Influence Of Admixtures Research Articles

Influences of Different Admixtures on the Drying Shrinkage Characteristics of Metakaolin-based Geopolymer Mortar

Influences of Different Admixtures on the Drying Shrinkage Characteristics of Metakaolin-based Geopolymer Mortar

Influence of chemical admixtures on buildability and deformation of concrete for additive manufacturing

In this study, the buildability of three-dimensionally (3D) printed (3DP) concrete that uses coarse aggregate was evaluated in the fresh state according to the contents of three chemical admixtures (high-range water-reducing agent (HRWRA), viscosity-modifying agent (VMA), and setting-time modifying agent), and the correlation between fluidity changes and buildability was analyzed. Polycarboxylate HRWRA and VMA contents were varied to control the flowability and static yield stress, which affect the workability. In addition, the SMA content was varied, and slump tests and table flow tests were performed at 30-minute intervals up to 6.5 h after mixing to measure flowability. Simultaneously, static yield stress was measured to analyze rheological changes, and penetration resistance and green strength tests were performed to analyze the main factors influencing buildability over time. The highest buildability was observed when the VMA content was 1.5 %. The static yield stress of fresh concrete could be ≤3000 Pa to guarantee adequate 3DP concrete transport performance while that at 1 h after mixing could be ≥2000 Pa to secure buildability. When the penetration resistance of fresh concrete is ≥80 kPa, the deflection of concrete may be <10 %. Through this, buildability can be approximately judged based on penetration resistance.

Testing the influence of bioethanol admixture in gasoline engine on the anti-knock properties of the fuel created

Rynek bioetanolu w UE nieodwołalnie wkroczył w nową erę biopaliw poprzez wdrożenie unijnej dyrektywy biopaliwowej RED III, czyli dyrektywy o odnawialnych źródłach energii. Większość rządów zdecydowała się na wprowadzenie obowiązkowego dodawania biokomponentów do paliw, kontynuując polityczne wsparcie dla odnawialnych źródeł energii. Przykładem może tu być wprowadzenie do sprzedaży w transporcie samochodowym benzyny E10, zawierającej 10% (V/V) bioetanolu. Bioetanol wykorzystywany jako paliwo do silników benzynowych może być stosowany poprzez bezpośrednie zmieszanie z benzyną lub przerobiony na eter etylowo-tert-butylowy (ETBE). Pierwsze rozwiązanie, bezpośrednie dodanie do benzyny pod postacią bezwodnego etanolu o 99-proc. zawartości czystego alkoholu, jest proste do zastosowania, gdyż silniki spalinowe ZI mogą działać bez potrzeby ich modyfikacji przy zawartości w paliwie do 10% (V/V) etanolu – większe domieszki wymagają przystosowania silnika. Natomiast ETBE powstający przez syntezę bioetanolu (49%) i izobutylenu (51%) miesza się z benzyną silnikową w ilości do 15% (V/V). W artykule przedstawiono wpływ bazowych benzyn silnikowych zawierających bioetanol na parametry eksploatacyjne utworzonego biopaliwa. Procentową zawartość bioetanolu w benzynie silnikowej ustalono w granicach 15–25% (V/V). Przed rozpoczęciem badań silnikowych wykonano kontrolę parametrów jakościowych bioetanolu zastosowanego do badań liczby oktanowej na zgodność z wymaganiami normy PN-EN 15376:2014-11, poprzez analizę fizykochemiczną przeprowadzoną w INiG – PIB. Wykonano oznaczenia liczb oktanowych badawczej (LOB) i motorowej (LOM) próbek benzyn silnikowych zawierających bioetanol w zakresie 15–25% (V/V) i porównawczo oznaczono próbkę o zawartości bioetanolu na poziomie 10% (V/V), czyli maksymalnym dopuszczalnym przez normę PN-EN 228+A1:2017-06. Następnie na podstawie wyników oznaczeń liczb oktanowych próbek benzyn silnikowych z zawartością 15%, 20% i 25% (V/V) bioetanolu, podjęto odpowiednie działania w zakresie wyposażenia i pracy stanowisk silnikowych CFR Dresser Waukesha (USA) służącego do oznaczania liczby oktanowej. W zależności od zawartości bioetanolu w benzynie bazowej zgodnej z wymaganiami normy PN-EN 228+A1:2017-06 zweryfikowano zakres powtarzalności oznaczanych liczb oktanowych według najnowszych wydań norm PN-EN ISO 5164:2014-08 (LOB) i PN-EN ISO 5163:2014-08 (LOM) oraz określenie źródła niepewności wynikającego z precyzji wyznaczonej liczby oktanowej i parametrów pracy silników badawczych CFR.

