Effects of Aggregate and Specimen Sizes on Lightweight Concrete Fracture Energy

Fly ash is the largest source of industrial solid waste in China. Fly ash with its high content of unburned carbon has to be discarded in landfills and cause environmental problem. To reduce the environmental impacts, lightweight aggregate (LWA) was manufactured utilizing high-carbon fly ash (HCFA) (loss on ignition, LOI = ∼16.3%). Trial tests were conducted on high-carbon fly ash lightweight aggregate (HCFA-LWA) in a laboratory electric furnace and in a manufacturer's batch furnace. A new temperature profile was proposed for the HCFA-LWA sintering process in which carbon served as a partial fuel substitute during the burning period, which can decrease the sintering period in the sintering stage of the LWA and save energy. Then, the mechanical properties and microstructure of lightweight concrete made with the HCFA-LWA were studied. The microscopic investigation of the interfacial transition zone showed that the cement paste infiltrated into the rough surface of the HCFA-LWA and improved the mechanical interlocking between the cement paste and the HCFA-LWA. Test results showed that the HCFA-LWA concrete developed 91% of the 28 d compressive strength within 7 d. The modulus of elasticity and tensile strength were also comparable to similar grades of LWA concretes. Therefore, HCFA-LWA can be used for structural applications. The utilization of HCFA-LWA in concrete would solve the waste disposal problems that are associated with fly ash and help reduce pollution to the environment. Original language EnglishPages (from-to) 753-762

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“…Fig. 7 reported that LWA is the major component that controls the density and the compressive strength of concrete (Sim et al, 2013).…”

Section: Strength Of Hcfa-lwa Concretementioning

confidence: 99%

Manufacturing of sintered lightweight aggregate using high-carbon fly ash and its effect on the mechanical properties and microstructure of concrete

Cui

Memon

et al. 2016

Journal of Cleaner Production

108

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“…To realize the randomness of the concrete aggregate arrangement and distribution, the number and size of the aggregates must be known. The particle sizes of the ceramsite are determined according to reference (Sim et al, 2014), which are 4, 8, 13 and 19 mm, respectively. Based on the plane transformation formula of the Fuller grading curve deduced by Walraven J.C., the number of aggregates with different particle sizes is determined to ensure the compactness of concrete.…”

Section: Constructing a Meso-model Of Concretementioning

confidence: 99%

“…(Wu, 2017) and the internal length is L o 5 2.5 mm. The macro material parameters of lightweight concrete are provided by (Sim et al, 2014). The elastic modulus of the matrix and ITZ are 4/3 times and two-third times the elastic modulus of the concrete macro material, respectively, and the Poisson's ratio is the same as that of the macro material.…”

Section: Numerical Model Applicationsmentioning

confidence: 99%

“…Lightweight concrete has attracted the attention of many scholars due to its wide application in civil engineering. Sim et al (2014) studied the effects of the beam specimen size and aggregate size on the fracture energy of lightweight concrete. Three-point bending (TPB) tests were carried out on several beam specimens of different sizes, and different aggregate sizes and load-displacement curves were recorded.…”

Section: Introductionmentioning

confidence: 99%

“…Section 3 is the establishment of the meso-model of lightweight concrete. In Section 4, the uniaxial tensile, TPB and FPB mode-I failures and mixed-mode failure problems of the meso-model of lightweight concrete are analyzed based on the phase field method, and the results are compared with those of Sim et al (2014). Finally, the conclusions are given in Section 5.…”

Section: Introductionmentioning

confidence: 99%

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The meso-failure mechanism of lightweight concrete simulated by the phase field method

Wang

Gao

2021

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PurposeA mesoscopic phase field (PF) model is proposed to simulate the meso-failure process of lightweight concrete.Design/methodology/approachThe PF damage model is applied to the meso-failure process of lightweight concrete through the ABAQUS subroutine user-defined element (UEL). And the improved staggered iteration scheme with a one-pass procedure is used to alternately solve the coupling equations.FindingsThese examples clearly show that the crack initiation of the lightweight concrete specimens mainly occurs in the ceramsite aggregates with weak strength, especially in the larger aggregates. The crack propagation paths of the specimens with the same volume fraction of light aggregates are completely different, but the crack propagation paths all pass through the ceramsite aggregates near the cracks. The results also showed that with the increase in the volume fractions of the aggregates, the slope and the peak loads of the force-deflection (F-d) curves gradually decrease, the load-bearing capacity of the lightweight concrete specimens decreases, and crack branching and coalescence are less likely during crack propagation.Originality/valueThe mesostructures with a mortar matrix, aggregates and an interfacial transition zone (ITZ) are generated by an automatic generation and placement program, thus incorporating the typical three-phase characteristics of lightweight concrete into the PF model.

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Critical Crack-Tip Opening Displacement of SCLC

Mazloom

Karamloo

2018

Lecture Notes in Civil Engineering

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Effects of Aggregate and Specimen Sizes on Lightweight Concrete Fracture Energy

Cited by 28 publications

References 19 publications

Manufacturing of sintered lightweight aggregate using high-carbon fly ash and its effect on the mechanical properties and microstructure of concrete

Manufacturing of sintered lightweight aggregate using high-carbon fly ash and its effect on the mechanical properties and microstructure of concrete

The meso-failure mechanism of lightweight concrete simulated by the phase field method

Critical Crack-Tip Opening Displacement of SCLC

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