Innovative Applications of the MLS10 for Developing Pavement Design Systems
2008 (English)In: Third International Conference on Accelerated Pavement Testing: Impacts and Benefits from APT Programs, Madrid, 2008Conference paper (Refereed)
This paper presents innovative applications of accelerated pavement testing (APT) to advance pavement design in 3 case studies using MLS technology. Initially the MLS10 system was used to evaluate response and performance of cement stabilized coastal sand bases (CTB) in Mozambique. The aim was development of guidelines for a mechanistic-empirical design method. Trafficking speed was varied with dual wheel loads of either 60kN or 70kN and tire pressures at 800kPa under simulated environmental conditions. Integrated, cost-effective full-scale and MMLS3 scaled laboratory tests were used. Cost would have been 16 times more if full-scale testing were used for pre-selecting test sections. In both test modes, 2 unique failure mechanisms were identified; namely, horizontal shear within the CTB layer and debonding at the interface between surfacing and CTB. PSPA stiffness monitoring enabled progressive deterioration of pavements to be evaluated and performance modeled for subsequent use. The second MLS10 application evaluated performance of an innovative, ultra-thin reinforced concrete pavement (UTCRCP). The SA Road Agency (SANRAL) is investigating UTCRCP for reconstruction or rehabilitation of heavily trafficked freeways. Trafficking differed from HVS APT that had already yielded very positive results. Limited trafficking was applied to evaluate performance of a strengthened construction joint. Trafficking was primarily channelized and unidirectional. Loading frequency was 6.9 fold higher than the HVS'. Performance under MLS10 was positive with smaller deflection and joint movement as expected. No failure occurred. However, a sharp increase in deflection of the construction joint occurred with the switch to limited laterally distributed wet trafficking. This was ascribed to a change in pore pressure patterns. This could not be investigated further due to unavoidable early termination of trafficking. Should the trend continue performance life is likely to be negatively affected. Larger deflection was detected away from the construction joint throughout the test. This could be due to a deficiency in the sub base, or the smaller quantity of reinforcing steel compared to the reinforcing at the joint where additional steel had been added. The test provided guidance for planned validation of APT performance on a specially constructed highway trial section. A third application by EMPA in Switzerland tested a 20-yr-old untrafficked, heavy duty deep structured HMA pavement with cement treated sub-base on a spur of a trafficked freeway. Trafficking was terminated after 1 million 65kN channelized half axle load applications. The performance provided a basis for comparison with the adjacent freeway that had carried ca. 6.5 million equivalent E100’s with one intervention for replacement of 50mm surfacing. Ground penetrating radar (GPR) monitoring showed progressive distress with trafficking. This correlated with decline in PSPA seismic stiffness and increased surface deflection. Pumping was experienced with wet trafficking. Diagnostic trenching ratified indications from GPR and seismic stiffness trends that indicated delamination between the 2 HMA layers. The one million E130 load applications equate to ca. 4.9 million E100 axle load applications on the test section in terms of damage. A detailed diagnostic study of the trafficked freeway should provide invaluable information for a more thorough comparison of respective performances.
Place, publisher, year, edition, pages
IdentifiersURN: urn:nbn:se:kth:diva-88794OAI: oai:DiVA.org:kth-88794DiVA: diva2:502426
APT '08. Third International Conference
TSC import 1838 2012-02-14. QC 201203072012-02-142012-02-142012-03-07Bibliographically approved