Internal hydrophobic treatment for mortar containing supplementary cementitious materials: thermal analysis of kinetics and products of hydration

AbstractThe presented research investigates the application of the organosilicon admixtures based on triethoxyoctylsilane (OTES) on the hydration of the cement-based material with addition of supplementary cementitious materials (SCM) such as blast furnace slag and microsilica. The influence of silane-based admixtures on the kinetics of hydration was investigated by isothermal calorimetry. The calorimetric results disclosed that applied admixtures affect the hydration process of cement paste with SCM. The DTA/TG analysis provided the information about impact of triethoxyoctylsilane on the composition and formation of the mineral phases. The DTA/TG measurements showed noticeable changes in the thermal decomposition of the tested materials and amount of bounded water. The impact of OTES on the microstructure and pore size distribution of pastes was examined by mercury intrusion porosimetry. The result showed significant changes in the range of pore diameters. The influence of organosilicon admixtures on the compressive strength of mortars after 2, 7, 28, 56 and 90 days was also investigated. The effect depended on the mineral additive used. In case of blast furnace slag, the development of compressive strength was only delayed, however, in the case of microsilica, it was stopped.

Influence of N2 admixture on mode transition of discharge in N2–Ar helicon plasma

Effects of N2 admixture on multiple wave modes and transitions were investigated in N2–Ar helicon plasma under fixed input power and magnetic field. The structures of helicon waves were measured by a B-dot probe to verify the different eigenmodes. The experimental results show that the plasma morphology, emission spectrum, and spatial profile change significantly during mode transitions with the N2–Ar ratio. The calculated results from the pressure balance model indicate that the densities of species N2, N+, Ar, and Ar+ will change largely during mode transition around some specific N2 percentages, which will help to improve the application of N2–Ar helicon plasma in material processing greatly.

Influence of Chemical Admixtures on Expansive Behavior and Mechanical Properties of K-Type Self-Stressing Concrete in CFST Systems

Influence of Chemical Admixtures on Expansive Behavior and Mechanical Properties of K-Type Self-Stressing Concrete in CFST Systems

Admixture Mapping of Chronic Kidney Disease and Risk Factors in Hispanic/Latino Individuals From Central America Country of Origin.

Chronic kidney disease (CKD) is highly prevalent in Central America, and genetic factors may contribute to CKD risk. To understand the influences of genetic admixture on CKD susceptibility, we conducted an admixture mapping screening of CKD traits and risk factors in US Hispanic and Latino individuals from Central America country of origin. We analyzed 1023 participants of HCHS/SOL (Hispanic Community Health Study/Study of Latinos) who reported 4 grandparents originating from the same Central America country. Ancestry admixture findings were validated on 8191 African Americans from WHI (Women's Health Initiative), 3141 American Indians from SHS (Strong Heart Study), and over 1.1 million European individuals from a multistudy meta-analysis. We identified 3 novel genomic regions for albuminuria (chromosome 14q24.2), CKD (chromosome 6q25.3), and type 2 diabetes (chromosome 3q22.2). The 14q24.2 locus driven by a Native American ancestry had a protective effect on albuminuria and consisted of 2 nearby regions spanning the RGS6 gene. Variants at this locus were validated in American Indians. The 6q25.3 African ancestry-derived locus, encompassing the ARID1B gene, was associated with increased risk for CKD and replicated in African Americans through admixture mapping. The European ancestry type 2 diabetes locus at 3q22.2, encompassing the EPHB1 and KY genes, was validated in European individuals through variant association. US Hispanic/Latino populations are culturally and genetically diverse. This study focusing on Central America grandparent country of origin provides new loci discovery and insights into the ancestry-of-origin influences on CKD and risk factors in US Hispanic and Latino individuals.

