Sulphate-resisting Portland Cement Research Articles

Modeling of Accelerated Hardening of Self-Compacting Concrete by Methods of Mathematical Experiment Planning

Modeling of Accelerated Hardening of Self-Compacting Concrete by Methods of Mathematical Experiment Planning methods of mathematical planning of the experiment makes it possible to comprehensively assess the influence of prescription and technological factors on the strength characteristics of heat-treated self-sealing concrete. It was found that for the studied self-sealing concrete on sulfate-resistant Portland cement, the holding time before applying the coolant should be 4.8 hours, and the maximum heating temperature of concrete should not exceed 48оC.

Optimization of Silica Fume and Slag in Roller Compacted Concrete by Taguchi Method

Roller Compacted Concrete Pavement (RCCP) is one type of concrete poured and compacted with the same machines utilized to construct heavy-duty pavements, log sorting, and parking. In this work, a combination of three factors was optimized to produce a sustainable RCCP. These factors were densified silica fume, ground granulated blast-furnace Slag, and mixing water contents. By weight, sulfate-resistant Portland cement was substituted with cementitious materials such as silica fume and slag in the amounts of (5, 7.5, and 10%) and (25, 27.5, and 30%), respectively. In addition, various percentages (5, 6, and 7%) of water content were utilized. Using the Taguchi approach, the impact of these factors was investigated based on the results of compressive strength and bulk density. The cubic specimens of compressive strength and bulk density, with 100 mm length, were tested at 7, 14, and 28 days. According to the results, the optimum percentages of silica fume, slag, and water contents were (5, 27.5, and 6%), respectively. Comparing the optimal mixture to the reference, the compressive strength enhancement was about 13.9%. According to Taguchi's study, water content has a most significant influence on the characteristics of RCCP than silica fume content. The slag content has the least impact on RCCP.

Investigating the role played by portlandite and C-A-S-H in the degradation response of pozzolanic and slag cements to external sulphate attack

Cements made with pozzolanic materials and/or latent hydraulic materials are developed to replace Portland cement and decrease the impact of cement production on the CO2 emissions. Those cements need to be qualified regarding their performances and durability, knowing they exhibit good behavior when exposed to external sulphate attack. Pozzolanic materials offer a specific composition of hydrated cement phases with less portlandite and more C-A-S-H than Portland cement. Moreover, they contain a reduced proportion of clinker, hence a reduced share of C3A. All these characteristics explain the unique response of pozzolanic cement to external sulphate attack. However, the pozzolanic reaction is more than often incomplete, with some remaining portlandite in the hydrated cement paste. In order to investigate the role played by this remaining portlandite fraction during external sulphate attack, the behavior of two CEM III and two CEM IV cement-based mortar samples were studied and compared to two CEM I- type cements, one SR and one non-SR. The pozzolanic nature of these cements has been investigated by monitoring the portlandite content of cement paste over time by thermogravimetric analysis. In addition, the behavior of synthetic C(-A)-S-H containing portlandite and in suspension in sulphate solutions has been assessed by X-ray diffraction and scanning electron microscopy. Results have confirmed the sulphate resistance of the studied blended cements compared with a sulphate-resistant Portland cement (CEM I SR3), although the cements still containing portlandite did undergo a slight expansion. The test on C(-A)-S-H showed that the presence of portlandite encourages the precipitation of ettringite within the C-A-S-H nano porosity, even in the absence of pH regulation.

Effect of nano-silica on structure and properties of high sulfate resistant Portland cement mixed with mineral powder or fly ash

