Superplasticizer Research Articles

Avaliação da trabalhabilidade de pastas cimentícias autonivelantes através da variação do teor dos aditivos superplastificante e modificador de viscosidade

Abstract To meet the self-leveling pastes’ performance requirements, its flowability is linked to the absence of segregation or exudation, which makes a high cohesion between the components mandatory. Therefore, the ideal dosage for these materials is an essential topic to provide such specific properties. To evaluate the composition effect on fresh state, a method was proposed to quantify self-leveling pastes’ uniformity through the analysis of the spread pastes’ diameter and borders. Thus, different dosages were tested varying some input contents. The uniformity was quantified with the development of indexes such as Perimeter Ratio (PR) and Input Relation (IR). It was concluded that lower spread diameters incurred in higher uniformity index. Furthermore, it was observed that to achieve an ideal dosage for pastes, there is a tendency of direct correlation between the uniformity index and the water/powder ratio (w/p) and superplasticizer (SP) content and an inverse one between it and viscosity modifying admixture (VMA).

Workability and durability analysis of waste based geopolymer concrete

GPC as a promising material, started gaining momentous attention from the researchers and construction specialists because of its advantages in using by-products from agriculture and industries to replace cement thereby reducing greenhouse gas emission. Workability and durability tests were carried out, so as ascertain the efficiency of the rice husk ash and rice husk as sodium silicate and super plasticizer, for solving efflorescence problem known with geopolymer concrete. The factory-made sodium silicate was also used and compared with laboratory-produced, before addition of other geopolymer binders such as kaolin clay and fly ash. Brunauer-Emmett-Teller (BET) scrutiny that delivers quantitative data on the specific surface area as well as porosity dispersal of solid materials revealed that correlation coefficient of RHA (0.994) was higher than that of cement (0.991). Besides, RHA has higher surface area (250.023 m3/g) than the cement utilized which stood at 211.49 m3/g. Though the c constant of cement exceeds the RHA values, RHA can serve as good pozzolanic material and cement substitute. It is seen that the workability of laboratory-produced sodium silicate and superplasticizer geopolymer concrete was enhanced significantly compared to that of prior geopolymer systems. It is observed that the workability of the geopolymer concrete was considerably enhanced compared to that of orthodox geopolymeric systems, especially at 2.5% rice-husk created superplasticizer and higher content of laboratory-produced sodium silicate.

Performance Study of Laterised Concrete Made with GGBS and Silica Fume as a Partial Replacement of Cement

Abstract -Sand has been utilized in the construction of civil engineering projects for a long time as a fine aggregate. As building costs have been rising over the past few years, the source of high-quality sand has been rapidly depleting. Now, laterite is thought to be a potential sand substitute for concrete mixtures. In this Paper, GGBS and silica fume is used as a partial cement replacement in laterised Concrete. This research deals with the viability study of GGBS and silica fume as partial replacement of cement in laterised concrete. Mixes to be prepared with replacement content of 5%,10%,15%,20% and 25% by the weight of ordinary Portland cement with GGBS and optimum silica fume (10%). However, the addition increases the strength levels with the aid of super plasticizer. Additional mixing lowers the laterite content to 15%. Same 15% of the weight of laterite soil can be used as partial replacement of sand exhibited the finest outcomes. As a result, it is showing use of laterite as a possible partial replacement for sand. In this research mixes are prepared by keeping optimum silica fume and Laterite soil constant for M1, M2, M3, M4, M5 and M6. Physical and mechanical experiments of M30 grade of concrete were used to analyze how these materials affected such attributes as compressive strength, split tensile strength, and flexural strength. Key Words: Laterised concrete, Ground granulated blast furnace slag (GGBS), Silica fume, Laterite soil.

The Categories and Application of PCE Superplasticizers in Concrete

Polycarboxylate ether superplasticizers (PCEs) are water reducers in the concrete mix that play a significant function in aspects of reducing the water-to-cement ratio, improving impermeability, increasing compressing strength, and meditating the shrinkage. This paper introduces the characteristics of PCEs, discusses the application, advantages, and disadvantages of concrete, and puts forward some measures. The mechanism of PCEs is the dispersion function of the molecular structure and the neutralization. Currently, PCEs are updated from one generation to another, conventional PCEs mainly include methacrylate ester, isoprenol ethe, and methallyl ether-PCEs. Another two major types of PECs are vinyl ether-based and calcium silicate hydrates PCEs, respectively. The application of PCEs revolutes novel types of concrete, such as ultra-high performance concrete and self-compacting concrete. When applying PCEs, retardation has to be considered. Meanwhile, another drawback of PCEs is that they can hardly work with other admixtures. A novel type that is considered clay properties can be another research field.

