Influence Of Superplasticizer Research Articles

Preparation of p-isopropylphenol polyoxyethylene ether and evaluation of its performance in concrete

P-isopropenylphenol polyoxylates (IPP-PE) were obtained by alkoxylation reaction using p-isopropylphenol phenol (IPP) and ethylene oxide (EO) as raw materials, and P-PCE polycarboxylic acid superplasticizer was obtained by free radical polymerization of ipp-PE and acrylic acid (AA) under the action of initiator and chain transfer agent. The effects of reaction temperature, acid-ether ratio, amount of chain transfer agent and initiator, and reaction time on the dispersion properties of superplasticizer were studied, and the molecular structure and microscopic morphology of the superplasticizer were characterized by FTIR,1HNMR, and SEM, and the influence of superplasticizer on concrete properties was evaluated by concrete performance tests. The test results determined that the optimal synthesis process of polycarboxylic acid superplasticizer was as follows: reaction temperature 40 °C, n(AA):n(IPP-PE)=6:1, chain transfer agent and initiator were 0.4% and 0.6% of the mass of large monomer, respectively, and the reaction time was 4.5h. The experimental results of the concrete performance test showed that the workability of concrete mixed with the self-made superplasticizer was excellent, and the initial and 1h longitudinal flowability of the superplasticizer reached 228 mm and 215 mm, respectively. The water reduction rate reached 36%, the 28d compressive strength reached 56.8 MPa, the initial slump reached 226 mm, and it had a certain retarding and air entrainment effect.

Early-age inhomogeneous deformation of 3D printed concrete: Characteristics and influences of superplasticizer and water-binder ratio

3D printed concrete (3DPC) commonly experiences significant shrinkage along the printing direction (x-direction) at the early-age for its high cementitious material content, low water-binder ratio and formwork-free manufacturing process. This shrinkage with gradient along the vertical direction (z-direction) can cause interlayer slippage and further deformation within each filament. To investigate these early-age deformations and their dependence on materials, digital image correlation (DIC) was used to monitor the inhomogeneous deformation of 3DPC at the age of 0.5–6.5 h. It was found x-direction inhomogeneous shrinkage pattern is correlated with early-age hydration process and elastic modulus. After conducting mechanic analysis, it was found that an individual filament could be treated as a Winkler foundation beam with frictional moment, which can provide a semi-quantitative explanation of the phenomenon that the bottom filament shows significant downward deflection, while other layers show minimal upward deflection or almost no deflection. Additionally, the influence of superplasticizer and water-binder ratio on early-age inhomogeneous deformation was monitored. There exists an optimal dosage range for superplasticizer that ensures both better printing quality and lower x-direction shrinkage, shrinkage gradient as well as bottom layer deflection. With the same printing quality, early-age shrinkage, shrinkage gradient and the bottom layer deflection were reduced by adopting higher water-binder ratio. The influence of materials on the moisture evaporation rate and early-age strength was also measured and correlated with early-age x-direction shrinkage, shrinkage gradient of 3DPC and the extent of early-age bottom layer deflection.

Experimental Investigation on the Influence of Superplasticizer on Mechanical Behavior of Recycled Aggregate Concrete

Needs for renovation and efficient use of available land space have led to the destruction of numerous deteriorated civil structures. Consequently, a huge amount of concrete demolished waste is generated annually worldwide. This demolished concrete waste has created an extra burden on the environment and landfills, making the development projects unsustainable. Demolished waste can be recycled and reused for sustainable development and to reduce the demand for fresh natural aggregates (NA). However, the poor performance of recycled aggregate concrete (RAC) compared to natural aggregate concrete (NAC) may be a significant drawback in the recycling and reusing of demolished concrete wastes. This limitation can be overcome by using a superplasticizer, which has the ability to improve different mechanical properties of concrete. The objective of this paper is to assess the effects of the superplasticizer on the mechanical characteristics of RAC. Concrete specimens were prepared to have replacement ratios (0%, 25%, 50%, and 100%) of fresh NA by recycled stone aggregates (RSA) and recycled brick aggregates (RBA). Half of the prepared concrete specimens were admixed with the superplasticizer, having 15% water reduction for concrete mixes. The obtained test results encourage the use of superplasticizers for improving the mechanical properties of RAC. It is observed that fresh, natural coarse aggregates in a concrete mix can be replaced with 50% RSA and 25% RBA with the addition of the superplasticizer without compromising the mechanical performance.