Hydrating-hardening properties of high sulfate resistance Portland cement (HSRPC) mixed with 35 wt% mineral powder (MP) or fly ash (FA) and the action mechanism of nano-silica (NS) under the condition of low-calcium hydrating phase were studied in this paper. Rheology, fluidity, setting time and compressive strength were investigated to explore the effect of NS on the basic physical properties of HSRPC doped with MP or FA. Mercury intrusion porosimetry (MIP), ultrasonic crack analysis, hydration heat and thermogravimetry (TG) were investigated to analyze the hardened structure and the hydration mechanism. The conclusions were as follows: For HSRPC with MP, the 0.1–0.5 wt% NS increased the yield stress, decreased the fluidity and prolonged the setting time. However, when NS content increased from 0.1 wt% to 0.5 wt%, the cumulative porosity increased by 9.8% and the 60 h (60 h) cumulative hydration heat decreased by 14.6% because NS with high specific surface area inhibited the hydration of HSRPC, but its particle filling increased the porosity of harmless pores to improve the 3day (3d) compressive strength slightly. After 28d of hydration, the compressive strength increased by 2.8%, ultrasonic amplitude increased by 19.3%, and calcium hydroxide (CH) decreased by 6.6%, indicating that NS fully reacted with CH generated by HSRPC hydration. For HSRPC with FA, the 0.1–0.3 wt% NS increased the yield stress, setting time and 3d compressive strength and decreased the cumulative porosity. The 60 h cumulative hydration heat increased from 155.9 J/g to 198.5 J/g. The ultrasonic amplitude of 28d hardened paste increased from 10.91 V to 17.01 V and the CH content decreased from 15.29% to 14.1%. It indicated that the 0.1–0.3 wt% NS with high activity reacted with CH and further promote cement hydration to generate a large number of hydration products to improve the densification and performance, especially at the early age.

Concrete Mix Strength and Permeability with Various Supplementary Cementitious Materials

In order to reduce the amount of cement required, improve workability, mechanical properties, and durability, and have a positive environmental impact, supplementary cementitious materials are frequently utilized as a partial replacement for cement in concrete mixes. In this experimental investigation, the effects of employing waterproof and supplemental cementitious materials such as flyash, silica fume, and nano silica along with a water reduction agent were examined to increase the effectiveness and performance of concrete. The cement employed in this investigation, sulfate-resistant Portland cement, was partially substituted by the supplemental cementing components mentioned earlier to create concrete with a w/b ratio of (0.30-0.35) and C35 compressive strength. Thirteen various concrete mixtures were designed and tested at 28 days of age for compressive strength, splitting tensile strength, water sorptivity, absorption, and penetration depth under pressure. To enhance the dependability of the outcomes, three samples were evaluated, and their mean value was recorded. According to the research, mixing the chemicals with concrete resulted in a brand new substance that may meet the rising need for construction materials. All of the materials utilized in this study, with the exception of Water Proof, also showed good resistance to water absorption and strength improvement.

Long-Term Performance of Concrete Made with Different Types of Cement under Severe Sulfate Exposure

Concrete sulfate attack is of great interest as it represents one of the main reasons of concrete deterioration and poor durability for concrete structures. In this research, the effect of different cement types on concrete sulfate resistance was investigated. This included three concrete classes, namely, low strength concrete, medium strength concrete, and high strength concrete. Blast furnace cement (BFC), sulfate resisting Portland cement (CEM I-SR5), and ordinary Portland cement (OPC) were used in a total of eighteen concrete mixes. Three binder contents of 250 kg/m3, 350 kg/m3, and 450 kg/m3 and a constant silica fume (SF) content were applied in this experimental study. The water/binder (w/b) ratio was varied between 0.4 and 0.8. Concrete specimens were immersed in highly severe effective sodium sulfate solutions (10,000 ppm) for 180 days after standard curing for 28 days. The fresh concrete performance was evaluated through a slump test to attain proper workability. Concrete compressive strength and mass change at 28 days and 180 days were measured before and after immersion in the solution to evaluate the long-term effect of sulfate attack on the proposed concrete durability. Scanning electron microscopy (SEM) analysis was conducted to study the concrete microstructure and its deterioration stages. The obtained results revealed that BFC cement has the best resistance to aggressive sulfate attacks. The strength deterioration of BFC cement was 3.5% with w/b of 0.4 and it increased to about 7.8% when increasing the w/b ratio to 0.6, which are comparable to other types of cement used. The findings of this research confirmed that the quality of concrete, specifically its composition of low permeability, is the best and recommended protection against sulfate attack.

From selective dissolution to crystal chemistry of brownmillerite in sulfate resisting cement

AbstractThe aim of this study is to extract brownmillerite from sulfate resisting Portland cement (SRPC) in order to determine its crystal chemistry and the effects of dissolution protocols. Brownmillerites (C4AF) from four SRPC were extracted and systematically studied by X‐ray diffraction (XRD), electron probe microanalysis (EPMA), and X‐ray fluorescence spectroscopy.Two extraction steps were used. The first is the salicylic acid/methanol (SAM) protocol that leaves a residue rich in ferrite, C3A and sulfates. Precipitated hydrated sulfate minerals are also observed for clinker with high molar SO3/Na2Oeq ratio. The second, developed in this paper, uses acetic acid (AcA) extraction to dissolve C3A and sulfates.The Rietveld refinements showed that all brownmillerites of this study crystallize in Ibm2 space group. Two families of brownmillerite were identified by their aluminum content and cell parameters, related to the presence of C3A in the clinker. EPMA indicated that ferrites from SR0 and SR3 cements have Al/Fe ratios about 0.7 and 0.8–1.0, respectively. XRD allows to predict the (Al+Mg+Si)/Fe ratio in brownmillerite in good agreement with EPMA. The SAM protocol is the best way to study crystal chemistry of brownmillerite and the AcA protocol is recommended to dissolve sulfates and C3A for further reactivity studies.