Methodology to design eco-friendly fiber-reinforced concrete for 3D printing

Greater use of locally available supplementary cementitious materials (SCM) to reduce cement content and addition of fiber reinforcement can enhance the performance of 3D printing (3DP) technology in construction. In this study, three classes of eco-friendly 3D printable fiber-reinforced mixtures were targeted, namely ultra-high-performance concrete (UHPC), high-performance concrete (HPC), and conventional concrete (CC). A step-by-step methodology was proposed to maximize the substitution rate of cement with SCM and limestone filler and optimize fiber volume for the successful development of 3D printable fiber-reinforced materials. Binder combinations were initially investigated on the paste level to determine the packing density and robustness. Selected binder systems were narrowed down on the mortar level by evaluating the superplasticizer (SP) demand, plastic viscosity, forced bleeding, final setting time, and 3-day compressive strength. The 6-mm steel and 8-mm polyvinyl alcohol (PVA) fibers were incorporated for further evaluation of key properties of fiber-reinforced concrete. The printability of the fiber-reinforced mixtures was validated using an extrusion-based 3D printer. Developing such print materials with adequate strength and toughness can improve the cost-effectiveness of 3DP construction, and extend 3DP technology to remote areas.

In-vitro and In-vivo Evaluation of Cevimeline HCl Fast Dissolving Films

The primary aim and objective of the present work was to formulate the cevimeline HCl fast-dissolving films and assess the films, a pharmaceutical compound utilized for the management of xerostomia symptoms linked to Sjogren’s disease. Fast-dissolving films of cevimeline HCl were formulated by utilizing the solvent casting technique and the sodium carboxy methyl cellulose, HPMC E5, polyvinyl alcohol, and polyvinyl pyrrolidone were used as film-forming agents. Additionally, polyethylene glycol 600 and sodium starch glycolate were used as a super disintegrant and plasticizers. The formulation contains citric acid and stevia powder, which serve the purpose of stimulating saliva and providing sweetness, respectively. This study focused mainly on the development and assessment of cevimeline HCl fast-dissolving films, specifically examining parameters such as film thickness, folding resistance, drug content, air bubble entrapment, and film curling. The obtained results were found to be consistent with the preset ranges established for these parameters. The drug release from the fast-dissolving films formulated with PVP K30 was 99.91% released within 5 minutes timeframe. The results indicates that the films prepared with PVP K30 show enhanced solubility, rate of dissolution, flexibility, and tensile strength in comparison to the films formulated with sodium carboxy methyl cellulose, HPMC E5 and Polyvinyl alcohol. Fourier transform infrared (FTIR) and differential scanning calorimetry (DSC) studies were done to characterize the pure drug, polymers and to C11 the optimized formulation. These findings indicated, no observed incompatibilities among the drug and polymers utilized in this study. Moreover, in-vivo investigations were conducted on optimized formulation C11, which demonstrated its notable stability.

Impact of Admixtures on Environmental Footprint, Rheological and Mechanical Properties of LC3 Cemented Paste Backfill Systems

This study investigates the time-dependent rheological behavior of cemented paste backfill (CPB) that contains calcined clay as a binder, particularly with LC3 (Limestone Calcined Clay Cement) compositions, using two different PCEs (Polycarboxylate Ether) superplasticizers. Rheological measurements have been conducted on four different mix designs using the Bingham model to describe the CPB mixtures. Both yield stress and plastic viscosity have been reported, and the impact of the admixture on these parameters has been investigated. Unconfined compressive strength (UCS) was measured over 182 days for all mix designs. Both admixtures showed better workability in all cases, with significantly improved yield stress and plastic viscosity compared to the reference, while showing little to no negative impact on strength over time. This study highlights that both from a binder and an admixture point of view, relevant to the industry, these calcined clay systems are ready to be used in a CPB and could make a significant impact on the sustainability of a mining operation in the near future.

