Technical memorandum: instrumentation for APT and LTPP

Abstract

The GDPTW makes extensive use of instrumentation in their Accelerated Pavement Testing (APT) and Long Term Pavement Performance (LTPP) programmes. In order to remain at the forefront of technology, this project investigates the available technologies to monitor these projects, identifies the most appropriate instruments to measure each of the relevant parameters and makes recommendations regarding instrumentation requirements for the GDPTRW. This project has been performed in 3 phases. In these phases, the parameters to be monitored on APT and LTPP sections have been identified, appropriate instruments and sensors for monitoring these parameters have been identified, and recommendations made regarding new developments, required upgrading of sensors and instruments for the GDPTRW APT and LTPP programmes. The following conclusions are drawn: There is a large range of potential parameters that can be monitored during APT and LTPP projects. However, the specific parameters required for each project should still be identified to ensure that parameters are not just monitored for the sake of monitoring them. A standard checklist can be used to ensure that relevant parameters are monitored using appropriate sensors and instruments; A variety of sensors and instruments exist for monitoring the identified parameters. However, while some of these sensors and instruments provide good data, others require improvements to enable reliable data to be collected consistently for APT and LTPP projects; Due to developments in electronics, smaller and improved sensors are constantly being developed. Some of these sensors may be appropriate for APT and LTPP once they are adapted to be used in the specific road material environment; There are specific requirements for new or upgraded sensors and instruments for the GDPTRW APT and LTPP programmes that need to be pursued. Some of these are already being addressed, while further research will be required for others. The following recommendations are made: The checklist provided for the planning and execution for instrumentation on APT and LTPP projects should be used to ensure that appropriate parameters are being monitored using appropriate sensors and instruments; The current suite of sensors and instruments used on the GDPTRW APT and LTPP projects should be kept, with the focus on upgrading of the following instruments: Wireless RSD and profilometer (currently being addressed at CSIR); Wireless MDD (to be addressed once wireless RSD and profilometer has been completed); Improved in situ moisture measurement sensors / instruments to be procured (not currently being addressed); A plan should be developed for a systematic approach towards addressing the potential development of nano- and micro-scale sensors and instruments for the measurement of stresses, strains, deformations and translations inside pavement layers, and The development of non-destructive thermography for pavement layer evaluation should be addressed to determine the feasibility of using this technology.