Sulfate attack on fiber reinforced mortar with cassava peel ash as a partial replacement for cement

The environmental impact of cement production has prompted the search for sustainable alternatives, including the use of agricultural waste as supplementary cementitious materials. Cassava peel ash (CPA), a byproduct of cassava processing, has shown pozzolanic potential for partial cement replacement, while fiber reinforcement is known to enhance concrete durability. This study investigates the sulfate attack on fiber-reinforced mortar incorporating CPA, with a focus on resistance to sulfate attack and microstructural performance. Mortar mixes were prepared with CPA replacing cement at 0%, 7%, 14%, and 21%, combined with sisal fiber at 0%, 1%, and 2%. A total of twelve mixes (C1–C12) were evaluated for sulfate resistance by immersing specimens in a 5% Na₂SO₄ solution for up to 120 days. Results showed that the mix containing 14% CPA and 1% fiber (C8) exhibited the least compressive strength loss (5.93%), indicating optimal sulfate resistance. Microstructural analyses via SEM and XRD confirmed a denser matrix and stable silica phases in this mix. Higher CPA levels increased susceptibility to degradation. This research demonstrates that 14% CPA with 1% fiber is an optimal blend for enhancing durability while promoting waste valorization and sustainability in mortar production.