Effect of recycled powder on the yield stress of cement paste with varied superplasticizers

The influence of superplasticizer on the yield stress of cement pastes with recycled powder (RP) was examined in the study. Four superplasticizers were used to obtain the similar fluidity by adjusting the dosage. The results show that the 10% RP decreases the yield stress of paste compared to the reference paste at the same fluidity, but 20% and 30% RP increases the yield stress, ranging from 11 to 599%. The superplasticizer with adsorptive group of phosphate-type minimizes the yield stress of paste than that of polycarboxylate -type, but it made a significant increment in yield stress as the incorporating of RP increased. Besides, the polycarboxylate superplasticizer with the higher molecular weight of side chain and charge density led to lower yield stress. Based on the Yodel model, the yield stress of paste with RP was analyzed by the polymer adsorption and particle packing density of particles to reveal the influence of RP with different superplasticizers on the colloidal interaction and contact network among the particles. The packing density of particles with recycled powder was a little higher than the reference paste, but the higher fraction of fine particles made a stronger PSD effect, which improved the particle contact interaction. On the other hand, due to the higher polymer adsorption of recycled powder than cement, especially for superplasticizer with phosphate group, the average surface coverage was increased, which extended the separation distance, so that colloidal interaction among particles was weaken.

Alkali activation of fly ash in self-consolidating concrete at low molar concentration

As a means of minimising the negative effects on the environment, the use of industrial byproducts in the building industry is becoming more popular. Recently, alkali activation of precursors has boomed in the market since activation of precursors improves mechanical properties and reduces the carbon footprint. However, one risk factor in alkali activation is molar concentration. This is because the increase in the molar concentration of sodium hydroxide/sodium silicate and the release of volatile substances from those acids is more harmful to the environment. Therefore, the present study investigates the activation of the precursor at low molar concentration, thereby equalising performance through the dosage of superplasticisers. In this regard, fly ash was activated at 5 M sodium hydroxide (NaOH) and replaced cement at varying percentages in the range of 0–30% by weight. The performance of self-consolidating concrete (SCC) was evaluated through fresh and hardened characteristics and microstructural analysis. The blended mixtures of SCC, activated fly ash (AFA) at 5 M sodium hydroxide, 0.89% of superplasticisers and 15% of replacement performed better than the control SCC. The outcome of the present study will provide a platform for activating a precursor at low molar concentration through the influence of superplasticisers.

Effect of nano-metakaolin on establishment of internal structure of fly ash cement paste

The study aims to enhance the viscosity and establishment of internal structure of fly ash (FA) cement paste through the addition of nano-metakaolin (NMK). Various tests, including apparent viscosity test, small amplitude oscillatory shear test, and calorimetric test, were conducted to investigate the effects of FA content, NMK content, superplasticizer content, and test temperature. The results showed that NMK increased the apparent viscosity of FA cement paste while weakening its shear thinning behavior. Specifically, incorporating 5 wt% NMK increased the apparent viscosity of cement paste containing 30 wt% FA by 60%. Furthermore, NMK accelerated the growth of storage modulus (G') and facilitated the rapid establishment of internal structure in FA cement paste, the optimal amount of NMK admixture in a 30 wt% FA cement paste is determined to be 5 wt%. However, the presence of superplasticizer hindered the increase in G' and delayed the establishment of internal structure in NMK/FA cement pastes. For cement paste containing 5 wt% NMK and 30 wt% FA, the growth rate of G' within 60 min decreased to 26% when 0.12 wt% superplasticizer was added compared to the cement paste without superplasticizer. Temperature had a significant impact on the establishment process of internal structure in NMK/FA cement pastes within 90 min but had minimal effect on the final state at 90min. For N5FA30 cement paste hydrated for 30 min and 90 min respectively, G' at 10 °C was approximately 7.3% and 66.7% compared to that at 40 °C. Moreover, a power function correlation was observed between G' and cumulative hydration heat per gram of cement (Hc) in NMK/FA cement pastes. The inclusion of superplasticizer decreased both G' and Hc in the cement paste. Notably, the influence of superplasticizer on G' was more pronounced than its impact on Hc during the hydration process.

