Portland Cement Hydration Process Research Articles

Effect of waste glass powder and liquid glass on the Physico-Chemistry of Aluminum-Based Ultra-Lightweight concrete

The research aims to utilize waste glass powder in aluminum-based ultra-lightweight concrete (ULWC). It is a cheaper alternative to autoclaved aerated concrete. The study proposed obtaining glass powder and liquid glass from municipal solid waste. It was discovered that waste glass powder at the early hydration stage is not an active pozzolanic material. However, it helps to accelerate the Portland cement hydration process. Furthermore, a combination of waste glass powder and liquid glass can replace up to 30 % of Portland cement and increase almost twice the compressive strength of ULWC. The study aligns with the EU waste policy, which motivates extracting valuable resources from the dumpsite and converting them to functional materials, thus reducing global CO2 emissions.

Monitoring the Effect of Calcium Nitrate on the Induction Period of Cement Hydration via Low-Field NMR Relaxometry

The hydration process of Portland cement is still not completely understood. For instance, it is not clear what produces the induction period, which follows the initial period of fast reaction, and is characterized by a reduced reactivity. To contribute to such understanding, we compare here the hydration process of two cement samples, the simple cement paste and the cement paste containing calcium nitrate as an accelerator. The hydration of these samples is monitored during the induction period using two different low-field nuclear magnetic resonance (NMR) relaxometry techniques. The transverse relaxation measurements of the 1H nuclei at 20 MHz resonance frequency show that the capillary pore water is not consumed during the induction period and that this stage is shortened in the presence of calcium nitrate. The longitudinal relaxation measurements, performed at variable Larmor frequency of the 1H nuclei, reveal a continuous increase in the surface-to-volume ratio of the capillary pores, even during the induction period, and this increase is faster in the presence of calcium nitrate. The desorption time of water molecules from the surface was also evaluated, and it increases in the presence of calcium nitrate.

Effect of Waste Glass on Portland Cement Hydration Process

Glass is an amorphous material, which could be a good pozzolanic material and can be beneficial in compressive strength gain. However, if waste of glass powder has undesirable contaminations (aluminium, clay impurities, sulphates, etc.) it can negatively affect hydration process. In the research were used two types of waste glass (with and without harmful impurities). Waste glass shards were obtained from a local waste recycling plant and its properties were investigated in the Portland cement hydration process. Properties of waste glass were analysed by SEM, XRD test methods, pozzolanicity of glass powder was investigated by Chappelle test method. The hydration process of Portland cement was researched by the semi-adiabatic test method and XRD analysis. Properties of hardened cement paste was analysed by: density, flexural and compressive strength test methods The main aim of this research is to analyse waste glass, which after primary cleaning is not suitable for secondary reuse and investigate its suitability in cement-based systems.

Research on the Compatibility of Bamboo and Portland Cement.

This paper researches the compatibility of bamboo and Portland cement by measuring the hydration temperature of Portland cement. Meanwhile, bamboo shavings and Portland cement, which were utilized as main raw materials, were prepared into bamboo Portland cement particle boards through cold compression forming, so as to further verify the compatibility of bamboo and Portland cement and research the practicability of preparing bamboo Portland cement particle boards by using bamboo. Research studies show that bamboo contain water-soluble saccharides, such as polysaccharide, disaccharide, and glucose, and organic carboxylic acids, such as formic acid and acetic acid. Water-soluble saccharides are converted into saccharic acid after dissolving in water, then a saccharide–calcium complex with a pompon-like structure is formed through a reaction between saccharic acid and calcium ions of Portland cement hydrates, and the saccharide–calcium complex covers the surfaces of the cement particles and prevents further hydration of the cement, achieving a certain anticoagulation effect on Portland cement; a chelation reaction between the carboxyl of the organic carboxylic acid and the calcium ions of Portland cement hydrates takes place and the concentration of calcium ions in the hydration system is reduced, which exerts an influence on further hydration process of Portland cement and achieves a certain anticoagulation effect. Because of the poor compatibility of Portland cement and bamboo, the physical and mechanical properties of bamboo Portland cement particle boards prepared from bamboo shavings and Portland cement directly cannot meet the requirements of the national standards (GB/T24312-2009) of cement particle boards.

