Evaluation of elastic modulus of cement paste in sodium sulfate solution by an advanced X-CT–hydration–deterioration model with SC method

Li, Yue; Guan, Zhongzheng; Wang, Zigeng; Zhang, Guosheng; Ding, Qingjun

doi:10.1680/jadcr.18.00142

Cited by 7 publications

(6 citation statements)

References 33 publications

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“…Therefore, the corrosion degree of mortar was uneven inside and outside. Considering the influence of temporal and spatial distribution for the process of sulfate attack on mortar, the author of this paper coupled the effects of cement hydration and sulfate corrosion and established an X-CT-hydration–deterioration model [ 42 ]. On level I, the corroded cement paste matrix was regarded as a composite material composed of 10 phases on the micro-scale.…”

Section: Evaluation Of the Elastic Modulus Of Corroded Mortar By Homo...mentioning

confidence: 99%

Experimental–Computational Investigation of the Elastic Modulus of Mortar under Sulfate Attack

Guan,

Zhang,

Gao

et al. 2023

Materials

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External sulfate attack is an important factor causing a decrease in the mechanical properties of cement-based materials. In this paper, a computational prediction model of elastic modulus, considering the characteristics of sulfate corrosion from outside to inside and the influence of the interface transition zone (ITZ), was established to predict the elastic modulus of mortar under the external sulfate attack. Firstly, the backscattered electron (BSE) images of mortar and the algorithm of image threshold segmenting were used to determine a reasonable thickness of corroded ITZ. Secondly, the nanoindentation test was adopted to acquire the microscopic elastic parameters of phases (sand, cement, and ITZ) in corroded mortar. Moreover, the mortar mix proportion and Lu and Torquato’s model were adopted to calculate the volume fractions of phases. Finally, a computational prediction model of elastic modulus of mortar under sulfate attack was proposed with homogenization methods. The results indicate that the thickness of corroded ITZ is 20 mm, and the error values of elastic modulus between the theoretical prediction results and the experimental results are within 8%, indicating that the macroscopic elastic modulus of corroded mortar can be precisely predicted by the computational prediction model of elastic modulus.

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Section: Evaluation Of the Elastic Modulus Of Corroded Mortar By Homo...mentioning

confidence: 99%

Experimental–Computational Investigation of the Elastic Modulus of Mortar under Sulfate Attack

Guan,

Zhang,

Gao

et al. 2023

Materials

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“…The elastic parameters of the equivalent matrix in the corroded mortar were deduced by two-step homogenization methods [ 40 ]. The solution process of the elastic parameters was as follows: On the microscale, the corroded cement paste was regarded as a composite of 10 microphases [ 13 ]. Considering the influence of the erosion time and the spatial distribution of sulfate ions, the mechanical parameters and volume fractions of the microphases of the corroded cement paste were determined from the results of nanoindentation tests and the X-CT–hydration–deterioration model [ 40 ].…”

Section: Mesoscale Fe Simulation Of Corroded Mortar Under Uniaxial Co...mentioning

confidence: 99%

“…The compressive strength of the cement paste at 88d was 54.992 MPa (M1) and 60.54 MPa (M2) [ 13 ]. According to the plane section assumption and the minimum compressive strain criterion, the compressive strength values of the equivalent matrix in the M1 and M2 mortar could be obtained using the Voigt parallel model with the volume fractions, elastic modulus, and compressive strength of the ITZ and cement.…”

Section: Mesoscale Fe Simulation Of Corroded Mortar Under Uniaxial Co...mentioning

confidence: 99%

“…Many environments, such as seawater, brine, groundwater, decaying organic matter, and industrial effluent, contain a large amount of sulfate, which can significantly corrode concrete structures [ 6 , 7 , 8 ]. The study of the durability and mechanical properties of cement-based materials under external sulfate attack has become a major issue in structural engineering in recent decades [ 9 , 10 , 11 , 12 , 13 ]. As is well-known, the mortar scale is the midpoint between the cement scale and the concrete scale.…”