Influence of superplasticizers on the workability and mechanical development of binary and ternary blended cement and alkali-activated cement

A comparative study of the effect of superplasticizers on different formulations of binary and ternary cement and alkali-activated cement (AAC) is presented. The need to find sustainable alternatives to the manufacture of Ordinary Portland Cement (OPC), together with the increasing demand for superplasticizer admixtures for a range of applications, motivate this study. Superplasticizer admixtures are designed for OPC so, in presence of supplementary cementitious materials, such as metallurgical slags and combustion ashes, or in alkaline environments, their performance may differ. To assess the influence of the admixtures on these formulations in presence of additions and alkaline media with high and low pH, the fresh and hardened properties of the cementitious matrixes are evaluated. Experimental results show that plasticizing effect in composite cement does not depend on the addition nature (slag or fly ash) and it is well maintained for at least the first two hours after mixing but, in the case of AAC, this effect drops rapidly probably due to lack of chemical stability of the admixtures in alkaline media. Regarding the properties in the hardened state, polycarboxylate admixtures in composite cement do not imply significant variations in mechanical strengths at an early age, but they do in AAC, which presents a detriment of around 17%. Mercury intrusion porosimetry reveals that the incorporation of polycarboxylate refines the pore structure of the cementitious matrixes.

The influence of superplasticizers on the porous structure and thermal conductivity of lime foam concrete waste

the results of laboratory experiments are presented, where the use of lime waste (sludge) in foam concrete and the possibility of their use as a filler for foam concrete are analyzed. It is shown that the total porosity, thermal conductivity and structural quality of foam concrete with waste lime were taken as parameters of the porous structure.

Influence of Superplasticizers (Conplast Conplast SP 430) on Fresh Properties of Self-Compacting Concrete: An Experimental Investigation

Abstract: Super plasticizer has played a significant part in the recent issues of stability, particle suspension, particle segregation, flow properties, and cohesiveness in concrete. This study looked at how self-compacting concrete's characteristics and workability were affected by super plasticizer (SCC). Super plasticizers Conplast Conplast SP 430 is employed in the current investigation with concrete grades M30 and M40. Fresh concrete was used for the workability slump, compressive strength, and flexural strength test. On the hardened concrete, a test for compressive strength was performed. While every mix was acceptable, the one containing Conplast SP 430 had the best workability, compressive strength, and flexural strength. In the present investigation, it is show, how the cement content decreased by 23% and increasing compressive strength, flexural strength and reduced water –cement ratio also.

Influence of superplasticizer on workability and strength of ambient cured alkali activated mortar

Alkali activated materials contain aluminosilicates, which can be used for building with a low environmental impact by repurposing waste resulting in cost-effective construction. The impact of nature and superplasticizer dosage on fly ash slag-based ambient cured mortar activated with sodium silicate and sodium hydroxide is not yet definitive. This paper studies the influence of various superplasticizers on fly ash-based ambient cured mortar activated with sodium silicate and sodium hydroxide. The effect of superplasticizers was evaluated by adding various superplasticizers including melamine, polycarboxylate ether and naphthalene-based superplasticizers in different dosages from 0 to 3% at 0.5% intervals. Fresh properties of alkali-activated mortar with various percentages of superplasticizer were tested using flow table apparatus and compared with mortar without superplasticizer. The hardened property of the alkali-activated mortar was tested by checking the compressive strength of the mortar cube. From the test results, naphthalene and polycarboxylate ether-based superplasticizers are compliant with alkali-activated mortar. Melamine-based superplasticizer shows a slight reduction on strength of alkali-activated mortar. In the ambient cured mortar, the optimum concentration for naphthalene and polycarboxylate ether-based superplasticizers is 2.0 percent, whereas melamine-based superplasticizer exhibits maximum strength for 2.5 percent. Even though naphthalene and polycarboxylate-based superplasticizers are effective for alkali-activated mortar, the most efficient type is the polycarboxylate ether-based superplasticizer.

