Numerical modelling of plastic–damage response and crack propagation in RAC under uniaxial loading

Abstract

In order to better understand the failure mechanism of recycled aggregate concrete (RAC), a numerical study on modelled recycled aggregate concrete (MRAC) was conducted to investigate the plastic–damage response and crack propagation under uniaxial loading. In the numerical model, the nanoscale mechanical properties and the thickness of the interfacial transition zones (ITZs) were obtained based on advanced nanoindentation. The constitutive relationships of new and old cement mortars and corresponding ITZs were developed using plastic–damage constitutive relationships. The effects of the relative mechanical properties between new and old cement mortars on the failure pattern and stress–strain response of MRAC were investigated. After calibration and verification with the uniaxial compression test, the numerical model was found to be able to reveal the failure pattern and stress–strain curves of MRAC under uniaxial tension. The results showed that microcracks usually first appear around the weak new and old ITZs, and then propagate into the new and old cement mortars. With an increase in the relative strength between new and old cement mortars, the microcrack initiation locations gradually shifted from the new ITZs to the old ITZs. Therefore, the numerical results can provide insight into the modification of RAC using mix design optimisation and ITZ enhancement.

A review study on encapsulation‐based self‐healing for cementitious materials

“…Compared with experimental methods, numerical simulation seems more convenient and low‐cost, although the accuracy is sacrificed through idealizing the real self‐healing behavior and the complex properties of cementitious materials . Nevertheless, numerical analysis is a valuable technique to investigate self‐healing mechanics with parametric analysis, if there are improvements in assumptions of the nonuniform and multiaxial load conditions and consideration of the inconsistency between the capsules and cement matrix .…”

Base force element method based on the complementary energy principle for the damage analysis of recycled aggregate concrete

“…It is commonly found that the structure and characteristics of RAC are different from natural aggregate concrete (NAC) . Compared with NAC at the mesoscale, the structure of RAC is much more sophisticated, and the primary ingredients of an RAC model are regarded as a five‐phase system .…”

“…To save the resources, energy, time, and costs associated with experimental testing when conducting scientific research, [1][2][3][4] numerical investigations have become an extremely effective discipline for studying the mechanical properties of materials [5][6][7][8] and structures 2,9 and have therefore been widely used by many researchers. 6,[10][11][12][13][14] The finite element method (FEM) was first proposed by Clough.…”

“…It is commonly found that the structure and characteristics of RAC are different from natural aggregate concrete (NAC). 3,42,48,49 Compared with NAC at the mesoscale, the structure of RAC is much more sophisticated, and the primary ingredients of an RAC model are regarded as a five-phase system. 17,48 In addition to aggregates, new cement mortars, and new interfacial transition zones (New ITZs) between them, the RAC has two more mesophases compared with that of NAC: one is the old adhered mortar intrinsically clinging to the surfaces of recycled aggregates, and the second is the old ITZs between the old adhered mortars and the recycled aggregates.…”

“…1,4,6,8,68 Meanwhile, it has proven to be an important approach to compensating for the shortages of experimental work, such as observing the expansion of internal cracks, reducing the test costs, and cutting down the test time. Xiao et al developed a nine aggregates model 3,8,65 and a lattice model 13 to study the fracture process of RAC. Peng et al 7,69,70 established several random models to investigate the cracks mechanism and the stress distribution of RAC.…”