Investigation into Creep Characteristics and Model of Recycled Construction and Demolition Waste Used in Embankment Filler

Abstract

The creep deformation of recycled construction and demolition waste (CDW) filler is an important factor affecting road performance. In this paper, a series of laboratory tests, including a compaction test, sieving test, California bearing ratio (CBR) test, creep test and unloading test are conducted on CDW filler. The engineering properties of different ratios of CDW mixture are systematically analyzed, the CBR value of CDW filler meets the requirements of an embankment. The creep type of CDW filler under a test load is stable creep, the results of the creep characteristics are analyzed from a microscopic point of view. The filler with a 7:2:1 ratio (brick slag: concrete: mortar) has the densest structure, which is dense and less porous, and the deformation is the smallest. Reasonable proportion control is the key to reducing embankment deformation. The improved Burgers model, which can better describe the creep characteristics of CDW filler, and the effects of load and ratio on the creep parameters are analyzed using the equivalent creep compliance. This study is of great significance for the promotion of CDW and meets the requirements of sustainable development.Sustainability 2020, 12, 1924 2 of 22 for the adverse effects of recycled aggregates [12][13][14]. When recycled aggregate is used to produce recycled asphalt, Subhy et al. [15] and Menegusso et al. [16] have studied the effects of its content and treatment method on fatigue performance. In addition, recycled aggregates are used for roadbed fillers, Javier et al. [17] found that the bearing capacity of the recycled aggregates increased with time in the structural layer, which is inconsistent with the trend of natural aggregates. Vegas et al. [18] and Yin et al. [19] studied the properties of recycled concrete applied to an embankment and introduced its permanent deformation characteristics.The application of CDW materials to embankments has great economic and environmental benefits, but the composition of recycled CDW material is complex, and its settlement after construction is difficult to predict and control, therefore, a study into its creep characteristics and mechanisms is urgently needed. The CDW mixture belongs to coarse-grained materials and the creep deformation of coarse-grained materials can be divided into stable creep and unstable creep types, according to the magnitude of stress [20,21]. The rheological curve of coarse-grained materials can be divided into three stages: linear, decaying rheology, and stability [22]. With the increase in dam height, the particle breakage of the rockfill in the rock dam increased significantly, and the particle breakage directly changed the rockfill structure [23,24]. From their triaxial creep shear test, Jiang et al. concluded that particle motion, rotation, and damage are the main causes of coarse-grained material deformation [25]. In addition to the time-dependent strain under a constant load, changes in the external environment tend to have a large effect on creep deformation, especially as immersion i...

Nonlinear Elasto-Visco-Plastic Creep Behavior and New Creep Damage Model of Dolomitic Limestone Subjected to Cyclic Incremental Loading and Unloading

“…The time-dependent deformation characteristics of rock, especially the creep behaviors, are related to the long-term stability of underground rock engineering, such as tunnels and roadways [1][2][3][4][5][6][7][8][9][10][11]. Many scholars have carried out extensive research on creep mechanical behaviors of different types of rocks.…”