Polycarboxylate Superplasticizer Research Articles

Unlocking cementitious performance: nano‐lubrication via polycarboxylate superplasticizers

AbstractPolycarboxylate (PCE) superplasticizers are the most important additive in concrete, which can effectively improve the workability of cement slurry. Different from the traditional regarding of PCEs as dispersants, here, we understand the PCEs as nano‐lubricants. By employing the molecular dynamics simulation, a sophisticated model was used to evaluate the interfacial friction between the C–S–H particles. The results reveal that the PCEs can reduce the interfacial friction between the C–S–H particles, and thus increase the fluidity of cement slurry. Further analyses infer the role of PCE segments in lubrication. The carboxylates on PCEs ensure the anchoring and hinder the separation of Ca ions. The side chains are used to lubricate the C–S–H surface, due to the weak adsorption between the side chains and the C–S–H surface. Predictably, this study not only provides a method to directly evaluate the performance of PCEs but also suggests new insights into the colloid dispersion of the low‐water content system.

Effect of the structure of macromonomer in polycarboxylate superplasticizer on viscosity and workability of concrete

AbstractReducing the water‐to‐cement (w/c) ratio was the most direct way to decrease the dosage of cement while ensuring compressive strength of concrete. However, the concrete system tend to be more stickiness at low w/c ratio. Four types of polycarboxylate superplasticizers (PCEs) were synthesized using HPEG, IPEG, EPEG, or VPEG as macromonomers. The impact of PCEs on the viscosity and workability of cement and concrete was investigated. The mechanism behind the macroscopic properties exhibited by these four PCEs was explored through surface tension analysis, GPC analysis, NMR analysis, and adsorption capacity evaluation. The results indicated that, at high w/c ratio (≥0.35), concrete mixed with four types of PCEs demonstrated almost the same flow velocity and viscosity, at low w/c ratio (≤0.3), the V‐funnel time of concrete which mixed with 67EPC3.5 reached 8.5 s, showed the fastest flow velocity and lowest viscosity, due to the structure of 67EPC3.5 containing the highest content of combined units of AAA which resulted in rapid adsorption rate and maximum adsorption quantity, and the viscosity effect was independent of surface tension. Concrete mixed with 67IPC3.5 displayed the superior workability at any w/c ratio primarily because the structure of 67IPC3.5 contained the highest content of polyoxyethylene ether which effectively reduced surface tension.

Synergistic Effects of Ethylene Glycol Solution and Polycarboxylate Superplasticizer on the Hydration of Calcium Sulphoaluminate Cement at −10°C

Synergistic Effects of Ethylene Glycol Solution and Polycarboxylate Superplasticizer on the Hydration of Calcium Sulphoaluminate Cement at −10°C

Preparation of amphoteric polycarboxylate superplasticizer at low temperature and its application in cement-calcined kaolin blended system

As one of supplementary cementitious materials (SCMs), calcined kaolin (CK) has received increasing attention in the development of green and sustainable SCMs. When CK was applied into cement, the regular anionic polycarboxylate superplasticizer (PCE) is insufficient to disperse the cement-calcined kaolin blended system (CMT-CK system). Herein, a novel amphoteric polycarboxylate superplasticizer (VDA-1) was synthesized with hydroxybutyl vinyl polyoxyethylene ether (VPEG), acrylic acid (AA) and dimethyl diallyl ammonium chloride (DMDAAC) at low temperature (10 °C). Among a series of synthesized PCE samples, VDA-1 (nVPEG:nAA:nDMDAAC = 1:2.25:0.75) exhibits the best performance in the CMT-CK system. Results showed that the fluidity of the CMT-CK mixed slurry with VDA-1 increased by 127.9 % compared with pure CMT-CK slurry. Meanwhile, the mixed slurry with VDA-1 had good flow retention. The great fluidity of the mixed slurry with VDA-1 is attributed to that VDA-1 can be adsorbed on the surface of cement and calcined kaolin, which was demonstrated by total organic carbon (TOC) adsorption amount analysis. Besides, compared with pure CMT-CK system, the compressive and flexural strength of blended cement with VDA-1 was enhanced 2.26% and 10.60%, respectively. Split Hopkinson Pressure Bar (SHPB) test showed that the CMT-CK system containing VDA-1 exhibited large stress value before instability stage and the maximum absorption energy in the whole process.