Research on sulfate resistance of PC, SRPC and CSAC mortars incorporating coral waste filler

• Sulfate resistance of PC, SRPC and CSAC with CSP compared to LSP were studied. • CSP filler (≥20 %) replacing PC and SRPC suffered severe thaumasite attack at 5 °C. • CSAC-CSP specimens possess greater sulfate resistance than PC and SRPC specimens. • CSP filler in contrast with LSP results in less sulfate resistance of mortars. Coral waste filler partial replacing Portland cement facilitates the utilization of coral debris waste, the reduction of the economic cost of oceanic construction as well as the CO 2 emission. Thaumasite-related sulfate attack needs to be concerned because of rich calcium carbonate in form of aragonite in coral waste filler and the sulfate resources in the oceanic environment. The sulfate resistance of Portland cement (PC), sulfate resistant Portland cement (SRPC), and calcium sulfoaluminate cement (CSAC) incorporating coral sand powder (CSP) were studied under corrosion in 5 wt% NaSO 4 solution at 5 and 20 °C up to 540 days. The results show that CSAC-CSP specimens possess greater sulfate resistance than PC and SRPC specimens incorporating with CSP filler. Cracking was the main way for PC and SRPC specimens’ failure under sulfate attack at 20 °C. Exceeding 20 % of CSP filler replacing PC leads to server thaumasite-related sulfate attack exposure at 5 °C for 540 days. The formations of sulfate products including gypsum, ettringite, and thaumasite in PC-CSP and SRPC-CSP specimens were confirmed by XRD and FTIR tests. The ettringite-thaumasite cluster and deteriorated products were detected in PC and SRPC blended specimens. CSP filler in contrast with limestone powder (LSP) filler results in less sulfate resistance of blended specimens.

Crystal chemistry of extracted brownmillerite from sulfate-resisting Portland cement

Crystal chemistry of extracted brownmillerite from sulfate-resisting Portland cement

Natural Resources Exploitation in Sulfate-Resisting Portland Cement Manufacturing: Towards Quality Improvement and Reduction of Environmental Impact.

Sulfate-resisting (SR) Portland cement is commonly used in building works to improve concrete’s durability against external sulfate attack. This attack is considered a very serious chemical aggression that causes damage and cracking of concrete structures. These special cements have a very particular mineralogical composition, C3A ≤ 3% and (2C3A + C4AF) ≤ 20%, which makes the cementitious matrix resistant to sulfate attack. This kind of product is very difficult to manufacture since low alumina (C3A) necessitates the use of a high kiln temperature in order to keep a sufficient liquid phase necessary to maintain the stability of the cement manufacturing process. In this context, this study aims to optimize SR Portland cement raw meals using natural materials collected from different regions in Tunisia, mainly ordinary limestone, siliceous limestone, black marl, grey marl, iron ore, and natural fluorapatite. The collected specimens were characterized by an X-ray fluorescence spectrometer in order to determine its elemental chemical composition. The optimization of the SR Portland cement raw meal combinations was done by means of a calculation tool based on the chemical composition of each used raw material and the variation of burning modules (LSF, SIM, and ALM). It has been found that natural fluorapatite integration (0%–15%) in raw mix preparation leads to the raw meals required for the SR Portland cement standard (C3A ≤ 3% et 2 C3A + C4AF ≤ 20%). Moreover, it was shown that the estimated SR raw meals ensure the cement manufacturing process stability (acceptable burning modules “LSF = 100; SIM = 3; ALM = 0.91 and sufficient liquid phase) and decrease the CO2 emissions in cement production.