Influence of carbon nanotubes and polycarboxylate superplasticiser on the Portland cement hydration process

The aim of this study was to investigate the changes in the heat of hydration of Portland cement in case of its modification by a complex admixture (CA) based on multi-walled carbon nanotubes/carboxymethyl cellulose (MWCNT/CMC) suspension and polycarboxylate ether (PCE) plasticiser. The application of the CA leads to the prolongation of the duration of the induction, acceleration and later appearance of the peak at deceleration periods of Portland cement hydration by 4 h 55 min, 15 h 45 min and 21 h 30 min, respectively. The CA decreases the heat flow of cement by 35% in the acceleration period and total hydration heat emission by 26% after 48 h. The CA decreases the formation of portlandite and ettringite while the stability of gypsum increases. The identified tendency of changes in formed hydrates explains the retardation of C3S hydration. The evaluation of the cement hydration rate during the acceleration period by the angle of the linear function of the cement hydration heat flow curve was proposed. The cement modified by the CA can be useful in construction practice for the concreting of massive structures where low heat emission is a requirement, for the development of the mixture for new concrete technologies like massive concrete structures, hot weather concreting etc.

Effects of nano-C-S-H seed crystal on early-age hydration process of Portland cement

Nano-C-S-H seed crystal, as an early strength agent for cement-based materials, has great application prospects. In order to investigate the effect of nano-C-S-H seed crystal on the early-age hydration process of Portland cement, in this article, low-field nuclear magnetic resonance (NMR) technology with 1H as a probe was used to in situ monitor the microstructure evolution of cement paste during the hydration process. Other micro-test methods including mercury intrusion porosimetry (MIP), scanning electron microscope (SEM), and X-ray diffraction (XRD) were also applied to characterize the microstructure of hardened cement paste. The results showed that nano-C-S-H seed crystal can promote the early hydration of cement, and the hydration promotion effect decreased with the hydration time and increased with the content of nano-C-S-H seed crystal. The average hydration rate of C-0.75 paste with addition of 0.75% nano-C-S-H seed crystal was the highest within 1 day of hydration, which was 7.75 times higher than that of pure cement C-0 paste. Nano-C-S-H seed crystal had a great effect on the pore size refinement of cement paste. After 7 days of hydration, the total porosity of all samples decreased to about 5%.

Effect of ultra-sonic dispersion time on hydration process and microstructure development of ultra-high performance glass powder concrete

This article is the continuous research on the successful attempt to utilize glass powder in ultra-high performance concrete. The previous study showed, that glass powder has a positive effect on the Portland cement hydration process, however, one problem was unable to overcome: about half the amount of unreacted clinker mineral remained in the composition, even when thermal treatment was applied. This research proposes a successful adaptation of the ultra-sonic dispersion method. The proposed method allowed to increase even further hydration process of the binder as well to develop a more favourable microstructure. Experiment research was investigated by XRD analysis, Chapelle, semi-adiabatic calorimetry, 29Si MAS NMR, mercury intrusion porosimetry, and compressive strength test methods. Results revealed, that high-frequency ultra-sonic dispersion can significantly increase the hydration degree of binder and the compressive strength up to 16%.

Fullerene synthesis and modification of building materials with fullerenes C60 and C70

The article presents the results of the study of plasma chemical synthesis fullerenes using composite electrodes and the results of thermodynamic modeling Portland cement hydration. Boron was used as the additive. Boron acts as a catalyst and increases the yield of higher fullerenes C70 in plasma chemical synthesis. The carbon soot was used as a carbon nanomodifier. Carbon nanomodifier contains fullerenes C60 and C70. Thermodynamic calculations make it possible to evaluate the contribution of the carbon nanomodifier to the hydration process of Portland cement. Using thermodynamic calculations, changes in the phase composition and general properties of the system (complete enthalpy, entropy) were determined when introducing a carbon nanomodifier.

Influence of Glass Powder Additives on the Hydration Process of Portland Cement

This article presents the results of microcalorimetric studies of the process of the interaction of the hydration products of Portland cement with additives of glass powders of various chemical compositions. It is found that when glass is added in a powder state, an increase in the rate of hydration of Portland cement is observed.

Hydration heat evolution of Portland cement paste during unsteady steam curing process: Modelling and optimization

The hydration process under unsteady steam curing condition is difficult to monitor in real time by experimental method. This study developed a numerical method to describe the hydration heat release characteristics of Portland cement under atmospheric steam curing condition. Instantaneous activation energy and an iterative algorithm were employed in this method to improve the accuracy. It was found that prolonging the precuring time to over 7 h or heating time to over 3 h would both decrease the peak value of hydration heat release rate, while a treatment time over 8 h would slightly affect the total heat release during steam curing. The validity of the method was confirmed by the experimental results. This proposed method can rapidly analyze the effect of steam curing regimes on hydration heat release behavior of Portland cement and thus optimize the hydration process of Portland cement under steam curing process in order to mitigate or avoid heat damage of steam curing concrete.