Non-shrink, self-flowing dry mortar with a compressive strength of over 80 MPa using fine blast furnace slag

Non-shrink self-flowing dry mortar is commonly used in Vietnam to repair hollow, damaged concrete structures, or fill structural gaps. The manufacturing of non-shrink self-flowing mortar requires the use of many different types of additives. In addition, it is difficult to combine them to meet both technical and economic requirements. This article presents the results of research on producing non-shrink self-flowing dry mortar using fine blast furnace slag with a compressive strength after 28 days of over 80MPa. The input materials were all selected in dry powder form. The water/mortar ratio was 0,13. The fine blast furnace slag contents used were 15%, 20%, and 25%, and the powdered polycarboxylate superplasticizer was used at a content of 0.23% compared to the binder. In practice, the amount of water and superplasticizer must be chosen to maintain stability for the workability of dry mortar. The experimental results on flow, compressive strength, flexural tensile strength, and shrinkage show that the non-shrink self-flowing dry mortar meets the requirements of packaged dry mortar.

The synthesis and adsorption-dispersion properties of PPEGMA-PVPA copolymers in cement paste.

This study reports the synthesis of a novel superplasticizer, poly(poly(ethylene glycol)methacrylate)-poly(vinylphosphonic acid) (PPEGMA-PVPA), containing phosphate moieties via solution radical polymerization. By adjusting the feed ratios of monomers, PPEGMA-PVPA copolymers with different phosphate group densities were obtained, and their chemical structure was characterized via FT-IR, 1H NMR spectroscopy and ICP-OES. The results demonstrated that about 70% of the VPA monomer was polymerized. The thermostability of PPEGMA-PVPA was also determined through DSC and TGA. The adsorption-dispersion performance onto cement pastes was investigated using mini-slump test, TOC and zeta potential analysis. It was demonstrated that the adsorption capacity of PPEGMA-PVPA onto cement paste was about 1.4 times stronger than that of the reference polycarboxylate superplasticizer and exhibited excellent adsorption-dispersion performance.

Fine-grained self-sealing concrete for green construction of agro-industrial facilities

The research results reflecting the features of the technology of fine-grained self-sealing concrete with aggregates from construction waste for the green construction of agro-industrial facilities are presented. The effect of the type and dosage of polycarboxylate superplasticisers on the properties of cement compositions and concrete mixtures was evaluated by rheological characteristics. It has been established that the rheological compatibility of the superplasticiser with a specific Portland cement is achieved with a rational dosage of an additive that does not provoke water separation of cement. A joint assessment of the rheological characteristics of concrete mixtures and strength parameters of fine-grained selfcompacting concrete was performed. A filler from construction waste – sand from crushed concrete – was used as an enlarging component of natural very fine sand. The grain content of crushed concrete in the fine aggregate varied from 20 to 40% with an interval of 10%. When determining the spread of a normal concrete cone, a visual assessment of the spreading character of the concrete mixture was performed. It was revealed that the rheological properties of self-sealing mixtures are more influenced by the dosage of the superplasticiser. The strength characteristics of fine-grained concrete at an early and design age depend more on the content of the enlarging component in the composition of the fine aggregate. It has been established that the maximum strength of concrete, provided that a stable non-delaminating mixture is obtained, is achieved with a rational dosage of superplasticiser and a sand content of crushed concrete in an amount of no more than 35%.

