Published in 1971
The statistically oriented specification for bituminous concrete production reviewed in this report was used as a basis for acceptance of more than one million tons of bituminous concrete in 1970. Data obtained from this system were analyzed for gradation and asphalt content for such comparisons as how well the production average matched the stated job mix formula; how well the variability of lot means matched the variability measure the limits were based on; and how well the range method of predicting the standard deviation matched the actual standard deviation. It was found that the 1970 bituminous concrete production was consistent with that of 1967, on which the specification was based; that the range method can predict standard deviations accurately and can be used on a lot-by-lot basis; and that, although the present tolerances are working well, there are some areas where improvements are possible.
Last updated: February 12, 2024