Synthesis and characterization of a PAMAM dendrimer‐based superplasticizer and its effect on the properties in cementitious system

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In order to investigate the effect of double bond content in the crosslinkers on the performance of superplasticizers, three different crosslinked polycarboxylate superplasticizers were synthesized herein with various respective crosslinkers. Their impacts on the fluidity, absorption, and hydration behavior of cement systems were studied. The results showed that the polymer, which was synthesized using a crosslinker with four double bonds and five/six double bonds, had higher fluidity and the highest fluidity reached up to 395 mm at W/C of 0.35. Additionally, thermogravimetric analysis and hydration heat tests showed that the crosslinked polycarboxylate superplasticizers could prolong the hydration process of cement slurries. Among these three kinds of crosslinked polycarboxylate superplasticizers, the induction period of cement slurry containing the polymer with crosslinker of four double bonds was significantly extended to facilitate the processing of the concrete. The purpose of this study is to provide strategies for studying high-performance polycarboxylate superplasticizers with novel topological structure.

Section: Resultsmentioning

confidence: 50%

Section: Fluidity and Retention Performancementioning

confidence: 92%

Section: Introductionmentioning

confidence: 99%

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Effect of crosslinked polycarboxylate superplasticizers with varied structures on cement dispersion performance

Lin

Liao

et al. 2020

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“…In addition, the ester groups in the core were hydrolyzed and the carboxylate anion was slowly released, which also played a small part in improving the dispersibility and retarding effect. Zhao et al 29 synthesized a dendrimer core via a Michael addition reaction between methyl acrylate and ethylenediamine, and then copolymerized this core with other monomers to form a branched polycarboxylate superplasticizer. This divergent structure promoted the adsorption of this superplasticizer onto cement particles in comparison with that achieved with common superplasticizers, and thus provided a better dispersion performance.…”

Section: Introductionmentioning

confidence: 99%

Effects of crosslinked polycarboxylate superplasticizers with crosslinking agent containing ester and amide groups on the properties of cementitious systems

Lin

Pang

Wei

et al. 2021

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Herein, crosslinked polycarboxylate superplasticizers were synthesized using acrylic acid, sodium methylallyl sulfonate and methyl polyethylene glycol acrylate as monomers, and monomers that contain either ester or amide groups as crosslinking agents. The superplasticizers that were synthesized from the ester-and amide-based crosslinking agents were respectively denoted as SP-E and SP-N. In addition, a series of performance characterizations were carried out to explore the influence of different functional groups in crosslinking agents on the performance of superplasticizers. Fluidity test results showed that the dispersibility and fluidity retention of cement pastes treated with the SP-E were better than those of cement pastes treated with SP-N. Meanwhile, the viscosity of the sample containing SP-E was lower than that containing SP-N. In addition, the amount of the two superplasticizers that had become adsorbed onto the surfaces of cement particles also differed, and in this case the adsorption capacity of SP-E was greater than that of SP-N. X-ray diffraction, thermogravimetric analysis, and scanning electron microscopy tests showed that the ester-group based SP-E superplasticizers promoted cement hydration to a greater degree than that was achieved with their amide-bearing SP-N counterparts. This study would provide valuable insight for the development of crosslinked polycarboxylate superplasticizers.

“…In recent decades, polycarboxylate superplasticizer (PCE) has been widely used in high‐performance concrete field on account of the unique properties such as low dosage, nonpollution in production process, and excellent dispersion of cement particles which can obtain higher workability concrete system by using less water. Moreover, the PCE shows flexible designability in molecule structure, thus multifunctional PCE can be obtained via adjusting molecule structure to meet application requirements in construction industry. The PCE has unparallel advantages in improving concrete performances compared to traditional water reducer such as naphthalene sulfonate and melamine sulfonate.…”

Section: Introductionmentioning

confidence: 99%

Synthesis and characterization of a novel early‐strength polycarboxylate superplasticizer and its performances in cementitious system

Xia

Zhou

Ni³

et al. 2020

A novel early-strength type polycarboxylate superplasticizer (PCE) was synthesized by a new design of molecule structure such as introducing long polyoxyethlene side chains, functional monomer (2-acrylamide-2-methylpropanesulfonic acid), and optimizing monomer composition. In this study, with introducing the sulfonate groups into PCE structure, its dispersion capacity and the absorbed amount are increased firstly and then decreased, but the retardation hydration effect is weakened gradually. The molecular weight, adsorbed amount, and dispersion capacity of PCEs firstly increased and then decreased with increasing the AA/TPEG monomer molar ratio, and the same trend as the compressive strength harden concrete with PCEs at the age of 1, 3, and 28 days. The early-strength type PCE exhibits good dispersive capacity and weak retardation hydration effect in cementitious system, and the early age strength of concrete with addition of early-strength type PCE develops quickly. This study indicates that reasonable design of PCE molecule structure and synthesis method can obtain a novel early-strength type PCE which makes a good balance between workability and fast development of early age strength in cementitious system.