Properties Of Cement-based Materials Research Articles

The influence and mechanism analysis of aluminum sulfate as an environmentally friendly early strength agent on the properties of cement-based materials

Environmentally friendly chemical admixtures are becoming important in the cement industry. The research objective of this paper is to use aluminum sulfate as an early-strengthening agent to achieve the goals of a large increase in early strength and a reduction in CO2 emissions. The experimental design was as follows: The macroscopic properties and microscopic characteristics of aluminum sulfate were experimentally investigated on five different replacement ratios of 0%, 1%, 2%, 3%, and 4% paste specimens of cement at different ages. The results show that (1) AS4 demonstrated a notable enhancement in early strength, while AS2 and AS3 contributed to increased late-stage strength. Over time, the Ultrasonic Pulse Velocity (UPV) of all samples exhibited a steady rise. Additionally, aluminum sulfate was found to reduce the electrical resistivity of the samples. (2) aluminum sulfate increased the rate of exothermic heat release of samples at induction and acceleration phases, advanced the accumulated heat was high in the samples with high aluminum sulfate content, and the accumulated heat was strongly correlated with the compressive strength. FT-IR and XRD results show that aluminum sulfate promoted the formation of AFt while depleting the CH content, and the TGA results show the content of bound water in the samples increased from Day 1 to Day 28, which had a positive effect on the compressive strength. UHR-SEM results show that increasing aluminum sulfate substitution results in the formation of a denser microstructure. (3) for all the various mixtures, AS2 has the lowest CO2 emissions per unit strength.

Influence of Eggshell Powder on the Properties of Cement-Based Materials.

Replacing cement with industrial by-products is an important way to achieve carbon neutrality in the cement industry. The purpose of this study is to evaluate the effect of eggshell powder on cement hydration properties, and to evaluate its feasibility as a substitute for cement. The substitution rates of eggshell powder are 0%, 7.5%, and 15%. Studying the heat of hydration and macroscopic properties can yield the following results. First: The cumulative heat of hydration based on each gram of cementitious material falls as the eggshell powder content rises. This is a result of the eggshell powder's diluting action. However, the cumulative heat of hydration per gram of cement rises due to the nucleation effect of the eggshell powder. Second: The compressive strengths of ES0, ES7.5, and ES15 samples at 28 days of age are 54.8, 43.4, and 35.5 MPa, respectively. Eggshell powder has a greater negative impact on the compressive strength. The effect of eggshell powder on the speed and intensity of ultrasonic waves has a similar trend. Third: As the eggshell powder content increases, the resistivity gradually decreases. In addition, we also characterize the microscopic properties of the slurry with added eggshell powder. X-ray Diffraction (XRD) shows that, as the age increases from 1 day to 28 days, hemicaboaluminate transforms into monocaboaluminate. As the content of the eggshell powder increases, FTIR analysis finds a slight decrease in the content of CSH. Similarly, thermogravimetric (TG) results also show a decrease in the production of calcium hydroxide. Although the additional nucleation effect of eggshell powder promotes cement hydration and generates more portlandite, it cannot offset the loss of portlandite caused by the decrease in cement. Last: A numerical hydration model is presented for cement-eggshell powder binary blends. The parameters of the hydration model are determined based on hydration heat normalized by cement mass. Moreover, the hydration heat until 28 days is calculated using the proposed model. The strength development of all specimens and all test ages can be expressed as an exponential function of hydration heat.

Experimental study on cement-based materials for grouting/replacement of broken rock mass in coal mine

In deep high-pressure mines, the surrounding rock of soft broken roadways often faces issues such as poor anchorability, support difficulties, high maintenance costs, and the inadequacy of traditional materials for site requirements. To tackle these challenges, this study focuses on grouting reinforcement in coal mine sites and prefabricated bearing arch form (grouting or replacement) under specific conditions, aiming to meet the material requirements. Through an orthogonal test, various properties of cement-based materials were investigated, including fluidity, initial setting time, water separation rate, early (≤1d) compressive strength, fracture strength, and later (28d as a reference) strength. The objective was to develop a cost-effective cement-based material with high strength and toughness, suitable for underground coal mines. The experimental results demonstrate that the self-developed cement-based materials exhibit rapid setting, excellent fluidity, high early strength, and strong durability compared to traditional alternatives. Analyses of the comprehensive properties reveal that the influencing factors, in order of significance, include the mass ratio of cement and sand, water cement ratio, rubber content, and bonding mortar master material content. By employing extreme treatment and efficiency coefficient methods, the comprehensive performance of materials under different ratios was evaluated. Consistent findings were obtained, indicating that the optimal mass ratio of cement-based materials is 500:500:20:15:10:5:8:10 for cement, sand, fly ash, silica fume, mineral powder, steel slag powder, bonding mortar master material, and rubber, respectively. Additionally, the best comprehensive performance was achieved with a water cement ratio of 0.5, which confirms the results of the orthogonal test. Macroscopic failure characteristics and SEM microscopic analysis further validate the superior performance of the materials under the aforementioned ratio. The reaction process of the material can be roughly divided into four stages: initial hydrolysis stage, induction stage, acceleration stage, decay and stability stage, and finally the formation of stone body. A comparison with ordinary materials highlights the advantages of the developed cement-based materials, and suggestions are proposed for the development of field-applicable materials.

