Concrete strength test results from three prestressing plants utilizing steam curing were evaluated statistically in terms of the concrete as received and the effectiveness of the plants' steaming procedures. Control charts were prepared to show trends in the data, the batch-to-batch variability of the strengths for both the 28-day moist cured and the steam cured samples (age approximately 20 hours), and the fluctuations in the efficiency of the processing. The moving averages for range were computed to supplement the information provided by the control charts. Analysis of variance were used as a means of examining the flow of variations within and between batches and for comparisons of steam cured versus moist cured strength variations. The statistical techniques employed in this study revealed considerable promise as a means of aiding the production of uniform, high quality, steam cured concrete for prestressing. It is hoped, therefore, that this study may form the basis for the development of statistical plans, programs, and procedures for effective and economical quality control in the production of steam cured concrete. While the techniques have been applied to concrete, they are equally applicable to other materials such as bituminous and pug mill mixtures, and stabilized materials that are subjected to processing.

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