The Central Materials Laboratory (CML) will accredit the District Materials Laboratories and maintain records of the accreditation for five years. The CML Staff will check the following prior to accrediting a laboratory:


1.   Check for current manuals and test procedures covering the accredited testing.

2.   Check the certification and training records of the testing personnel.

3.   Document that proper equipment is available to perform qualified testing.

4.   Check documentation system.


Scheduling of the annual accreditation review will be discussed with the laboratories needing accreditation.


Table 1 is the list of items to be reviewed.



A laboratory that does not meet the requirements of the IM is subject to elimination from the qualification program.


The CML and the District Materials Engineer will resolve disputes concerning calibration and correlation of equipment.


TABLE 1 - Laboratory Accreditation Checklist



Minimum Calib./Verif. Interval

Calib./Verif. Procedure

Tester Qualifications-Proper Iowa DOT certifications




Current Test Procedures




Current Calibration Procedures & Records




Documentation of correlation results and corrective actions taken for previous construction season










  12 months

Iowa 917



  12 months

Iowa 1501

Mechanical Shakers


  12 months

Iowa 1502

Gyratory Compactor T-312


    6 months

Iowa 1522

Comp. Test Machine T-245


  12 months

Iowa 1505



    6 months

Iowa 1506

Thermometers - Test


    6 months

Iowa 1607

Thermometers - Ref.


  12 months

Iowa 1607

Timers T-201, T-202


    6 months

Iowa 1508

Sand Equivalent T-176


  12 months

Iowa 1509

Gyratory Compactor Molds T-312


  12 months

Iowa 1524

Vacuum Systems T-209


  12 months

Iowa 1510

Pycnometers T-228, T209


  12 months

Iowa 1618

Fine Aggregate Anularity T-304


  12 months

Iowa 1525

Dynamic Shear Rheometer T-315


    6 months

Iowa 1612

Balance Weights M-231


  12 months


Sample Splitters T-248


  12 months

(visual condition)