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Open AccessArticle

Microstructural Effects of Sulphate Attack in Sustainable Grouts for Micropiles

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Departamento de Ingeniería Civil, Universidad de Alicante, Ap. Correos 99, 03080 Alacant/Alicante, Spain
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Departamento de Ingeniería Civil, Urbanismo y Aeroespacial, Escuela de Arquitectura, Ingeniería y Diseño, Universidad Europea, c/Tajo s/n, 28670 Villaviciosa de Odón, Spain
*
Author to whom correspondence should be addressed.
Academic Editor: Claudio Ferone
Materials 2016, 9(11), 905; https://doi.org/10.3390/ma9110905
Received: 30 August 2016 / Revised: 20 October 2016 / Accepted: 28 October 2016 / Published: 8 November 2016
Nowadays, the use of micropiles has undergone a great development. In general, they are made with cement grout, reinforced with steel tubing. In Spain, these grouts are prepared using OPC, although the standards do not forbid the use of other cements, like sustainable ones. Micropiles are in contact with soils and groundwater, in which the presence of sulphates is common. Their deleterious effects firstly affect to the microstructure. Then, the aim of this research is to study the effects of sulphate attack in the microstructure of micropiles grouts, prepared with OPC, fly ash and slag commercial cements, compared to their behaviour when they are exposed to an optimum hardening condition. The microstructure evolution has been studied with the non-destructive impedance spectroscopy technique, which has never been used for detecting the effects of sulphate attack when slag and fly ash cements are used. Its results have been contrasted with mercury intrusion porosimetry and “Wenner” resistivity ones. The 28-day compressive strength of grouts has been also determined. The results of microstructure characterization techniques are in agreement, although impedance spectroscopy is the most sensitive for following the changes in the porous network of grouts. The results showed that micropiles made using fly ash and slag cements could have a good performance in contact with aggressive sodium sulphate media, even better than OPC ones. View Full-Text
Keywords: micropiles; special geotechnical works; impedance spectroscopy; microstructure; fly ash; ground granulated blast furnace slag; sulphate attack; cement grouts micropiles; special geotechnical works; impedance spectroscopy; microstructure; fly ash; ground granulated blast furnace slag; sulphate attack; cement grouts
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MDPI and ACS Style

Ortega Álvarez, J.M.; Esteban Pérez, M.D.; Rodríguez Escribano, R.R.; Pastor Navarro, J.L.; Sánchez Martín, I. Microstructural Effects of Sulphate Attack in Sustainable Grouts for Micropiles. Materials 2016, 9, 905.

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