Early contributing nanostructured cementitious matrix designs: Benefits in durable features at early ages

• Published in: Construction & building materials 2020-04, Vol.241, p.117941, Article 117941
• Main Authors: Garcia, Ramiro, Henao, Nelson, De la Rubia, Miguel Angel, Moragues, Amparo, Fernandez, Jaime
• Format: Article
• Language: English
• Subjects: Diffusion chloride; Early durable features; High durability; Marine exposure; Metakaolin; Micro and nano combinations; Nanosilica; Resistivity
• ISSN: 0950-0618; 1879-0526
• DOI: 10.1016/j.conbuildmat.2019.117941

Blends of cement mortars type IIIA 42,5 with metakaolin and different nanosilicas submerged into an aggressive environment at early ages, allow obtaining a design service life around three or four times greater than that of the reference mortar after 28 days of curing. [Display omitted] •The highest electrical resistivities results in the best durable behaviours.•Mixes of cement, metakaolin (MK) and nanosilica (NS) are suitable for marine uses.•Synergy between MK and NS allows obtaining high durable properties at early ages.•Metakaolin is related to chloride binding capacity.•Nanosilica maximises porosity refinement. Blends of cement mortars type IIIA 42,5 with metakaolin and different nanosilicas have been studied. The application of these materials is like offshore concrete elements such as concrete drawers, oil and gas offshore platforms…etc, where service-life design requires a high degree of durable contribution and by manufacturing requirements at an early ages. Structural, microstructural characterization and durable behaviour have been carried out by electrical resistivity, mechanical properties, DTA-TG analysis, MIP and chloride diffusion. The study shows a clear benefit at early ages due to synergic effects combining one or two types of nanosilica and metakaolin in the same matrix design, contributing physically by refining the final porous structure and chemically by increasing the chloride binding ability of the cementitious matrix design. It is estimated that the designed service live is of the order of 3 and 4 times greater for the blends exposes to chlorides at early ages (4 and 7 days) than for the reference cement exposed at 28 days.