Cement Mixtures Research Articles

A single‐sided 1H NMR study of the self‐drying properties of a ternary self‐levelling underlayment

AbstractSelf‐leveling underlayments (SLU) are used for smoothing and levelling sub‐floors before any flexible flooring is applied. Though being comparatively simple in its requirements, commercial SLUs have become one of the most complex cementitious mixtures in dry‐mortar technology. By using ternary binders, most SLUs are designed to be self‐drying, binding most of the mixing water in crystalline cementitious phases, allowing a fast work progress. In this study, the simultaneous hydration and drying of a commercial SLU are monitored with single‐sided 1H nuclear magnetic resonance (NMR). This technique allows the quantification of chemically bound water and water in different pore environments with superior time and depth resolution. The technique is combined with conventional testing techniques enabling a more comprehensive view on the processes at hand. Results allow quantification of hydration and self‐drying, superimposed by physical drying effects over time. Additionally, the drying of a PVC adhesive through water absorption into a well‐dried SLU are visualized with this technique. The results are discussed in the context of moisture transport processes and floor‐laying readiness of the material.

Prediction of microstructural evolution in fly ash-modified cementitious system: A computational study

Abstract The intricate interaction between supplementary cementitious materials (SCMs) and cementitious systems profoundly influences the performance and sustainability of cementitious composites. This study explores the microstructural evolution of fly ash (FA)-modified cement paste by employing a three-dimensional cement hydration and microstructure development (CEMHYD3D) modeling package. Through comprehensive simulations, the influence of varying FA content on hydration phase evolution and pore structure within the cementitious system is revealed. As the proportion of FA within the cementitious mixtures increases, there is a substantial enhancement in the rate of hydration. Notably, the incorporation of FA introduces a significant augmentation in the hydration rate, a phenomenon with potential implications for the long-term performance of FA-modified cementitious materials. The prediction results also highlight that increasing FA substitution in cement leads to finer and more interconnected pore networks due to the pozzolanic reaction. These perceptions hold significant implications for optimizing cementitious mixes and advancing sustainable construction practices. The model-predicted results have been validated with experiments, and they are successful in predicting the microstructural evolution in FA-modified cement paste. In summary, the prediction model bridges the theoretical and practical implementation gaps by providing a thorough understanding of the microstructural evolution of FA-modified cement paste. Furthermore, it provides invaluable guidance for tailoring FA-blended cement compositions, thus promoting their enhanced performance and sustainability in the realm of cementitious materials.

Masquelet Technique: Visualization of Cement Spacer Utilizing Methylene Blue

Masquelet Technique: Visualization of Cement Spacer Utilizing Methylene Blue

Effect of Incorporating Titanium Dioxide Nanoparticles into White Portland Cement, White Mineral Trioxide Aggregate, and Calcium Enriched Mixture Cement on the Push-out Bond Strength to Furcal Area Dentin.

Bond strength of furcation repair materials is an essential factor in clinical success. Studies on the effect of adding titanium dioxide (TiO2) nanoparticles on the push-out bond strength of commonly used endodontic cements for furcation perforation repair is limited. This study aimed to evaluate the effect of adding TiO2 nanoparticles to white Portland cement (PC), white mineral trioxide aggregate (MTA), and calcium enriched mixture cement (CEM) on their push-out bond strengths. In this in vitro study, 120 endodontically treated molars were assigned to six groups (n=20) based on the material used to repair the perforation. In three groups, the cements (white PC, white MTA, and CEM) were placed in pure form, and in the three remaining groups, 1 weight % of TiO2 was added. The push-out bond strength was measured using a universal testing machine at a strain rate of 0.5 mm/min. Data were analyzed using one-way ANOVA and post hoc Games-Howell test (p< 0.05). One-way ANOVA showed significant differences in the mean bond strength values between the six groups (p= 0.002). The post hoc Games-Howell test showed that the bond strengths in MTA+TiO2 and PC+TiO2 groups were significantly higher than those in MTA and PC groups, respectively. However, there was no significant difference in the bond strength between CEM and CEM+ TiO2 groups. The incorporation of TiO2 into MTA and PC increased their push-out bond strength. However, it did not affect the push-out bond strength of CEM cement.