Influence of Polycarboxylate Superplasticizer on the Calorimetric and Physicomechanical Properties of Mortar

The use of polycarboxylate ether superplasticizer PCE in the preparation of mortars and concretes influences the hydration kinetics and the amount of total heat released. This leads to a modification of certain properties of the mortar, namely workability, calorimetry and mechanical resistance. In this study two ether polycarboxylate superplasticizers with different chemical structures were used; they were incorporated at different dosages into a standardized cement-based mortar. The objective of this work is to study the effectiveness of these superplasticizers and to select the most compatible product with cement and the most suitable for use according to the climates of the country. The impact of superplasticizers on fresh cement was studied by measuring the Marsh cone flow time and calorimetric measurement. In the hardened state, the mechanical properties were provided by measuring the compressive strength. The results show that low dosages of ether polycarboxylate superplasticizer promote grain hydration and produce more heat. On the other hand, high dosages delay the contact of the cement grains with the mixing water and cause a reduction in the final heat released and a delay in setting. The ether polycarboxylate superplasticizer with high carboxylic density gives the best mechanical resistance compressive at 7 and 28 days.

The Role of MWCNTs in Enhancing the Foam Stability and Rheological Behavior of Cement Pastes That Contain Air-Entraining and Superplasticizer Admixtures.

This research delves into the intricate dynamics between multi-walled carbon nanotubes (MWCNTs), air-entraining admixtures (AEAs), and a range of superplasticizers (SPs) in cementitious systems, shedding light on key aspects of construction material innovation. The focus is on how MWCNTs, AEAs, and specific SPs-namely, lignosulfonate (LS), polycarboxylate (PCE), and polyacrylate (PA)-influence the stability of foams and the viscosity and setting times of cement pastes. To assess the impacts of these components, we employed foam stability assessments, viscosity measurement techniques, electrical conductivity analysis, and evaluations of dispersion and setting times. Results indicate that MWCNTs enhance foam stability and viscosity, with the degree of improvement contingent on the type and concentration of SPs and the presence of AEAs. Notably, SPs, particularly PCE and PA, markedly influence the properties of cement paste, including increasing dispersion values and modulating setting times, especially when combined with MWCNTs and AEAs. The study concludes that strategically combining MWCNTs with specific SPs and AEAs alters the physical properties of cementitious materials significantly, underscoring the potential for customizing material design in the construction sector.

Synergetic effect of viscosity modifying admixtures and polycarboxylate ether superplasticizer on key characteristics of thixotropic UHPC for bonded bridge deck overlay rehabilitation

Thin bonded ultra-high-performance concrete (UHPC) overlay is an advanced technology for bridge deck rehabilitation. UHPC should be tailored to secure adequate flowablility and high thixotropy to facilitate mixing and placement with a low risk of sagging of the material on sloped bridge deck surfaces. The synergetic effect between nanoclay (NC) and polycarboxylate ether (PCE) superplasticizer or cellulose-based viscosity modifying admixture (VMA) and PCE on the rheological properties (yield stress, plastic viscosity, and thixotropy), cement hydration, autogenous shrinkage, compressive strength, and porosity was systematically investigated. The bond strength between conventional concrete (CC) representing existing bridge deck concrete and thixotropic UHPC and the flexural performance of UHPC-CC composite beams were determined. Test results indicate that the incorporation of 1% cellulose-based VMA combined with 0.4% PCE can increase thixotropy from 12 to 60 Pa/min when the initial fluidity of the mortar phase of the UHPC was maintained at 200 mm. Such increase was limited to 19 Pa/min in mixtures prepared with 1% NC and 1.55% PCE. The thixotropic UHPC containing NC and cellulose-based VMA provided tensile bond strength higher than 3 MPa. The combination of NC and PCE improved the flexural toughness and strength by up to 45% and 30%, respectively, for composite beam specimens. It also led to slightly higher compressive strength associated with greater cement hydration and decreased porosity. The combined use of cellulose-based VMA and PCE led to 15% and 40% greater flexural strength and toughness, respectively, despite the 10% lower compressive strength due to a 30% increase in the volume of pores with diameters larger than 5 µm.

