Next Article in Journal
Effect of Ni, N Co-Doped on Properties of AgSnO2 Contact Materials
Next Article in Special Issue
Crystal Chemical Relations in the Shchurovskyite Family: Synthesis and Crystal Structures of K2Cu[Cu3O]2(PO4)4 and K2.35Cu0.825[Cu3O]2(PO4)4
Previous Article in Journal
Effect of High Pressure and Temperature on the Evolution of Si Phase and Eutectic Spacing in Al-20Si Alloys
Previous Article in Special Issue
Crystal Chemistry and Structural Complexity of the Uranyl Carbonate Minerals and Synthetic Compounds
Article

Bentonites in Southern Spain. Characterization and Applications

Escuela Técnica Superior de Ingenieros de Minas y Energía, Universidad Politécnica de Madrid, C/Ríos Rosas, 21, 28003 Madrid, Spain
*
Author to whom correspondence should be addressed.
Academic Editor: Zhaohui Li
Crystals 2021, 11(6), 706; https://doi.org/10.3390/cryst11060706
Received: 23 May 2021 / Revised: 17 June 2021 / Accepted: 17 June 2021 / Published: 20 June 2021
(This article belongs to the Special Issue Mineralogical Crystallography Volume II)
The objective of this work was to investigate and demonstrate the pozzolanic properties of the bentonites found at the San José–Los Escullos deposit, located in the southeast of the Iberian Peninsula, to be used in the manufacturing of more durable and environmentally compatible pozzolanic cements, mortars and concretes. These bentonites are mainly composed of smectites, with montmorillonite as the main clay mineral. They were formed by the hydrothermal alteration of tuffs, volcanic glasses, dacites, rhyolites and andesites. For this research, samples were taken from outcrops on the south, north and west side of the San José–Los Escullos deposit, and in the Los Trancos deposit located 19.3 km to the northeast. All samples consisted of bentonites, except for a zeolite sample taken from the northern flank of the San José–Los Escullos deposit, which was used to contrast and compare the behaviour of bentonite in some of the analyses that were done. An investigation of the mineralogical, petrological, chemical and thermogravimetric characteristics of the samples was carried out using various methods, such as XRD, OA (Oriented aggregates), TGA, XRF, SEM and thin section petrography (TSP). In addition, a chemical analysis of pozzolanicity (CAP) was done at 8 and 15 days to determine the pozzolanic capacity of the samples. XRD, XRF, SEM and TSP studies showed that these bentonites have a complex mineralogical constitution, composed mainly of smectites of the montmorillonite variety, as well as halloysite, illite, vermiculite, biotite, muscovite, kaolinite, chlorite, mordenite, feldspar, pyroxene, amphibole, calcite, volcanic glass and quartz. Thermogravimetric analysis (TGA) established the thermal stability of the bentonites studied at above 800 °C. Chemical analysis of pozzolanicity (CAP) confirmed the pozzolanic character of the bentonites, exhibited in their reactive behaviour with Ca(OH)2. The pozzolanic reactivity increased significantly from 8 to 15 days. These results show that the materials studied can be used as quality pozzolans for the manufacture of pozzolanic cements, mortars and concretes. View Full-Text
Keywords: bentonite; mordenite; smectite; pozzolanicity test; cement; concrete bentonite; mordenite; smectite; pozzolanicity test; cement; concrete
Show Figures

Graphical abstract

MDPI and ACS Style

Costafreda, J.L.; Martín, D.A. Bentonites in Southern Spain. Characterization and Applications. Crystals 2021, 11, 706. https://doi.org/10.3390/cryst11060706

AMA Style

Costafreda JL, Martín DA. Bentonites in Southern Spain. Characterization and Applications. Crystals. 2021; 11(6):706. https://doi.org/10.3390/cryst11060706

Chicago/Turabian Style

Costafreda, Jorge L., and Domingo A. Martín. 2021. "Bentonites in Southern Spain. Characterization and Applications" Crystals 11, no. 6: 706. https://doi.org/10.3390/cryst11060706

Find Other Styles
Note that from the first issue of 2016, MDPI journals use article numbers instead of page numbers. See further details here.

Article Access Map by Country/Region

1
Back to TopTop