A micro-experimental insight into the mechanical behavior of sticky rice slurry-lime mortar subject to wetting-drying cycles

• Published in: Journal of materials science Vol. 51; no. 18; pp. 8422 - 8433
• Main Authors: Yang, Rongwei, Li, Kefei, Wang, Linlin, Bornert, Michel, Zhang, Zhiling, Hu, Tao
• Format: Journal Article
• Language: English
• Published: New York Springer US 01.09.2016; Springer; Springer Nature B.V
• Subjects: Characterization and Evaluation of Materials; Chemistry and Materials Science; Classical Mechanics; Composite materials; Crystallography and Scattering Methods; Cultural heritage; Cultural resources; Deformation; Digital imaging; Drying; glutinous rice; Lime; Materials Science; Mechanical properties; Microcracks; microstructure; Mortars; Mortars (material); Original Paper; Polymer Sciences; Propagation; Relative humidity; Scanning electron microscopy; Slurries; Solid Mechanics; Strain measurement; wet-dry cycles; Wetting; Moisture Gradient; Environmental Scanning Electron Microscopy; Repair Material; Digital Image Correlation; Clayey Soil
• ISSN: 0022-2461; 1573-4803
• DOI: 10.1007/s10853-016-0099-x

As an organic-inorganic composite material, sticky rice slurry-lime mortar (SLM) is being used more and more as a repair material in the preservation of cultural heritage. Taking advantage of environmental scanning electron microscopy and the digital-image correlation technique, the microdeformation and damage mechanisms of SLM subject to wetting/drying are investigated in this study. Three wetting-drying cycles between 20 and 98 % relative humidity (RH) are carried out with different hydric loading rates (i.e., 10 % RH/min, 40 % RH/min, instantaneous RH change). Micro-observation and full-field strain measurement are performed on a domain of size 400 × 345 μ m 2 . The results reveal that SLM subject to wetting-drying exhibits a heterogeneous strain field that correlates well with the heterogeneous microstructure of the SLM. In the first cycle, the global swelling strain is 0.25 % when RH increases from 20 to 98 %; when re-drying back to 20 % RH, we found an irreversible strain 0.04 %. The latter is demonstrated to arise from the propagation of pre-existing microcracks during the drying path. However, in the following two wetting-drying cycles, the microcracks become stable, and the irreversible strain changes slightly.