Hydration Behavior Of Cement Research Articles

Effect of side chain ionizability of polycarboxylate superplasticizer on cement hydration

Although the side chain ionizability (the adsorption group density and adsorption space are changed) of polycarboxylate superplasticizer (PCE) serve as the key structural parameter in affecting the cement hydration, its effect on cement hydration is unclear. Based on PCE with nonionizable side chain (NSC-PCE) and the PCE with ionizable side chain (ISC-PCE), the influence of the side chain ionizability of PCE on the hydration behavior of cement was studied. Compared with NSC-PCE, ISC-PCE has a stronger ability to change the migration of water and ions, thus delaying the crystal nucleation and growth of cement hydration (better morphology and distribution, the crystal size was reduced by more than 20 %), increasing the crystal growth index (tendency toward spherical growth), prolonging the phase boundary reaction (reduce micro-cracks), which was conducive to the formation of more uniform and dense crystals (good strength, ISC-PCE: 50.0 MPa > NSC-PCE: 49.2 MPa > Blank: 48.7 MPa). These findings provide the design basis and theoretical guidance for the innovative development of PCE.

Luminescent Properties of (Ca7ZrAl6O18-Ca3Al2O6-CaZrO3):Eu3+ Composite Ceramics and Tracing in the Hydration Process

In this work, solid-state reaction sintering was used to fabricate Ca7ZrAl6O18-Ca3Al2O6-CaZrO3:Eu3+ ternary composite ceramics and cements. The structural, microstructural, and spectroscopic properties of the ceramics with different Eu2O3 content were characterized by X-ray diffraction (XRD), Fourier-transform infrared spectroscopy (FT-IR), scanning electron microscopy (SEM) and energy dispersive X-ray spectroscopy (EDS), and spectrofluorimetry, respectively. The XRD patterns analyzed with Rietveld refinement confirm the presence of the orthorhombic phase of Ca7ZrAl6O18 and the cubic phase of Ca3Al2O6 in all the samples, indicating that doping of Eu3+ slightly changes the crystalline structure of both aluminate phosphors. EDS analysis revealed that the Eu doping element was strongly concentrated to the two phases, i.e., Ca7ZrAl6O18 and Ca3Al2O6, with the Eu concentrations of 8.45 wt.% and 8.26 wt.%, respectively. The luminescent properties of the ceramics doped with different Eu3+ ion concentrations were investigated by excitation and emission spectroscopy at room temperature. These results were compiled using a laser with an optical parametric oscillator (OPO) system. The obtained spectra indicated changes in the luminescence intensity and shape occurring with phase composition and Eu2O3 concentration. The emission spectra of the ceramics exhibit a strong dependence on the excitation wavelength in the range from 210 to 300 nm, and invariably, five peaks were assigned to the 5D0 → 7FJ (J = 0, 1, 2, 3, 4) transitions of Eu3+. The luminescence spectroscopy was then used to trace the early and long-term hydration behavior of cements. Thus, luminescence spectroscopy may provide a new tool for non-destructive testing of cement-based structures.

The influence of silica-coated nanoscale titanium dioxide on the microstructure, mechanical properties, and carbonation resistance of cementitious materials

Nanomaterials possess great application prospects in improving the performance of cementitious materials. However, their high agglomeration hinders their efficient utilization in cementitious matrices. Consequently, surface modification has recently attracted attention as a method to enhance dispersibility. In this study, silica was employed to modify the surface of nanoscale titanium dioxide (NT), resulting in the synthesis of silica-coated nanoscale titanium dioxide (SCNT) composite material. In particular, the dispersibility of SCNT was investigated, and its influence on the compressive strength development of modified cement paste was analyzed. Additionally, the mechanisms affecting cement hydration behavior and microstructure evolution were comprehensively analyzed. Lastly, the impact of SCNT on the carbonation resistance of cementitious materials was further explored. Interestingly, the research results indicate that the surface SiO2 coating treatment improves the dispersibility of NT. More precisely, compared to 3 % NT, the addition of 3 % SCNT can increase the compressive strength of cement paste by 20.52 % at 3 days and 16.52 % at 28 days. Specifically, the incorporation of SCNT promotes cement hydration, refines the crystal size of Ca(OH)2, reduces the crystal orientation growth index of Ca(OH)2, and enhances the polymerization degree of calcium silicate hydrate (C-S-H), optimizing the pore structure. Furthermore, the 28-day permeability coefficient of 3 % SCNT mortar is reduced by 99.98 % compared to the blank group, effectively enhancing the carbonation resistance of cementitious materials. Overall, the findings of this study will contribute to the development of high-performance and multifunctional nanocomposite cementitious materials.