The influence of different types of SCMs on microstructure and macroscopic properties of cementitious materials

In our study, the influence of different supplementary cementitious materials (SCMs) such as metakaolins, silica fume (microsilica) or filtered coal fly ash on the performance of concrete is discussed. The effects of different types and dosages of the SCMs have been investigated. Centrilit NC (MK1) and Metaver N (mk2) type metakaolins, Microsit® 20 (MS) type filtered coal fly ash or Centrilit Fume SX (SF) silica fume suspension was chosen as the replacement for the CEM I 42.5 N-SR0 sulphate resistant Portland cement. In addition to the two-component mixtures, we also examined the behaviour of the ternary blends, i.e. the combinations of SCMs. For the experiments, mortar prisms and cylindrical mortar specimens were prepared with water to binder ratio of 0.4. The paper presents the test results performed up to two years. The compressive strengths of the mixtures were examined. The most critical property of the cement-bound materials, the chloride migration coefficient of each mixture, was determined. The microstructure of the mixtures was determined by mercury intrusion porosimetry at the age of one year. Our results indicated (i) the best compressive strength was achieved for MK2 and for MK1 with combination of SF; (ii) the pore structure is much finer in the case of MK1 mixtures compared with those of MK2 or MS mixtures; (iii) the whole most frequent pore diameter interval falls into the range of medium capillaries only in case of MK1 (10 w%), for other mixtures the large capillaries are present in different extent. The SCMs greatly influence the extent of the enhancement in chloride migration coefficients with age: the less reduction was found for the mixtures of MK1, and the highest reduction was found for mixtures of MS. There is no direct function between the compressive strength, total porosity, specific surface of porosity or chloride migration coefficients.

STRUCTURAL CHARACTERISTICS AND PERFORMANCE OF CONCRETE WITH A COMPOSITE MODIFYING ADDITIVE

Introduction: The paper addresses the effect of a composite modifying mineral additive based on waste — tailings from the Balkhash Mining and Processing Plant — and microsilica on the structural characteristics and performance of heavy concrete. Purpose of the study: We aimed to select optimal B25 and B35 concrete mixes based on the MV-D20 modified binder with the composite additive in its composition and evaluate the characteristics of concrete. Methods: In the course of the study, standard methods were used to design concrete mixes and test the characteristics of concrete. Proportioning was performed in accordance with State Standard GOST 27006-86 “Concretes. Rules for Mix Proportioning”. The physical and mechanical properties of heavy concrete were determined in accordance with State Standard GOST 10180-2012 “Concretes. Methods for Strength Determination Using Reference Specimens”. The strength of concrete was assessed in accordance with State Standard GOST 18105-2018 “Concretes. Rules for Control and Assessment of Strength”. Results: It was established that in terms of the rate of strength gain, the designed heavy concrete mixes are fast-curing. In the initial curing period of 7 days, B25 and B35 concretes gain 90.1 and 85.4% of the required standard strength, respectively. The average values of water absorption in B25 and B35 concretes are 4.20 and 3.46%, respectively. In terms of water tightness, concrete mixes have W10 and W12 grades. The application of the MV-D20 modified binder with the composite additive consisting of tailings and microsilica instead of standard sulfate-resistant Portland cement will reduce the relative deformation of B35 concrete in an aggressive environment by 12%.

Importance of sulphate-resistant Portland cement in construction

Importance of sulphate-resistant Portland cement in construction

Study on the Strength and Hydration Behavior of Sulfate-Resistant Cement in High Geothermal Environment.

The hydration process and compressive strength and flexural strength development of sulphate-resistant Portland cement (SRPC) curing at 20 °C, 40 °C, 50 °C, and 60 °C were studied. In addition, MIP, XRD, SEM, and a thermodynamic simulation (using Gibbs Energy Minimization Software (GEMS)) were used to study the pore structure, the types, contents, and transformations of hydration products, and the changes in the internal micro-morphology. The results indicate that, compared with normal-temperature curing (20 °C), the early compressive strength (1, 3, and 7 d) of SRPC cured at 40~60 °C increased by 10.1~57.4%, and the flexural strength increased by 1.8~21.3%. However, high-temperature curing was unfavorable for the development of compressive strength and flexural strength in the later period (28~90 d), as they were reduced by 1.5~14.6% and 1.1~25.5%, respectively. With the increase in the curing temperature and curing age, the internal pores of the SRPC changed from small pores to large pores, and the number of harmful pores (>50 nm) increased significantly. In addition, the pore structure was further coarsened after curing at 60 °C for 90 d, and the number of multiple harmful pores (>200 nm) increased by 17.9%. High-temperature curing had no effect on the types of hydration products of the SRPC but accelerated the formation rate of hydration products. The production of the hydration products C-S-H increased by 13.5%, 18.6%, and 22.8% after curing at 40, 50, and 60 °C for 3 d, respectively. The stability of ettringite (AFt) reduced under high-temperature curing, and its diffraction peak was not observed in the XRD patterns. When the curing temperature was higher than 50 °C, AFt began to transform into monosulfate, which consumed more tricalcium aluminate hydrate and inhibited the formation of “delayed ettringite”. Under high-temperature curing, the compactness of the internal microstructure of the SRPC decreased, and the distribution of hydration products was not uniform, which affected the growth in its strength during the later period.