Rheological properties and workability of PVA fiber and nano-SiO2 modified cement-based materials

Nanoparticles and fibers are frequently applied to improve the mechanical properties and durability of cement-based materials (CBM). In this study, rheology, workability and compressive strength tests were carried out to investigate the effect of PVA fiber (PF) and nano-SiO2 (NS) on rheological properties, workability and mechanical properties of CBM. Also, the function relationships of PF/NS content with rheological and workability parameters, rheological parameters with compressive strength were established separately. In addition, the effect mechanism of PF and NS was explained in depth. Finally, the fuzzy matrix method was employed to make a comprehensive evaluation on CBM performance. The results indicated that PF had negative influence on both rheological properties and workability of CBM. Whereas, NS only exhibited an increase in rheological properties of CBM at 0.5% content and a slight improvement in workability at 1.0% content. The comprehensive performance of CBM reached the optimum with PF content of 0.6%.

Effect of heat transfer and storage ability of silicon carbide (SiC) ceramic particles on the microwave deicing characteristics of cement-based materials

Microwave heating has been applied to improve cement-based materials (CBMs) structures deicing efficiency, which reduce the effect of icing on their service life. Moreover, the enhanced thermal properties of CBMs can further improve their deicing efficiency. In this study, silicon carbide (SiC) ceramic particles with favorable thermal properties were used to prepare the SiC cement-based materials (SCBMs). The effect of SiC ceramic on the mechanical strength of CBMs was investigated. Next, the heat transfer and storage ability of CBMs were investigated to analyze the changes in their thermal-physical parameters. Then, the surface thermal responses of the CBMs during microwave heating and off were recorded to characterize their temperature evolution in a low-temperature condition. Furthermore, the deicing efficiency of CBMs was determined using the ice layer shedding time (ILST) as the index. The results show that the filling effect of SiC ceramic on CBMs improved their mechanical strength within a certain content range. However, a large content of SiC ceramic caused an increase in the weak area and porosity within the CBMs, further reducing their mechanical properties. The thermal-physical parameters of CBMs were improved after adding SiC ceramic. The thermal conductivity and thermal effusivity of SCBMs-100 were 13.17 W/(m·K) and 1.44 W/(mm2·K), respectively, 7.90 and 2.35 times higher than the control group. Due to the favorable thermal properties of SCBMs, their heating rate and surface temperature field distribution characteristics were further improved. Furthermore, with the increase of SiC ceramic content, the ILST of SCBMs was further reduced during microwave heating. Therefore, the SiC ceramic was a favorable material, improving the thermal properties and deicing efficiency of CBMs to a certain extent. However, considering its effect on the deterioration of the mechanical properties of CBMs, the optimal content of SiC ceramic might be 75%.

Study on the Performance of Polymer-Modified Conductive Cement-Based Materials

In order to study the synergistic effect of polymer and conductive functional materials on the properties of cement-based materials, polymer conductive cement-based materials were prepared by mixing four polymer lotions of silicon–acrylate emulsion (SG), phenylacrylic emulsion (SR), waterborne epoxy resin emulsion (SH), and acrylic emulsion (SX) with carbon fiber (CF) and carbon black (CB), two conductive functional materials, in a certain proportion. The effects of the different polymer–cement ratios (P/C) of the four polymers on the physical, mechanical, and electrical properties of conductive cement-based materials were studied. The results illustrated that SH improved the fluidity of cement paste, and the four polymers all had a delaying effect, which led to the hardening of the specimens and the extension of the demoulding specimens to varying degrees. SH and SR can increase the ratio of flexural strength to compressive strength (F/C) in cement paste and improve the toughness of materials, and the maximum value is reached when the P/C is 0.15. Except for SX, the other three polymer lotions can reduce the resistivity of cement paste, which is beneficial to the improvement of conductivity. The improvement sequence is SH > SR > SG. Among them, both SH group and SR group achieved the lowest electrical resistivity at the P/C of 0.15. The four kinds of polymer lotion can significantly reduce the water absorption of the specimen and promote the waterproof performance. The improvement effect: SH > SR > SG > SX. Among them, both the SH group and SR group achieved the minimum water absorption at the P/C of 0.15.

