Effect of supercritical carbonation on the strength and heavy metal retention of cement-solidified fly ash

Zha, Xiaoxiong; Ning, Jiaqian; Saafi, Mohamed; Dong, Lijun; Dassekpo, Jean-Baptiste Mawulé; Ye, Jianqiao

doi:10.1016/j.cemconres.2019.03.005

Cited by 36 publications

(13 citation statements)

References 38 publications

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“…Moreover, it was found that the box dimension declined when the carbonation depth increased, indicating that the data of compressive strength were increasingly centralized. Therefore, it was concluded that carbonation-induced corrosion can result in the decrease of compressive strength of concrete, in agreement with conclusion Zha [35].…”

Section: Range Of Carbonation Depth (Mpa)supporting

confidence: 86%

Time-Varying Reliability Evaluation of Concrete Based on Carbonation Depth

et al. 2019

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When studying concrete impairment, the carbonation depth of concrete is regarded to be variable. Therefore, a time-varying reliability evaluation is important to perform a structural safety assessment. By analyzing 13,198 data on the carbonation depth of concrete, we propose a time-varying reliability evaluation based on the third-moment (TM) method to predict the service life of concrete. Validated by Monte Carlo (MC) simulation, the errors of the calculated results using time-varying reliability evaluation were within 4%. It is shown that the TM method proposed in this paper is more practical than traditional approaches such as MC simulation and second-moment (SM) methods in probability analysis. In this paper, exponential distribution was used to characterize the distribution of carbonation depths. Since paint was present on the concrete surface, numerous uncarbonized concrete components were found in the experiments; to develop a time-varying model considering the uncarbonized components, a function for evaluating the ratio of carbonized concretes is proposed. Overall, the time-varying TM method provided in this paper can act as a foundation for other investigations on probabilistic analysis, e.g., of compressive strength, deflection, and crack of concrete, which can be used to evaluate the reliability of concrete.

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Section: Range Of Carbonation Depth (Mpa)supporting

confidence: 86%

Time-Varying Reliability Evaluation of Concrete Based on Carbonation Depth

et al. 2019

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“…In addition, it is known that the carbonation depth increased with the increase of time. Therefore, combined with the definition of carbonation depth, it was concluded that carbonation-induced corrosion can result in the decrease of compressive strength of concrete, which agrees with the conclusion drawn from Zha [40].…”

Section: Prediction For the Mean Value Of Compressive Strengthsupporting

confidence: 84%

“…On the basis of the building code calibration, concrete quality is determined by the guaranteed rate of above 95% [40]. Therefore, to evaluate concrete failure time based on reliability, the guaranteed rate was applied in this paper.…”

Section: Concrete Guaranteed Rate and Concrete Failure Timementioning

confidence: 99%

Prediction of Concrete Failure Time Based on Statistical Properties of Compressive Strength

et al. 2020

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Since the heterogeneity of the cement-based material contributes to a random spatial distribution of compressive strength, a reliability analysis based on the compressive strength of concrete is fundamental to carry out structural safety assessment. By analyzing 10,317 datapoints on compressive strength of concrete, a time-varying reliability evaluation based on the third-moment (TM) method was proposed to predict the service life of concrete. Unlike the second-moment (SM) method, skewness is taken into account in the TM; thus, the calculated result of concrete failure time based on the TM is more accurate. In this paper, the errors of the calculated results using time-varying reliability evaluation are within 3%, as shown by Monte Carlo (MC) simulation. In addition, the proposed model (aiming to calculate the equivalent design compressive strength) verifies the concrete failure time calculated by time-varying reliability. According to the results, concrete failure times calculated by these two models are in good agreement. Overall, based on the simple and effective methodology adopted in this paper, it is feasible to develop time-varying reliability based on other factors that might also lead to concrete failure, such as carbonation-induced corrosion, cracking, or deflection of the concrete.

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“…Supercritical carbonation can accelerate the study of the aging characteristics of solidified products [90]. Zha et al [91] used a CO 2 closed-cycle system [92] to study the heavy metal leaching characteristics of supercritical carbonated cement product, and found that supercritical carbonation promoted the leaching of Cu and Pb.…”

Section: Principle Of Cement Solidification Methodsmentioning

confidence: 99%

“…In addition, the aging and carbonation of solidification products resulted in an increasing amount of calcium carbonate in the voids of the cement. The generated calcium carbonate exceeded the limit of the pores, which caused additional internal pressure and micro-cracks, thereby reducing the mechanical strength of the cement product [91]. It is evident that the cement solidified product of MSWI fly ash can only be used as a low-strength road basement, and base construction material [99].…”

Section: Effect Of Cement Solidification Of Fly Ash On the Mechanicalmentioning

confidence: 99%

Review of harmless treatment of municipal solid waste incineration fly ash

Zhang

Fang

et al. 2020

Waste Dispos. Sustain. Energy

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Incineration is widely adopted in municipal solid waste management, which produces large amounts of municipal solid waste incineration (MSWI) fly ash. The harmless treatment of MSWI fly ash requires the appropriate disposal of heavy metals and dioxins that are enriched in fly ash. This review summarizes recently developed harmless disposal methods for MSWI fly ash including solidification/stabilization, thermal treatment, and separation/extraction. In addition, we discuss heavy metal and dioxin fixation, and the removal capacity of fly ash via solidification/stabilization (including cement solidification, chemical stabilization, hydrothermal processes, and mechano-chemical methods), thermal treatment (including sintering, fuel-burning, or electric melting/vitrification), and separation/extraction (including water-washing, chemical reagent leaching, biological leaching, electrodialysis separation, chemical reagent extraction, and nanomaterials extraction). The advantages and disadvantages of different harmless treatment methods are compared and future research prospects and suggestions are summarized. This review provides general guidelines for the harmless treatment of MSWI fly ash in the future.

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Effect of supercritical carbonation on the strength and heavy metal retention of cement-solidified fly ash

Cited by 36 publications

References 38 publications

Time-Varying Reliability Evaluation of Concrete Based on Carbonation Depth

Time-Varying Reliability Evaluation of Concrete Based on Carbonation Depth

Prediction of Concrete Failure Time Based on Statistical Properties of Compressive Strength

Review of harmless treatment of municipal solid waste incineration fly ash

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