Evaluating the influence of synthetic cotton textile waste fibres on CO2 uptake, flexural strength, and wet-dry ageing of slag-based binders

The construction sector is seeking sustainable alternatives to reduce CO 2 emissions, with cement replacement being a key strategy. Mineralised steel slag is a promising binder due to its reactive CaO and MgO content, enabling CO 2 sequestration via accelerated carbonation while maintaining mechanical performance. Incorporating textile waste cotton fibres offers complementary benefits, enhancing flexural strength and potentially increasing CO 2 uptake through improved porosity and carbonation pathways. Given the global textile waste surplus and low recycling rates, this approach supports circular economy goals. This study examines composites combining carbonated steel slag with synthetic cotton fibres at three dosages, assessing carbonation uptake and flexural strength under standard curing and wet–dry ageing cycles. Results indicate that fibres promote higher CO 2 uptake by creating diffusion channels and improve mechanical behaviour, particularly at higher dosages. Although durability cycles reduce toughness, they enhance environmental performance by facilitating greater carbonation. • Fibre incorporation increased total porosity and led to a shift in pore structure • Porosity and fibres degradation facilitates CO 2 diffusion and deeper carbonation • Waste textile fibre boost CO 2 uptake and mechanical strength of slag-based binders • High textile waste fibre content increases MOR and improves post-cracking behaviour • Samples subjected to wet-dry cycles reduce in toughness, but increase CO 2 uptake