Ancient materials and substitution materials used in thai historical masonry structure preservation

Abstract

The historical structures of Thailand are some of the most fascinating ancient sites in Asia. Their architectures reveal past cultures, traditions, knowledge, and expertise. Masonry materials are the major materials used to con-struct the historical structures in Thailand. One of the essential problem of Thai historical structure preservation is a shortage of engineering properties data for the structural stability assessment. Moreover, the in-depth engineering properties and the suitable substitution materials for Thai historical preservation are rarely found. There-fore, the engineering properties of the ancient masonry materials have to be explored together with the development of suitable substitute materials. This paper presents the physical and engineering properties of ancient materials and substitution materials for the preservation of Thailand’s historical structures. The ancient materials, including brick and mortar, are collected from historical places in the Bangkok and Ayutthaya Pro-vinces. The physical and engineering properties of the masonry materials, such as the chemicalcomposition, mineralogical composition, density, porosity, absorption, water vapor transmission, compressive strength, and modulus of elasticity, were evaluated in the laboratory. Fly ash was used as a pozzolanic material to partially replace the slaked lime to restore the historical mortar. The binder to sand ratio was controlled at 1:3 by weight. The slaked lime was substituted by fly ash at the rates of 10–30% by weight of binder. The engineering properties of the substitution mortars were also evaluated and compared with the ancient masonry materials. A masonry prism was also constructed to evaluate the compressive strength and the modulus of elasticity of the masonry structures. The physical and engineering properties of the ancient masonry materials obtained in this study can be included in a database for the preservation of Thailand’s historical masonry structures. The use of fly ash to partially replace the slaked lime could decrease the setting time and increase the compressive strength of historical repair mortar. The empirical equation obtained from this study could be used to predict the com-pressive strength of the masonry prisms of Thailand’s historical structures.