Impact of cation type and fly ash on deterioration process of high belite cement pastes exposed to sulfate attack

Jiang, Chunmeng; Jiang, Linhua; Li, Shuangxi; Tang, Xinjun; Zhang, Lei

doi:10.1016/j.conbuildmat.2021.122961

Cited by 28 publications

(10 citation statements)

References 27 publications

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“…In addition, when the depth reached a particular value, the values of SO 4 2− content almost remained constant, similar to the variation of the HV with the depth. It is reported that the corrosion depth under sulfate attack could be fixed by the variation of the SO 4 2− content, from the exposed surface to the position with an almost constant SO 4 2− content [ 14 , 44 ]. The sample with the largest corrosion depth was S, then followed by 2-O, 5-O, 2-C, and 5-C.…”

Section: Resultsmentioning

confidence: 99%

“…Mass variation and porosity are the commonly used indicators to evaluate the cement paste’s sulfate corrosion degree. During this experiment, the mass variation (

) and porosity (

) of specimens were calculated as follows:

where

and

are the mass of the same cylindrical specimens with and without sulfate exposure, respectively, which were air-dried to a constant value in the laboratory before measurement;

is the saturated surface dry mass of subsample B (in Figure 3 );

is the mass of subsample B (in Figure 3 ) after drying at 40 °C for 24 h;

is the volume of subsample B (in Figure 3 ) measured using the drainage method; and

is the water density [ 14 ].…”

Section: Methodsmentioning

confidence: 99%

“…For instance, Müllauer et al [ 5 ] and Yu et al [ 6 ] revealed the expansion damage mechanisms of cement-based materials in the sulfate environment. Xiong et al [ 12 , 13 ] and Jiang et al [ 14 ] evaluated the influence of sulfate type, cation type, and fly ash on the deterioration process of cement paste exposed to sulfate. Qin et al [ 15 ] assessed the effect of CO 2 curing and low-temperature sulfate solution on the performance degradation of cement-based materials.…”

Section: Introductionmentioning

confidence: 99%

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Effect of Layered Double Hydroxides on the Deterioration Process of Cement Paste under Sulfate Attack

et al. 2022

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This study investigated the effect of layered double hydroxides (LDHs) on the deterioration process of cement paste in the sulfate environment. Cement pastes with the addition of original and calcined LDHs at 2.5 wt.% and 5.0 wt.% of cement were exposed to Na2SO4 solution for 360 days. The macroscopic performance of the cement paste was assessed based on mass variation, porosity, compressive strength, and content of sulfate ions. Furthermore, the microhardness, microstructures, and composition of the degraded pastes were examined using Vickers hardness (HV), mercury intrusion porosimetry (MIP), scanning electron microscope (SEM), X-ray diffraction (XRD), and thermogravimetric analysis (TGA). The results indicate that cement paste incorporated with LDHs can mitigate the corrosion caused by sulfate effectively, especially in the case of calcined LDHs (C-LDHs), which primarily increase the adsorption of sulfate. Compared with the control specimen, the 180 d compressive strength loss ratio of specimens with 2.5 wt.% and 5.0 wt.% of C-LDHs decreased by 63.66% and 80.51%, respectively. Moreover, LDHs can reduce the amount of ettringite crystals, densify the microstructure, and refine the pore structure to mitigate the cement paste’s sulfate corrosion significantly. Compared with the control specimen, the 180 d harmful pore volume fraction of specimens laced with 2.5 wt.% and 5.0 wt.% C-LDHs decreased by 43.77% and 54.51%, respectively. In terms of the content of C-LDHs, an optimal content of C-LDHs could ensure the dominant effect of adsorption, while excessive C-LDHs could refine pores. In addition, Vickers hardness has an excellent correlation with compressive strength, which could precisely predict the compressive strength. Moreover, by combining the Vickers hardness distribution and content distribution of sulfate ions, the cross-section of the paste could be classified into four regions to evaluate the deterioration process accurately: the degraded zone, the strengthened zone, the invaded zone, and the intact zone.

