Durability Assessment of Calcined Ginger Nuts-Based Anchor Grouts Used in the Conservation of Earthen Sites

Abstract

ABSTRACT Calcined ginger nuts (CGN)-based grouts are widely utilized in anchoring conservation of unstable earthen sites in the northwest of China. However, the long-term performance of the anchor system, which is dominated by the durability of anchor grouts in the real environment remains unclear. In this study, durability of CGN admixed with fly ash (F) and quartz sand (S) in the real environment were evaluated regarding physical properties (density, surface hardness, water penetration capacity, and permeability), soluble salts content and micro-structure (SEM). Grouts concretions of CGN admixed with F and S were buried at the feet of Ming Great Wall, Gulang County, Gansu Province, China for six years. The results indicate that two decay patterns including extensive crack formations along specimens’ edges and micro-cracks and materials losses (granular disintegration) on the surface were captured. Moreover, crust structure, which is inferred as carbonation front was detected on the surface of specimens. The performance of the grouts in the real environment is quite different from that in the laboratory, in particular, specimens of CGN admixed with S singly were already broken due to the crack formation. Long-term performance priority of CGN-based grouts is CGN-FS>CGN-F>CGN-S.