Durability of Concrete Made with Coal Bottom Ash Portland Cements

The Portland cement industry, responsible for approximately 7.4% of global anthropogenic carbon dioxide emissions, must balance rising cement demand with ambitious greenhouse gas reduction targets. In parallel, the rapid accumulation of industrial solid waste highlights the need for effective valorization routes. Reducing the clinker factor remains a powerful measure to mitigate climate impacts in the cement sector. This study evaluates the durability of concretes made with ground coal bottom ash (CBA), a newly standardized Portland cement constituent, using the depth of penetration of water under pressure test (EN 12390-8). The experimental results show that concretes produced with CEM II/B-Z and CEM II/C-M cements meet both average (≤30 mm) and maximum (≤50 mm) water penetration criteria for mass, reinforced, and prestressed concrete across all EN 206-1 exposure classes. Concretes made with CEM VI (S-L) and CEM VI (S-Z) comply for XS1, XS2, XD, XA1, XM, and XF classes. However, for XS3, XA2, and XA3, compliance (≤20 mm and ≤30 mm) is not achieved when using mix design B (300 kg/m³, w/c = 0.50). These findings provide robust technical evidence supporting CBA as a viable cement constituent that enhances durability while enabling clinker factor reduction.