Development of wet-cast Portland-cement-free concrete based on steel slag and ambient-pressure carbonation activation

Steel slag (SS) is rarely used as a sole binder in wet-cast concrete production, which, however, is successfully realized in this study through early-age ambient-pressure carbonation activation without cement involvement. Standard mechanical, performance-based, and microstructural investigation methods including compressive strength test, sulfate attack test, thermogravimetric analysis (TGA), mercury instruction porosimetery (MIP), etc., were adopted to verify the performance of the product. First, the cement-free wet-cast SS concrete presented comparable carbon sequestration capacity as OPC concrete. Second, the superior strength gain was verified on full-scale concrete products, and carbonation-activated wet-cast SS concrete pipes demonstrated improved performance, attributed to the high carbonation degree for SS and the densified microstructure. Last, the environmental and economic assessments confirm that 100 % substitution of cement with SS can significantly reduce CO2 emissions, energy consumption, and total cost for carbonation-activated wet-cast SS concrete, which contributes to both environmental protection and sustainable development in the construction industry.