Effect of Sustained Loading on the Direct Shear Behaviour of Recycled C&D Material–Geosynthetic Interfaces

Abstract

Recycled construction and demolition (C&D) wastes have been pointed out as a feasible alternative to traditional backfill materials of geosynthetic-reinforced structures, but the current knowledge about the interface behaviour between these unconventional (recycled) materials and the reinforcement is still limited, particularly as far as the time-dependent response is concerned. In this study, a series of large-scale direct shear tests was conducted using an innovative multistage method to evaluate the influence of shear creep loading on the direct shear response of the interfaces between a fine-grained C&D material and two different geosynthetic reinforcements (high-strength geotextile and geogrid). The peak and large-displacement interface shear strength parameters obtained from tests involving sustained loading were compared with those from conventional interface tests. Test results have shown that the shear creep deformation of the interfaces increased with the magnitude of sustained loading. The test specimens experienced additional vertical contraction during the creep stage, which tended to increase with the applied normal stress. For the recycled C&D material–geotextile interface, the sustained loading induced a reduction in the apparent cohesion and a slight increase in the friction angle, when compared to the values estimated from conventional tests. In turn, for the geogrid interface, the apparent cohesion values increased, whereas the friction angle did not significantly change upon shear creep loading.

Insight into the Micro Evolution of Backfill Paste Prepared with Modified Gangue as Supplementary Cementitious Material: Dissolution and Hydration Mechanisms

“…Then, all the components required to describe the hydration processes were chosen, including H, C, N, O, Na, Mg, Al, Si, S, Cl, K, Ca, and Fe. The activity and ionic strength of the ions, such as Ca 2+ , were calculated using the Extended Debye-Hückel model in Equation (2). Afterwards, the mix proportions for the pastes (Table 2) were next input into GEMS and the reactions were performed.…”

“…Low carbon cementitious materials (LCMs) are becoming more and more popular in mine backfills [1,2], bridges [3], dams [4], and buildings [5] due to their low cement and high solid waste content, which makes the materials more affordable and have a lower CO 2 footprint. This is due to the significant environmental impact associated with coal mining and cement manufacturing.…”

Assessing and Predicting Geogrid Reduction Factors after Damage Induced by Dropping Recycled Aggregates

“…Designers must also consider essential parameters for a safe and economical design, strengthening its position as a desirable alternative [13]. In the past decades, in addition to the research evaluating the environmental and economic aspects related to using RCDW materials [20][21][22][23][24][25], several studies have reported the potential substitution of natural aggregates by RCDW materials in pavement layers [6,[26][27][28][29][30][31][32][33] and backfill material for geosynthetic reinforced structures [8,12,[34][35][36][37][38][39][40][41][42]. However, Delongui et al [26] emphasized that the RCDW characteristics are valid for the research's specific application conditions (e.g., type of CDW generated, recycling process).…”