Minero-petrographical, chemical and physical characterisation of the ancient mortars from Fort Jesus Heritage Site, In Mombasa, Kenya

Fort Jesus, one of the UNESCO World Heritage sites, faces degradation due to harsh environmental exposure, and inappropriate restoration, thus its existence in the future is at risk. The study's objective is to determine the composition of raw materials and mix proportion of the ancient mortars...

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Main Authors: Asmait Hadish Sium, Gariy Zachary, Mutuku Raphael, John Mwero
Format: Article
Language:English
Published: Elsevier 2025-07-01
Series:Case Studies in Construction Materials
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Online Access:http://www.sciencedirect.com/science/article/pii/S2214509525002815
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author Asmait Hadish Sium
Gariy Zachary
Mutuku Raphael
John Mwero
author_facet Asmait Hadish Sium
Gariy Zachary
Mutuku Raphael
John Mwero
author_sort Asmait Hadish Sium
collection DOAJ
description Fort Jesus, one of the UNESCO World Heritage sites, faces degradation due to harsh environmental exposure, and inappropriate restoration, thus its existence in the future is at risk. The study's objective is to determine the composition of raw materials and mix proportion of the ancient mortars used in the construction of Fort Jesus. Eight samples were collected from different wall locations. A hydrochloric acid digestion test was used to separate the binder from the aggregate. X-ray powder diffraction (XRPD), Optical microscopy (OM), X-ray fluorescence (XRF), and scanning electron microscopy (SEM) were employed to analyse the mineralogical composition, petrographic characteristics, chemical properties, and microstructure of the mortars, respectively. High-carbonated calcite as a binder and quartz as a fine aggregate were dominant in all samples. The primary binder was found to be lime, mixed with different clay content. The binder-to-aggregate ratio was found to vary from 1:2.4–1:6.8 dominated by fine sand, likely sea sand. The findings of this study revealed variations in the mortars production methods among the Portuguese, Omani, and the Museum of Kenya applied in 1593,1698 and 2001 respectively. The main cause of the degradation was found to be the use of incompatible restoration mortar. Therefore, the findings from this study are vital for formulating compatible restoration mortar that aligns with the restoration needs of Fort Jesus.
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spelling doaj-art-8f6448c7db584eb7bbbd9d7cf603d7272025-08-20T01:58:27ZengElsevierCase Studies in Construction Materials2214-50952025-07-0122e0448310.1016/j.cscm.2025.e04483Minero-petrographical, chemical and physical characterisation of the ancient mortars from Fort Jesus Heritage Site, In Mombasa, KenyaAsmait Hadish Sium0Gariy Zachary1Mutuku Raphael2John Mwero3Civil Engineering Department, Institute for Basic Science, Technology and Innovation, Pan African University Hosted at Jomo Kenyatta University of Agriculture and Technology, PO Box 62000, Nairobi 00200, Kenya; Civil Engineering Department, Eritrea Institute of Technology, Mai-Nefhi, Eritrea; Corresponding author at: Civil Engineering Department, Institute for Basic Science, Technology and Innovation, Pan African University Hosted at Jomo Kenyatta University of Agriculture and Technology, PO Box 62000, Nairobi 00200, Kenya.Civil Engineering Department, Jomo Kenyata University of Agriculture and Technology, Nairobi, KenyaBuilding and Civil Engineering Department, Technical University of Mombasa, KenyaSchool of Civil and Resource Engineering, The Technical University of Kenya, Nairobi, KenyaFort Jesus, one of the UNESCO World Heritage sites, faces degradation due to harsh environmental exposure, and inappropriate restoration, thus its existence in the future is at risk. The study's objective is to determine the composition of raw materials and mix proportion of the ancient mortars used in the construction of Fort Jesus. Eight samples were collected from different wall locations. A hydrochloric acid digestion test was used to separate the binder from the aggregate. X-ray powder diffraction (XRPD), Optical microscopy (OM), X-ray fluorescence (XRF), and scanning electron microscopy (SEM) were employed to analyse the mineralogical composition, petrographic characteristics, chemical properties, and microstructure of the mortars, respectively. High-carbonated calcite as a binder and quartz as a fine aggregate were dominant in all samples. The primary binder was found to be lime, mixed with different clay content. The binder-to-aggregate ratio was found to vary from 1:2.4–1:6.8 dominated by fine sand, likely sea sand. The findings of this study revealed variations in the mortars production methods among the Portuguese, Omani, and the Museum of Kenya applied in 1593,1698 and 2001 respectively. The main cause of the degradation was found to be the use of incompatible restoration mortar. Therefore, the findings from this study are vital for formulating compatible restoration mortar that aligns with the restoration needs of Fort Jesus.http://www.sciencedirect.com/science/article/pii/S2214509525002815Ancient mortarCharacterisationXRPDXRFSEMFT-IR
spellingShingle Asmait Hadish Sium
Gariy Zachary
Mutuku Raphael
John Mwero
Minero-petrographical, chemical and physical characterisation of the ancient mortars from Fort Jesus Heritage Site, In Mombasa, Kenya
Case Studies in Construction Materials
Ancient mortar
Characterisation
XRPD
XRF
SEM
FT-IR
title Minero-petrographical, chemical and physical characterisation of the ancient mortars from Fort Jesus Heritage Site, In Mombasa, Kenya
title_full Minero-petrographical, chemical and physical characterisation of the ancient mortars from Fort Jesus Heritage Site, In Mombasa, Kenya
title_fullStr Minero-petrographical, chemical and physical characterisation of the ancient mortars from Fort Jesus Heritage Site, In Mombasa, Kenya
title_full_unstemmed Minero-petrographical, chemical and physical characterisation of the ancient mortars from Fort Jesus Heritage Site, In Mombasa, Kenya
title_short Minero-petrographical, chemical and physical characterisation of the ancient mortars from Fort Jesus Heritage Site, In Mombasa, Kenya
title_sort minero petrographical chemical and physical characterisation of the ancient mortars from fort jesus heritage site in mombasa kenya
topic Ancient mortar
Characterisation
XRPD
XRF
SEM
FT-IR
url http://www.sciencedirect.com/science/article/pii/S2214509525002815
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