Microstructural Effects of Sulphate Attack in Sustainable Grouts for Micropiles

Microstructural Effects of Sulphate Attack in Sustainable Grouts for Micropiles

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...

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Bibliographic Details
Published in:Materials Vol. 9; no. 11; p. 905
Main Authors: Ortega Álvarez, José Marcos, Esteban Pérez, María Dolores, Rodríguez Escribano, Raúl Rubén, Pastor Navarro, José Luís, Sánchez Martín, Isidro
Format: Journal Article
Language:English
Published: Switzerland MDPI AG 08-11-2016
MDPI
Subjects:
Cement
Cements
Contact
Fly ash
Grout
Hydration
Microstructure
Process control
Spectrum analysis
Sulfates
Sustainability
Spain
cement grouts
sulphate attack
impedance spectroscopy
microstructure
ground granulated blast furnace slag
special geotechnical works
fly ash
micropiles
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Summary: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.
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ISSN:1996-1944
1996-1944
DOI:10.3390/ma9110905