Synergistic effect of PTB emulsion, CaCO3 whisker and Nano-SiO2 on the properties of cement-based materials

With the rapid development of the civil engineering industry, performance requirements for building materials are also increasing rapidly. It is particularly critical to improve the performance of cement-based materials using admixtures. In this study, the synergistic effect of PTB (COMPAKTUNA.PRO) emulsion, calcium carbonate whisker (CaCO3 whisker) and nano-silica (nano-SiO2) on material properties was analyzed. Macroscopic properties such as rheology, compressive strength, flexural strength, durability, bond strength, and permeable pressure were tested. Microstructures were analyzed using the porosity, hydration heat, X-ray diffraction, and scanning electron microscopy methods. The results revealed that the PTB emulsion, CaCO3 whiskers, and nano-SiO2 increased the plastic viscosity and yield stress of the cement. When the nano-SiO2 content was high, the fluidity of the slurry decreased significantly. Overall, PTB emulsion, CaCO3 whisker and nano-SiO2 can improve the strength, durability, bond strength, and permeability of composite materials. PTB emulsions can prolong the hydration process, resulting in low early strength and reduced compressive strength. However, they play a key role in terms of improving durability, bond strength, and permeability pressure. CaCO3 whiskers yield slight improvements in various properties. Nano-SiO2 can promote the hydration rate and hydration effect, thereby improving the strength, compactness, and properties of composite materials. Performance can be optimized by leveraging these synergistic effects and each material has its own unique advantages and limitations. In engineering applications, critical properties should be considered when selecting appropriate admixture contents. This study aimed to improve various properties and to develop materials that are suitable for the complex environment of underground engineering.

Atomistic insights into the effect of temperature on capillary transport of water molecules in epoxy-modified calcium silicate hydrate nanopore: diffusion, kinetics, and mechanism

The movement of water molecules at the atomic scale within the calcium silicate hydrate (C–S–H) gel pores serves a dual role: it creates an environment for harmful chemical reactions within the pores and functions as a carrier for the transport of detrimental ions, thereby affects the mechanical properties and durability of cementitious materials. However, direct experimental observation poses substantial challenges. This study offers new insights into how temperature (253 K, 273 K, 293 K, and 313 K) affects the capillary transport of water molecules in epoxy-modified C–S–H. The findings demonstrate that the pore size undergoes continuous changes during immersion due to epoxy clustering or detachment, resulting in three scenarios: narrowing of epoxy/C–S–H channels (253 K, 273 K), channel blockage (293 K), and complete detachment (313 K). Moreover, the interactions between water molecules and epoxy lead to epoxy detachment or cluster formation on the C–S–H surface. As the temperature increases, the interaction between C–S–H and cross-linked epoxy resin weakens. The coordination between C–S–H and epoxy resin decreases, while the coordination with water increases. This paper provides valuable insights into the transport behavior of liquids within the epoxy-modified C–S–H pores of cement-based materials. It contributes to a better understanding of how liquids move and interact within the modified pore structure, which is beneficial for enhancing the performance and properties of cement-based materials.

Properties of Cement-Based Materials with Low Water–Binder Ratios and Evaluation Mechanism under Further Hydration Effect

Unhydrated cementitious materials in high-performance concrete (HPC) and ultra-high-performance concrete (UHPC) undergo further hydration when they are further supplied with water. A further hydration experiment on cement pastes was conducted to study the effects of temperature and humidity on their macroscopic properties. A rapid evaluation mechanism for further hydration was eventually presented. The results obtained under the four analysed humidity conditions indicated that the compressive strength and flexural strength increased by 22.6% and 75.2%, respectively, after further hydration for 180 d at a relative humidity (RH) of 95%. Considering water soaking under three analysed temperature conditions, water soaking at 60 °C had the largest impact on macroscopic properties, such as compressive strength and flexural strength, which showed an increase of 31.4% and a decrease of 13.8%, respectively, after further hydration for 180 d. Moreover, the expansion strain at 60 °C was 1.1 times higher than the strain determined under water soaking at 40 °C. Considering the stability of the evaluation indices, the combined water content for further hydration, expansion strain, and compressive strength were used to evaluate further hydration effect. Considering the acceleration and damaging effects, water soaking at 60 °C was an effective method to accelerate further hydration.

