Title: A Scientific Trial Method For Designing Conrete Mixtures

Author(s): R.E. Robb

Publication: Journal Proceedings

Volume: 25

Issue: 2

Appears on pages(s): 280-289

Keywords: none

DOI: 10.14359/15345

Date: 2/1/1929

Abstract:
For a number of years, the writer has been engaged in teaching scientific design of concrete mixtures to senior civil engineering classes. After repeated attempts to get them to grasp the methods commonly used, he was, with considerable reluctance, forced to the conclusion that the scientific method of design for concrete mixtures was too involved for general job use with the equipment now available except where a competent engineer could be employed continuously. This was further brought home to him when he was preparing for an extension class, consisting of engineers, architects, contractors, material men and foremen. It was simply unthinkable that in a period of 12 two-hour lessons these men, many of whom were unaccustomed to mathematical terms and calculations, would be able to find their own way through the maze of computations necessary for the mathematical design of concrete mixtures. Furthermore, it is freely admitted by the authors of this method of design that the charts and data on which it is based are absolutely correct only for certain aggregates and under certain conditions. It is freely admitted that these are valuable as a check, but it is also understood that they will not give the final answer in all cases. On the other hand, it seemed as though there must be some more scientific and at the same time more practical way than just the straight trial method of design, whereby we cut and try and try again until we think we have the most economical mixture. It was in the endeavor to arrive at this more scientific and yet practical method that the writer engaged in research during the past year.