Microstructure and Mortar Strength Characteristic of Lime Added with Glutinous Rice Paste Used for Repairing Architectural Cultural Heritage

Abstract

Historically, various additives were used to increase the functionality of lime mortar, and among the additives, the function and material properties of glutinous rice paste were identified. In this study, samples of lime paste and lime mortar were manufactured and exposed to various environmental conditions during the curing period, and then a comprehensive review was conducted on microstructural changes and strength characteristics. X-ray diffraction analysis of calcite minerals generated in an accelerated carbonation environment due to the addition of glutinous rice grass showed that it was about 2.1 times higher. The average size of calcite crystal grains was about 38.90 nm, which tended to decrease by 18%. Additionally, the average particle size of lime was confirmed to be reduced by 20% to about 17.93 µm. Under indoor curing conditions, glutinous rice paste reduced the drying shrinkage rate of lime mortar by about 6.8 times. As a result of the strength analysis, compression increased by 33% to 2.99(±0.24) MPa, tensile strength increased by 9% to 0.35(±0.03) MPa, and bending increased by 22% to 1.11(±0.06) MPa, confirming that all mechanical strengths were superior.