Assessment of the impact of municipal solid wasteincineration bottom ash used as partial cementreplacement in cement mixture using bioassays

Assessment of the impact of municipal solid wasteincineration bottom ash used as partial cementreplacement in cement mixture using bioassays

Synthesis of nano Fe2O3 cement compositions for concrete shielding

The world's most popular building material, concrete, is in constant demand. Because concrete is so widely used, the research trend to improve its sustainability and reduce its adverse effects during its production has gradually expanded. The future of contemporary concrete technology will be the addition of nanoparticles to concrete. Nanomaterials are now used to create inventive, resilient, and cutting-edge concrete constructions since they require less cement to be poured, have reduced overall project costs, and are environmentally conscious. Due to their distinctive features, titanium dioxide and nanocrystalline silica are among the best prospective nanomaterials for a variety of applications. Over the past ten years, there has been a significant rise in interest in nanotechnology as it relates to building materials. The workability of specimens containing 3% nano ferric oxide improves by up to 13.25% compared to control concrete. For concrete elements made with nano-Fe2O3, the values for flexural, split tensile, and compressive strength are respectively 7.90%, 7.4%, and 6.07% higher than for conventional concrete. Hydrophobic properties are produced when nano ferric oxide is used to substitute cement in concrete mixtures up to a particular amount. They aid in improving the self-sensing properties of concrete. Anti-iron oxide nanopowder has been employed in many products, such as corrosion coatings, plastics, silicones, rubber, alloys, lithium batteries, magnetic seals and certain drug delivery. Temperatures of around 450 degrees Celsius can be withstood by Fe2O3. Once they reach this temperature, the particles lose their magnetic characteristics. Because of their high aspect ratio, those particles cannot exist in nanoform without surface treatment.

Influence of phase change material and nano silica aerogel aggregates on the characteristics of cementitious composite: An experimental and predictive study

This paper studies the influence of two high-performance thermal insulating materials including aerogel and phase change materials (PCM) aggregates, on the key characteristics of cementitious composites in experimental and predictive aspects. Thermal conductivity (ThC), rapid chloride migration test (RCMT), permeable pore volume, compressive strength, dry density, and microstructural analysis were performed for the mechanical properties. Moreover, Least Squares Support Vector Regression (LSSVR) as a machine learning method was introduced to evaluate and provide a proper method for non-destructive evaluation of parameters. The results of experiments indicated that both aerogel and PCM aggregates were highly effective although the aerogel showed more efficiency in enhancing the thermal insulation property of cementitious mixtures. In addition, the compressive strength of the mixtures with PCM composites was higher than the aerogel aggregates, where the compressive strength of the mixture containing 20 % paraffin was 50 % higher than the aerogel mixture with similar incorporation levels. Moreover, the mixtures with PCM aggregates had significantly lower water and chloride permeability compared to those of plain mixtures, and mixtures consisted of aerogel aggregates. The scanning electron microscope (SEM) analyses, also, revealed that the use of the aerogel aggregates led to an open and porous structure of the mixtures; however, PCM aggregates had a weak interfacial transition zone (ITZ) in the vicinity of cement paste. Furthermore, LSSVR model provided a close prediction of the effective parameters with an acceptable accuracy in capturing the influences of important parameters.

Forecasting unconfined compressive strength of calcium sulfoaluminate cement mixtures using ensemble machine learning techniques integrated with shapely-additive explanations

Calcium sulfoaluminate (CSA) cement mixture design is challenging due to the influence of multiple features on its unconfined compressive strength (UCS). Consequently, the relationships between input features and the UCS exhibit non-linear behavior, making it difficult to understand using experimental methods alone. Therefore, for the first time, this study constructed non-linear ensemble machine learning (ML) models on a dataset compiled from experimental literature to accurately predict the UCS of CSA cement mixtures. After applying feature selection techniques, four different ensemble models were built on the modified datasets to predict the UCS. The extreme gradient boosting model built on the dataset modified by the least absolute shrinkage and selection operator method achieved the best prediction accuracy (coefficient of determination; R2 = 0.95) on testing data. Finally, the SHapely Additive exPlanations analysis could interpret the selected ML model both quantitatively and qualitatively, by explaining the independent relationships between each input feature and UCS.