Compressive Strength, Temperature Performance and Shrinkage of Concrete Containing Metakaolin

The influence of metakaolin (MK) on concrete was investigated as a partial replacement of cement, which is liable for high content of CO2 emission during the manufacturing process. The study aimed to assess the compressive strength, temperature performance and drying shrinkage of MK blended concrete. Different ratios of MK (5%, 10%, and 15%) as cement replacement, and two ratios of superplasticizer (SP), 1.5%, and 2% as cement weight were utilized in this study. The results indicated that using MK increased the compressive strength at 28¬ day. The improvement of strength is ascribed to the pozzolanic reaction and the packing effect of fine MK particles. MK blended concrete experienced a decrease in the temperature rise of heat of hydration (HOH) and low drying shrinkage when compared to the control concrete. The SP ratio does not have significant effect on the temperature of the concrete mixtures: however, using 1.5% SP slightly reduces the drying shrinkage of MK blended concrete compared to 2% SP. In conclusion, Incorporation of MK as partial cement substitute enhances the concrete strength, thus various types of concrete can be produced. Low temperature and drying shrinkage of MK blended concrete help in reducing thermal crack after casting process.

A mechanistic study on the effectiveness of star-like and comb-like polycarboxylate superplasticizers in cement pastes

In this paper, star-like polycarboxylate superplasticizer (SPCE) and comb-like polycarboxylate superplasticizer (CPCE) were prepared via atom transfer radical polymerization (ATRP) to study the mechanism of the effectiveness enhancement resulting from this transformation of topological structure. It was found that SPCE molecules acted higher adsorption amount and more Ca2+ complexes, and formed a lower and more compact adsorbed layer and larger surface coverage with a flat conformation on cement surface, depending on more anchored points per unit volume. Through this mechanism, cement particles adsorbed by SPCE showed stronger dispersible capability and colloidal interaction forces (the steric force was dominant), resulting in lower yield stress and plastic viscosity of the cement paste containing SPCE which behaved as an ideal Bingham fluid. The aim of this study is to clarify the mechanistic correlation between topological structure evolution and effectiveness promotion for PCE.

The Effects of Using Eco-friendly Materials for the Production of High Strength Mortar

This study aims to evaluate the effect of using eco-friendly mineral admixtures, such as calcined clay (CC), silica fume (SF), and limestone (L), as partial replacements for ordinary Portland cement (OPC) in the production of high-strength mortar(HSM). The use of these materials can help reduce the environmental impact of cement production by decreasing carbon dioxide emissions and preserving natural resources. To achieve the desired strength, different mixtures were proportioned by increasing the percentage of binder and limiting the water-to-binder ratio (w/b) with the aid of superplasticizer (SP) type G. The mechanical behavior and strength of the blended cements were evaluated, and the optimal mix was determined based on the results of mechanical behavior, strength, and flowability. The results revealed that the optimal mix that gives the best mechanical behavior is the mix F32 with combination of (8% SF + 4 %L+ 13% CC) with an increase about 35 % to control mix strength. The study concludes that using CC, SF, and L as partial replacements for OPC can improve the properties of modern concrete/mortar mixes, resulting in improved durability, service-life properties, and mechanical properties. The results of this study can be utilized as a base for future studies on the same concrete mix design.

High efficiency regulating sedimentation and rheological properties of copper tailings using polycarboxylate superplasticizers

The recovery of low grade and fine particle copper ore usually requires sufficient dissociation, which reduces the particle size to the submicron level, presenting new challenges in subsequent copper tailings disposal. Flocculants can improve tailings sedimentation efficiency, but they also change the rheological properties of the slurry, resulting in low efficiency and high energy consumption during long-distances pumping. To address this issue, this study introduced polycarboxylate ether (PCE) superplasticizers as auxiliary additives for tailings treatment to improve fine particles sedimentation efficiency while enhancing slurry flowability. The results showed that compared to non-ionic polyacrylamide (NPAM) treated slurries, the synergistic effects of PCE and NPAM increased the initial sedimentation rate (ISR) by up to 3.4 times while decreasing the yield stress by up to 8 times and the thixotropic loop area by 10.5 times. DLVO theory calculations showed that PCE mainly affects particle interactions through a significant decrease in electrostatic repulsion. By in-situ monitoring with a focused beam reflectance measurement (FBRM) device, it was demonstrated that the synergistic effect of PCE improved the flocculation ability, strength, and regrowth ability of flocs. Furthermore, strong correlations were found between floc properties and fluid rheological properties. Overall, this study indicated that PCE additive was a promising reagent for fine particles slurry rapid settling and flowability enhancement, providing a new approach for copper tailings disposal.