Assessing hydration kinetics and rheological properties of Limestone Calcined Clay Cement (LC3): Influence of clay-mitigating and superplasticizer admixtures

Limestone calcined clay cements (LC3) signify a trend in the construction sector aimed at reducing environmental impacts. However, the fresh state behavior of these cements, especially concerning clay properties and their interaction with chemical admixtures, needs to be better understood and investigated. This study is designed to assess the impact of a polycarboxylate-based superplasticizer (ADV) and a clay-mitigating (CM) admixture, along with exploring the synergistic effects that arise from combining both admixtures on the properties of LC3 cements. Hydration kinetics were evaluated in cement pastes using isothermal calorimetry and in-situ XRD, while fresh state properties were evaluated by rotational rheometry. The calorimetry results showed that the CM admixture provides a delay in the aluminate reactions of all LC3 systems, while it does not significantly affect the hydration of Portland cement pastes, suggesting a pronounced interaction of this admixture with clay particles. The incorporation of the CM admixture did not yield favorable workability conditions in LC3 mixtures when compared to the effectiveness of the ADV. In general, the assessment indicates that the CM admixture lacks effective dispersion capabilities and exhibits a limited influence on the formation of hydrated products in LC3 cements produced with calcined kaolinitic clay.

Robust prediction of workability properties for 3D printing with steel slag aggregate using bayesian regularization and evolution algorithm

This study addresses the growing interest in utilizing steel slag as a sustainable alternative to river sand in additive manufacturing of concrete, driven by the increasing scarcity of natural resources. The rheological properties of fresh material significantly impact the quality of 3D-printed filament, necessitating suitable workability for printability. The research focuses on evaluating the influence of steel slag aggregate and key admixtures, such as silica fume and superplasticizer, on the workability properties of fresh concrete. Through an extensive series of 90 slump tests, optimal combinations ensuring the desired workability for 3D printing applications were identified. To enhance the manufacturing of fresh concrete and develop user-friendly tools, a novel soft computing approach is introduced—Adaptive Elitist Differential Evolution coupled with Bayesian Regularization Artificial Neural Network (aeDE-BRANN). This advanced model considers five critical input parameters: silica fume to Portland cement ratio, steel slag to cement ratio, water to cement ratio, cement content, and superplasticizer dosage. The model outputs crucial workability metrics, including slump flow and slump. In a comprehensive comparative study, the aeDE-BRANN framework demonstrates superior performance in terms of both simplicity and efficiency when compared to other forecasting models. Feature analysis techniques, including Shapley values from game theory and partial dependence plots, provide valuable insights into the intricate relationships between input variables and workability properties. The findings underscore the water to cement ratio as the most influential factor on workability, followed by silica fume to Portland cement ratio and steel slag to cement ratio. This study contributes a reliable tool for predicting workability properties, aiding in the selection of suitable steel slag aggregate and admixtures. Ultimately, it facilitates the sustainable and innovative evolution of 3D concrete printing practices.

Fresh, hardened, durability and microstructure properties of seawater concrete: A systematic review

