2026-06-30T21:44:22Zhttps://riubu.ubu.es/oai/request

oai:riubu.ubu.es:10259/63722022-12-02T12:41:55Zcom_10259_6171com_10259_5086com_10259_2604col_10259_6172

00925njm 22002777a 4500 dc Revilla Cuesta, Víctor author Evangelista, Luís author Brito, Jorge de author Skaf Revenga, Marta author Ortega López, Vanesa author 2022-01 The high strength and durability of high-performance concrete (HPC) may be significantly reduced by shrinkage cracking. The use of reactive magnesium oxide (MgO) can reduce shrinkage of cement-based materials due to its expansive properties. This study intends to analyse the validity of MgO as shrinkage-reducing agent in recycled aggregate HPC. To do so, ten HPC mixes with 0%, 25%, and 100% of both early-age (7-days air curing) and matured (6-month air curing) RA were produced. In half of the mixes, 10% ordinary Portland cement was replaced with MgO. The use of MgO slightly worsened the mechanical behaviour of HPC, especially when combined with large amounts of RA. On the other hand, the expansion of MgO fully offset the autogenous shrinkage of HPC and reduced total shrinkage by around 20–40%. Water storage of RA, and its deferred release over time, produced a more efficient hydration of MgO, which in turn led to a further reduction of autogenous shrinkage. However, the increase of drying shrinkage caused by RA was greater than this decrease of autogenous shrinkage due to MgO, so the higher the RA content of HPC the lower the total shrinkage reduction when adding MgO. Thus, the decrease of total shrinkage caused by MgO was compensated by the shrinkage increase because of RA when adding amounts above 35% early-age RA and 42% matured RA. Therefore, despite the suitability of MgO as shrinkage-reducing agent in recycled aggregate HPC, its effectiveness was reduced with increasing amounts of RA. 0950-0618 http://hdl.handle.net/10259/6372 10.1016/j.conbuildmat.2021.125726 High-performance concrete Recycled aggregates Recycled aggregate’s maturity Magnesium oxide Autogenous shrinkage Drying shrinkage Mechanical performance and autogenous and drying shrinkage of MgO-based recycled aggregate high-performance concrete