Suitability of excavated London clay as a supplementary cementitious material: mineralogy and reactivity

Yuvaraj Dhandapani; Alastair T. M. Marsh; Suraj Rahmon; Fragkoulis Kanavaris; Athina Papakosta; Susan A. Bernal

doi:10.1617/s11527-023-02260-3

Suitability of excavated London clay as a supplementary cementitious material: mineralogy and reactivity

Yuvaraj Dhandapani, Alastair T. M. Marsh, Suraj Rahmon, Fragkoulis Kanavaris, Athina Papakosta, Susan A. Bernal

Department of Architecture & Civil Engineering

Research output: Contribution to journal › Article › peer-review

11 Citations (SciVal)

Abstract

This study evaluated the potential of producing supplementary cementitious materials (SCMs) using London Clay excavated from construction activities of the High Speed 2 rail project. A trade-off between enhancing reactivity versus decomposition of impurities (e.g., pyrite, carbonates) present in different London Clay samples was considered in selecting the calcination temperature. The additional reactivity obtained by calcining at 800 °C is deemed to be worth the cost of the small additional process emissions from decomposition of carbonate minerals. Blended cement formulations were developed with the produced SCMs, with replacement levels of 50 and 70 wt%. The optimal gypsum dosage was found to be 1 wt%, which resulted in improved reaction kinetics at early ages. Mortars produced with these binders developed ~50 MPa compressive strength after 90 days of curing even with 70 wt% replacement, which is sufficient for potential production of low to medium strength concretes. These findings demonstrate the excellent potential of London Clays for SCM production and present a systematic approach for characterisation, processing and utilization of excavated mixed clays obtained from infrastructure projects.

Original language	English
Article number	174
Journal	Materials and Structures
Volume	56
Early online date	3 Nov 2023
DOIs	https://doi.org/10.1617/s11527-023-02260-3
Publication status	Published - 1 Dec 2023

Data Availability Statement

The data associated with this paper are openly available from the University of Leeds Data Repository at https://doi.org/10.5518/1438.

Acknowledgements

Franco Zunino, ETH Zürich along with Wolf Wichmann and Apostolos Tsoumelekas from SCS Railways, London, UK are acknowledged for their involvement and discussions in the REAL Project.

Funding

This study was sponsored by The Skanska, Costain and STRABAG (SCS) joint venture (JV) and ARUP working in partnership with HS2, through an HS2 Innovation Fund. The London Clay SCM initiative was conceived and initiated by ARUP and planned and managed by SCS & ARUP. The participation of Y. Dhandapani, S.A. Bernal and S. Rahmon was partially sponsored by National Science Foundation (NSF) and the UK Engineering and Physical Sciences Research Council (EPSRC) through the awards #1903457 and EP/T008407/1, respectively. Participation of S.A. Bernal and A.T.M. Marsh was also partially sponsored through the EPSRC Early Career Fellowship EP/R001642/1. The donation of the superplasticiser by Dr. Martin Liska from Sika UK Ltd was very much appreciated.

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Cite this

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abstract = "This study evaluated the potential of producing supplementary cementitious materials (SCMs) using London Clay excavated from construction activities of the High Speed 2 rail project. A trade-off between enhancing reactivity versus decomposition of impurities (e.g., pyrite, carbonates) present in different London Clay samples was considered in selecting the calcination temperature. The additional reactivity obtained by calcining at 800 °C is deemed to be worth the cost of the small additional process emissions from decomposition of carbonate minerals. Blended cement formulations were developed with the produced SCMs, with replacement levels of 50 and 70 wt%. The optimal gypsum dosage was found to be 1 wt%, which resulted in improved reaction kinetics at early ages. Mortars produced with these binders developed ~50 MPa compressive strength after 90 days of curing even with 70 wt% replacement, which is sufficient for potential production of low to medium strength concretes. These findings demonstrate the excellent potential of London Clays for SCM production and present a systematic approach for characterisation, processing and utilization of excavated mixed clays obtained from infrastructure projects.",

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Suitability of excavated London clay as a supplementary cementitious material: mineralogy and reactivity

Abstract

Data Availability Statement

Acknowledgements

Funding

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