Evaluation of Adding Carbon Nanotubes to Lime Mortar: Mechanisms and The Effect of their Addition on Modifying the Internal Structure for Repairing Cracks in Heritage Buildings

Abstract

Lime mortar is one of the oldest building materials used since ancient times in temples and historical monuments that still stand today. It is characterized by its role as a natural binder, its relative flexibility, and its compatibility with traditional stone materials, which makes it suitable for restoration and maintenance of historical structures. However, lime mortar faces fundamental challenges that limit its use in advanced construction applications. With the evolving need to preserve historical heritage and develop more sustainable and environmentally friendly building materials, research has focused on integrating nanomaterials with traditional mortar to enhance its mechanical and physical properties. Carbon nanotubes (CNTs) have shown positive effects when incorporated with various materials due to their unique mechanical and physical properties. The combination of lime mortar as a traditional and environmentally friendly material with CNTs as a modern reinforcing material enables the development of a composite that merges traditional authenticity with high mechanical performance. This research aims to investigate the effect of incorporating CNTs in varying proportions within lime mortar and to evaluate their impact on compressive and flexural strength, as well as internal structure and porosity. CNTs have been synthesized and purified, then SEM-EDX and TEM analyses were conducted prior to mixing with lime mortar in ratios of 0.01%, 0.03% and 0.3%, followed by mechanical and physical testing of the prepared samples, but the results did not achieve the desired outcomes.