Modified high strength lightweight-aggregate concrete based on expanded clay: composition, structure, properties

The study is devoted to the development of increased strength lightweight concrete based on Portland cement modified with a complex organo-siliceous additive containing a polycarboxylate superplasticizer and an active fine-ground siliceous component. The effect of this complex additive on the physical and chemical characteristics of the hydration and structure formation processes was investigated and it was shown that the high kinetics of the strength gain is provided by directional formation of low-basic calcium hydrosilicates, hydrogranates and plazolite, which are crystallo chemically similar to each other, and provide a dense and strength cement stone matrix.
 Modification by a complex additive makes possible to obtain concrete mixes with S4 consistency while a portland cement consumption per 1m3 of not more than 330 kg, with a compressive strength of 55 MPa, watertightness up to W8, frost resistance up to F400, corrosion resistance coefficients Kc in the magnesium sulfate, sodium and ammonium solutions by 10 to 24%. The introduction of a complex additive also helps to reduce the relative shrinkage by 16 ... 19% compared to the control composition, which has a positive effect on the durability of the resulting concrete.

Effects of Sodium Gluconate on the Fluidity and Setting Time of Phosphorus Gypsum-Based Self-Leveling

To comprehensively utilize industrial by-products of gypsum while reducing the consumption of natural river sand, this experiment was conducted to prepare gypsum-based sandless self-leveling (PGSL) materials by using phosphorus-building gypsum (PBG) and portland cement (PC) as gelling raw materials with the addition of polycarboxylate superplasticizer (PCE), cellulose ethers (CE), and retarders. However, employing phosphogypsum as the source material results in a significant 30 min fluidity loss in the gypsum-based self-leveling system. Therefore, to enhance the flow characteristics of gypsum self-leveling, sodium gluconate was chosen for usage in this research. The impact of single and compound mixing of protein-based retarder (PR) and sodium gluconate (SG) on gypsum-based sandless self-leveling materials was evaluated in terms of heat of hydration analysis, pore structure, fluidity, strength, and setting time. According to the experimental findings, it was possible to considerably decrease the fluidity loss of gypsum-based sandless self-leveling materials, postpone the setting time, boost strength, and enhance pore structure when combined with 0.4% SG and 0.03% PR.

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.

Effect of additive compounding on early properties of belite sulfoaluminate cement

Belite sulfoaluminate cement is attracting increasing attention and being considered as a potential alternative to ordinary Portland cement owing to lower preparation temperature and carbon dioxide (CO2) emission. However, it still has disadvantages of poor workability and low early strength. This study investigated the effects of compound polycarboxylate superplasticiser (PCE) and early strength agent, calcium nitrite (Ca(NO2)2), on flowability and early strength of belite calcium sulfoaluminate (BCSA) cement. Variation patterns of setting time, fluidity, strength and polycarboxylate superplasticiser (PCE) adsorption of the paste were measured; the hydration products and microscopic morphology were also analysed by the heat of hydration, X-ray diffraction and scanning electron microscopy. Results showed that calcium nitrite effectively enhanced adsorption of PCE onto the surface of BCSA cement particles, leading to notable improvement in the fluidity of the paste (reaching up to 275 mm). In the initial hydration stage, 0.7% PCE compounded with 1.2% calcium nitrite inhibited the formation of ettringite (AFt), resulting in prolonged setting time. However, it deepened the degree of hydration of BCSA for 3 days and refined the hydration product, AFt crystals. Consequently, the compressive strength was increased to 95.75 MPa and 107.13 MPa for BCSA cement at 3 days and 28 days, respectively.