Seawater concrete (SWC) is an environmentally friendly construction material that addresses freshwater scarcity concerns by utilising seawater as a mixing water source. This review study comprehensively examines SWC by focusing on its fresh properties, hardened properties, seawater composition, microstructure and porosity, hydration process, durability, test methods and electrical resistivity. The study analyses the influence of additives and admixtures on SWC’s performance by considering constituents such as cement, aggregates and seawater. It also explores the impact of manufacturing techniques, including mix design. The potential of SWC is revealed and compared with that of conventional concrete by evaluating and comparing their mechanical properties, such as compressive strength, modulus of elasticity, stress-strain behaviours, tensile strength and flexural strength. This study primarily aims to thoroughly examine the characteristics of SWC in its fresh and hardened states. It also assesses the advantages and drawbacks of seawater as a mixing water source. Moreover, this study delves into the impact of seawater composition on crucial aspects, such as the hydration process, microstructure and porosity of concrete. It also used various test methods to explore SWC durability, including resistance to chloride ingress, sulphate attack and carbonation. Furthermore, the importance of electrical resistivity for corrosion prevention is discussed in this study. The carbon-negative cement production and carbonation curing of seawater concrete underscore groundbreaking advancements, emphasizing sustainability and climate mitigation in the construction industry. Overall, this study aims to enhance the comprehension of SWC and provide valuable insights for engineers, researchers and policymakers in concrete technology.

Effect of Mineral Admixtures and Curing Regimes on Properties of Self-Compacting Concrete

This study investigated the influence of mineral admixtures (fly ash, silica fume, metakaolin) and curing conditions (water immersion, polyethylene glycol, gunny bags, accelerated curing) on the properties of self-compacting concrete (SCC). The rheological properties, compressive strength, chloride penetration resistance, and microstructure were evaluated. Incorporating mineral admixtures improved the workability, strength (up to 53% increase), and durability of SCC compared to plain mixes, with 20% metakaolin replacement optimal. Water immersion curing enhanced the compressive strength (3–15% increase) and chloride resistance (up to 30% decrease in migration coefficient) owing to improved hydration and microstructural refinement. Mineral admixtures reduced the sensitivity of SCC to the curing method. Microstructural analysis showed higher density and additional C-S-H phases with mineral admixtures under wet curing. The study demonstrates that optimized SCC containing appropriate supplementary cementitious materials and proper external curing can achieve high performance.

The Influence of Chemical Admixtures on the Fluidity, Viscosity and Rheological Properties of Ultra-High Performance Concrete

The Influence of Chemical Admixtures on the Fluidity, Viscosity and Rheological Properties of Ultra-High Performance Concrete

МІЦНІСТЬ, ЗНОСОСТІЙКІСТЬ І МОРОЗОСТІЙКІСТЬ ФІБРОБЕТОНІВ ЖОРСТКИХ ДОРОЖНІХ ПОКРИТТІВ З БАЗАЛЬТОВОЮ ФІБРОЮ ТА ПОВІТРОВТЯГУЮЧОЮ ДОБАВКОЮ

Introduction. Increasing the durability of hard pavements allows you to reduce road maintenance costs by extending the intervals between repairs. Dispersed reinforcement is a well-known method of increasing the frost resistance and abrasion resistance of concrete, which has a positive effect on the durability of pavements in typical for Ukraine climatic conditions. Basalt fiber is resistant to corrosion and relatively inexpensive, which makes it promising for use in the road industry. Also, plasticizing and air-entraining admixtures must be used for concrete of hard pavement. Problem Statement. In modern economic conditions and taking into account the technological features of the preparation of mixtures, it is relevant to compare the effectiveness of the use of known methods of improving the properties of concrete for hard pavements: dispersed reinforcement and the use of air-entraining admixtures. Studying the expediency of the simultaneous use of these two methods of modifying the concrete mixture is also an important task from a scientific and practical point of view. Purpose. Determination of the influence of basalt fiber and air-entraining admixture on the strength, frost resistance and abrasion resistance of concrete of hard pavements.

Effect of Polycarboxylate Admixture on the Performance of Fluorogypsum-Based Self-Leveling Material