The Effect of Microwave Radiation on the Solidification of C-S-H Gels: Its Influence on the Solidified Cement Mixtures.

The present paper deals with the properties of hardened cement mixtures that have been exposed to microwave radiation. Microwaves fall under electromagnetic waves (EMW), and the main reason for using EMW radiation is to accelerate the drying of concrete as well as to reduce the time required to obtain the handling strength after it is removed from the mould. This paper is divided into two main parts. In the first part, three sets of cement samples were made. One set of samples solidified naturally in air and the second and third sets of samples were exposed to EMW radiation, with different exposure times for each. The solidification was then stopped, and the representation of the major minerals was experimentally determined. The second part of the experiment focuses on the properties of the hardened cement mixtures, both in terms of strength and physical properties. The experiment was carried out on two sets of samples. Each mixture was exposed to EMW radiation, the main differences being the exposure time and the position of the samples relative to the EMW generator. The aim of the experiments is to determine the resulting mechanical properties of the samples in comparison with those that were subjected to normal solidification in air. The data from these experiments suggest that microwave radiation can be used to accelerate the curing of concrete specimens, obtaining the handling strength in a relatively short time, but a reduction in the resulting strength can be expected compared to the reference specimens.

Assessing the results of work on strengthening the soils of the foundation of lock № 5 of the Volga-Don shipping canal and proposals for stabilizing the chamber position

The results of work to strengthen the soil foundation of the chamber of lock № 5 of the Volga-Don Shipping Canal, carried out in 2016–2017, are analyzed. The need to carry out work to strengthen the soil was caused by an increase in the intensity of sedimentation of the central sections of the lock chamber, which began in 2005. To stabilize the chamber position, the technology of two-component jet grouting is implemented. This technology assumes the formation of several longitudinal soil-cement walls in the soils of the lock chamber base, which would transfer the load from the weight of the chamber to the harder clay soils of the water-resistant layer. However, as a result of the work performed, the precipitation intensity has increased. Engineering-geological, hydrological and geophysical studies conducted in 2018–2020 recorded the absence of formed soil-cement elements in the soils of the chamber base. An analysis of the soil samples characteristics taken from the chamber base has showed that a layer of soils of 10–12 m thickness is composed of loess rocks, below which water-resistant clayey rocks lie. Initially, there were several confined and non-confined aquifers in the soils of the lock base, and the creation of a hydroelectric complex and the formation of a level difference between the upper and lower pools led to the formation of a filtration flow with a significant pressure gradient at the base of the chamber. An analysis of the properties and structure of loess soils has showed their predisposition to subsidence, transition to a floating state and liquefaction with an increase in water content. Under the conditions of weak water-saturated loess soils, the supply of a cement mixture into them under significant pressure did not lead to the formation of soil-cement elements. Thus, in accordance with the current regulatory documents, the technical condition of the gateway is defined as pre-emergency, and the security level is defined as unsatisfactory. Methods for reducing the intensity of the chamber sedimentation such as cutting through the loess layer with piles, physical and chemical strengthening of soils and water protection of the massif at the base of the chamber are considered and evaluated.

Increasing the Hydration Activity of Tricalcium Silicate by Adding Microdispersed Ettringite as a Nucleating Agent.

