Exploring the potential of tea waste ash in cement mortar: A focus on mechanical and durability properties

Agricultural wastes are particularly attractive due to their high availability and potential for valorization. Tea, the second most consumed beverage worldwide, generates substantial amounts of waste during processing, much of which is landfilled or incinerated, creating environmental concerns. Therefore, tea waste must be regarded as a significant waste stream requiring effective management and valorization.

In this study, tea waste was combusted under uncontrolled and controlled conditions to obtain two distinct ashes, which were subsequently characterized in terms of their chemical, mineralogical, and physical properties. The ash produced under controlled combustion—exhibiting a lower loss on ignition (LOI) and herein referred to as CTWA—was incorporated into cement mortars, and the resulting mixtures were evaluated with respect to their strength and durability performance. The research distinguishes itself from previous studies, which have predominantly focused on strength properties, by emphasizing key durability parameters such as drying shrinkage behavior and high-temperature resistance. Mortar samples were created with 2 %, 4 %, 6 %, 8 %, and 10 % tea waste ash substitution. Key parameters such as ultrasonic pulse velocity (UPV), flexural strength, and compressive strength were assessed on the 2nd, 7th, and 28th days. Drying shrinkage and mass loss were monitored from the 3rd to the 28th day. Samples were exposed to temperatures of 300 °C, 600 °C, and 900 °C, after which mass loss, UPV, strength, and visual inspections were conducted. Results indicated that higher CTWA substitution rates reduced mechanical properties but increased drying shrinkage due to elevated alkali content.