<p>Glass fibers have recently been adopted as reinforcing materials to control compressibility and desiccation cracks in the landfill liner. Past studies have used fly ash as a suitable additive along with bentonite for landfill liner construction. In this study, waste glass fiber was used along with bentonite, fly ash, and their mixes to reinforce the liner material. The physico-chemical, microstructural, and mechanical performance of bentonite-fly ash and bentonite-sand mixes reinforced with glass fibers are investigated. A total of 225 unconfined compressive strength tests were conducted after 14 days curing period for each sample. A detailed analysis is carried out to understand the influence of glass fiber content on stress-strain response of bentonite-fly ash and bentonite-sand mixes. It is observed that, as the glass fiber content increases from 0.0% to 1.5%, there is an increase in unconfined compressive strength by about 213%. In all the cases considered, the bentonite-fly ash mixes resulted in a greater unconfined compressive strength than the bentonite-sand mixes. Based on the experimental data sets of B-FA mixtures, a new correlation between UCS and pH of the mixes was proposed. An increase in pH from 8.5 to 10.5 resulted in an increase of UCS by about 236% in glass fiber-reinforced mixtures.</p>