Investigation of “elephant skin” on UHPC surface via a new test method: Influencing factors, formation mechanism and control measures

Shortly after the mixing of ultra-high performance concrete (UHPC), a viscoplastic layer forms on the surface, which is often colloquially called elephant skin. This layer can hinder the venting, through which air bubbles accumulate below the concrete surface, causing poor surface quality and aesthetics after finishing or resulting in an inferior composite in the case of multi-layer structural components. This paper aims to improve the surface performance of UHPC by reducing the effect of elephant skin. In the present work, the influence of various factors on the “elephant skin” formation on UHPC surface is firstly investigated using a newly developed test method that measures the development of the surface resistance of “elephant skin” on UHPC with time, based on the Vicat apparatus for testing the setting time of cement. Then, the formation mechanism of “elephant skin” on the surface of UHPC is discussed. Finally, some measures to minimize the effect of “elephant skin” on the UHPC surface are proposed. The results reveal that next to controlling the ambient relative humidity (RH) and temperature, an optimization of the concrete mix composition and manufacturing process, such as an increase of superplasticizer (SP) dosage, paste content and water-to-binder (W/B) ratio can help to slow down the “elephant skin” formation on UHPC surface, minimizing its negative effect while without significantly compromising the concrete compressive strength.

Prediction of compressive strength of nano-silica modified engineering cementitious composites exposed to high temperatures using hybrid deep learning models

This study estimated the compressive strength of nano-silica-modified engineering cementitious composites subjected to high temperatures using innovative hybrid deep learning models. The innovative hybrid models in this study were designed using autoencoder (AE)-decision tree (DT) and autoencoder (AE)-extreme learning machine (ELM). Additionally, ELM, DT, and deep AE models in this study were designed to compare the results of innovative hybrid deep learning models. The sensitivity analysis was used for the statistical assessment of the experimental results. The input variables of the models were selected as the cement amount, fly ash amount, sand amount, water amount, high-range water reducer amount, PVA (polyvinylalcohol) fiber amount, nano-silica amount, and the degree of exposure to high temperatures. The compressive strength was used as the output variable of the models. The mixture ratio in the experimental study was 583 kg/m3 cement, 467 kg/m3 sand, 700 kg/m3 fly ash, 187 kg/ m3 water, PVA fiber (0.5 %, 1 %, 1.5 % and 2 %) and nano silica (0 %, 1 %, 2 %, 3 % and 4 %) were used. The ELM, DT, and deep AE models estimated the compressive strength of nano-silica-modified engineering cementitious composites subjected to high temperatures with 93.86 %, 77.35 %, and 86.5 % accuracy, respectively. Also, the same compressive strength was estimated with 94.28 % and 98 % accuracy using the hybrid deep AE-DT and AE-ELM models. This study found that the innovative hybrid deep AE-ELM model predicted compressive strength with higher accuracy than the deep AE-DT, DT, ELM, and deep AE models. Additionally, the deep AE-DT model predicted compressive strength with higher accuracy than non-hybrid models. Thus, it can be stated that innovative hybrid deep models are more advantageous than other models in estimating the compressive strength of ECC. The sensitivity analysis obtained that the PVA fiber was the most significant variable affecting the compressive strength results of nano-silica-modified engineering cementitious composites subjected to high temperatures.

Self-heating performance of cement composites devised with carbon black and carbon fiber: Roles of superplasticizer and silica fume

This study introduces an innovative approach to enhancing the self-heating performance of electrically conductive cement composites (ECCCs) by integrating carbon black and carbon fiber. The main test variables were the contents of silica fume (SF) and superplasticizer (SP). Among the 15 mixtures tested, three mixtures of the 3 % SP series containing 0, 5, and 10 % SF, showing a lower electrical resistivity than the other series, were selected and subjected to 24-h heating performance tests. Subsequently, their hydration characteristics, dispersion of conductive agents, and thermal expansion were examined. The outcomes of these tests unequivocally affirmed that incorporating SF at levels of 0 %–5 % in conjunction with 3 % SP effectively preserved the long-term self-heating performance of ECCCs. This research not only confirms the feasibility of this novel composite formulation but also highlights its potential advantages in maintaining consistent thermal performance, demonstrating its substantial promise for a broad array of applications in construction.