Performance of cementitious and alkali-activated mortars exposed to laboratory simulated microbially induced corrosion test

This research presents a laboratory simulated microbially induced corrosion (MIC) test method allowing to assess the performance of low calcium fly ash based geopolymer mortar (FA-GPm), alkali-activated slag-based mortar (AASm), sulphate resistant Portland cement mortar (SRPCm) and calcium aluminate cement mortar (CACm). This experiment runs for a period of six months in which sulphur oxidizing microbes (SOMs) (A. thiooxidans and T. intermedius) were grown in liquid media containing the thiosulphate ion. This test methodology aims to investigate the bacterial attachment phase (stage 2) followed by the initiation of acid attack (stage 3) of MIC. Lowering of the pH of liquid medium and the growth of microorganism was measured to evaluate the aggressiveness of this microbial environment. Visual, physical, chemical and microstructural investigations of mortars were performed over time to estimate the deteriorations. Ions leaching from the matrix and formation of sulphate (SO42−) was monitored using inductively coupled plasma mass spectroscopy (ICP-MS) and ion chromatography (IC), respectively. The results showed that the neutralization of CACm after exposure to biotic reactor was lesser compared to the other mortars, indicating its resistance towards biocorrosion. Moreover, formation of sulphuric acid (H2SO4) and the growth of SOMs showed its dependence on the type of mortar. Scanning electron microscopy (SEM) with energy-dispersive X-ray (EDX) spectroscopy was used to predict the depth of degradation and morphological variations at microstructural level. Patterns of deterioration and nucleation of minerals identified were similar to infield exposure, indicating the suitability of this testing method to simulate sewer biocorrosion.

Effect of well water on the mechanical properties of concrete with using two types of cement

The effect of using different water resources and cement types on concrete strengths at late ages is investigated. Two types of cement including Ordinary Portland Cement (OPC) and Sulfate Resisting Portland Cement (SRPC) were employed to prepare concrete mixes with potable and well water. Compressive, flexural, and tensile tests on were conducted at 28, 90 and 180 days. Results show that the maximum decreasing of concrete strength was about 42.9% at 180 days compared with the control mix when using well water with OPC. This was due to the chemical contents of well water that are more than the allowed limits. While the reduction in compressive strength was about 31.3% when using well water with SRPC due to sulfate resisting cement. Flexural strength reductions of 50.5% and 42.8% was seen when using OPC and SRPC respectively with well water at 180 days. Same effect was observed for tensile strengths which indicates that using well water has negative effect on concrete strengths at late ages. Modulus of elasticity was calculated using the ACI 318 equation. Higher reduction of 24.5% was seen when using OPC with well water than 17.2% when using SRPC with well water at 180 days compared to control mix.

Sewer concrete subjected to biogenic acid corrosion: analysis of concrete deterioration phases using QEMSCAN

QEMSCAN (Quantitative Evaluation of Minerals by Scanning Electron Microscopy) was used to analyse the evolution of cementitious phases of sewer concrete after biogenic acid attack. Two concrete mixes; a blend of Sulphate Resisting Portland Cement and Fly Ash (SRPC+FA) and Calcium Sulpho-Aluminate (CSA) cement, with calcite and siliceous aggregates, were subjected to a field sewer environment, with a maximum H2S gas concentration of 100 ppm, for about two years. After exposure, both concretes experienced thickness losses, with CSA indicating mass gain and SRPC+FA mass loss. QEMSCAN analysis results indicated that SRPC+FA was rich in calcium silicate hydrates in the intact zone, Mg-silicate in the transition zone, and Al-silicate, gypsum, and quartz in the deterioration layer. CSA contained ettringite and portlandite in the intact zone, gypsum and aluminate phases in the deterioration zone, while the transition zone was challenging to observe due to the superimposition of ettringite before and after the attack. It was concluded that, despite CSA showing a lower corrosion rate than SRPC+FA, it exhibited severe deterioration under QEMSCAN. Therefore, QEMSCAN is a potential tool for preliminary analysing of concrete microstructural phases under biogenic acid attack. However, it should be incorporated with other microstructural analysis tools.

