Non-destructive testing of nano-silica for enhancing the durability of limestone structures in the Valley of the Kings, Luxor, Egypt

Abstract

The Valley of the Kings (KV) is a UNESCO world heritage site with more than thirty tombs that have been opened. Since the first tombs were constructed, at least 24 historical flash flood events have been identified, each of which has contributed to the destruction and deterioration of the tombs. After the floods of 1994, most of these tombs were inundated and damaged. Theban Tomb 109, or TT 109, is an example of one of these significant tombs. This study presents a novel technique which uses computer X-ray tomography (CT scan) as a non-destructive method to capture the morphology of the limestone's internal structure at Tomb 109 (TT 109), as well as the stone's grain texture and the surface features through 3D images and videos. Additionally, this research examines the ability of a nanomixture, consisting of tetraethoxysilane (TEOS) and nanosilica, to consolidate the limestone, which is also a novel approach that this study introduces. It is worth noting that the limestone of Tomb 109 has suffered harsh weather conditions such as groundwater and has been in an unfavourable burial environment, causing geostatic stress which in turn has led to stone abrasion and weakness in its mechanical properties. This study also presents a comprehensive morphological and spectroscopic study to confirm the efficiency of the nanomixture in the consolidation of the limestone structures. A cross-examination method using CT scanning, SEM, and XRF analysis before and after consolidation was employed. The final result shows that the nanomixture significantly enhanced the physical and mechanical properties of the limestone.