Deterioration assessment of the lime mortar against wet-dry and heat-cool cycles: a case study from the Gashmar ancient road, Nourabad city, Lorestan province

Authors

1 Associate Professor of Engineering Geology, Faculty of Basic Sciences, Lorestan University, Khorramabad, Islamic Republic of Iran

2 Assistant Professor of Archaeology, Department of History and Archaeology, Lorestan University, Khorramabad, Islamic Republic of Iran

Abstract

The weathering agents in the nature are diverse, which can lead to the deterioration of an ancient monument and even its decay and destruction. In the present study, the deterioration of the lime mortar used in the ancient Gashmar road located in Nourabad city (Lorestan province) has been evaluated against weathering factors caused by wet-dry and heat-cool cycles. To achieve this goal, wet-dry and heat-cool tests up to 50 cycles were applied on mortar samples. After every 10 cycles, the appearance (color and shape), physical (dry weight and porosity) and mechanical (point load index and P wave velocity) characteristics were determined. The results indicate that the mortar has undergone minor changes in its appearance as a result of wet-dry and heat-cool cycles. On the contrary, the data analysis showed that with the increase of cycles, the values of the physical and mechanical properties of the samples have changed more significantly. Based on the study of microscopic thin sections, the change in the physical and mechanical properties of the mortar has been closely related to the development and propagation of microcracks after the test cycles. The comparison of the results reveales that the weathering agents caused by wet-dry and heat-cool cycles had almost the same effect on the deterioration intensity of the mortar sample. P-wave velocity is a more suitable and accurate parameter to evaluate mortar deterioration compared to other physical, physical and mechanical properties, while the appearance properties cannot be a suitable parameter in this context. According to the results, it is suggested that the protective solution to prevent from the mortar deterioration used as masonry materials in the ancient Gashmar road located in Nourabad city should be selected and designed based on both wet-dry and heat-cool weathering agents.

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History

  • Receive Date: 17 March 2023
  • Revise Date: 01 May 2023
  • Accept Date: 03 May 2023

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