Compressive Behaviors of Prisms Made of Demolished Concrete Lumps and Fresh Concrete

Abstract

Directly adopting coarsely crushed demolished concrete lumps (DCLs) with pouring concrete (referred to as fresh concrete, FC) in new structural members has been demonstrated to be more efficient and environmental than the traditional approach of recycling waste concrete as coarse aggregate particles. In this study, 45 prisms made of FC and DCLs were tested under axial compressive loading up to failure. The varied parameters included the dimensions of the prisms, the replacement ratio of DCLs, and the characteristic size of the lumps. The compressive performance of 36 cubes and cylinders was also experimentally examined for comparison. A formula was developed to predict the strength of compound concrete prisms filled with DCLs. Empirical formulas were also established relating a prism's strength with its elastic modulus and peak strain. It was found that: (a) when the replacement ratio is between 20% and 40%, the strength of a prism is about 1.13 that of a cylinder, due to the casting direction of the prism being different from that of the cylinder; (b) as the size of filler lumps increases relative to the size of the specimen, the strength of prisms decreases faster than that of cylinders, which weaken faster than cubes; and (c) due to the coupling effect of the aggregate size of FC and the specimen size, the compressive strength of prisms first increases with their size and then declines gradually.

Behaviour of FRP-confined compound concrete–filled circular thin steel tubes under axial compression

“…Extensive research has been conducted by Wu’s group (Wu et al, 2013, 2014, 2015, 2016, 2018a, 2018b, 2018c, 2019; Wu and Jin, 2019; Zhao et al, 2016) in the previous decade, demonstrating the effectiveness of this recycling method. The Wu’s group research is mainly focused on compound concrete–filled steel tubes.…”

Axial Compressive Behavior of Geopolymer Recycled Lump Concrete

“…As a result, lower hydration heat is released during recycled lump concrete production. A series of studies showed that recycled lump concrete has comparable mechanical properties such as compressive strength and elastic modulus [19][20][21][22], tensile strength [23] and durability [24,25] with OPC concrete. The structural members, made of recycled lump concrete, exhibit similar flexural and shear behavior [26,27], compression behavior [28], fire resistance [29], seismic performance [30] and long-term creep behavior [31] as the benchmark members made with fresh OPC concrete alone.…”

Emerging Construction Materials and Sustainable Infrastructure

“…In the study of properties of sustainable construction materials, "green" concrete materials [20][21][22][23], composite materials [24,25], recycled materials [26][27][28], soil/rock materials [29,30] and other novel environmentally friendly construction materials [31,32] are reported in this issue. The investigations of the behaviours of structures constructed with different materials include demolished concrete structures [33,34], high-performance concrete structures [35], steel structures [36,37], steel-concrete composite structures [38,39] and fiber-reinforced polymer (FRP)-concrete hybrid structures [40][41][42][43]. In addition, seismic behaviour and the interaction behaviour between superstructure and substructure are discussed in two papers [44,45].…”