A mechanistic and economic analysis of two-lift concrete pavements

The government of India has embarked on the construction of major highways with concrete pavements to eliminate frequent maintenance of bituminous pavement, damaged by heavy commercial vehicles and moisture. Hence, it is necessary to re-examine the current pavement design with a sound analytical approach. The current practice in the construction of concrete pavement in India is to place pavement quality concrete (PQC) over dry lean concrete (DLC) layer with a bond-breaking layer of 125-micron plastic sheets between the DLC and PQC layers to eliminate possible reflective cracks from the DLC to the PQC layer. Concrete pavement can be bonded to lean concrete (LC) when both layers are laid one after the other with two pavers (‘fresh-on-fresh’ or ‘wet-on-wet’). This type of pavement is also known as two-lift concrete pavement (TLCP), and such pavements were constructed in India during the last three years. No readymade solutions are available to compute stresses in such TLCPs. The objectives of the research are manifolds. Firstly, this article illustrates the analysis of Two-Lift Concrete Pavement (TLCP) using Finite element programming software (ANSYS) with an interface layer CONTA 174, which is able to capture interfacial stresses occurring between layers due to non-linear temperature gradient distributed over the depth of the slab. Then the design of pavements with TLCP has been introduced using the cumulative fatigue damage method. Finally, the cost of construction for TLCP is determined and compared with that of conventional concrete pavement. It was found that the material cost for TLCP is less than that of conventional concrete pavement because the stresses induced due to both load and environmental effects in TLCP are significantly lower when compared to those on the conventional concrete pavement.