Alternatives for Fresh Water in Cement-Based Materials: A Review

Huge amounts of fresh water are used in the concrete industry every day. The quantity and quality of water play important roles in determining the quality, strength, setting time, and durability of cement-based materials (CBMs), such as paste, mortar, and concrete. Freshwater systems are under pressure due to climate changes, industrialisation, population growth, urbanisation, and the lack of proper water resource management. The lack of potable water has resulted in the search for possible alternatives, such as seawater, treated industrial wastewater, treated sewage wastewater, carwash service station wastewater, wastewater from ready-mix concrete plants, and wastewater from the stone-cutting industry. All of these water resources can be used in concrete to achieve adequate industry standards for the physical and chemical characteristics of concrete. This study is a comprehensive review of the existing information regarding the effects of alternate water resources on the fresh, physical, strength, and durability properties of CBMs. The review shows that the research on the utilisation of wastewater in CBMs is limited. The development of different procedures and methods is urgently needed to utilise various wastewaters in concrete production. The usage of various wastewaters in concrete construction overcomes their adverse impacts on the environment and human health.

Effect of low-vacuum environment on the strength and permeability of cement-based materials

The exposure of cement-based materials to low-vacuum environments will result in fast moisture loss, which will cause phase transformation and pore structure changes, as well as variations in mechanical and permeability performances. In this study, a series of experiments were conducted to investigate the effects of various drying conditions (i.e., standard drying, low-vacuum drying, and oven drying conditions) on the properties of cement-based materials, including paste, mortar, and concrete. The tested properties included the mass loss during the exposure to drying conditions, as well as the compressive strength and permeability after the exposure. Results show that the drying rate of cement-based materials was higher under low-vacuum conditions than oven drying for the first two hours, but slower thereafter. Vacuum drying led to a greater enhancement in compressive strength than oven drying, with the most significant effect identified in cement paste. Additionally, oven drying showed more significant deterioration effects on permeability of cement-based materials compared to vacuum drying. The presence of aggregates in concrete has two contrasting effects on the medium permeability: intricated pathways would decrease permeability, but the microcrack formation at the interface during drying would increase permeability. Conventional two-phase material models based on the results of cement paste permeability tests cannot accurately predict the permeability of mortar or concrete after exposure to drying conditions in this study. The paper is expected to provide a basis for the investigation of the mechanical properties and durability evolution of cement-based materials under a low-vacuum environment.

Effect of complexation of alkanolamine in accelerators on the initial stage of cement hydration

In this study, diethanolamine (DEA) and triethanolamine (TEA) were used to prepare a series of liquid alkali-free accelerators to investigate the different effects of complexation of DEA and TEA in accelerators towards the initial stage of cement hydration. Two types of accelerators respectively containing DEA (dosages of 0, 6, 8, 10, 12%) and TEA (dosages of 0, 0.25, 0.5, 0.75, 1, 8%) were prepared, and after addition, the setting time of cement pastes and compressive strength of mortars were tested. The result showed that the optimum dosage of DEA and TEA in accelerators was 8% and 0.25% respectively, and the early-strength effect of TEA was stronger than that of DEA. The mechanisms of DEA and TEA in accelerators were further revealed in terms of complexation capacity, concentration of Ca2+, and hydration products and microstructure morphology of cement pastes. DEA and TEA complexed with Al3+ in accelerators and promoted the formation of ettringite (AFt) in cement pastes, and the complexation capacity of TEA to Al3+ was stronger than that of DEA, causing that high dosage of TEA in accelerator promoted the formation of AFt more than DEA and covered at the surfaces of C3A and C3S, which inhibited the hydration. DEA in accelerator could promote the hydration of C3S in the initial stage due to the transformation of complex DEA-Al to DEA-Ca. This study aims to interpret the different influences of complexation effects of DEA and TEA in accelerators on the properties of cement-based materials and their working mechanisms.

