Polycarboxylate Superplasticizer Research Articles

Defoaming and Toughening Effects of Highly Dispersed Graphene Oxide Modified by Amphoteric Polycarboxylate Superplasticizer on Oil Well Cement

The aggregation of graphene oxide (GO) during the hydration process limits its wide application. Polymer superplasticizers have been used to improve the dispersion state of GO due to their adsorption and site-blocking effects, though the formation of a large amount of foam during the mixing process weakens the mechanical properties of cement. A highly dispersed amphoteric polycarboxylate superplasticizer-stabilized graphene oxide (APC/GO) toughening agent was prepared by electrostatic self-assembly. Results demonstrate that the APC/GO composite dispersed well in a cement pore solution due to the steric effect offered by the APC. Additionally, the well-dispersed GO acted as an antifoaming agent in the cement since GO nanosheets can be absorbed at the air–liquid interface of APC foam via electrostatic interactions and eliminate the air-entraining effect. The well-dispersed APC/GO sheets promoted cement hydration and further refined its pore structure owing to the nucleation effect. The flexural and compressive strength of the cement containing the APC/GO composite were enhanced by 21.51% and 18.58%, respectively, after a 7-day hydration process compared with a blank sample. The improved hydration degree, highly polymerized C-S-H gel, and refined pore structure provided enhanced mechanical properties.

Effect of ultra-low dosage graphene oxide on the properties of recycled cement-based materials

The utilization of recycled fine powder (RFP) from crushed concrete waste as partial cement replacement is limited by its low reactivity. Graphene Oxide (GO) is a two-dimensional amphiphilic conjugated polymer that can effectively improve the properties of cement-based materials, but its application is limited due to its high cost. This study investigates the ultra-low dosage GO on the properties of recycled cement-based materials. GO was dispersed using polycarboxylate superplasticizers (PCE) before incorporation in the pastes containing 25 % RFP as the binder. The results show that PCE can effectively improve the dispersion of GO in cement-based materials. The improvement effect of well-dispersed ultra-low dosage GO on the strength of recycled cement-based materials in the early stage was better than that in the later stage, and the improvement effect on the flexural strength was better than that on the compressive strength. The GO dosage was optimized at 0.004 % which improved the 3 days flexural strength by 52 % compared to the control sample without GO. Results showed that well-dispersed ultra-low dosage GO accelerated the hydration of recycled cement-based materials due to the nucleation effect and template effect, promoted the formation of additional C–S–H gels, and facilitated the development of C–S–H gels more orderly, reduced the porosity of the hardened pastes, and refined the microstructure. However, excessive GO reduced strength due to agglomeration. The improvement in strength and microstructure refinement demonstrates the positive role of GO in enhancing the reactivity of recycled cement-based materials. This process successfully reduced the dosage of GO in cement-based materials by about 90 % and provided an approach to utilizing recycled fine powder.

Enhancing the Mechanical Properties and Water Permeability of Pervious Planting Concrete: A Study on Additives and Plant Growth.

Pervious planting concrete (PPC) is in line with the concept of ecological environmental protection. However, due to its own porous structure, it is difficult to obtain excellent mechanical properties and water permeability at the same time, which hinders its promotion and application. In this paper, natural gravel (NG), ordinary Portland cement (OPC), polyvinyl alcohol latex powder (PVAP) and polycarboxylate superplasticizer (PS) were used to prepare the PPC, and its mechanical properties and water permeability were studied. Three kinds of plants were planted in the PPC and their planting properties were studied. At the same time, the effect of Bacillus on the planting properties was studied. The results show that when the water-binder ratio (W/B) was 0.28 and the PVAP content was 0.8%, both the mechanical properties and water permeability of the PPC were optimal. The compressive strength and permeability coefficient were 14.2 MPa and 14.48 mm/s, respectively. The mechanical properties and water permeability of PPC prepared with 10~20 mm NG were better than those prepared with 5~10 mm NG. Among the three plants, the germination rate and growth of Elymus dahuricus Turcz (EDT) were the best. The incorporation of Bacillus can optimize its planting properties and promote the effective combination between plants and the PPC substrate.

Effect of Mineral Admixtures on Physical, Mechanical, and Microstructural Properties of Flue Gas Desulfurization Gypsum-Based Self-Leveling Mortar.