Tricalcium silicate (C3S) as a binder material has a decisive influence on the processes of hardening and strength gain of cements and concretes. One of the promising directions is the introduction of dispersed additives into cement mixtures, which allow micro-level control of the composition of hydration products and change the dynamics of the structure formation of cement stone. In this paper, the effect of a microdisperse ettringite additive on the kinetics of the hydration and hardening process of tricalcium silicate was studied. It was shown that ettringite crystals selectively adsorb Ca2+ and OH- ions from a saturated solution of calcium hydroxide, which contributes to the formation of hydrosilicate nuclei on their surface during cement hydration. Hydration of C3S in the presence of ettringite proceeds more intensively; the addition of ettringite contributes to an increase in the content of calcium hydrosilicates in hydration products at the initial stage of the process. Addition of 10 wt.% ettringite to C3S reduces the induction period of the beginning of the main phase of heat release by around two times and increases the amount of heat released on the 1st day of hydration by 15% compared to the control sample. According to electron microscopy data, it was found that during the first hours of hydration of modified C3S, a significant number of nuclei of fibrous particles of calcium hydrosilicates with sizes of 0.2-2 microns were formed on the surface of ettringite crystals. According to the results of kinetic modeling of the setting process of cement pastes using the Avrami-Erofeyev model, it was shown that in the presence of the addition of microcrystals of ettringite, the setting rate is characterized by a slowdown in nucleation, whereas for a sample without an additive, this process proceeds with an acceleration of the formation of solid-phase nuclei. Based on the comparison of kinetic results and mechanical measurements, it is concluded that needle crystals of ettringite during C3S hydration and cement stone hardening are preformed centers for the growth of hydrosilicate nuclei, and they also act as a reinforcing filler, increasing the bending strength of modified samples. The results of the work can be used in practice in the development of methods for controlling the processes of hydration and hardening of cements, as well as for controllable structure formation of cement stone which is important in particular for 3D printing of building products and constructions.

Influence of calcium carbonate sludge on cement-stabilized subgrade quality as investigated by means of electrical resistivity measurements

Calcium carbonate [CaCO3] is a key raw material used in the clarification of sugarcane juice for syrup production. The CaCO3 sludge produced during the clarification process is waste that needs to be stored, creating a geoenvironmental problem. On the other hand, it has been found that cement-stabilized subgrade is a suitable alternative for improving the quality of a subgrade course. This study aimed to investigate the influence of calcium carbonate sludge on the quality of the subgrade. The subgrade was composed of a mixture of 10% to 30% CaCO3 sludge, 1% to 3% of original Portland cement (OPC), and 67% to 100% of unqualified crushed rocks by weight. The modified Proctor method was used to compact soil–cement admixture samples, which were then tested for mechanical properties and electrical resistivity. The Wenner electrode array was used to measure electrical resistivity and compare it to the unconfined compressive strength of 16 different types of soil–cement mixtures after 7 days. The results of experiments show that the basic properties of CaCO3 sludge, when mixed with OPC and packed down, can make the best soil–cement mixture. As a result of this study, electrical resistivity was found to be in good correlation with unconfined compressive strength, thus opening up a time-saving and cost-effective way to check the quality of a soil–cement mixture.

Development of porous composite ceramic with sugarcane fiber filler for sound absorber materials

Porous ceramic composite materials are fabricated for sound absorber materials. The ceramic composites are made from silica (SiO2) with a filler mixture to change the pore structure. Natural fillers synthesized from sugarcane bagasse with compositions of 0.5, 0.75, and 1.0 g are considered for sound absorber fabrication. Each filler weight comes with three different fiber sizes, namely 212, 425, and 630 µm. Subsequently, a blowing agent made of Al2O3 and CaCO3 is added to create pores in the composite, while a binder made of a mixture of gypsum powder and Portland Composite Cement (PCC) is used to bind the whole ceramic composite materials. Sound absorption coefficients α of each sample are evaluated by using impedance tube measurements according to ISO 10534-2. The results suggest that adding 0.5, 0.75, and 1 g filler gives the composite an absorption coefficient of 50%–80%, 60%–90%, and 75%–90%, respectively.