Effect of Vibration Procedure on Particle Distribution of Cement Paste

Vibration procedures significantly affect the performances of cement-based materials. However, studies on the distribution of certain particles within cement-based materials are limited due to the complexity and difficulty of identifying each specific particle. This paper presents a new method for simulating and quantifying the movements of particles within cement paste through the use of "tagged materials". By separating the tagged particles from the cement paste after vibration, the distribution of the particles in the cement paste can be calculated statistically. The effect of the vibration time and frequency, fresh behavior, and powder characteristics of cement paste on particle motions are investigated. The results demonstrate that when the vibration exceeds 1800 s, it induces a significant uneven dispersion of microparticles. This effect is more pronounced at low viscosities (<1 Pa·s) of cement paste or high vibration frequencies (>200 Hz). Larger and denser particles exhibit greater dispersion. This method provides a valuable tool for investigating the theory of particle motion in cement paste, which is crucial for understanding the influence of vibration on the properties of cement-based materials.

Effect of defoaming agent on the properties of cement mortars with hydroxyethyl methyl cellulose through adjusting air content gradient

Pore structure plays one of the most important role in the properties of cement-based materials. Hydroxyethyl methyl cellulose (HEMC) has the air entrainment effect, which may significantly change the pore structure and further affect the performance of this materials. Incorporating defoaming agent (DA) may weaken this effect, due to its defoaming effect which needs to be fully evaluated. Therefore, the working efficiency of DA and the changes of pore structure caused by stepwise adjustment of the air content were mainly studied. The results show that incorporating DA can effectively eliminate air bubbles, while the defoaming effect is weak with the air content approaching to 6.0%. There is a certain negative correlation between fresh bulk density and air content, and a positive correlation between fluidity and air content. Incorporating an appropriate dosage of DA is beneficial to control the air content of the cement mortars with HEMC, so as to ensure the cement mortars have better mechanical strengths and low drying shrinkages. With the increase of DA dosage, the large capillary pores, macro pores and total porosity all show a gradual decreasing trend due to the air content decreasing. The content of connected capillary pores in cement mortars tends to increase as the air content level decreases, but shows a small decrease at the low air content of less than 6.0%.

Effects of ground coal bottom ash on the properties of cement-based materials under various curing temperatures

Steam curing is usually used in the production of precast concrete for modern industrial buildings. To promote the recycling of industrial waste and further reduce the amount of cement used in prefabricated construction materials, this study aims to investigate the effects of coal bottom ash (CBA) on the performance of cement-based materials under various curing temperatures. The microstructures and mineral phases of hydrated cement pastes were analyzed. The hydration reactivity of CBA was improved via grinding and elevating the curing temperature. Results showed that under the curing condition of 20 °C, the compressive strength of cement mortar added with 30 wt% of CBA-40 (the ash after 40min's grinding) was increased by 12.59% compared with the one made with 30 wt% of CBA-10 (the ash after 10 min's grinding). With the same addition of 30 wt% CBA-40, the compressive strength of cement mortar cured under 192 °C was increased by 12.66% compared with that cured under 20 °C. In general, finer CBA particles and higher curing temperature exhibited positive effects on improving the properties of cement materials. This study provides a novel approach to utilize the CBA to prepare high quality mineral admixtures for being used as a replacement of cement. It was concluded that the combination of suitable steam curing regime and proper fineness of CBA could produce low cost steam-cured concrete with excellent performance which possesses significant environmental benefits.

Effect of a New Multi-Walled CNT (MWCNT) Type on the Strength and Elastic Properties of Cement-Based Mortar

Creating new construction materials with improved strength, elasticity, and durability properties represent the focus of many research works. Significant research effort has been invested in investigating the use of carbon nanotubes (CNTs) in cementitious materials, especially multi-walled carbon nanotubes (MWCNTs) which consist of a series of concentric graphite tubes. The use of MWCNTs is closely related to the use of surfactants and ultra-sonication procedures which may alter their properties and the properties of cement-based materials. The paper presents the preliminary results of an experimental investigation on the suitability of using a new, modified, MWCNT type aimed at eliminating the need of using surfactants and ultrasonication. The modified MWCNTs have a much lower surface energy compared to “classical” ones which would result in a decreased tendency of self-aggregation. A comparison was carried out from the point of view of density, flexural and compressive strength as well as dynamic modulus of elasticity of the obtained mortars. The mortar mix incorporating the modified MWCNTs showed improved mechanical properties even for a low percentage of CNT addition (0.025% by mass of cement). The results are discussed based on the material structure determined from a series of scanning electron microscopy (SEM) and X-ray diffraction (XRD) analyses.