Machine learning enables prompt prediction of hydration kinetics of multicomponent cementitious systems

Carbonaceous (e.g., limestone) and aluminosilicate (e.g., calcined clay) mineral additives are routinely used to partially replace ordinary portland cement in concrete to alleviate its energy impact and carbon footprint. These mineral additives—depending on their physicochemical characteristics—alter the hydration behavior of cement; which, in turn, affects the evolution of microstructure of concrete, as well as the development of its properties (e.g., compressive strength). Numerical, reaction-kinetics models—e.g., phase boundary nucleation-and-growth models; which are based partly on theoretically-derived kinetic mechanisms, and partly on assumptions—are unable to produce a priori prediction of hydration kinetics of cement; especially in multicomponent systems, wherein chemical interactions among cement, water, and mineral additives occur concurrently. This paper introduces a machine learning-based methodology to enable prompt and high-fidelity prediction of time-dependent hydration kinetics of cement, both in plain and multicomponent (e.g., binary; and ternary) systems, using the system’s physicochemical characteristics as inputs. Based on a database comprising hydration kinetics profiles of 235 unique systems—encompassing 7 synthetic cements and three mineral additives with disparate physicochemical attributes—a random forests (RF) model was rigorously trained to establish the underlying composition-reactivity correlations. This training was subsequently leveraged by the RF model: to predict time-dependent hydration kinetics of cement in new, multicomponent systems; and to formulate optimal mixture designs that satisfy user-imposed kinetics criteria.

Effect of phase change composites on hydration characteristics of steam-cured cement paste

The application of phase change materials (PCMs) in building materials has attracted more and more attention. However, there is little information on the interactions between PCMs and cementitious material during hydration process. This study investigates the influence of PCMs on cement hydration behavior under steam curing condition. Three kinds of composite phase change material (CPCM) are synthesized, denoted by D/P, EG/P and D/EG/P, respectively. The thermal stability and crystalline phase of PCMs are characterized. The effects of above PCMs on hydration process of cement are evaluated by several testing methods, including isothermal calorimetry, thermogravimetric analysis, X-ray diffraction and scanning electron microscopy. Results indicate that CPCMs exhibit good thermal stability compared with single paraffin when the operating range is less than 200 °C. The time to reach the heat release rate peak of binders containing paraffin, D/P, EG/P and D/EG/P is 20 min, 20 min, 20 min and 30 min earlier than the cement pastes without PCM at 60 °C isothermal condition, respectively. The addition of a small amount of CPCM can accelerate the early hydration of steam-cured cement paste due to the combined action of paraffin and carriers with high surface area that can provide nucleation sites. Moreover, the combination of two carriers promotes cement hydration better than the single carrier. However, the number of hydration products and phase compositions of steam-cured cement paste are almost not affected by the addition of CPCM.

Hydration behavior of cements with reduced clinker factor in mixture with sulfoaluminate binder

CO2 regulation and raw material availability will strongly influence the future cement market and a wider use of composite cements containing limestone and pozzolan or slag is expected.In the present paper, the possibility to combine Portland cements (PCs) with reduced clinker factor with sulfoaluminate cement (CSA), is explored. Low Portland clinker cements are prepared in laboratory using different supplementary cementitious materials (limestone, slag, pozzolan and fly ash) and mixed with a sulfoaluminate cement: the hydration behavior of the resulting binders is investigated up to 90 days through a multi-technique approach involving X-ray diffraction, differential scanning calorimetry and nuclear magnetic resonance spectroscopy. Understanding the interaction mechanisms between SCMs and CSA/PC blends will support the development of innovative high performing binders based on CEM III or CEM V, or even on new standardized CEM II. Results highlight that slag is particularly suitable promoting late strength development.

