Durability performance of natural rubber latex and high-volume fly ash incorporation in hybrid fibres concrete under aggressive environments

Abstract

This study investigates the combined effect of natural rubber latex (NRL) and high-volume fly ash (HVFA) on the durability performance of hybrid fibres concrete. Previous study has shown that incorporating 2.5% NRL and HVFA as cement replacement produces optimum mechanical properties of hybrid fibres concrete mix at 28 days (52 MPa - coded OM), compared to the control mix (56 MPa - coded CM). The specimens were then exposed to sulfuric acid (H₂SO₄, 5%), sodium sulphate (Na₂SO₄, 5%) and sodium chloride (NaCl, 3%) solutions. Results show that under acidic conditions, both mixes deteriorated severely, from 52 MPa and 56 MPa to 8 MPa and 9 MPa (180 days exposure). However, OM samples showed superior residual compressive strength, that is, higher 18%, 28%, and 17% at 56, 90, and 180 days exposure, respectively, and lower mass loss, less 20.5%, 68%, and 51.2%, compared to CM, complementing FESEM results showing pore refinement due to latex incorporation. Under sulphate and chloride exposures, both mixes show high resistance, with OM samples outperformed CM up to 90 days sulphate exposure, demonstrated through increased strength compared to 28 days strength and mass gain (peak 2.24% at 90 days – sulphate and 3.1% at 56 days - chloride) instead of mass loss. However, at 180 days, OM started to deteriorate, with reasonable strength losses (21% and 19%) but insignificant mass loses (1% and 0.3%) under sulphate and chloride, respectively. Physical observations confirmed volume changes in acid-exposed specimens, whereas no deterioration or significant volume change under sulphate and chloride environments.