Effect of Basalt Powder on Hydration, Rheology, and Strength Development of Cement Paste

Basalt materials (e.g., basalt powder, aggregate, and fiber) are commonly used in cement-based materials. To understand the mechanism of the influence of basalt on the properties of cement-based materials (i.e., fluidity, hydration, and strength), zeta potential tests with different Ca2+ concentrations were carried out using basalt powder (BP). It is found that BP has a weaker absorption for Ca2+ compared to cement and quartz particles, which is directly related to its surface chemical properties. This weak absorption has a significant influence on the rheology and early-age hydration of cement paste. Moreover, the morphology of hydrate on the surface of the material observed by scanning electron microscope (SEM) also shows that the growth of CSH on the surface of BP particles is smaller than that of cement particles, indicating that BP delays the formation of CSH. Rheological tests showed that the reduction of BP's adsorption of calcium ions weakened the electrostatic repulsion between particles, which led to the reduction of rheological properties. The influence of BP on the strength of cement paste was studied through crack characterization and fracture observation. The results show that the interfacial strength between BP and hydration products is very weak and does not increase with the hydration process, and the chemical reaction of BP is not obvious. In addition, the substitution of BP for cement leads to a dilution effect. These factors cause the strength of cement paste to decrease.

A Review of the Influence of Copper Slag on the Properties of Cement-Based Materials

Global copper slag (CS) emissions reached 57.2 million tons in 2021. Despite the increasing reuse of CS, the treatment of CS is still dominated by landfill so far, which not only occupies land resources but also causes damage to the environment. The application of CS to cement-based materials (CBMs) is one of the main approaches to its comprehensive utilization and has important economic and social implications. This article reviews the physicochemical properties, activity excitation, and heavy metal leaching properties of CS and summarizes the effect of CS on the working properties, mechanical properties, and durability of CBMs. At the end of the article, the existing problems in the research are analyzed, and the development trend is proposed, which provides technical guidance and reference for further research and application of CS in CBMs in the future.

Retardation and compressive strength enhancement effect of upcycling waste carrot as bio-admixture for cement mortars

The use of bio-admixtures instead of traditional chemical admixtures to prepare green concrete has attracted immense attention. In this study, a new and clean method to upcycle waste carrot into a novel natural admixture for cement mortars was proposed, and the effect of carrot extract (CS) on the properties of cement-based materials was systematically studied at the macro and micro levels through multiple means of detection. The results revealed that CS effectively inhibited the early hydration of cement and prolonged its setting time. The setting time of the pastes containing CS was 1.1–2.7 times that recorded for the control group (without CS) (CON), and the retarding effect was positively correlated with CS concentration. The compressive strength of the mortar of the M-CS1 (the value of CS to water was 1:100) group was increased by 12.5%, 11.6%, and 4.5% at 3-, 7-, and 28 d, respectively,which was due to the fact that CS accelerated the generation of calcium hydroxide (CH) and calcium silicate hydrate(C–S–H). In summary, CS can be used as a retarder and compressive strength enhancer in concrete simultaneously, and the experimental results in this study can provide experimental data and a basis for the preparation of green concrete. • The setting time of the pastes containing CS was 1.1–2.7 times that recorded for CON, and the addition of CS with appropriate concentration can also improve the compressive strength of the mortar. • CS contains a large number of hydrophilic group - hydroxyl, which has good water retention performance in cement. • The CS solution did not lead to the formation of new hydration products but promoted the formation of CH and CSH in the system, which has a positive effect on the compressive strength of mortars. • CS can improve the micro pore structure of mortar. • The use of low dose CS exhibited better sustainability and higher cost-effectiveness as confirmed by the economic and environmental analysis.

On the Application of Carbon Nanomaterials as Modifying Additives in Cement-Based Composites

This article presents the results of a study on the effect of carbon nanosized additives on the structure and properties of cement-based materials. The use of a carbon black dispersion as an alternative to an expensive dispersion of carbon nanotubes is proposed. Based on the experimental data, it is proven that the introduction of carbon black particles into the composition of the cement matrix in an amount of 0.2% by the weight of cement leads to an increase in strength of the cement stone, in both compression and bending, by 21% and 8%, respectively. This increase is compatible with the results obtained when cement matrix was modified with a dispersion of carbon nanotubes.IR spectral and thermal analysis of the modified cement matrix, as well as the study of its microstructure, confirm the formation of a dense net of cement hydration products, including low-basic calcium silicate hydrates and secondary nanosized globular thaumasite formations that contribute to the compaction of the material structure and the following increase in strength.