The study explores the influence of polycarboxylate admixture (PCE) on fluorogypsum-based self-leveling material (FSLM) performance. Wev conducted an array of tests to assess workability and mechanical properties, and utilized XRD, TG-DSC, SEM, and MIP techniques for microscopic analysis. The fresh state results showed that PCE enables FSLM to achieve good workability at lower water demand. It was found that PCE partially inhibited plaster hydration from anhydrite to dihydrate, as observed by X-ray diffraction analysis and thermogravimetric analysis, and with the increasing in PCE, the mass loss of samples reached 15.66% at 28 days. The mechanical properties and the microstructure studies proved that the optimal PCE doping level is 0.14%. At this doping level, there is an enhancement in the denseness of the hardened structure, a reduction in porosity—especially when the pores are more than 200 nm, optimization of pore size distribution, an increase in crystal aspect ratio, an enhancement in effective intergranular overlap, and a significant improvement in the 28-day flexural and compressive strength to 7.2 MPa and 36 MPa, respectively. The FSLM prepared under these conditions demonstrates good performance and meets the primary performance index requirements of the Chinese Industry Standard JC/T 1023-2021 (gypsum-based self-leveling floor compound), thereby promoting the comprehensive utilization of fluorogypsum.

New Insights into the Dissolution Kinetics of Alite Powder and the Effects of Organic Toughening Materials.

Alite dissolution plays a crucial role in cement hydration. However, quantitative investigations into alite powder dissolution are limited, especially regarding the influence of chemical admixtures. This study investigates the impact of particle size, temperature, saturation level, and mixing speed on alite powder dissolution rate, considering the real-time evolution of specific surface area during the alite powder dissolution process. Furthermore, the study delves into the influence of two organic toughening agents, chitosan oligosaccharide (COS) and anionic/non-ionic polyester-based polyurethane (PU), on the kinetics of alite powder dissolution. The results demonstrate a specific-surface-area change formula during alite powder dissolution: SS0=0.348e1-m/m0/0.085+0.651. Notably, the temperature and saturation level significantly affect dissolution rates, whereas the effect of particle size is more complicated. COS shows dosage-dependent effects on alite dissolution, acting through both its acidic nature and surface coverage. On the other hand, PU inhibits alite dissolution by blocking the active sites of alite through electrostatic adsorption, which is particularly evident at high temperatures.

Application of Kaplan–Meier and Weibull Procedures for Qualitative Assessment of Recycled Aluminum Bronzes

The article describes the application of the Kaplan–Meier and Weibull procedures for the qualitative assessment of aluminum bronzes obtained from the remelting of metals (e.g., copper, aluminum, iron, manganese). The analysis was carried out on the example of selected bronzes, evaluating the influence of chemical composition on fatigue strength. Melting kinetics and method of casting alloys as well as the influence of admixtures on the castings’ properties are important for quality assessment of mentioned alloys. The performed analyses of bronze production show that small changes in the technological process can have a significant impact on the content of individual elements in the alloy, thus determining the properties of the cast element. The calculations carried out allowed for the estimation of the "survivability" function, including the probability of failure using fatigue tests on randomly selected samples. The tests carried out showed that the BA1032 alloy withstands a maximum of 4.89 h (out of 5 h assumed during the strength test) of loads with the parameters assumed in the company. The quality of production was improved by applied methods of statistical assessment of chemical composition allowed to obtain the probability of destruction at the level of 6.13%.

The influence of graphene admixture on strength properties of cement-based composites

Cement-based composites pose a long tradition in the construction industry and are used in various forms such as structural concretes, masonry and plaster mortars, injection and special mixtures for three-dimensional concrete printing. Fine granular composites intended for injection and printing activities may have increased tend to shrinkage and cracking. The application of nanomaterials may bring a partial solution to toughening of cement-based composites. For this reason, the effect of the addition of various amounts of graphene admixture up to 0.03 wt.% on the strength properties of fine granular cement-based composites was researched. All prepared fresh mixes had the constant w/c ratio, and the behavior of modified composites was compared with plain reference material. On hardened test specimens, compressive strengths obtained after 1, 7 and 28 days of curing time were evaluated. The experimental investigation revealed, on the one hand, the partial worsening of workability of fresh mixes being compensated with an increasing amount of a superplasticizer and, on the other hand, the increment of compressive strength up to 12.5 % even for specimens with the lowest addition of graphene.

