Characterizing and Predicting the Resilient Modulus of Recycled Aggregates from Building Demolition Waste with Breakage-Induced Gradation Variation

Abstract

Building demolition waste (BDW) has been massively stockpiled due to increasingly rapid urbanization and modernization. The use of recycled BDW as unbound granular base/subbase materials is among the sustainable, cost-effective, and environmentally friendly pavement construction alternatives. The resilient modulus is an important mechanical property of BDW-derived aggregates and mechanistic design input of pavements incorporating BDW. This paper presents the results of a comprehensive laboratory study on the shear strength and resilient modulus characteristics of BDW-derived aggregate materials. A series of monotonic triaxial compression tests and repeated-load triaxial (RLT) tests were conducted with five different gradations representing particle breakage and different stress paths. The apparent cohesion and internal friction angle of recycled BDW aggregates under consolidated drained conditions ranged from 35.3 to 57.5 kPa and from 30.2° to 54.3°, respectively. The apparent cohesion and internal friction angle also increased and decreased non-linearly with the increasing relative content of fine particles, respectively. The resilient modulus of recycled BDW aggregates gradually decreased with increasing relative content of fine particles at the same stress level. Both the deviator stress and confining pressure exhibited significant influences on the resilient modulus, while the effect of confining pressure was more profound. Based on laboratory testing data, a mechanistic-empirical model was developed to predict the resilient modulus of recycled BDW aggregates from gradation and stress-state variables. The findings could be useful for extended engineering applications of BDW in unbound granular pavement base/subbase construction.

Evaluation of Construction and Demolition Waste and Other Alternative Fills for Strip-Reinforced Soil Walls

“…Morever, considering the data presented in Figure 9, the f * values proposed by [65], considering gravelly materials as fill in MSE walls, overestimate the experimental results for RG. This could be due to the breakage of larger aggregates [25,43,44] during pullout, as the stresses mobilized may exceed the stresses initially applied to the reinforcement, as schematically shown in Figure 5c. This behavior may be more pronounced due to the use of CDW aggregate and the relatively large dimensions of the gravelly fill, which exacerbate stress concentrations at the contacts between the gravel particles.…”

“…These cracks could impact the performance of these aggregates under service conditions. Indeed, prior research [25,43,44] has associated the loss of CDW aggregate performance with the possibility of particle breakage, particularly in larger aggregates such as the RG employed in this study. An overall rough surface was also observed for RG.…”

Development of Artificial-Neural-Network-Based Permanent Deformation Prediction Model of Unbound Granular Materials Subjected to Moving Wheel Loading

“…Meanwhile, the fine particles with particle sizes smaller than 2.36 mm were sieved using sieve opening sizes of 0.6 mm and 0.075 mm. Subsequently, the gradations tested in this study were properly designed and controlled by the gravel-to-sand ratio ( G / S ) parameter proposed previously by the authors [ 35 , 36 , 37 , 38 ]. In fact, the G / S parameter can be calculated from Equations (1) and (2).…”

Pavement Analysis with the Consideration of Unbound Granular Material Nonlinearity

“…The resilient modulus (M R ) of base course materials is considered as an important material input for pavement design, and the determination of the M R is achievable through laboratory testing [26]. Despite being dependent on classical laboratory testing, its importance continuously revives since new materials and gradients appear as alternatives, like the reclaimed asphalt pavement (RAP), which is also used widely in the AC layers [27][28][29]. So, existing testing methods and models for the granular materials are worthy of investigation and/or recalibration.…”