Impact of Polyester Recron 3s Fiber on Fly Ash-based Portland Pozzolana Cement Mortars at Various Total Dissolved Solids Levels

Abstract

This research investigates the effect of total dissolved solids (TDS) concentration on the properties of cement mortar, including setting time, flowability, compressive strength, water absorption, and permeability, with a constant addition of 0.5% Recron fiber. TDS levels were categorized as <500 ppm, 500–1500 ppm, 1500–2500 ppm, and >2500 ppm to reflect different water qualities. Results highlight the significant role of chloride ions in TDS, accelerating cement hydration and reducing setting time, particularly at 1500–2500 ppm. However, excessive TDS (>2500 ppm) causes flocculation, slightly delaying the setting process. Moderate TDS levels (500–1500 ppm) improved early compressive strength by filling cement pores, but strength declined beyond this range. Flowability remained consistent across all samples (105–115% flow), regardless of fiber inclusion or water quality variations. Higher TDS levels slightly reduced water absorption due to pore filling, while improving impermeability. A minor increase in permeability at elevated TDS concentrations suggests complex interactions affecting mortar durability. Additionally, Fourier Transform Infrared Spectroscopy (FTIR) and Scanning Electron Microscopy (SEM) analysis revealed changes in silicate structures influencing durability. This research is novel in simultaneously investigating TDS concentration and fiber reinforcement, offering practical recommendations for coastal construction.