Development of a durability indicator to forecast the efficiency of preventive measures against external sulphate attack

Currently, the C3A content of binders is considered the most important factor contributing to external sulphate attack (ESA) deterioration. However, portlandite is also deemed to play a major role in ESA development. Yet, there are very few researches on this topic. This paper evaluates physical (i.e., induced expansion and mass variation, ultrasonic pulse velocity, dynamic modulus of elasticity, modulus of rupture and compressive strength) and chemical (i.e. X-ray diffraction and thermogravimetry) properties of seven mortar mixtures presenting distinct binders (i.e. cement types, inert fillers and supplementary cementing materials) and exposed to different sulphate solutions (i.e. sodium and magnesium). Correlations are conducted between data obtained in the laboratory, and a theoretical approach to describe cementitious mixtures’ susceptibility against ESA is then proposed. Results show that the proposed durability indicator (i.e., predicted portlandite amount and potential of ettringite formation) are well correlated with ESA-induced expansion and damage. Moreover, the influence of portlandite on ESA seems to depend on the type of sulphate attack (i.e., Na2SO4 or MgSO4). Finally, highly reactive SCMs and consequent higher portlandite consumptions seem to increase the overall deterioration due to MgSO4 exposure.

The Effect of Using Different Aspect Ratios of Sustainable Copper Fiber on Some Mechanical Properties of High-Strength Green Concrete

To achieve sustainability, use waste materials to make concrete to use alternative components and reduce the production of Portland cement. Lime cement was used instead of Portland cement, and 15% of the cement's weight was replaced with silica fume. Also used were eco-friendly fibers (copper fiber) made from recycled electrical. This work examines the impact of utilizing sustainable copper fiber with different aspect ratios (l/d) on some mechanical properties of high-strength green concrete. A high-strength cement mixture with a compressive strength of 65 MPa in line with ACI 211.4R was required to complete the assignment. Copper fibers of 1% by volume of concrete were employed in mixes with four different aspect ratios (20, 40, 60, and 120). At 7, 28, and 60 days after typical curing, the samples' mechanical characteristics (compressive strength, flexural strength, and split tensile strength) are assessed. A reported increase in compressive strength of (2, 1.6, and 1.4) in (7, 28, and 60 days) for concrete with a high aspect ratio 120, compared to concrete with a low aspect ratio 20. The flexural strength of high-strength green concrete with fibers of a higher aspect ratio 120 was (23, 11, and 12.6%) times higher for all ages compared to low aspect ratio 20. The split tensile strength rose (1.7, 1.5, and 1.6%) for (7, 28, and 60 days), respectively, for concrete with a high aspect ratio 120, compared to concrete with a low aspect ratio 20. It was found that using fibers with a large aspect ratio improved the mechanical properties of concrete more than fibers with a small aspect ratio.

Compressive Strength Investigations Of Foamed Mortar Incorporating Sandblasting Waste As Supplementary Cementitious Materials

Silica sand is one of the abrasive materials commonly used in the sandblasting process. The production of sandblasting waste is raising yearly, linear with the rapid development of the shipping industries. Silica sand was produced as by-product waste, approximately 400 ton per year. This research focused on compressive strength investigations of the foamed mortar incorporating silica sand as a supplementary cementitious material (SCM). Foamed mortar is a lightweight mortar made from a mixture of water, cement, sand, and foam, which can reduce the density of the mortar for construction purposes. Prior to use as SCM, the silica sand was pre-treated by using mechanical grinding to produce finer materials similar to cement. The observations were applied to pre-treated silica sand, such as chemical compositions, particle size analysis, normal consistency test, and setting time test. The specimens used in this research were mortar concrete with dimensions 5 x 5 x 5 cm and tested according to ASTM C579-01. The pre-treated silica sand varied from 10%, 20%, and 30% by weight of cement, were applied in this investigation. The compressive strength and spesific gravity were also observed. The results show that 20% cement replacement with pre-treated silica sand is the optimum composition and has 52.2 MPa in compressive strength at 28th days. These investigations conclude that pre-treated silica sand is potentially used as SCM in foamed mortars for sustainable concrete materials.

Determination of Adiabatic Temperature in Hardening Concrete According to Different Standards

The problem of thermal cracking in mass concrete structures still remains unsolved. There are many factors that influence the thermal regime in these concrete structures, the main ones being the type and content of cement in the concrete mixture, the thickness of the concrete layer, and the ambient temperature. However, the most important factor is the cause of the heat generated. Currently, there are a large number of standards and empirical formulas for determining the origin of a heat source using adiabatic equations. This paper provides a comparison of formulas for determining the adiabatic temperature in hardening concrete as the basis for determining the thermal regime in large-sized concrete structures.

