Fly-ash-based geopolymer as stabilizer form embankment materials

Flyash in the recent decades has become abundant resulting to improper waste disposal. However, it is also known to be a precursor to the process of geopolymerization which is categorized under waste utilization. Geopolymer has become known for its strength characteristic which is on par with cement and other chemical stabilizers. It has been used in numerous studies focusing on concrete and soil stabilization. This study proposes a wide application of flyash through the use of flyash-based geopolymer as a stabilizer for embankment purposes wherein the process of creating the geopolymer is unconventional. This geopolymer was applied on three different soil types to identify its reaction with each soil type and to obtain the recommended mix for different embankment purposes. The unconventional method used in producing geopolymer is known as the dry-mix method. This method requires all necessary materials (aluminosilicate precursors and alkali activators) to be in its dry state wherein adding water to the dry-mix would result to geopolymerization. In order to test this method to strengthen embankment materials, the following tests which were the CBR Test (ASTM D1833) and the UCS test (ASTM D2166) were performed on each soil type. Results have shown improvements of the geopolymer-stabilized soil in terms of CBR index and Unconfined Compression Strength. However, these improvements vary for all three types of soil used in the study. The recommended geopolymer concentration was found to be at 30% geopolymer concentration which produced the highest increase for all soil types with a maximum CBR index of 51.33% and a maximum Unconfined Compressive Strength of 1349.74 kPa