Synthesis of novel polyelectrolyte sacrifice agents and their effects on the adaptability of polycarboxylate superplasticizer with clay-containing cement paste

Synthesis of novel polyelectrolyte sacrifice agents and their effects on the adaptability of polycarboxylate superplasticizer with clay-containing cement paste

Influence and mechanism analysis of different types of water reducing agents on volume shrinkage of cement mortar

This study investigated the impact of five commonly employed water-reducing agents on the fluidity of cement paste at varying dosages firstly. The agents considered in this research are sodium lignosulfonate (LS), naphthalene superplasticizer (PNS), aliphatic superplasticizer (HSB), and two types of polycarboxylate superplasticizers (PCEs), specifically PCE-5C and PCE-6C. Subsequently, the impact of water reducing agents on both the total drying shrinkage and autogenous shrinkage of cement mortar was investigated. This was done by maintaining a consistent water-cement ratio, ensuring good workability, and adjusting the dosage of various water-reducing agents to achieve comparable slump flow in the mortar. Furthermore, the study delved into the mechanisms behind the influence of different types of water-reducing agents. The findings indicate the following: 1) Polycarboxylate superplasticizers (PCEs) exhibit superior dispersion performance with cement, trailed by naphthalene superplasticizer (PNS) and aliphatic superplasticizer (HSB), while sodium lignosulfonate (LS) demonstrates the least effective dispersion performance. The fluidity of cement paste is most responsive to variations in the dosage of PCEs, followed by PNS and HSB, whereas the fluidity of cement paste undergoes minimal changes when the dosage of LS is increased. 2) The effects of various water reducing agents on the volume shrinkage of cement mortar are distinct, and their influence is the outcome of multiple factors working in tandem. These factors include the postponement of the exothermic peak during cement hydration, reduction in solution surface tension, and decrease in the proportion of larger pores and smaller-sized capillary pores within the porosity of cement-based materials, and all these aspects collectively contribute to minimizing the volume shrinkage of cement-based materials. 3) In the realm of concrete engineering, opting for PCEs as water-reducing agents has proven effective in reducing the overall drying shrinkage of cement-based materials. Notably, PCE-5C demonstrates a superior ability in minimizing shrinkage compared to PCE-6C.

A novel method for enhancing coating performance of emulsified asphalt mortar to RAP in cold recycled mixture

Emulsified asphalt mortar (EAM) is prone to agglomeration and has poor adhesion to reclaimed asphalt pavement material (RAP) with residual-aged asphalt, which can deteriorate the durability of emulsified asphalt cold recycled mixture (EA-CRM). In this work, silane coupling agent (SCA, 3.75 wt% and 6.25 wt% by weight of emulsified asphalt) and polycarboxylate superplasticizer (PCS, 3.75 wt%, 7.5 wt%, and 11.25 wt%) were used to modify the EAM in order to improve the coating performance of EAM on RAP. Seven kinds of samples with different modifier dosages were prepared. Modification mechanism, micro-morphological changes, workability, rheological property, and coating degree of EAM on RAP were investigated. Furthermore, action mechanism of the SCA/PCS composite modifier (SPCM) in EAM/RAP and the cost-benefit were analyzed. Results show that EAM is physically modified by SPCM. Carboxylic group and polyethylene glycol side chain in PCS possess excellent improvement on the workability of EAM, while silanol group generated by hydrolysis of SCA plays a major role in improving coating performance. An appropriate dosage of SPCM can improve the workability of EAM, and enhance its shear deformation resistance and elastic properties. Meanwhile, SPCM can improve the coating degree of EAM on RAP, but SPCM with a PCS dosage exceeding 7.50 wt% can cause EAM to slightly detach from RAP surface. Therefore, 6.25 wt% of SCA and 7.50 wt% of PCS were proposed to modify EAM to obtain the best overall performance. The application of SPCM had a good cost performance and additional environmental benefits based on the optimal dosage. This work provides a novel method to enhance the coating performance of EA-CRM while facilitating the expansion of RAP applications.

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.

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.

On the CO2 footprint of polycarboxylate superplasticizers (PCEs) and its impact on the eco balance of concrete

The global warming potential (GWP) of structurally different MPEG PCEs was investigated considering CO2 emissions from their major raw materials (EO, methacrylic acid, NaOH). An average value of 2250 ± 143 kgCO2–eq/t was found per dry mass, with precast PCEs exhibiting slightly higher GWPs than ready-mix products. Furthermore, the CO2 emission of 40 % PCE admixture is ∼900 kg/t. In OPC based concrete, PCE contributes only negligibly to its GWP, whereas in low carbon “green” binders (PPC, LC3, PSC) PCE contribution becomes noticeable because of higher dosages; yet, PCEs do not impact the environmental attractiveness of these binders.