Effect of ion chelator on hydration process of Portland cement

Ion chelator is a novel crystalline additive which can chelate Ca2+ and migrate in concrete to promote self-healing of surface crack and internal pore. In order to further explore the effect of ion chelator on hydration process of cement, the hydration heat, chemically bound water, compressive strength, hydration products, pore-size distribution and microstructure of cement paste with ion chelator were investigated in this paper. Results of the experiments showed that the ion chelator accelerated the hydration of the cement paste. Incorporation of ion chelator in cement greatly enhanced the chemically bound water content and the mechanical property. Compared with control cement paste, the chemically bound water content and compressive strength of cement paste with 0.5 wt% ion chelator increased by 13.3% and 16.8% after curing for 28 days. According to the DTA-TG and XRD tests, the ion chelator can promote the hydration of C3S and C2S, which was conducive to the generation of calcium silicate hydrate gels. Furthermore, the addition of ion chelator improved the pore-size distribution and microstructure of cement paste, and a large number of floccules and needles appeared in the pores of cement paste.

Thermodynamic calculations on system «Portland cement – water – carbon nanomodifier»

The article presents the results of thermodynamic modelling in a cement-water-carbon nanomodifier system. A carbon nanomodifier contains fullerenes C60 and C70. Thermodynamic calculations make it possible to evaluate the contribution of a carbon nanomodifier to the hydration process of Portland cement. Using thermodynamic calculations, changes in the phase composition and general properties of the system (total enthalpy, entropy) with the introduction of a carbon nanomodifier were determined.

Research of composite binders with nanomodifiers for dry mixes

The article discusses the application of various mineral materials for the modification of Portland cement in order to obtain dry mixes. The main component in the composition of dry mixes is Portland cement, affecting its physical, mechanical and technological properties. To modify Portland cement, which is used to obtain dry mixes, various micro- and nano-additives were used: volcanic slag, microsilica, nanosilica. Mechanical parameters of modified Portland cement at various hardening periods are determined. The introduction of micro- and nano-additives positively affects the hydration process of Portland cement, which is confirmed by the study of the microstructure of the modified cement stone using scanning electron microscopy. It has been established that when using various micro- and nano-additives, the amount of low-basic calcium hydrosilicates changes, affecting the increase in the mechanical properties of cement stone. The use of volcanic slag and nanosilica allows to improve the technological and quality indicators of dry mixes. Studies of determining the angle of repose of the composition of composite binders based on Portland cement and volcanic slag, as well as the introduction of nanosilica in Portland cement show a significant change in this indicator indicating an improvement in the flowability of the material.

Factors influencing ultrasonic pulse velocity in concrete

Abstract The hydration process of Portland cement triggers reactions of stabilization of minerals from the contact of the clinker with water, which is the Hydrated Calcium Silicate (C-S-H), the Etringite (3CaO.Al2O3.3CaSO4.32H2O) and the Portlandite (Ca(OH)2). In order to understand the effects of the evolution of hydration in cement, it is possible to apply non-destructive tests. In this context, the objective of this work is to evaluate the influence of the type of cement, the curing age, of the format and humidity of the test specimens of concrete in the ultrasonic pulse velocity (UPV). In order to do that, 36 cylindrical test specimens (10 x 20 cm) and 9 cubic ones with 25 cm of edges, with mix proportion of 1:2,7:3,2 (cement/sand/gravel), water/cement ratio of 0.58 and three types of Portland cement (CP II-Z-32, CP IV-32 RS and CP V-ARI) were molded. With data obtained it was possible to correlate the increase of concrete strength along time (at ages of 7, 14, 28, 70 and 91 days) with the increase of the ultrasonic pulse velocity. Besides, it was possible to prove the direct influence of the concrete moisture and of the degree of hydration in the UPV. The shape of the test specimen generally had no influence on the results, except in the case of cement CP V ARI.

Study of the Hydrosilicate Phases Formation Process of Portland Cement with Disaccharide Additives

The article is devoted to the study of the cement stone hydrate phases formation in the presence of significant amounts (2%) of isomeric disaccharides - sucrose, maltose and lactose. Attention to disaccharides as modifying agents of cement stone is due to their ability to influence the ratio of high and low density cement gels in the composition of cement stone. To implement Portland cement hydration process in the presence of significant amounts of disaccharides cement grinding in the presence of carbohydrate solutions was used. It was found that the molecular structure of carbohydrate does not affect the elemental and phase composition of hydration products. Hydrosilicates in the presence of carbohydrates and aside of the molecular structure of the latter form the phases of the cryptocrystalline structure. The formation of cryptocrystalline phases is accompanied by occlusion of disaccharides; the residual content of disaccharides in the liquid phase of suspensions does not exceed 0.3% of the initial amount of modifying carbohydrate.

