Correlation sampling and testing of the field density test result insures that testing equipment is operating properly and the results are within the range of tolerance. Investigations are conducted and corrections made when results do not correlate.
A sample consists of all the cored specimens of one day's paving production.
These specimens must be identified and stored in a manner, which will not affect their densities. Upon request from the District Materials Laboratory, cores are to be taken and transported the next working day. A completed Daily Plant Report, Form #800241 shall accompany each set of cores.
The District Materials Office, on a random basis for correlation will select samples as specified. A minimum of one sample per project will be obtained.
The District Laboratory shall test each specimen of the submitted sample in accordance with IM 321. The test results of each specimen will be compared to each corresponding field test result for correlation. Bulk Specific Gravity (Gmb) results that do not correlate to within 0.020 will be considered suspect. Other information gained through this correlation testing, such as trends developing, will also give cause to suspect the results. Immediate investigation must be conducted and correction made on all suspect test results.
NOTE: Each District Laboratory procedure and equipment is accredited and monitored through the established program with the Central Laboratory, which includes Cooperative Testing.
The District Materials Office shall submit reports of the correlation of field density tests to the project file along with the documentation of what action was taken for suspect results.