A Novel Method of Preparing A Standard Weathered Sandstone Specimen: A Case Study of Red Sandstone from the Leshan Giant Buddha (Sichuan, China)

In the laboratory study of the restoration and conservation of weathered stone relics, it is necessary to prepare standard weathered stone specimens for selection, effectiveness evaluation, and lifetime prediction of the conservation materials since the naturally weathered stone cannot meet testing requirements. This paper introduces a novel method of preparing the weathered sandstone specimen. Firstly, a systematic investigation was conducted on naturally weathered sandstone samples to obtain the essential information. The standard sand with the same particle size distribution as moderately weathered sandstone was selected as raw material. The influence of the types of cement materials, addition order of raw materials, number of hammering strikes during preparation, and the CO2-curing time on the physical properties (i.e., dry density, water absorption, total porosity, and compressive strength) was studied. Finally, the proposed method was proved to be effective, reproducible, and capable of inducing controllable microstructural, physical, and mechanical alterations by control of the variables in the preparation process to achieve an expected weathering degree. Moreover, the obtained specimens exhibited good precision in compressive strength values, and similar physical properties to the naturally weathered sample, so it is believed that the specimen could be used for the testing of conservation materials.

Automated summary

This paper presents a novel method for preparing weathered sandstone specimens, which can achieve controlled microstructural, physical, and mechanical alterations by controlling the variables in the preparation process. The obtained specimens exhibit good precision in compressive strength values and similar physical properties to the naturally weathered sample.