Critical roles of synthetic zeolite on the properties of ultra-low cement-bonded Al2O3-SiC-C castables

Calcium aluminate cement-bonded Al2O3-SiC-C castables are widely used in practice due to sufficient initial strength and operability. However, a high amount of cement leads to deteriorated high-temperature properties due to the formation of low-melting-point phases. The present work aimed at optimizing the comprehensive properties of the ultra-low cement-bonded Al2O3-SiC-C castables with the introduction of high purity synthetic zeolite. The influences of additives on the properties of castables and the hydration behavior of cement were investigated. The results showed that zeolite had the following advantages: it promoted the hydration of cement through enhancing the physical absorption and potential chemical complexation of Ca2+ and eventually induced growth of the predominant plate-like hydrates (C2AH8) at 25 ℃. The formation of more C2AH8 was beneficial to improve the green strength even with less cement. The substitution of cement with 0.5 wt.% synthetic zeolite contributed to improved high-temperature properties by reducing CaO content.

In situ examination of engineered local additives in cement paste via neutron based scattering techniques

Hydration behavior of cements with additives is complicated due to the multifarious nature of hydration products formed at various stages of hydration. Neutron-based scattering techniques are useful in detecting both the microstructural evolution and water dynamics of hydrating cement pastes. This work investigates the effect of early-age hydration on microstructural evolution of cement paste with local volcanic ash using neutron-based beamline techniques. Early-age hydration dynamics of Portland cement paste with volcanic ash was examined via inelastic neutron scattering (INS), while the evolution of microstructure was observed with small angle neutron scattering (SANS). The data obtained from the ratio of volume fractal to surface fractal clearly showed that greater than 30% substitution of volcanic ash leads to unreacted volcanic ash and coarser morphology, which could influence the chemo-mechanical properties of the resulting hydration products. INS results showed that the effect of finer-particle-sized volcanic ash contributes to initiation of gelation, which accommodates higher conversion of free water to bound water. The multi-scale analysis that combines a time-resolved study of water dynamics along with microstructure is found to provide a basis for effectively utilizing engineered additives for the local cement industry.

The Effect of Sodium Gluconate on Pastes’ Performance and Hydration Behavior of Ordinary Portland Cement

The goal of this paper provides better understanding of the effect of sodium gluconate (SG) on ordinary Portland cement (OPC) hydration behavior. Pastes’ performances of ordinary Portland cement, including setting time at 20°C and 35°C curing temperature, mechanical strength, fluidity, and zeta potential are studied. Furthermore, the effects of SG on cement hydration behaviors are investigated by the means of isothermal calorimetry measurements, X‐ray diffraction (XRD), and thermogravimetric analysis (TGA). The results show that SG is difficult to maintain significant retarding effect at the temperature of 35°C compared to that at the temperature of 20°C. SG is able to reduce the cement cumulative hydration heat and delay the occurrence time of heat evolution peak in a certain extent, but it has little impact on reducing the cement evolution rate peak. The effects of SG on mechanical properties and dispersion properties of cement depend on its dosages. Specifically, the positive effect occurs when the addition dosage is less than 0.15% (i.e., by cement weight), but the negative effect emerges if the addition dosages exceed this limitation. Similarly, SG plays different roles on cement hydration at different hydration periods. It inhibits the hydration of C3S and the formation of portlandite (CH) at the early hydration period. On the contrary, it promotes the C3S hydration when hydration time is beyond 1 d. Meanwhile, SG also plays different roles on cement hydration at different dosage additions. Specifically, SG promotes ettringite (AFt) formation at the dosage less than 0.06%, but it inhibits AFt formation at the dosage more than 0.06%.

A new hydration kinetics model of composite cementitious materials, part 1: Hydration kinetic model of Portland cement

AbstractThis work is the first part of an overall research project that aims to model the hydration kinetics of modern composite cementitious materials. The aim of this part is to build a hydration kinetic model to characterize the hydration behavior of cement at all ages. In this paper, the nucleation and growth of CSH and the diffusion of water are described by a modified BNG model and a modified Jander's model. The kinetic parameters are obtained by simulative fitting of the model to the experimental data. The linear functions between the nucleation and growth rates and the W/C ratios are given in this paper. The apparent activation energy of the nucleation rate constant, growth rate constant, and generalized diffusion constant are approximately 36.0, 37.5, and 42.0 kJ/mol, respectively. Finally, the phase compositions of hardened cement paste are calculated according to the kinetic model and the reaction formula of cement.