The production of flue gas desulfurization gypsum poses a serious threat to the environment. Thus, utilizing gypsum-based self-leveling mortar (GSLM) stands out as a promising and effective approach to address the issue. β-hemihydrate gypsum, cement, polycarboxylate superplasticizer, hydroxypropyl methyl cellulose ether (HPMC), retarder, and defoamer were used to prepare GSLM. The impact of mineral admixtures (steel slag (SS), silica fume (SF), and fly ash (FA)) on the physical, mechanical, and microstructural properties of GSLM was examined through hydration heat, X-ray diffractometry (XRD), Raman spectroscopy, and scanning electron microscopy (SEM) analyses. The GSLM benchmark mix ratio was determined as follows: 94% of desulfurization building gypsum, 6% of cement, 0.638% each of water reducer and retarder, 0.085% each of HPMC and defoamer (calculated additive ratio relative to gypsum), and 0.54 water-to-cement ratio. Although the initial fluidity decreased in the GSLM slurry with silica fume, there was minimal change in 30 min fluidity. Notably, at an SS content of 16%, the GSLM exhibited optimal flexural strength (6.6 MPa) and compressive strength (20.4 MPa). Hydration heat, XRD, and Raman analyses revealed that a small portion of SS actively participated in the hydration reaction, while the remaining SS served as a filler.

Rheological properties of seawater-mixed seashell powder calcined slag cement slurries: Effect of polycarboxylate superplasticizer and temperature

In this study, the effects of temperature and a polycarboxylate superplasticizer (PCE) on the rheological properties of seawater-mixed seashell powder calcined slag cement (SCSC) slurries were examined, revealing the mechanism of action of the PCE in them. The results showed that the shear stress and viscosity of the seawater-mixed SCSC slurries tended to decrease and then increase with increasing PCE content, reaching a minimum value at 0.8% PCE content, reducing the viscosity by 31.8% compared to the SCSC slurry without PCE. Temperature variations did not change the flow pattern of the seawater-mixed SCSC slurries; however, the rheological parameters were greatly affected. The viscosity, shear stress, and consistency coefficient decreased gradually with increasing temperature, whereas the rheological index exhibited the opposite trend.

Polycarboxylate Superplasticizers Used in Concrete: A review

Modern concrete frequently uses a variety of chemical admixtures, like setting time-retarding admixtures, viscosity-modifying admixtures (VMA), and superplasticizers (SPs). These chemical admixtures greatly impact cement components like film-forming capacity, flowability, and film drying time. Currently, the market provides a broad variety of chemically distinct polycarboxylate (PCE) products; of these IPEG and HPEG PCEs have a wide market share due to their cost-effectiveness. New PCE types such as GPEG and EPEG PCEs are currently being introduced, which will expand the family of vinyl ether (VPEG) SPs. In summary, this study examines the chemistry, functionality, the interaction between the chemical structure of PCEs and their behavior with concrete and/or cement-based materials (CBM). The performance of concrete and/or CBM is significantly influenced by the chemical structure of PCE, along with their main chain, anchoring group, side chain, molecular weight, and structure. In conclusion, more precise quantitative micro-analytical methodologies and modelling tools are required to get a comprehensive grasp of the variables influencing the microstructure of concrete and to apply PCE SPs to create more durable concrete.

Preparation and Properties of Polycarboxylate Superplasticizer Based on Chain Transfer Agents with Various Structures

AbstractPolycarboxylate superplasticizer (PCE) is a common admixture in high performance concrete. In the design of PCE molecules, it is necessary to ensure that the molecular weight of the polymer is moderate and the acid‐ether ratio is appropriate to improve the dispersion effect. Chain transfer agent is usually added in the synthesis of PCE to adjust the molecular weight and distribution of PCE. In this study, three sulfhydryl chain transfer agents with different electron‐withdrawing groups or electron‐donating groups were synthesized by nucleophilic addition reaction based on sodium hydrosulfide method. Then, three kinds of PCE containing sulfhydryl chain transfer agent were prepared and compared with commercial β‐mercaptopropionic acid superplasticizers. The yield stress and plastic viscosity of cement paste samples prepared by PCE−A and PCE−M were close to those prepared by PCE−P. PCE−M and PCE−A prepared by chain transfer agent with electron‐withdrawing group had higher dispersion and retention capacity than PCE−P, and had more obvious delay of cement hydration and lower hydration accumulated heat. Therefore, the optimization of molecular structure of chain transfer agent is helpful to improve the properties of concrete superplasticizer.