Comparative Study of Various Fibers in Concrete Subjected to Elevated Temperatures

In this paper fiber reinforced concrete is a two-phase material consisting of a matrix which is reinforced with randomly oriented small diameter fibers to improve the mechanical properties of the matrix. It increases the tensile strength of the concrete. Two types of fibers have been used in this paper i.e steel fiber and glass fiber. Steel fiber reinforced concrete is a homogeneous distribution of randomly oriented discontinuous and discrete steel fibers. It is available in the forms of Carbon steel or stainless steel. It has a high tensile and compressive strength. The Glass fibers are formed by drawing the molten material rapidly from a melted batch in a crucible or furnace. Glass fibers do not have a negative effect on the well-known high compressive strength of concrete. Thus, it shows that the fiber reinforced concrete is in good workable condition rather than without super plasticizer. The addition of 2% steel fiber and 0.5% -1% of glass fiber in concrete is found to be optimum as well as effective and economical as it gives good compression, tensile, and flexural strength for the concrete. Carbon fiber is composed of carbon atoms bonded together to form a long chain. The fibers are extremely stiff, strong, and light, and are used in many processes to create excellent building materials. Carbon fiber material comes in a variety of "raw" building-blocks, including yarns, uni-directional, weaves, braids, and several others, which are in turn used to create composite parts. The properties of a carbon fiber part are close to that of steel and the weight is close to that of plastic. Thus, the strength to weight of a carbon fiber part is much higher than either steel or plastic (Polyvinyl alcohol) (PVA) is well known as a synthetic biodegradable polymer and possesses excellent mechanical properties. PVA “displays strong interaction with carbon nanotubes” (CNTs), resulting in exceptional properties that are not found in another polymer

Investigating the effects of superplasticizer and recycled plastics on the compressive strength of cementitious composites using neural networks

The potential application of neural network (NN) models to estimate the compressive strength (CS) of cementitious composites under a variety of experimental settings and cement mixes was investigated. The data were extensively collected from previous literature, and the bootstrap resampling tests were applied to estimate the statistics of the parameter correlations. We find that the NN model that involves the coarse and fine natural aggregates (CA and FA), superplasticizer (SP) and recycled plastics (RP) as the features can accurately predict the CS (R2 ∼ 0.9), without the need to specify the type of SP and the structure of RP in advance. The developed NN model holds promise for revealing the global dependency of CS on these parameters. It suggested that increasing 100 kg/m3 of CA could increase CS by ∼4 MPa, but the usage of CA more than 700 kg/m3 could negatively affect CS. How the CS varying with FA is apparently nonlinear. Within the optimum limit, adding 1 kg/m3 of SP could enhance the CS by ∼2 MPa. Contrarily, additional 1 kg/m3 of RP results in a decrease of ∼0.2 MPa of CS. The mixture-type independent models developed here would broaden our understanding of the global influential-sensitivity among these variables and help save cost and time in the industrial applications.

Compressive Strength Prediction of Concrete Containing Used Cooking Oil Using Ann

To mitigate the detrimental impacts of disposing of used cooking oil (UCO) into the environment, which adversely affects marine life, human health, and agricultural outputs, this research proposes a novel approach incorporating this waste material into the concrete industry as a chemical admixture. To investigate this, an initial experimental program is designed to examine how used cooking oil affects various fresh properties and compressive strength at 3, 7, and 28 days of age of concrete. Concrete batches of M40 grade are meticulously prepared with varying proportions (ranging from 0% to 2%) of used cooking oil. To predict strength characteristics, an Artificial Neural Network (ANN) is employed, consisting of three layers. The input layer comprising quantities of cement, coarse aggregate, fine aggregate, water content, super plasticizer, and the percentage of the chemical admixture (UCO), hidden layer for predicting the network system and the output layer providing the concrete's compressive strength.