This study investigates several aspects of concrete mix design. The variability of compressive strength, slump and air content from batch to batch is examined. The effect of increasing the sand content per cubic yard of concrete on the compressive strength is studied with another series of laboratory batches. Finally, the effect of the maximum coarse aggregate size on compressive strength is evaluated with a third set of laboratory batches. The differences between the mean compressive strength of batches were evaluated using the Student 1 statistic. Some of the findings were: 1) Variability in average 28-day compressive strength between laboratory batches of the same design is very low. 2) The average 28-day compressive strength of concrete made with a 10% increase in the sand content is higher than that of concrete made with standard mix proportions. The workability of the former as measured by the slump is lower. 3) The average 28-day compressive strength of concrete made with 3/4-in. maximum size aggregate is significantly higher than concrete made with 1 1/2-in. maximum size aggregate.

Media Info

  • Features: References; Tables;
  • Pagination: 37 p.

Subject/Index Terms

Filing Info

  • Accession Number: 00622311
  • Record Type: Publication
  • Report/Paper Numbers: FHWA-OR-MA-92-12
  • Contract Numbers: 5277
  • Created Date: May 31 1996 12:00AM