Study of the basic mechanical properties and degradation mechanism of recycled concrete with tailings before and after carbonation

Li, Tao; Wang, Sheliang; Xu, Fan; Meng, Xiangyin; Li, Binbin; Zhan, Meng

doi:10.1016/j.jclepro.2020.120923

Cited by 67 publications

(34 citation statements)

References 31 publications

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“…In Figure 9b, we observed a large amount of calcium silicate hydrate (C-S-H) gel, needle-like crystals (ettringite), and IOTs. IOTs had a certain pozzolanic activity and can react with calcium hydroxide to form C-S-H gel, which made the microstructure of the concrete denser, improving the strength of RAC [33,38]. This result was consistent with that of our previous study that showed that IOTs improved the compressive strength of RAC [13].…”

Section: Microstructuresupporting

confidence: 90%

“…Five concrete mixtures were prepared with water-cement ratio of 0.4, as shown in Table 5. In our previous papers, RAC containing 30% IOTs exhibited the best mechanical properties [13,[31][32][33]. Consequently, control concrete was prepared by adding 30% RCA instead of NCA and 30% IOTs instead of natural sand.…”

Section: Mixture Proportion and Specimen Preparationmentioning

confidence: 99%

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Compressive Behavior, Microstructural Properties, and Freeze–Thaw Behavior of Tailing Recycled Aggregate Concrete with Waste Polypropylene Fiber Addition

et al. 2021

Materials

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To improve the high brittleness of recycled aggregate concrete containing iron ore tailings (TRAC), the feasibility of adding polypropylene fiber (PPF) to TRAC was studied by performing a compression stress–strain curve test, scanning electron microscope characterization, and a freeze–thaw cycle test. The results indicated that PPF had a beneficial impact on reducing the brittleness of TRAC. With the increase in PPF content, the peak strain increased, the elastic modulus decreased, and the peak stress and energy absorption capacity increased at first and then decreased. Furthermore, the microstructure investigation revealed that the interface friction between the PPF, aggregate, and cement matrix was the main source of energy dissipation. When the load acted on the concrete, the stress was dispersed to the fiber monofilaments, thus effectively enhancing the peak stress and peak strain of concrete and suppressing the generation and development of cracks in the concrete. In terms of freeze–thaw resistance, adding a small amount of PPF could reduce the negative effects of the freeze–thaw process on the cement matrix. On the premise of ensuring strength, the waste utilization should be as high as possible. Therefore, it was suggested that the content of PPF in fiber-reinforced tailings recycled aggregate concrete (TRAC-PP) should be 0.6%.

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Section: Microstructuresupporting

confidence: 90%

Section: Mixture Proportion and Specimen Preparationmentioning

confidence: 99%

Compressive Behavior, Microstructural Properties, and Freeze–Thaw Behavior of Tailing Recycled Aggregate Concrete with Waste Polypropylene Fiber Addition

et al. 2021

Materials

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“…Furthermore, the compressive strength of concrete firstly increased and then decreased with the increasing dosages of dolomites and iron tailings. This was attributed to the fact that the filling effect of dolomites and iron tailings could improve the compactness of concrete, thus increasing the compressive strength of the concrete [40,41]. Moreover, the active substances of dolomites and iron tailings could promote the hydration of cement, thus improving the compressive strength [42].…”

Section: The Compressive Strength and Chloride Ion Permeabilitymentioning

confidence: 99%

Influence of Dolomite Rock Powder and Iron Tailings Powder on the Electrical Resistivity, Strength and Microstructure of Cement Pastes and Concrete

et al. 2022

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Dolomite rock powder (the waste stone residue in the production of machine-made sand and stone processing) and iron tailings powder formed by mineral processing industry are solid wastes, which occupy land resources, pollute the environment and release toxic substances without reasonable processing. The dolomite rock powder and iron tailings powder composing a large number of active substances could be advantageous to the cement-based materials. In this study, the electrical resistivity of cement paste and concrete was measured. Meanwhile, the influence of dolomite rock powder and iron tailings powder on the compressive strength of concrete was investigated. The electric flux of concrete was determined to estimate the chloride ion permeability. The scanning electron microscope (SEM) and X-ray diffraction were obtained to investigate the hydration of cement paste. Results showed the electrical resistivity of all specimens presented in this order: specimens with iron tailings < specimens with dolomite rock powder < blank specimens < specimens with ground granulated blast-furnace slag (GGBS) < specimens with fly ash. The correlation between electrical resistivity and curing age of cement paste or concrete has been deduced as a quadratic function. The addition of GGBS could improve the compressive strength of concrete. Meanwhile, when the other three types of mineral admixtures were added, 5% by mass ratio of the total binder materials was the optimum for the compressive strength. The curing ages, the fly ash, the GGBS and 5% dolomite rock powder or 5% iron tailings powder demonstrated a positive effect on the chloride ion impermeability. However, when higher dosages of dolomite rock powder or iron tailings powder were added, the effect was the opposite. Finally, the compactness of the microstructure and the Ca(OH)2 of cement paste could be improved by a small dosage of dolomites or iron tailings (less than 5%).

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“…Their massive accumulation will not only cause land pollution, poor water quality, and aggravation of dust but also threaten human health [10]. The managers of mining enterprises need to spend more resources to maintain IOT ponds every year [11]. More seriously, the existence of tailing dams is a potential safety hazard, and the human life safety events caused by the tailings dam breaks around the world are increasing every year [9].…”

Section: Introductionmentioning

confidence: 99%

Effects of HPMC on Workability and Mechanical Properties of Concrete Using Iron Tailings as Aggregates

Zhang

et al. 2021

Materials

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Iron ore tailings (IOTs) are gradually used as building materials to solve the severe ecological and environmental problems caused by their massive accumulation. However, the bulk density of IOT as aggregate is too large, which seriously affects the concrete properties. Therefore, in this paper, the effect of hydroxypropyl methylcellulose (HPMC) on the workability, mechanical properties, and durability of concrete prepared from IOT recycled aggregate was studied. The action mechanism of HPMC on the workability and the mechanical properties of the IOT concrete was analyzed by mercury intrusion porosimetry (MIP) and scanning electron microscope (SEM). The results show that HPMC can effectively improve the segregation problem caused by the sinking and air entrainment of IOT aggregate and improve the crack resistance of concrete with little effect on its compressive strength and electric flux. These results are due to the air-entraining thickening effect of HPMC, which improves the slurry viscosity, hinders the sinking of aggregate, and improves the workability. At the same time, HPMC film, after concrete hardening, will bridge the slurry and aggregate through physical and chemical effects, hinder the propagation of microcracks, and improve the crack resistance.

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Study of the basic mechanical properties and degradation mechanism of recycled concrete with tailings before and after carbonation

Cited by 67 publications

References 31 publications

Compressive Behavior, Microstructural Properties, and Freeze–Thaw Behavior of Tailing Recycled Aggregate Concrete with Waste Polypropylene Fiber Addition

Compressive Behavior, Microstructural Properties, and Freeze–Thaw Behavior of Tailing Recycled Aggregate Concrete with Waste Polypropylene Fiber Addition

Influence of Dolomite Rock Powder and Iron Tailings Powder on the Electrical Resistivity, Strength and Microstructure of Cement Pastes and Concrete

Effects of HPMC on Workability and Mechanical Properties of Concrete Using Iron Tailings as Aggregates

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