Investigating the influence of fly ash on the hydration behavior of cement using an electrochemical method

Fly ash is an industrial by-product that is widely used in the cement industry. Traditional methods used to investigate the influence of fly ash on the hydration behavior of cement are destructive and cannot accomplish a continuous tracing of the hydration process. In this study, the influence of fly ash incorporation on the hydration process of cement is evaluated using measured electrochemical data obtained from the electrochemical impedance spectroscopy approach. A novel equivalent circuit model that considers the electrochemical characteristics of cement during the hydration process is proposed to investigate the electrochemical property of the blended cement. The resistance parameter of the model, Rct1, was found to have a positive correlation with hydration degree and compressive strength during hydration. With this parameter, the method can be used to non-destructively trace and characterize the effects of fly ash incorporation on the cement hydration process.

Investigation on early hydration behavior of cement based on piezoelectric sensor

Cement is one of the most important building materials whose hydration behavior has great influence on quality of concrete. In this study, lead zirconate titanate (PZT) piezoelectric ceramic sensors were tailored and embedded into cement paste to monitor the early cement hydration reaction process in terms of the electromechanical impedance technique. The results show that the early hydration characteristics of the cement paste can be obtained by investigating the electromechanical impedance spectra of the PZT sensors. The impedance spectra of the PZT piezoelectric sensors exhibit distinguished variations with cement hydration reaction. The hydration index has been developed in terms of the impedance spectra variation by utilizing the piezoelectric sensors, and the early cement hydration reaction can be categorized as three periods based on this method – namely, the induction period in the initial 4 h of hydration, the accelerated period in 4–8 h of hydration and the late acceleration period in 8–12 h of hydration.

Portland Cement Hydration Behavior at Low Temperatures: Views from Calculation and Experimental Study

Environmental condition affects the property of construction materials. This study gives an initial understanding of Portland cement hydration under low temperatures from the views of laboratory experiments (including electrical resistivity, degree of hydration (DoH), and maturity) as well as thermodynamic calculation. The hydrates of Portland cement at the given period were detected with X-ray diffraction (XRD), and their microstructure was observed by scanning electron microscope (SEM). Experiment result (i.e., DoH and electrical resistivity) indicated that the hydration of Portland cement was delayed by low temperature without hydration stopping at −5°C. Based on a basic kinetics model, the thermodynamic calculation predicted that the final hydrate differs in dependence on environmental temperatures. The mechanical behavior trend of Portland cement paste affected by low temperatures potentially is linked to the appearing of aluminate compounds and reduction of portlandite.

Hydration Mechanism of the Hydrogen-Rich Water Based Cement Paste

With the aim to speed up the construction process, utilization of the hydrogen-rich water as a cement set accelerator would be a unique approach. The investigation deals with the effectiveness of the hydrogen-rich water in controlling the setting and the hydration behavior of cement. Analyzing the setting time using Vicat apparatus, the initial and final setting time of the control cement is measured to be 197 ± 6 and 257 ± 3 min, respectively, while the same is measured to be 8 ± 3 and 14 ± 3 min, respectively, for the 0.5 ppm hydrogen-rich water-based cement sample. The change in surface potential of the hydrogen-rich water based cement paste may lead to agglomerate the cement particle immediately. Additionally, the hydration test reveals that the hydrogen-rich water accelerates the cement hydration reaction. This phenomenon is primarily governed by the rapid dissolution of the cement component, followed by the early nucleation and flocculation of the hydrated products, which is confirmed monitoring the...

Development and application of microcapsule for cement hydration control

When concrete is placed in extreme climates, quality control of concrete is so difficult that cracking due to hydration heat easily occur. In the paper, new encapsulation technique is developed for control of cement hydration reaction through encapsulation of chemical admixtures. Lithium carbonate (Li2CO3) as accelerator and tartaric acid (C4H6O6) as retarder are respectively selected for core material. For wall material of microcapsule, acrylic resin, silicon monoxide, and starch is synthesized. Several tests including chemical shrinkage, setting time, compressive strength, and adiabatic temperature are performed for evaluating an effect of the invented microcapsule on cement hydration behavior. Through encapsulation of accelerator and retarder, cement hydration behaviors like setting time, strength, shrinkage, and hydration heat are reasonably controlled. The developed encapsulation technique can be applied for manufacturing high durable concrete in harsh environmental condition avoiding cracking.