Magnetoelectric properties of multiferroic ceramic composites

The paper analyzes the influence of hard and soft admixture on the functional properties of multiferroic ceramic composites. Two composite materials via solid-state reaction route were obtained. PZT-type materials (with hard or soft admixture) were selected as the ferroelectric component (90%), and nickel–zinc ferrite as the magnetic component (10%). The influence of the doping type (soft and hard admixture of the ferroelectric composite component) on multiferroic composites’ dielectric, ferroelectric, electromechanical, magnetic, and magnetoelectric properties were analyzed. Microstructural studies revealed the microstructure of composites with the correct distribution of the magnetic component in the ferroelectric matrix, suitable for maintaining both the ferroelectric and magnetic properties of composite materials. Research has shown that using a ferroelectric component as the PZT (from the morphotropic region and doped with the ferroelectrically soft niobium admixture) shows many advantages, positively influencing the functional properties of the multiferroic composite. It ensures effective polarization of the composite sample, obtaining a high magnetoelectric effect, which is required in sensors or magnetoelectric converters. PZT with a hard admixture shows higher stability of physical parameters, but its characteristic property also hinders the effective polarization of the composite sample.

The Mechanism of Viscosity-Enhancing Admixture in Backfill Slurry and the Evolution of Its Rheological Properties

Since filling slurry is a cement-based material, viscosity-enhancing admixture exerts a significant effect on its rheological performance and mechanical properties. Viscosity-enhancing admixture can improve pipeline transportation performance and reduce pipeline wear during the filling process of a kilometer-deep mine by changing the plastic viscosity and yield stress of high-concentration filling slurries. In order to reveal the influence mechanism of viscosity-enhancing admixture on rheological performance in slurry, the influence of viscosity-enhancing admixture on the rheological performance of slurry is explored by adjusting viscosity-enhancing admixture dosage and conducting bleeding test, liquidity test, and rheological performance test. The extended DLVO theory is employed to analyze the mechanism of HPMC on the stability of filling slurry. The results show that compared with ordinary slurry, after adding HPMC and XG, the particles of filling slurry are prone to link to form a mesh structure. Besides, the increasing frictional force between particles results in a significant decrease in the bleeding rate and liquidity of the slurry. Such an effect becomes more obvious with the increase of viscosity-enhancing admixture dosage. Meanwhile, the overall effect of HPMC molecules is better than that of XG molecules since HPMC can reduce inter-particle repulsion and facilitate particle aggregation. The optimal dosage is about 0.1%, at which time the yield stress of the filling slurry increases from 89.236 to 160.06 Pa, the plastic viscosity increases from 0.296 to 1.063 Pa·s, and the compressive strength increases from 2.58 to 3.59 MPa in 28 days. The study reveals the influence of viscosity-enhancing admixture on the rheological performance of filling slurry and its evolution characteristics, which provides theoretical support for the development of filling resistance and wear reduction technology.

Sustainable ultra-high performance concrete with incorporating mineral admixtures: Workability, mechanical property and durability under freeze-thaw cycles

This paper evaluates the influence of mineral admixtures partially replacing cement, sea sand replacing quartz, sea water replacing fresh water on ultra-high performance concrete (UHPC). The fluidity and mechanical properties were studied. Besides, the impermeability, chloride resistance and freeze-thaw resistance were investigated. Failure modes, scanning electron microscope (SEM) analysis, mass loss, relative dynamic modulus of elasticity and mechanical properties of UHPCs after freeze-thaw cycles were conducted. The results showed the fluidity of UHPC paste gradually increases with the improvement of water-binder ratio. It is recommended that the water-binder ratio of UHPC be set at 0.19. The fluidity also increases with the improvement of the content of slag, fly ash and water reducer, but decreases with the improvement of silica fume content. The flexural and compressive strengths of UHPC enhance with the improvement of the content of silica fume, but reduce with the improvement of the content of fly ash and slag. The UHPCs made of quartz sand, river sand and sea sand, all, achieve a high strength. UHPCs prepared at standard curing conditions, with or without steel fibers, mixed by artificial seawater and made of sea sand, exhibited excellent impermeability and chloride resistance. The frost resistant grade of all UHPC specimens prepared by standard curing are greater than F500 exhibiting excellent freeze-thaw resistance and sustainability.