Calcium hydroxide content and hydration degree of cement in cementitious composites containing calcium silicate slag

Bai, Ru; Ju, Zhang; Yan, Changwang; Wang, Xiaoxiao; Yang, Zhijie

doi:10.1016/j.chemosphere.2021.130918

Cited by 18 publications

(5 citation statements)

References 21 publications

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“…Combined with the decomposition temperature limits between C–S–H, Ca(OH) 2 , and CaCO 3 of various researchers, the temperature ranges and corresponding mass losses of L dh1 , L dh2 , L dh3 , and L dc are assigned, as shown in Figure and Table . − The hydration degree coefficient α and Ca(OH) 2 content W CH of each cement paste specimen at different ages calculated according to eqs – are shown in Table .…”

Section: Resultsmentioning

confidence: 99%

Enhancement of Cement Paste with Carboxylated Carbon Nanotubes and Poly(vinyl alcohol)

Zhao

Zhang

Qiao

et al. 2022

ACS Appl. Nano Mater.

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Cement has been a major consumable material for construction in the world since its invention, but its low flexural strength is the main defect affecting the service life of structures. To adapt cement-based materials to a more stringent environment, carboxylated carbon nanotubes (CNTs-COOH) and poly(vinyl alcohol) (PVA) are proposed to enhance the mechanical properties of cement paste. This study systematically verifies the synergistic effect of CNTs-COOH/PVA on the performance of cement paste. First, UV–Vis spectroscopy and FTIR spectroscopy prove that CNTs-COOH can provide attachment sites for PVA and PVA can improve the dispersion and stability of CNTs-COOH in water, which demonstrates the feasibility of synergistically enhancing cement paste. When a 0.015% CNTs-COOH suspension with 0.1% PVA is added, the flexural strength of the cement paste increases by 73, 32, and 42% compared with control specimens at curing ages of 3, 7, and 28 days, respectively. The strength enhancement mechanism is revealed from the aspects of cement matrix enhancement and interface enhancement. Thermogravimetric (TG) analysis and mercury intrusion porosimetry (MIP) prove that CNTs-COOH can enhance the hydration degree of the cement matrix and fill the pores introduced by PVA. Based on the fact that PVA can improve the dispersibility and the nucleation site effect of CNTs-COOH in cement paste, molecular dynamics simulation confirms that PVA can bridge CNTs-COOH and C–S–H to enhance the interfacial bonding by 64.1%.

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Section: Resultsmentioning

confidence: 99%

Enhancement of Cement Paste with Carboxylated Carbon Nanotubes and Poly(vinyl alcohol)

Zhao

Zhang

Qiao

et al. 2022

ACS Appl. Nano Mater.

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“…This behavior is attributed to factors such as the water content that reduces the function of Na 2 SiO 3 . The low porosity as a function of time is explained by the high initial concentrations of SiO 4 in the pore solution and the increasing dissolution of quartz [31]. Another factor is the production of calcium hydroxide in the cementitious hydration processes, resulting in the formation of hydrated calcium silicates that fill the existing pores in the concrete mixtures, reducing porosity [32,33].…”

Section: Electrochemical Impedance Spectroscopymentioning

confidence: 99%

“…Figure 6 shows the results obtained by applying the ASTM C1202 standard to determine the permeability of concrete to chloride ions. This methodology measures the passage of an electrical current through concrete samples [31,32]. The behavior of the analyzed concretes as a function of the transferred load is observed (Figure 6).…”

Section: Resistance To Chloride Ion Penetrationmentioning

confidence: 99%

Effect of Immersion Time in Chloride Solution on the Properties of Structural Rebar Embedded in Alkali-Activated Slag Concrete

