Potential application of over-burnt brick and fly ash for sustainable inverted pavement structure

The scarcity of natural aggregate required for infrastructural development (including road construction) is a global problem. Therefore, researchers have constantly been exploring the possibility of different kinds of non-conventional aggregate for sustainable road construction. In this context, over-burnt brick is one among the most common wastes from the construction industry in India, which can be utilized as non-conventional aggregates in the granular layer of pavement structure with the help of a stabilization technique. Pavement structure containing stabilized/cementitious underlying base/sub-base layer is termed as inverted pavement (asphalt layer supported by a relatively stiffer stabilized layer). Attempts have been made in the past to utilize over-burnt brick as an alternative aggregate in different types of pavement structures. However, whether such over-burnt aggregate can be utilized in the stabilized layer of the inverted pavement structure is still unknown. Therefore, this research aimed to explore the potential application of over-burnt brick with the help of stabilization using a cement-fly ash mixture for the base layer of inverted pavement. Likewise, the mixture of fly ash and cement mixture was investigated for their potential application in the subbase layer of the inverted pavement structure. The optimal quantity of cement in both layers for stabilization was initially determined based on strength and durability criteria. Finally, the inverted pavement was analyzed based on the design of experiment approach using the response surface methodology. The analysis of strength and durability components indicated that cement content equal to 6% for brick-fly ash mixture is suitable for the base layer of the inverted pavement. Likewise, cement content equal to 7% with fly ash was found to be suitable for its application in the sub-base layer. It is expected that this research work will help improve the sustainability quotient associated with an inverted pavement structure.