You also want an ePaper? Increase the reach of your titles
YUMPU automatically turns print PDFs into web optimized ePapers that Google loves.
observation. For long term abrasion and determination of the base binder level it is suggested<br />
that the range of soak periods are the same as are used for CAT test. The WTAT will be<br />
needed to determine the long term performance properties of the S3 mixes.<br />
4.3 LABORATORY TEST METHODS EVALUATION<br />
4.3.1 Evaluation of Automated Mixing Test (AMT)<br />
The proposed AMT test method covers measurement of constructability of slurry surfacing<br />
materials once the basic ratios of the components have been established. By automatic and<br />
constant recording of the complete torque-measurement-curve, the mixing curve indicates each<br />
variation during the breaking process—the process where the mixture changes from a<br />
homogenous flowing consistency to a stiff non-flowing consistency.<br />
The AMT procedure was developed with the intention of providing additional information about<br />
the breaking process for a particular mix system after initial mix proportions were established by<br />
using TB-113 and to eliminate operator variability.<br />
Differences between proposed and current test methods:<br />
• In TB-113, the curing condition for humidity is not specified.<br />
• The current hand mixing method allowed the use of various mixing bowls or containers,<br />
and mixing stirrers.<br />
• The current hand mixing method required a specified rpm during the manual mixing, but<br />
that would vary from operator to operator.<br />
• The original hand mixing method did not specify any details to the direction of rotation or<br />
depth of the stirrer into the mixture during the mixing process, so that would vary from<br />
technician to technician.<br />
• In TB-113, mix proportions were adjusted to meet the minimum mixing times in the<br />
project specifications. This tended to produce a mix with a higher viscosity than the<br />
viscosity of the system used during placement in the field.<br />
Advantages of the proposed test method:<br />
The AMT method standardizes testing conditions for humidity, mixing bowl, stirrer, mixing<br />
rotations and mixing rate. In the current TB-113 procedure, these variables greatly influence the<br />
final result and it varies from technician to technician and laboratory to laboratory.<br />
In addition, another advantage is that this method evaluates the mix system for the type of<br />
break the system has by measuring the mixing torque, spread time and maximum torque.<br />
70
Change language