In-situ early-age hydration study of sulfobelite cements by synchrotron powder diffraction

Eco-friendly belite calcium sulfoaluminate (BCSA) cement hydration behavior is not yet well understood. Here, we report an in-situ synchrotron X-ray powder diffraction study for the first hours of hydration of BCSA cements. Rietveld quantitative phase analysis has been used to establish the degree of reaction (α). The hydration of a mixture of ye'elimite and gypsum revealed that ettringite formation (α ~ 70% at 50 h) is limited by ye'elimite dissolution. Two laboratory-prepared BCSA cements were also studied: non-active-BCSA and active-BCSA cements, with β- and α′H-belite as main phases, respectively. Ye'elimite, in the non-active-BCSA system, dissolves at higher pace (α ~ 25% at 1 h) than in the active-BCSA one (α ~ 10% at 1 h), with differences in the crystallization of ettringite (α ~ 30% and α ~ 5%, respectively). This behavior has strongly affected subsequent belite and ferrite reactivities, yielding stratlingite and other layered phases in non-active-BCSA. The dissolution and crystallization processes are reported and discussed in detail.

Effect of Jute as Fiber Reinforcement Controlling the Hydration Characteristics of Cement Matrix

The present investigation deals with the effect of jute as a natural fiber reinforcement on the setting and hydration behavior of cement. The addition of jute fiber in cement matrix increases the setting time and standard water consistency value. The hydration characteristics of fiber reinforced cement were investigated using a variety of analytical techniques including thermal, infrared spectroscopy, X-ray diffraction, and free lime estimation by titration. Through these analyses it was demonstrated that the hydration kinetics of cement is retarded with the increase in jute contents in cement matrix. A model has been proposed to explain the retarded hydration kinetics of jute fiber reinforced cement composites. The prolonged setting of these fiber reinforced cement composites would be beneficial for applications where the premixed cement aggregates are required to be transported from a distant place to the construction site.

Interpretation of the Early Hydration Procedure of Standard Cement Materials by Electrodeless Resistivity Method

In this paper, the early hydration procedure of standard cement materials is tested and analysized with electrodeless resistivity method. The experimental results show that for standard cement material, the early hydration procedure can be divided into 4 stages: dissolution period, setting period, acceleration period and deceleration period, respectively. Moreover, the characteristic point according the experimental data can be defined to determined stage in the hydration procedure, and be related with the key parameters for cement materials in hydration procedure, such as water/cement ratio. The electrodeless resistivity method can be used to predict the hydration behavior, especially early hydration behavior of cement as a new measurement technology.

Interpretation of the Early Hydration Procedure of Standard Cement Materials by Electrodeless Resistivity Method

In this paper, the early hydration procedure of standard cement materials is tested and analysized with electrodeless resistivity method. The experimental results show that for standard cement material, the early hydration procedure can be divided into 4 stages: dissolution period, setting period, acceleration period and deceleration period, respectively. Moreover, the characteristic point according the experimental data can be defined to determined stage in the hydration procedure, and be related with the key parameters for cement materials in hydration procedure, such as water/cement ratio. The electrodeless resistivity method can be used to predict the hydration behavior, especially early hydration behavior of cement as a new measurement technology.

An experimental study on the concrete hydration process using Fabry–Perot fiber optic temperature sensors

This paper describes the contribution of Fabry–Perot (FP) fiber optic temperature sensor to investigate the effects of concrete hydration process. The FP temperature sensor was easily fabricated by controllable chemical etching and adjustable fusion splicing. Detailed optical properties of the sensor were theoretically analyzed and temperature calibration experiments were performed. A sensor with a 90μm cavity length was demonstrated to have a temperature sensitivity of 0.01nm/°C and the linearity coefficient of 0.99. Furthermore, the FP sensor was embedded in the concrete structure for sensing the temperature change during the early age of hydration. During the concrete hydration experiments, the measured peak temperatures of the concrete specimens with different water-to-cement (w/c) ratios of 0.4, 0.5 and 0.6 were 51.42°C, 52.88°C, and 55.08°C, respectively, corresponding to final setting times of 13.52h (w/c=0.4), 14.16h (w/c=0.5) and 15.2h (w/c=0.6) after concrete casting. Temperature profiles will be used for concrete hydration heat study, which will help us to have a better understanding of cement hydration behavior.