Aperador

Bautista-Ruiz

Sánchez-Molina

2022

Metals

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The electrochemical impedance spectroscopy (EIS) technique is widely used in the study of the corrosion of metallic materials. This method also allows for the electrical characterization at the ceramic–metal interface in contact with an aqueous solution composed of chloride ions. EIS makes it possible to discriminate the contribution of the phenomena that occur in the interface to determine the porosity of the cementitious material. The porosity determines the degree of corrosion of the metallic material and the diffusion processes on the electrode surface. In this study, the degradation of a type of non-Portland cement obtained from blast furnace steel slag and activated alkali was evaluated. This type of cement is of great interest because it avoids the emission of CO2 during its manufacture. Estimating the porosity determined the degree of deterioration suffered by the steel embedded in the concrete as a function of the evaluation time. The hydrated samples were also characterized by 29Si magic angle spinning nuclear magnetic resonance (MAS-NMR) to determine the structure of the formed calcium silicate hydrate (C-S-H) gel. This mixture formed a C-S-H gel, constituted mainly of silicon in the middle groups, in chains in the disilicates. The effect of the slag was remarkable in improving the other evaluated characteristics, i.e., in the porous matrix, the concrete was found to significantly reduce the current passing through as a function of time, showing a reduction in porosity and an increase in impedance because of the generated pozzolanic reaction.

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“…Slag can induce the "volcanic ash effect", reacting with calcium hydroxide produced by cement hydration to form hydrated calcium silicate [18], hydrated aluminum silicate, and other cementitious materials. This reduces the aggregation of calcium hydroxide crystals in the interfacial zone of the ITZ, thereby improving the adhesion between cementitious materials and aggregates [19,20].…”

Section: Introductionmentioning

confidence: 99%

Performance Analysis and Admixture Optimization of GBFS-HPMC/Fiber Pervious Concrete

Yan,

Wang,

Sun

et al. 2023

Materials

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Permeable pavements can decrease the volume of stormwater, thereby mitigating the risk of flooding and reducing the urban heat island effect. This study investigated the influence of incorporating granulated blast-furnace slag (GBFS), hydroxypropyl methylcellulose (HPMC), and polypropylene plastic textile fiber (PPTF) on the mechanical properties and water permeability of pervious concrete. Orthogonal tests were employed to conduct the analysis. The findings indicate that the pervious concrete with GBFS, HPMC, and PPTF (termed GBFS-HPMC/fiber pervious concrete) exhibited the highest cubic compressive strength, ultimate tensile strength, and flexural strength. These values were 25.22 MPa, 3.36 MPa, and 5.39 MPa, respectively. The standard deviations for cubic compressive strength, split tensile strength, flexural strength, water permeability coefficient, and porosity, as calculated using SPSS, were 1.57, 0.1, 1.17, 0.35, and 0.4, respectively. Scanning electron microscopy (SEM) and energy-dispersive spectroscopy (EDS) were used to analyze the microstructure and compositional combinations of the pervious concrete. The analyses revealed that the calcium-silicate-hydrate (C-S-H) gel, produced by GBFS hydration, enhanced the bonding within the interfacial transition zone (ITZ) and between the fibers and aggregates. Additionally, the anchoring and supporting effects of the PPTF in the matrix contributed to stabilizing the overall matrix structure. Lastly, a gray correlation analysis was applied to optimize the admixture. The findings indicate that following the optimization, the cubic compressive strength increased by 7.2%, splitting tensile strength by 2.1%, and flexural strength by 2.5%. In summary, the mechanical properties of pervious concrete improved after optimizing the admixture.

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Calcium hydroxide content and hydration degree of cement in cementitious composites containing calcium silicate slag

Cited by 18 publications

References 21 publications

Enhancement of Cement Paste with Carboxylated Carbon Nanotubes and Poly(vinyl alcohol)

Enhancement of Cement Paste with Carboxylated Carbon Nanotubes and Poly(vinyl alcohol)

Effect of Immersion Time in Chloride Solution on the Properties of Structural Rebar Embedded in Alkali-Activated Slag Concrete

Performance Analysis and Admixture Optimization of GBFS-HPMC/Fiber Pervious Concrete

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