Utilization of Waste Bricks as a Cement Substitution Material in Concrete Mixture

Concrete is the main material in building construction. The use of Portland cement as a binder in concrete mixes causes high concrete production costs. Apart from that, cement production also produces high CO2 emissions. Therefore, this research aims to utilize brick waste discarded from the brick industry as a partial substitute for cement in the concrete mixture. The brick powder is sieved to 80 mesh size and then used to replace cement with variations of 0%, 5%, 10%, 15% and 20% based on the weight of the cement. The compressive strength of the concrete was tested at 7, 14 and 28 days. Test results show that the use of brick waste up to 10% can increase the compressive strength of concrete. At 15% and 20% substitution, there was a decrease in the compressive strength of the concrete due to incomplete pozzolanic reaction. So it is concluded that brick waste can be used as a substitute for cement up to 10% in the concrete mixture without reducing its compressive strength. This research can provide solutions for environmentally friendly waste utilization and reduce the use of cement in concrete mixtures.

Recycled glass powder for enhanced sustainability of limestone calcined clay cement (LC3) mixtures: mechanical properties, hydration, and microstructural analysis

The large quantities of nondegradable waste glass led to landfill overflow, causing severe environmental harm. Measures need to be taken to reduce the environmental problems associated with waste glass. Limestone calcined clay cement (LC3) has excellent performance and a low-carbon footprint. However, its environmental benefits still require improvement. This study proposes a strategy to partially replace LC3 with recycled glass powder (RGP) to utilize waste glass while reducing CO2 emissions further. RGP replacement percentages are 10 and 20 %. Experimental studies were systematically conducted to investigate the performance, product composition, and CO2 emission of RGP-LC3. Experimental tests on a macro scale include workability, mechanical properties, and ultrasonic pulse velocity. The composition and microstructure of the material were characterized using thermogravimetric, Fourier-transform infrared, X-ray diffraction, and scanning electron microscopy. The CO2 emissions of LC3 at different stages of its lifecycle were compared and discussed how RGP can reduce these emissions. The results show that RGP helps to increase the workability of the slurry. LC3 containing 10 % RGP showed similar compressive strength to the control group, and 20 % RGP resulted in a decrease in strength. As the replacement percentages increase from 0 to 10 and 20 %, the CO2 emissions per unit volume decrease from 606.46 to 545.14 and 484.43 kg m3/MPa.

Clayshale Stabilization using Portland Pozzolan Cement Type II to Increase the Shear Strength of Soil

Clayshale soil was found 5 meters below ground level in the Hambalang area. The fragility of clay shale soil results in clay shale soil being rarely used in construction needs. The physical condition of clayshale is not optimal when it is dry and also when it is mixed with water. This research is carried out so that the cohesion value and shear strength in the clayshale is close to perfection with the stabilization process. Disturbed sampling was carried out in the Hambalang area, providing that the granules passed the 4mm filter. Tests carried out to obtain soil parameters include physical properties testing and mechanical properties testing. Based on the results of laboratory tests, the original clayshale soil has a plasticity index (IP) value of 27.07%, so clayshale soil included CL (Clay-Low plasticity) according to the USCS category. The use of Portland pozzolan cement in this study is because it has high resistance to salts and sulfuric acid. Mixing of PPC cement test materials was carried out to determine the optimal cohesion value and shear strength by mixing 5%,8%, and 11% of clayshale weight per sample. The addition of cement variations can increase the specific gravity value of the soil and the optimum moisture content, but it can reduce the dry weight value of the soil and the value of the plasticity index on clayshale soils. The cohesion values and soil shear strength obtained after Triaxial UU testing on samples with the addition of Portland pozzolan cement (PPC) increased; however, the increase that occurred was varied and significant at the time of the PPC cement mixture.