Stabilization of Aeolian Sand for Pavement Subbase Applications Using Alkali-Activated Fly Ash and Slag

Using local materials to construct building elements as well as transport road facilities, including highways, intercity roads, and roads, in remote areas is a top topic of scholarly research all over the world. The main reason for that is the fact that these kinds of materials not only ease the intensity of material transportation but are also cost-efficient. In desert areas, aeolian sand is a commonly used local material and it has been investigated in unbound and cement-stabilized pavement base/subbase applications. However, the production of cement is associated with a high carbon footprint, leading this research to seek alternative low-carbon binders. This research investigated the strength properties and the carbon footprint of fly ash (FA) and a ground-granulated blast-furnace slag (S)-based geopolymer-stabilized aeolian sand. Setting time, compressive strength, California bearing ratio (CBR), and temperature shrinkage measurements of the stabilized aeolian sand were carried out in this research. The maximum strength of the stabilized aeolian sand was found at the optimal ratio of Si/Al ratio of 2.5 and Na/Al ratio of 1.0. The compressive strength increased as the geopolymer stabilizer content increased. A stabilizer content ranging between 8% and 20% is recommended in practice. The carbon footprint of the geopolymer-stabilized aeolian sand was lower than that of cement-stabilized aeolian sand. This tendency became more evident in the samples with higher strength, indicating the effectiveness of geopolymer as an alternative green soil stabilizer to traditional Portland cement.