Mitigation potential of sulfate-resistant Portland cement for internal sulfate attack

Mitigation potential of sulfate-resistant Portland cement for internal sulfate attack

Characterization and adaptability of layered double hydroxides in cement paste

Layered double hydroxides (LDHs) improve the durability of concrete, whereas theirs characterization and adaptability in cement-based matrix has not been systematically investigated. Setting time, chemical shrinkage, rheology, compressive strength, hydration degree, pore structure as well as micro-mechanisms of high sulphate-resistant Portland cement (HSRPC) incorporating different LDHs, namely, CaFe-NO3 LDHs (LDHs-CF), CaAl-NO3 LDHs (LDHs-CA), and CaFeAl-NO3 LDHs (LDHs-CFA), were explored. At any types of LDHs, the trend of compressive strength of HSRPC pastes increased firstly and then decreased afterward with the addition of LDHs dosage, while the addition of LDHs increased the chemical shrinkage values of pastes during the early stage, but 28 d chemical shrinkage values were not particularly notable. Furthermore, radar map showed that the shortening of setting time, the increase of dynamic yield stress of samples presented great change with the increase of LDHs dosage, whereas the 28 d chemical shrinkage value changed little in all samples. LDHs, especially LDHs-CF and LDHs-CFA, reduced the volume fractions of harmful pores, refined on pore structure and increased tortuosity of samples since Fe-based LDHs have smaller nanoscale dimension and lower crystal transformation. The acceleration of cement hydration, decrease of workability and improvement of mechanical property at early stages were due to the interstitial filling and crystal seed effects, crystal transformation, or/and absorption of free water by LDHs 2D nano-platelets. In conclusion, LDHs shows good adaptability in cement paste, and as an effective hardening accelerator for HSRPC hydration.

Study of the Hydration Kinetics of Cement Paste by Measuring Electrical Conductivity

The hardening cement paste is a highly concentrated polyelectrolyte that changes over time. From this point of view, the main electrochemical characteristics of the hydration process of cement paste can be the electrical conductivity and electrode potentials of metals lowered into cement pastes. In the process of setting and hardening of cement dough, complex physical and chemical processes of interaction of clinker minerals with water occur. In this case, new chemical compounds are formed, the concentration of Ca2+, Mg2+, A13+, Si4+, Na+, H+, OH− ions in the liquid phase changes, and the amount of free water decreases. Therefore, the electrical conductivity of the cement paste will change during the hydration of Portland cement minerals. The kinetics of hydration of cement paste is studied by measuring the electrical conductivity depending on the water-cement ratio and in the presence of additives SP C-3 and PDO-M. The parameter of electrical resistance of cement paste was studied using a digital voltmeter of type B7-27A/1. In experimental studies, we used additive-free sulphate-resistant Portland cement with an activity of 41.0 MPa with a normal density of 0.24 and pure clinker minerals – C3S и β-C2S. After preparation, the cement paste was placed in the assembled cell and compacted by vibration. Graphs of changes in the complex electrical resistance of cement pastes are obtained, which show that the curves have an oscillatory character. It was found that with an increase in the water-cement ratio, the vibrational nature of the interaction of water with Portland cement minerals weakens. When the water-cement ratio is equal to 0.42, there are no fluctuations in electrical conductivity. This can be explained by the fact that when the amount of water in the cement paste increases, the influence of cations on the degree of its ordering decreases. Curves of changes in the electrical conductivity of cement pastes obtained at W/C=0.26, without additives, as well as in the presence of SP C-3 and PDO-M additives. It can be seen that in the presence of SP C-3, fluctuations in electrical conductivity are weakly expressed. It can be assumed that SP C-3 has a disordering effect on the water in the cement paste. The addition of PDO-M, on the contrary, orders the structure of water, there are fluctuations in electrical conductivity. It is shown that in the CaO–SiO2–H2O system, a state of instability develops at certain ratios of the rate constants of individual stages of the hydration process. SP C-3, adsorbed on the adsorption centers of polysilicon acid, slows down some processes, which accelerates others, and the difference between the speed constants of individual stages increases.