Effect of microstructure and curing conditions upon the performance of a mortar added with Treated Sediment Aggregates (TSA)

This experimental study investigates the performance of mortars added with water-saturated treated sediment aggregates (TSA), used as sand substitution (0, 33, 66 and 100% sand volume). As compared to industrial practice, two extreme curing conditions are used, either water immersion (most favorable to cement hydration), or air curing (highly deficient curing condition). Independently of curing conditions, porosity is shown to increase hugely with TSA amount, while apparent density decreases linearly with porosity increase. Nevertheless, up to 33% substitution, elastic Young's modulus, uniaxial compressive strength and apparent gas permeability are all improved as compared to reference 0%-substitution mortar. Maturity is attained from 28 to 60 curing days. The positive internal curing effect of TSA is more significant under air curing. The negative effect of brittle lightweight TSA is significant above 33% substitution. Micro-structural changes have also been observed by SEM and EDS analysis, along with thermo-gravimetry analysis (TGA).