Department of Civil Engineering
Reno, NV 89557
Tel: 775-784-6565
Fax: 775-784-1429
Research &
Development
E-Mail PCTC
FUTURE RESEARCH ACTIVITIES
Additional placement and aging of coal tar emulsions onto new asphalt pavement to demonstrate new pavements readily crack.
Apply a coal tar emulsion on a light application rate on a new pavement (in conjunction with above) for jobs that require a protective fuel resistant coating to be applied immediately.
Evaluate the applicability of the tests the PCTC has developed for asphalt based sealers.
CURRENT RESEARCH ACTIVITIES
Evaluation of Aging Characteristics of Coal Tar Materials
Objective
The objective of this research effort is to evaluate the impact of aging on the rheological properties of coal tar emulsions. The changes of the rheological properties of coal tar emulsions as a function of aging could explain the field cracking phenomena of coal tar emulsions.
Summary
Several types of RT12 materials were identified and will be tested for their rheological properties at their original and aged stages. Also the impact of emulsifiers and clay on the aging characteristics of RT12 are evaluated.
Program
A total of four sources of RT12, two emulsifiers and one clay were identified to be included in the testing program. The program uses the dynamic shear rheometer (DSR) to evaluate the rheological properties of the coal materials at various temperatures. It also uses the pressure aging vessel (PAV) to simulate the long term aging of the materials. The rheological properties properties are measured in terms of the dynamic shear modulus which represents the resistance of the materials to shear stresses/ strains which could cause surface cracking. The following levels will be included in the program:
Four RT12 materials
Two emulsifiers at 1% level
One clay at 30, 35, 40, and 45% of ash contents
Data
The PCTC laboratory has made several preliminary measurements to assess the impact of aging on the behavior of RT12. The behavior of RT12 materials was compared with the behavior of a commonly used asphalt binder. This data showed that aging impact RT12 materials and common asphalt binder in similar manners. Following these findings, the PCTC started an extensive testing program to evaluate the aging characteristics of RT12 materials and the impact of emulsifiers and clay on the characteristics.
DEVELOPMENTS
Development of Tests for Coal Tar Emulsion Sealers
Task 1.0 Recommend a Durability Test
1.1 Preliminary Evaluation
1.1.1 Evaluation of the Scrub Test
1.1.2 Repeatability and Consistency of the Scrub Test
1.2.1 Evaluation of the WTAT
1.2.2 Repeatability and Consistency of the WTAT
1.2 Data Analysis
1.3 Recommendations of the Preliminary Evaluation
1.4 Further Evaluation of the Scrub Test
1.4.1 Develop a simple test procedure
1.4.2 Identify two different emulsions
1.4.3 Determine testing precision
1.4.4 Conduct round robin testing
Task 2.0 Develop a Field Fuel Resistance Test
2.1 Evaluation Program
2.2 Summary and Recommendations
Task 3.0 Modify the Freeze/Thaw Cracking Test
3.1 Experimental Plan
3.2 Summary and Recommendations
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