Effect of the Alkyl Density of Acrylic Acid Ester on the Viscosity-Reducing Effect of Polycarboxylate Superplasticizer.

Concrete is vital for the development of modern buildings. However, they suffer from the high viscosity problem in their application process due to the use of a low water-cement ratio in order to maintain their high strength. Developing PCEs with the presence of ester functional groups in their molecular structure is one of the most effective measures to improve the flowability of concrete. Here, three PCEs with different alkyl densities of acrylic acid ester: PCE-M, PCE-E, and PCE-B were designed to explore their viscosity-reducing effect on the performance of cement and concrete. The structures of the three PCEs were characterized via Fourier transform infrared (FTIR) spectra, proton nuclear magnetic resonance (1H NMR), and gel permeation chromatography (GPC). Their properties were also determined via zeta potential, surface tension, and rheological experiments. It was found that PCE-M had the best performance, with the lowest surface tension, highest zeta potential, and therefore highest charge density on the cement particles, lowest viscosity, and highest flowability of cement paste, and exhibited the best performance of concrete in terms of workability. The best performance of PCE-M in reducing the viscosity of cement and concrete can be ascribed to the smallest amount of water-repellent alkyl groups, enhancing the electrostatic repulsion and reducing the viscosity, thereby boosting the dispersion and stabilization of cement pastes and concrete. This study shed lights on designing other PCEs with high viscosity-reducing effects via an ester group control.

The Effects of Silica Fume and Superplasticizer Type on the Properties and Microstructure of Reactive Powder Concrete.

This paper deals with the optimization of reactive powder concrete mixtures with respect to the addition of silica fume and the type of polycarboxylate superplasticizer used. First, the properties of reactive powder concrete with eight different commercial polycarboxylate superplasticizers were tested in terms of workability, specific weight, and mechanical properties. It was found that different commercially available superplasticizers had significant effects on the slump flow, specific weight, and compressive and flexural strengths. The optimal superplasticizer (BASF ACE430) was selected for further experiments in order to evaluate the influences of silica fume and superplasticizer content on the same material properties. The results showed that the silica fume and superplasticizer content had considerable effects on the mini-cone slump flow value, specific weight, flexural and compressive strengths, and microstructure. There were clearly visible trends and local minima and maxima of the measured properties. The optimal reactive powder concrete mixture had a composition of 3.5-4.0% superplasticizer and 15-25% silica fume.

Value-added utilization of ultrafine ferronickel slag as a novel type of high-quality mineral admixture: A feasibility study

In this study, a novel type of high-quality mineral admixture, ultrafine ferronickel slag, is manufactured and designed, and the feasibility of its utilization in cement and concrete is systematically investigated. It was found that after mechanical grinding, ultrafine ferronickel slag can be used as a novel and special high-quality mineral admixture, which improves the microstructures and properties of concrete in an efficient way. Ultrafine ferronickel slag shows little adverse effect on the early-age strength, and effectively increases the later-age strength of concrete. It improves the resistance to chloride ion penetration and the resistance to sulfate attack of concrete. It also reduces the total porosity and refines the pore in concrete. With the increase of ultrafine ferronickel slag content, the proportion of large pores with diameters more than 100 nm decreases, and the proportion of pores with diameters less than 100 nm increases significantly, especially for the small pore with diameters less than 10 nm. In addition, ultrafine ferronickel slag presents good compatibility with polycarboxylate superplasticizer and significantly produces a pozzolanic reaction consuming portlandite. This study provides a new way for the value-added utilization of ferronickel slag and promotes the sustainable development of high-quality active mineral admixture in alternative binder design.