Ortega, José Marcos, Esteban Pérez, María Dolores, Rodríguez Escribano, Raúl Rubén, Pastor Navarro, José Luis, Ibanco, Francisco José, Sánchez, Isidro, Climent, Miguel-Ángel Long-Term Behaviour of Fly Ash and Slag Cement Grouts for Micropiles Exposed to a Sulphate Aggressive Medium Ortega JM, Esteban MD, Rodríguez RR, Pastor JL, Ibanco FJ, Sánchez I, Climent MÁ. Long-Term Behaviour of Fly Ash and Slag Cement Grouts for Micropiles Exposed to a Sulphate Aggressive Medium. Materials. 2017; 10(6):598. doi:10.3390/ma10060598 URI: http://hdl.handle.net/10045/66557 DOI: 10.3390/ma10060598 ISSN: 1996-1944 Abstract: Nowadays, one of the most popular ways to get a more sustainable cement industry is using additions as cement replacement. However, there are many civil engineering applications in which the use of sustainable cements is not extended yet, such as special foundations, and particularly micropiles, even though the standards do not restrict the cement type to use. These elements are frequently exposed to the sulphates present in soils. The purpose of this research is to study the effects in the very long-term (until 600 days) of sulphate attack in the microstructure of micropiles grouts, prepared with ordinary Portland cement, fly ash and slag commercial cements, continuing a previous work, in which these effects were studied in the short-term. The microstructure changes have been analysed with the non-destructive impedance spectroscopy technique, mercury intrusion porosimetry and the “Wenner” resistivity test. The mass variation and the compressive strength have also been studied. The impedance spectroscopy has been the most sensitive technique for following the sulphate attack process. Considering the results obtained, micropiles grouts with slag and fly ash, exposed to an aggressive medium with high content of sulphates, have shown good behaviour in the very long-term (600 days) compared to grouts made with OPC. Keywords:Micropiles, Sustainability, Special geotechnical works, Impedance spectroscopy, Microstructure, Compressive strength, Fly ash, Ground granulated blast furnace slag, Sulphate attack, Cement grouts MDPI info:eu-repo/semantics/article