Influence of Superplasticizers on the Workability and Mechanical Development of Binary and Ternary Blended Cement and Alkali-Activated Cement

Influence of Superplasticizers on the Workability and Mechanical Development of Binary and Ternary Blended Cement and Alkali-Activated Cement

Experimental Investigation on the Influence of Superplasticizer on Mechanical Behavior of Recycled Aggregate Concrete

Experimental Investigation on the Influence of Superplasticizer on Mechanical Behavior of Recycled Aggregate Concrete

Influence of Superplasticizers on the Microstructure and Elastic Properties of Concrete

Influence of Superplasticizers on the Microstructure and Elastic Properties of Concrete

Micro-Cement for Injection Consolidation of Base Soils

Issues of development of compositions of injectable materials on inorganic basis for underground and transport construction are considered in the paper. Inorganic binders for aqueous suspensions for strengthening of low-strength sandy and debris soils by injection into the fortified massif are proposed. The use of silica gel in combination with hydrated lime for injectable aqueous suspensions is justified. The influence of superplasticizer on the technological properties of suspensions is shown. The properties of micro-cement of different compositions are presented. Optimal ratios of components were determined. The following properties of aqueous suspensions have been studied: viscosity, sedimentation and penetrating power. The viscosity was up to 40 s, sedimentation up to 1.4%. Soil-concrete obtained by injecting the aqueous suspension based on composite binders has the compressive strength in the range of 3.3-6.2MPa.

Influence of superplasticizers and retarders on the workability and strength of one-part alkali-activated fly ash/slag binders cured at room temperature

One-part alkali-activated fly ash/slag binders have been promoted as an environmentally friendlier alternative to Ordinary Portland Cement (OPC). However, its tendency towards flash setting and high sensitivity of the mixture’s strength to water content have been sources of major concern in the industry. This study investigates the effects of different w/b ratios, admixtures (such as superplasticizers and/or retarders) and the dosage of the selected admixture on the fresh and hardened properties of one-part alkali activated fly ash/slag based binders. To evaluate the fresh properties of binders, setting time and flowability tests were carried out. The compressive and flexural strength tests were conducted to determine the mechanical strength of the samples. The mineralogy and microstructure of the samples were studied using X-ray diffraction (XRD) and scanning electron microscope (SEM) in conjunction with energy dispersive spectroscopy (EDS) which was used to observe the elemental composition. Additionally, an optical microscope was also used to study the surficial physical properties of the hardened binders. The experimental results showed that an increase in w/b ratio led to an improvement in fresh properties of binder but significantly decreased the mechanical strength. A w/b ratio of 0.3 was deemed to be optimal in this study because at this ratio the hardened samples showed no surficial cracking and had enough compressive strength to be viable as a construction material. Test results also showed borax to be superior to all the other admixtures tested when both mechanical strength and workability are considered.

E-Modulus and Creep Coefficient of Self-Compacting Concretes and Concretes with some Mineral Additives

The applicability of a proposed model similar to a well-known Hirsch's model for predicting the E-modulus of concrete and the creep coefficient of concrete depending on the composition of the concrete, the properties of the components of concrete mix and the possible effect of the superplasticizer on the deformation properties of cement stone both under short-term and long-term loading is proved. Value ​​of the E-modulus of self-compacting concrete can be reduced to 20% with respect to the ordinary concrete of equal compressive strength, which is confirmed by the model calculation data and some experimental data. For concretes with mineral additives, the influence of mineral additives on the E-modulus was not established. Both an increase and decrease in the E-modulus is possible. The effect depends on the type of additive. The creep coefficient of self-compacting concrete, obtained by calculation according to the model, due to the increased content of cement stone and the possible influence of superplasticizer on the creep of cement stone, can be from 1.3 to 1.8 of the coefficient of creep of ordinary concrete. This result agrees well with some experimental data. The creep coefficient of concrete with mineral additives (silica fume, white ash and metakaolin), obtained by calculation according to the model, can be from 0.5 to 0.6 of the coefficient of creep of ordinary concrete. This result agrees well with some experimental data.