Review on the durability properties of sustainable alkali activated concrete

Portland cement acts as binding material for the aggregates when it hydrates and forms C-S-H gel in conventional concrete and further, cement production growing 5% annually. For 1-ton cement production, a large quantity of energy is required approximately 120–130 electricity units and it emits 0.6–0.75ton CO2 in the atmosphere, which is responsible for the greenhouse effect and 7% pollutants in the atmosphere. This study was done to check the performance of the durability behavior of AAC. However, it is the polymerization process that makes fly ash a binding material in alkali-activated concrete. Calcium hydroxide is produced in the earlier case upon the hydration process of Portland cement, while no C-S-H gel and lime are produced in alkali-activated concrete. Therefore, a futuristic sustainable material that can be alkali-activated concrete requires confirmation of durability when exposed to an aggressive environment. In alkali-activated concrete strength is gained through polymerization and hydration. The study has been undertaken to place data in one place for the convenience of future research and identify the scope of various durability aspects for future research. Various aspects of durability which have been discussed in this paper are sulphate, chloride, acid resistance, and permeability.

Lanthanide Luminescence Revealing the Phase Composition in Hydrating Cementitious Systems.

The hydration process of Portland cement in a cementitious system is crucial for development of the high‐quality cement‐based construction material. Complementary experiments of X‐ray diffraction analysis (XRD), scanning electron microscopy (SEM) and time‐resolved laser fluorescence spectroscopy (TRLFS) using europium (Eu(III)) as an optical probe are used to analyse the hydration process of two cement systems in the absence and presence of different organic admixtures. We show that different analysed admixtures and the used sulphate carriers in each cement system have a significant influence on the hydration process, namely on the time‐dependence in the formation of different hydrate phases of cement. Moreover, the effect of a particular admixture is related to the type of sulphate carrier used. The quantitative information on the amounts of the crystalline cement paste components is accessible via XRD analysis. Distinctly different morphologies of ettringite and calcium−silicate−hydrates (C−S−H) determined by SEM allow visual conclusions about formation of these phases at particular ageing times. The TRLFS data provides information about the admixture influence on the course of the silicate reaction. The dip in the dependence of the luminescence decay times on the hydration time indicates the change in the structure of C−S−H in the early hydration period. Complementary information from XRD, SEM and TRLFS provides detailed information on distinct periods of the cement hydration process.

FTIR study on early-age hydration of carbon nanotubes-modified cement-based materials

In this paper, the hydration process of Portland cement at early age was characterised by Fourier transform infrared spectroscopy (FTIR); the results showed that FTIR is a simple and rapid research method in operation, which can reflect the basic variation in the primary cement hydration products. As the hydration reaction proceeded, the peak value corresponding to silicon–oxygen (Si–O) vibrations in the FTIR spectrum shifted from low wavenumbers to high wavenumbers, which not only reflected the polymerisation process of silicon–oxygen tetrahedrons in the calcium–silicate–hydrate gel, but also the hydration reaction speed of cement paste at this stage. This was confirmed by experiment on samples with added superplasticiser. The shifting characteristics of the absorption peaks in the range 800–1025 cm−1 for samples at the ages of 8–12 h were comprehensively investigated in this study. The research results showed that the shifting speed of the characteristic peak for the blank sample was exactly the same as that for the sample reinforced with carbon nanotubes (CNTs). Therefore, the addition of CNT materials into Portland cement did not influence the hydration reaction at the early age. This conclusion was verified by the thermometry test for hydration temperature.

Hydration of Portland cements in solutions containing high concentration of borate ions: Effects of LiOH

The hydration process of Portland cement in solutions containing high concentration of borate ions is studied. The mechanism of retarding effects induced by borate ions on Portland cement is investigated and a solution for mitigating these effects is proposed by adding LiOH into the cement paste. Formation of a loose covering layer rich in borate around C-S-H nuclei and the consequent prevention of C-S-H growth is found to cause the strong retarding effects of borate ions at early ages. Adding LiOH accelerates the early age hydration of Portland cement with borate, and increases the compressive strength of the hardened paste. The LiOH promotes the dissolution of the covering layer on the C-S-H nuclei, and hence counteracts the retarding effects of borates on hydration of Portland cement.

Impact of Temperature Rising Inhibitor on hydration kinetics of cement paste and its mechanism

This study examines the effect of Temperature Rising Inhibitor (TRI) on Portland cement hydration process and analyzes the mechanism. The investigation of the impact of TRI on cement dissolution, C-S-H nucleation and growth process shows that TRI has little influence on the dissolution kinetics of cement and crystal-solution interfacial energy of C-S-H. In contrast, the modification of C-S-H grain size in solution and the C-S-H growth rate in cement suspensions are observed. Experiments involving TRI and synthesized C-S-H confirm that TRI will preferentially adsorb on the C-S-H surface and inhibit growth of C-S-H.