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

Abstract

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.

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

“…A considerable amount of research has been conducted to develop highperformance PCEs with different backbones, different side chain lengths, and different functional groups in order to improve the fluidity and high strength of concrete at low water to cement ratios during its application process [6][7][8][9][10][11][12][13]. The ester functional group in PCEs has been reported to have various functions when they are applied in concrete, such as slump retention, retardation, and viscosity reduction [14][15][16][17]. For example, the slump-protecting PCE was synthesized via the copolymerization reaction of poly(ethylene glycol) methyl ether methacrylate, acrylic acid (AA), and ester or amide groups by Lin's group, which not only improves the dispersion performance but also has an excellent slump-protecting effect [6].…”

“…It was found that PCEs prepared using esters have better performance than those synthesized using amides. Therefore, they also used trimethylolpropane triacrylate and trimethylolpropane ethoxylate triacrylate to prepare four PCEs containing ester groups [15]. They concluded that PCEs with higher ethoxy group contents exhibited better workability.…”

Polycarboxylate-based superplasticizer with added silica sub-microspheres for use in Portland cement materials

“…PCE superplasticizers were used to modify the surface of the sand in the preparation of the cement mortar and increased its compressive strength at 7 and 28 days of age (Noaman et al, 2020). Cement pastes treated with polycarboxylate synthesized with ester-based had better behaviour of dispersibility, fluidity retention and viscosity than those treated with polycarboxylate with amide-based (Lin et al, 2021). PCE copolymers based on isoprenyl ether, vinyl, allyl, and methacrylate macromonomers were synthesized and it was found that those with higher hydrophilic-lipophilic balance (HLB) values significantly reduced the plastic viscosity of mortars and concretes and low water-to-cement ratios.…”