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Section: Resultsmentioning

confidence: 99%

“…Mass variation and porosity are the commonly used indicators to evaluate the cement paste’s sulfate corrosion degree. During this experiment, the mass variation (

) and porosity (

) of specimens were calculated as follows:

where

and

are the mass of the same cylindrical specimens with and without sulfate exposure, respectively, which were air-dried to a constant value in the laboratory before measurement;

is the saturated surface dry mass of subsample B (in Figure 3 );

is the mass of subsample B (in Figure 3 ) after drying at 40 °C for 24 h;

is the volume of subsample B (in Figure 3 ) measured using the drainage method; and

is the water density [ 14 ].…”

Section: Methodsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Effect of Layered Double Hydroxides on the Deterioration Process of Cement Paste under Sulfate Attack

et al. 2022

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“…In terms of application properties, belite-rich cements provide lower water demand, better compatibility with most plasticizing admixtures, lower heat evolution and lower drying shrinkage compared to OPC [ 3 ]. Last but not least, belite cements have also been shown to have better durability in terms of resistance to sulfates [ 5 ] and acids [ 6 ], mainly due to a smaller amount of portlandite in the hydration products. Unfortunately, these advantages are overshadowed by lower early strength development.…”

Section: Introductionmentioning

confidence: 99%

Effect of Alkali Salts on the Hydration Process of Belite Clinker

et al. 2022

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Belite-rich cement is a low carbon footprint binder. However, its use is accompanied by a low initial rate of hydration. This can be partially eliminated by grinding to a high specific surface or through the addition of admixtures (mineralizators or activators). The influence of alkaline activators CaSO4, Na2SO4 and Na2CO3 (in the amount of 5 wt.% related to the clinker weight) on the hydration course, as well as the quantity of hydration products in belite-rich cements, were investigated in this paper. Belite-rich clinker was laboratory-synthetized and ground together with activators to prepare various belite-rich cements. Next, the hydration kinetics and the hydrated phase assemblage were investigated using isothermal calorimetry, X-ray powder diffraction and thermogravimetric and differential thermal analyses. The use of selected admixtures allowed us to obtain belite-rich cements with higher hydraulic activity in the initial period.

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“…In recent years, with the increase in the construction of sewer pipes and underground structures, durability design against sulfate attack has emerged as an important issue [15,16]. For the analysis of sulfate ingress, previous studies have mainly employed methods such as the evaluation of the deterioration depth, considering the sulfate ion diffusion coefficient and the cement components [14,17], evaluation of the rate of strength reduction through an accelerated sulfate ion resistance test [13,18], or diffusion analysis considering the multiple deteriorated layers [19,20]. Furthermore, underground structures are always exposed to ground water and are difficult to maintain, so repair techniques that are resistant to bio-chemical deterioration are required.…”

Section: Introductionmentioning

confidence: 99%

Enhancement of Strength and Resistance to Sulfate Attack in Bio-Coating Material through Negative Pressure Method for Bacteria Immobilization

2021

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In recent years, many studies have been performed on the crack repairing technique in concrete or the protection of the concrete surface against sulfate ions. Bacterial immobilization and survival rate are the dominant influencing factors for the repair of concrete. In this study, a negative pressure method (NPM) was developed to forcibly remove air in the porous materials of concrete, which was applied for surface repair through bio-coating using Rhodobacter capsualtus. For normal repair—repair using the conventional simple soaking method (SSM) and repair through NPM—various evaluations of the concrete strength and durability were performed. Since a reinforced concrete (RC) structure for the application of these repair methods is a sewer pipe exposed to sulfate ingress, variations in concrete mass and strength were analyzed by the accelerated sulfate resistance test. The diffusion coefficient of the sulfate ion in the repair materials and the bacterial count after the accelerating test were also measured. In order to investigate the changes in the properties of the concrete hydrates, surface analyses with SEM, XRD, and TGA were carried out on the concrete under the repair layer after the tests. In all the experimental results, the bacterial immobilization rate was evaluated, and the high immobilization rate indicates the excellent shielding of sulfate ions as well as improves the survival rate of bacteria. This not only improves the service life of the coating repair but also extends the service life of the structure itself. As a result of analyzing the composition of concrete protected by different types of repair, the results most similar to the general concrete composition without sulfate attack were obtained in the case of applying NPM, which shows the least damage from sulfate attack.

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Impact of cation type and fly ash on deterioration process of high belite cement pastes exposed to sulfate attack

Cited by 28 publications

References 27 publications

Effect of Layered Double Hydroxides on the Deterioration Process of Cement Paste under Sulfate Attack

Effect of Layered Double Hydroxides on the Deterioration Process of Cement Paste under Sulfate Attack

Effect of Alkali Salts on the Hydration Process of Belite Clinker

Enhancement of Strength and Resistance to Sulfate Attack in Bio-Coating Material through Negative Pressure Method for Bacteria Immobilization

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