Influence of Moisture Content on Physical and Mechanical Properties of Chinese Ash Bolts for Anchoring Earthen Sites

Abstract

Abstract Chinese ash bolts are extensively utilized for anchoring earthen sites in China, but their physical and mechanical properties are influenced by changes in moisture content during the grout curing process. This study reveals significant effects on compressive strength parallel to the grain and flexural strength, with a comparatively lower influence on tensile strength parallel to the grain. As moisture content increases, the failure mode shifts from fiber fracture to inter-fiber destruction, resulting in a transition from brittleness to elastoplasticity in the bolts’ properties. Additionally, we observed that the diameter of the samples has a less pronounced effect on mechanical strength and modulus compared to moisture content, though it notably enhances resistance to deformation. Scanning electron microscopy images show interlocking textures within the wooden fibers, effectively enhancing the strength and toughness of the bolts. Importantly, this research presents quantitative results: Chinese ash bolts exhibit a natural density range of 0.65 to 0.78 g/cm3 and a saturation moisture content spanning from 93.15 to 114.15 %. Furthermore, in their natural state, these bolts display remarkable tensile strength (126.56 MPa), compressive strength (55.91 MPa), and bending strength (106.34 MPa). This study highlights the critical significance of carefully choosing the most suitable bolt diameters to fortify resistance against deformation. The concrete data provided contribute significantly to improving conservation practices for earthen sites.