Insight into the interaction mechanism of polycarboxylate superplasticizer and polyacrylamide in cementitious materials

Due to the economic and environmental benefits, manufactured sand is gradually replacing natural sand in concrete production. However, the residual polyacrylamide (PAM) in manufactured sand negatively affects the concrete rheology, and thus more polycarboxylate superplasticizer (PCE) is required. This study investigates the interaction mechanism between typical PAM and PCE, and further demonstrates their effect on cement hydration. Results show that there is competitive adsorption between PAM and PCE, and PAM occupies the adsorption sites of PCE on the surface of cement particles. Meanwhile, Ca2+ can combine PCE and PAM to form a polymer group, making part of PCE ineffective. Cationic PAM has the most significant effect on the adsorption of PCE on the surface of cement particles, whereas nonionic PAM has the least effect. The result of this study helps optimize the compatibility of PCE with manufactured sand concrete.

Effects and Mechanism of Hyperbranched Phosphate Polycarboxylate Superplasticizers on Reducing Viscosity of Cement Paste.

The adsorption behavior and dispersing capability of hyperbranched phosphated polycarboxylate superplasticizers (PCEs) containing phosphate monoester and phosphate diester were investigated. The hyperbranched structures were constructed using a special monomer dimethylaminoethyl methacrylate (DMAMEA) to create the branches during the polymerization. Meanwhile, the polymer architectures were tailored by varying the content of phosphate monoester and phosphate diester in the backbone via free radical solution polymerization. In contrast to comb-like PCE, hyperbranched PCEs presented a weaker dispersion capability at w/c = 0.29, but with a lower water-to-cement ratio (w/c), the hyperbranched PCEs exhibited a better dispersion capability than the comb-like PCEs. The dynamic light scattering (DLS) and transmission electron microscope (TEM) analysis showed that the adsorption layer of hyperbranched PCEs were thicker than that of comb-like PCEs. A thicker adsorption layer thickness generated thinner diffusion water layer thickness. The increase of the free water amount due to the thinner water diffusion layer is the key mechanism for improving the dispersibility and decreasing the viscosity of cement paste.

Polycarboxylate superplasticizer modified 3D graphene as long-term-efficient water-based lubricating additive under heavy load conditions

At present, due to the excellent properties of graphene, which can significantly enhance the performance of lubricants, researchers are conducting extensive studies on it. However, the poor dispersion of graphene limits its application in lubrication, which becomes an urgent problem for researchers to solve. Moreover, with the concept of green environmental protection becoming more and more popular, the research on water-based lubricants is of great significance. Therefore, we modify three-dimensional graphene (3DG) by polycarboxylate superplasticizer (PCE) to prepare a water-based lubrication nano-additive with long-term dispersion stability, named PCEG. PCEG nanomaterials can stably disperse in water for more than three months, which effectively solves this problem. Tests show that friction coefficient and wear volume of the lubricant with 0.5 wt% PCEG are reduced by 31.1 % and 23.1 %, respectively, compared to the base fluid at 20 N (2.7 GPa) heavy load conditions. The enhanced lubrication performance is attributed to the fact that PCEG, which has excellent dispersion stability, forms a strong adsorption and continuous dense lubrication film on the friction surface. In addition, it fills and polishes the grooves and pits, thus improving the friction-reduction and anti-wear properties. This study not only greatly solves the problem of poor dispersion stability of graphene and develops a nano-lubricant that is consistently effective under heavy load conditions, but also provides an important reference value for the subsequent development of high-performance and stable graphene-based lubricants.

The dispersion and influence of graphene-oxide-modified polycarboxylate superplasticiser in alkaline cement solution

The aggregation of graphene oxide (GO) in alkaline solutions is a critical factor that limits its potential applications in cement-based materials. In this study, a polycarboxylate superplasticiser (PCE) was employed as a dispersant and a GO–PCE water-reducing agent was synthesised through the method of dropwise addition. This synthesis approach not only preserved the water-reducing capabilities of PCE but also enhanced the dispersibility of GO in alkaline cement solutions. Furthermore, the synthesis method is straightforward. The results showed that that GO–PCE had excellent dispersion in a saturated calcium hydroxide (CH) solution. Furthermore, it was found that the GO–PCE enhanced the workability of cement, accelerated cement hydration, reduced the crystallite size of the CH and increased the compressive strength of the cement mortar.

Effects of Lithium Carbonate and Superplasticizer on Ultra-Early Strength of Alite-Ye'elimite-Belite-Ferrite Cement.

Alite-ye'elimite-belite-ferrite cement (AYBFC) integrates the advantages of calcium sulfoaluminate cement and Portland cement, but its ultra-early strength needs to be further improved when applied to rush repair and construction works. In this study, the ultra-early strength of AYBFC was improved using lithium carbonate (Li2CO3) and superplasticizer. The results showed that an appropriate amount of Li2CO3 could significantly improve the ultra-early strength of AYBFC, since it was capable of promoting the hydration reaction of AYBFC. After polycarboxylate superplasticizer was doped on this basis, the ultra-early compressive strength of AYBFC was further improved. This was because the superplasticizer could markedly enhance the matrix compactness despite its inhibitory effect on the hydration reaction of cement and the generation of hydration products.

