“Basic“ concrete mix design method
The Basic Mix design method was devised by Philip Owens when at the C&CA, now the BCA. It gives tabulated data to provide initial trial mix proportions for 4 fine aggregate grading zones to BS 882 (now withdrawn), 3 workabilities and 3 aggregate sizes (10, 15, 20mm to BS 882). Suggestions are given for adjusting the initial mix (after the trial) to produce the “basic mix“ of correct workability and cohesion. A procedure is given to modify the basic mix over a range of cement contents, with a constant free water content to maintain the required fresh concrete properties, such that further trials can be undertaken on a systematic basis. This procedure exploits the near-linear relationship between strength and w/c ratio for medium strength mixes and provides a range of strengths within which a suitable mix can be selected for the required strength value.
Other simplified methods include the BRE (1987) and ACI (1991).