Recycling alkali-activated powders for the production of lightweight aggregates for pavement applications

The objective of this thesis is to create an innovative approach to the development of flexible pavements with the use of synthetic aggregates for the production of porous layers. The synthetic aggregates are produced by the alkali-activation process. The potential application of artificial aggregates in the pavement, paves a way to reduce the use of natural materials to certain extends. This also helps to utilize the increasing growth of waste by-products generated from different kinds of industries. Furthermore, in this research the conventional Bitumen for asphalt concrete was substituted with a transparent binder. Hence this will hope to decrease the impact of carbon dioxide and carbon monoxide which are emitted from the production of traditional mixtures with Bitumen in the road industry. The first part of experimental phase includes the recipe of making the geopolymer aggregates. The precursors concerned with this production are basalt powder and metakaolin. These powders are activated by the mixture of reagents such as Sodium hydroxide and Sodium Silicate. After discovering the optimum percentage of each precursors and solid-liquid ratio, the productions of synthetic lightweight aggregates start. The next experimental phase involves the Mix design and characterization of a porous mixture. In this part, it has been decided to replace the natural white aggregates by 21% with the synthetic lightweight aggregates to form a semi-porous pavement design as per the European Standards. This design also replaces the traditional bitumen with a transparent binder named ‘EVIzero-28’ which is a synthetic binder used to produce eco-friendly asphalt. After the selection of mix design, the samples are produced to find out the optimum percentage of transparent binder content. Once it gets, then the samples are prepared for the further experimental phases like testing as per European Standards.