Synthesis of Polycarboxylate Superplasticizers via Photoinitiated Radical Polymerization

Synthesis of Polycarboxylate Superplasticizers via Photoinitiated Radical Polymerization

Synthesis and study of the effect of the structure of HPEG-type polycarboxylate plasticizers on the properties of low-strength concrete

Polycarboxylate superplasticizers have been synthesized as copolymers of acrylamide with polyethylene glycol metallyl ether (HPEG), acrylic acid, and 2-hydroxyethylacrylate, with a molecular weight of 25–33 kDa. The copolymers were characterized using GPC and NMR, revealing that during copolymerization, the copolymer includes up to 10 mol.% HPEG 3500 Da. Copolymers at a dosage of 0.12 wt% provide significant retention time of the concrete mix. When considering the same mole ratios of HPEG/(other monomers) in the initial mixture, copolymers containing the carboxylate and hydroxyethyl acrylate group are the most effective. In terms of concrete strength, the use of quaternary copolymers (AA/AM/HPEG/2-HEA) results in a slowdown in strength gain at the ages of 1–3 days, while the strength at the age of 28 days exceeds that of double (AM/HPEG) and triple (AA/AM/HPEG) copolymers.

Mechanism study of the effect of superplasticizers in alkali-activated materials containing sludge

To realize the safe disposal of solid waste containing heavy metals, sewage sludge jointly with slag and metakaolin was used to prepare alkali-activated materials (AAMs), and the effect mechanism of polycarboxylate acid superplasticizer (PCE), naphthalene superplasticizer (NS) and aliphatic superplasticizer (AS) in AAMs were studied. The results showed that both the fluidity and strength of AAMs decreased with the addition of sludge. For the NaOH + Na2SiO3 activated mortar specimen, the incorporation of sludge can reduce their fluidity and strength from 206 mm and 80.25 MPa to 193 mm and 42.43 MPa, respectively. However, the addition of superplasticizers into sludge-containing AAMs leads to a reduction of 3–9% of the fluidity. Interestingly, it can enhance the strength of the AAMs, especially the NS and AS, which increase the strength by approximately 25%. This is attributed to the increase of particle dispersion by superplasticizers. However, the free water released in the process is reabsorbed by the sludge, which increases the local alkali concentration and promotes the activation of the activity. The dispersed sludge particles can play the role of physical filling, making the structure denser. HIGHLIGHTS Sludge is adverse effects on both the fluidity and strength of alkali-activated materials (AAMs). The addition of superplasticizers (SPs) increases the strength of AAM with sludge. SPs do not affect improving the fluidity of AAMs with sludge, even slightly bad. The dispersion effect of SPs on the sludge is beneficial to promote its activity in AAMs.

Effects of polycarboxylate superplasticizer and hydroxypropyl methylcellulose on the properties of ferric-rich sulfoaluminate cement

Ferric-rich sulfoaluminate cement (FR-SAC) is a promising low-carbon cement and is usually used to prepare precast products due to its short setting time. However, the fast setting of FR-SAC paste also leads to its poor fluidity and workability. Polycarboxylate superplasticizer (PCE) and hydroxypropyl methylcellulose (HPMC) can improve the fluidity and viscosity but may affect other properties of FR-SAC products. To get a suitable performance of FR-SAC by adding PCE or HPMC, the properties of FR-SAC paste with PCE and HPMC added and their influence mechanism were explored. The results indicate that PCE adsorbs on the surface of positively charged ettringite in the slurry under the electrostatic attraction, which makes the negatively charged or uncharged FR-SAC particles uniformly dispersed in the slurry, thus regulating the rheology and other properties of FR-SAC paste. The compressive strength of FR-SAC paste increases with the increase of PCE addition. PCE slightly retard the early hydration rate of FR-SAC but does not affect the formation of later hydration products. Adding HPMC to FR-SAC paste can decrease the fluidity and increase the viscosity of FR-SAC paste but has little effect on its hydration properties. Therefore, when PCE and HPMC are used to modulate the rheology of FR-SAC paste, it is necessary to combine the utilization process and compressive strength requirements to keep both the rheological parameters and compressive strength in the suitable condition.

