Constructibility aspects of ultra thin continuously reinforced concrete pavement

Abstract

Paper presented at the 28th Annual Southern African Transport Conference 6 - 9 July 2009 "Sustainable Transport", CSIR International Convention Centre, Pretoria, South Africa.

Ultra Thin Continuously Reinforced Concrete Pavement (UTCRCP) is a new rehabilitation technique for roads which was originally imported from overseas and redesigned for South Africa conditions. Initial development involved accelerated pavement testing (APT) with the Heavy Vehicle Simulator (HVS) on experimental sections at the Heidelberg Traffic Control Centre. The success of these short experimental sections shifted the emphasis to constructability issues and associated design issues on a larger scale. A test section of 50 mm thick UTCRCP was constructed in 2008 at the Heidelberg Traffic Control Centre (screener lanes for heavy vehicles). The main challenges of construction of the UTCRCP were examined, with the objective of achieving a methodology for the roll out on full scale projects.The construction aspects examined included the mixing technique of the concrete components, the position of the reinforcing mesh within the overall 50mm thickness of concrete layer, the compaction and vibration techniques of the fresh concrete, and the use of a pan mixer. Indicators such as slump values during construction and the normal mix design criteria such as water cement ratio were recorded, as well as flexural strength and compressive strength of this ultra strong concrete, were monitored. Additional test results such as the new composite centrally loaded round panel deflection test were also recorded.Initial conclusions and recommendations regarding constructability are made to help further technology development of the UTCRCP.