Section: Introductionmentioning

confidence: 99%

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Mesoscale Finite Element Modeling of Mortar under Sulfate Attack

Guan

Wang

et al. 2022

Materials

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In this paper, a 2D mesoscale finite element (FE) numerical model of mortar, considering the influence of the ITZ, was proposed to evaluate the corrosion of mortar in sodium sulfate. On the mesoscale, the corroded mortar was regarded as a three-phase composite material composed of sand, cement paste, and an interface transition zone (ITZ). Firstly, the volume fractions and mechanical parameters (elastic modulus, Poisson’s ratio, and strength) of the mesoscale phases were obtained. Then, the cement paste and the ITZ were combined to form an equivalent matrix by homogenization methods, and the calibrated constitutive relations of the equivalent matrix were established. Subsequently, a two-dimensional (2D) random circular aggregate (RCA) model and a 2D random polygonal aggregate (RPA) model of corroded mortar were established using the random aggregate model. The failure process of corroded mortar specimens under uniaxial compression was simulated by the mesoscale FE numerical model. Comparing the simulation results with the measured stress–strain curves of the uniaxial compression test, it was found that the simulation results of the 2D RP model were closer to the experimental results than those of the 2D RC model. Meanwhile, the numerical simulation results were in good agreement with the experimental results, and the error values of peak stress between the simulation results and the measured results were within 7%, which showed that the 2D mesoscale FE model could accurately predict the results of a uniaxial compression test of a mortar specimen under sulfate attack.

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“…As the structural change of concrete after damage has an important impact on its performance, the testing and analysis technology of concrete structure becomes a powerful support in the research of concrete damage. In various structural tests, CT scanning is extremely suitable for studying the evolution law of the internal microstructure of concrete samples in the process of erosion because it can continuously record the internal images of the samples [ 20 , 21 , 22 ]. With the help of digital model reconstruction technology, CT scan images can be restored into visual data models, which have positive significance for the study of the erosion process of the whole sample.…”

Section: Introductionmentioning

confidence: 99%

Compartmentalized Quantitative Analysis of Concrete Sulfate-Damaged Area Based on Ultrasonic Velocity

et al. 2023

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The corrosion of concrete in sulfate environments is a difficult problem in the durability of civil engineering structures. To investigate the variability of deterioration damage to concrete structures by sulfate erosion under non-destructive testing and quantify the protective effect of silane coatings on concrete under the action of sulfate erosion, an accelerated erosion experiment was carried out using field sampling in a tunnel project under a sulfate erosion environment. By means of ultrasonic velocity measurement and CT scanning, the samples protected by a silane coating under the sulfate attack environment were compared with those not protected. The deterioration characteristics of concrete under the sulfate attack environment and the protective effect of silane coating on the concrete structure were analyzed. In addition, a method for evaluating the sulfate damage to concrete based on CT images and ultrasonic velocity analysis was proposed. The results show that the samples prepared in the field show a significant difference in ultrasonic velocity in the process of erosion and deterioration according to the material difference at the measuring point interface. Through the overall damage evaluation analysis of the sample, it is concluded that the damage degree of the protected group sample is light and the heterogeneity is weak, whereas the local damage to the exposed group is serious. Combined with the CT image analysis of concrete before and after loading, the distribution characteristics of the damaged area divided by the concrete sulfate damage evaluation method proposed in this paper are highly similar to the real situation. The results of the study can provide a reference for similar projects for the detection, analysis, protection and evaluation of sulfate-attacked concrete.

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Evaluation of elastic modulus of cement paste in sodium sulfate solution by an advanced X-CT–hydration–deterioration model with SC method

Cited by 7 publications

References 33 publications

Experimental–Computational Investigation of the Elastic Modulus of Mortar under Sulfate Attack

Experimental–Computational Investigation of the Elastic Modulus of Mortar under Sulfate Attack

Mesoscale Finite Element Modeling of Mortar under Sulfate Attack

Compartmentalized Quantitative Analysis of Concrete Sulfate-Damaged Area Based on Ultrasonic Velocity

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