Preparation and performance analysis of polycarboxylate superplasticizer modified with fluorine-containing monomer and silicon dioxide nanoparticles

With the development of technology, the performance requirements for building materials in the modern construction industry are increasing. Nanomaterials and polycarboxylate superplasticizers (PCE) have good applicability in this field. Therefore, we develop a composite material by incorporating a fluorocarbon surfactant (FS) as a shrinkage-reducing agent into the PCE and modifying it with silicon dioxide nanoparticles (nano-SiO2) (SiO2-FS-PCE). Moreover, we investigate the preparation, dispersity, flowability, rheological properties, adsorption performance, and microstructure of the SiO2-FS-PCE composite. We observe that introducing an appropriate concentration of fluorine-containing monomer can effectively reduce surface tension in the solution and inhibit the shrinkage of the slurry. The rheological properties of the SiO2-FS-PCE1 slurry decrease significantly with time. When the dosage of nano-SiO2 exceeds 20%, the silicon hydroxyl groups on the material’s surface tend to polymerize, which affects the adsorption and dispersion of the superplasticizer, thereby reducing its fluidity. As the dosage of nano-SiO2 increases, there is a trend of increasing friction of SiO2-FS-PCE, followed by a decrease. This change is closely related to changes in the adsorption and morphology of SiO2-FS-PCE, providing higher adsorption sites than other materials. In conclusion, these findings provide insights for a deeper understanding of the synthesis and properties of nanocomposite materials, thereby offering a theoretical basis for further optimization of their preparation and performance.

Investigation on the early proceeding of cement hydration containing dispersed nano Calcium Silicate Hydrated (CSH) seeds

Steam curing process is a traditional method for accelerating the progression of cement hydration to satisfy the rapid development of compressive strength in precast concrete industry. However, steam curing would release significant amount of CO2 into the atmosphere. In order to avoid the serious environmental pollution caused by the steam curing process, Calcium Silicate Hydrate (CSH) dispersed by comb-like polycarboxylate superplasticizer (PCE), shorted as dispersed nano CSH seed, was utilized to promote the early cement hydration at normal temperature. This investigation aims at disclosing the hydration process of cement and the microstructure evolution of cement paste in the presence of dispersed nano CSH seed during the early stage via setting time, ultrasonic pulse velocity (UPV), compressive strength, conductivity, pH, thermogravimetric (TG), 29Si NMR and nitrogen adsorption/desorption. The results demonstrated that with the dispersed nano CSH seed increasing, the setting process of cement paste was shortened dramatically, the compressive strength and UPV of cement mortar increased significantly especially at 12 h. The variation of conductivity and pH of cement suspension indicated that the ion dissolution process was promoted by dispersed nano CSH seed, which therefore conducive to the precipitation of cement hydration products. TG curves exhibited that the formation of cement hydration products, including CH (Calcium Hydrated), AFt and CSH gel were accelerated by dispersed nano CSH seed. The 29Si NMR (Nuclear Magnetic Resonance) and nitrogen adsorption/desorption results validated that the incorporating dispersed nano CSH seed promoted considerably the polymerization of CSH gel. The aforementioned results are correlated well with the fast formation of microstructure and in turn the rapid development of compressive strength at early age.

Effective flotation separation of brucite and serpentine using eco-friendly PCE-11 as a novel regulator

ABSTRACT In this study, sodium oleate (NaOL) was employed as a collector to examine the role and adsorption mechanism of a novel regulator, the polyether polycarboxylate superplasticizer (PCE-11), in the flotation separation of brucite and serpentine. Efficient separation of brucite and serpentine was achieved under the reagent system with the PCE-11 dosage of 600 mg/L, NaOL dosage of 320 mg/L, and pulp pH of 11. Surface wettability analysis revealed that PCE-11 diminishes the hydrophobicity of serpentine in the NaOL system. Zeta potential analysis and adsorption capacity analysis demonstrated a significant reduction in NaOL adsorption capacity on the serpentine surface following interaction with PCE-11. Infrared spectrum analysis and XPS analysis revealed that PCE-11 is adsorbed on the surface of both brucite and serpentine, with a certain number of Mg sites remaining bonded to NaOL after PCE-11 occupies part of the Mg sites on the brucite surface. However, PCE-11 impedes NaOL adsorption on serpentine surfaces, enhancing the floatability difference between the two minerals.

Interaction mechanisms between polycarboxylate superplasticizers and cement, and the influence of functional groups on superplasticizer performance: a review

Interaction mechanisms between polycarboxylate superplasticizers and cement, and the influence of functional groups on superplasticizer performance: a review