A comparison between the influence of superplasticizer and organosilanes on different properties of cemented paste backfill

The water repellency influence of non-polar organosilanes (vinyl and methyl) and polycarboxylate superplasticizer were studied and compared on flow behavior, strength development, and microstructural properties of cemented paste backfill (CPB) composed of sulfidic and non-sulfidic tailings. The addition of water-repellent admixtures affects the water requirement and hence the total performance of cementitious materials. Based on the uniaxial compressive strength (UCS) test and slump height measurements, the addition of vinyl silane to CPB provided a higher UCS value and reduced the required amount of water for a specific slump height. The addition of vinyl and methyl organosilanes, however, was less advantageous on CPBs composed of sulfidic tailings since reduced the early strength development. The achieved differential thermogravimetric (DTG), mercury intrusion porosimetry (MIP), and scanning electron microscopy (SEM) results implicated that the use of vinyl silane was more efficient to densify the CPB matrix due to the hydration improvement and the formation of additional C-S-H gel specifically in non-sulfidic CPBs.

Influence of superplasticizers on mechanical properties and workability of cemented paste backfill

This paper presents new insights into the mechanical properties and workability of cemented paste backfills (CPBs) containing various superplasticizers. Effects of these admixtures on cement hydration were also evaluated. Five admixtures belonging to the main superplasticizer groups (lignosulfonate, naphthalene, melamine, and polycarboxylate) were used at 5, 7, and 10% by dry mass of binder (a mixture of 20% ordinary Portland cement (OPC) and 80% slag). The effects on CPBs formulated with OPC and the most effective superplasticizers were also studied. Results showed that superplasticizers influence on CPB performances depends on the type and dosage of the admixture. Polycarboxylate presented the best performances and allowed the achievement of the target consistency at lower water content (between 6 and 10%) without altering the mechanical strength of the CPBs. The results also reveal that a reduction in binder content (from 5 to 3%) could be achieved while still conserving CPB strength when using polycarboxylate admixtures.

Effect of superplasticizer type and siliceous materials on the dispersion of carbon nanotube in cementitious composites

The influences of superplasticizers and siliceous materials on the dispersion of carbon nanotube (CNT) in cementitious composites were investigated. Three types of superplasticizer were used, and the siliceous materials such as silica fume and nano-silica were utilized as dispersion agents. The dispersion characteristics of CNT in the state of aqueous solution were explored via the UV–Vis spectra, and the zeta potential, while those of CNT in the cementitious matrix were investigated via the electrical characteristics of the CNT-incorporated cementitious composites and scanning electron microscopy images. The dispersion mechanism of CNT induced by the superplasticizers and the siliceous materials was thoroughly examined. The superplasticizers containing polycarboxylate were effective to disperse CNT in cementitious composites compared to other types of superplasticizers used here. The addition of silica fume to cementitious composites utilizing the superplasticizers with polycarboxylate was further improved the dispersion of CNT, while nano-silica did not improve the dispersion of CNT.

The Influence of Superplasticizers Based on Modified Acrylic Polymer and Polycarboxylate Ester on the Plasticizing Effect of Cement Paste

The article aims to present a research into the impact of the dosage and effectiveness of superplasticizers based on modified acrylic polymer and polycarboxylate ester (from 0 to 1.2 %) on rheological properties of the cement pastes (yield stresses and plastic viscosities), of different testing times after mixing (from 0 to 90 min). Materials used in the study: Portland cement CEM I 42.5 R, superplasticizers SP1 (modified acrylic polymer based), SP2 (polycarboxylate ester based), and water. Investigation was carried out using rotational rheometer Rheotest RN4.1 with coaxial cylinders. The tests revealed that superplasticizer SP2 is more effective than SP1 – cement paste (W/C = 0.30) exhibits better flowability and improved rheological qualities. Superplasticizers SP1 and SP2 exhibit different levels of plasticizing effectiveness and ability to retain the effect’s duration. Due to the increase in the dosage of superplasticizers SP1 and SP2 from 0 to 1.2 %, plasticizing effect increases. It is also observed that larger dosage of SP1 (0.6-1.2 %) results in slower increase in plasticizing effects until the 90 min margin. In conclusion, from the start of mixing until the 90 min margin, the best plasticizing effect and its retention achieved by superplasticizer SP2. Recommended SP2 dosage – from 0.6 to 0.8 %.