Enhanced slump retention using polycarboxylate superplasticizers obtained by micro-crosslinking reaction

Abstract

In this paper, a facile method was adopted to synthesize polycarboxylate (PC) superplasticizers which rendered excellent initial fluidity and workability of mortar in 1 hour. Micro-crosslinking was introduced in the PC molecules and the ester groups in crosslinker can form carboxyl groups in the hydration solution of cement. The micro-crosslinked PC (MPC) superplasticizer was synthesized from butenyl alkylenepolyoxyethylene-polyoxypropylene ether, sodium methacrylate, acrylic acid with trimethylolpropane triacrylate (TMPTA) as the crosslinker in water medium. The effect of monomer content and the dosage of crosslinker on the performance of MPC were studied. Fourier transform infrared spectroscopy and dynamic light scattering analyses were conducted to characterize the molecular structure of MPC. The fluidity of mortar in 1 hour was tested to study the fluidity and the retention in fluidity of mortar with the presence of MPC, indicating that micro-crosslinking with trifunctional crosslinker TMPTA was an effective way to improve the fluidity retention without sacrificing the initial fluidity. Investigations on early hydration of cement with MPCs were performed using XRD and TGA. Results showed that the addition of MPCs can slightly improve the degree of early hydration.

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

“…Their results showed that the fluidity of this crosslinked superplasticizer diminished from its original value by only ~10 mm in 2 h, while the spread of a common polycarboxylate superplasticizer diminished by nearly 50 mm during the same duration, which demonstrated that the crosslinked superplasticizer had a superb slump retention effect. In addition, a similar result was also obtained by Cai et al, 20 they found that a crosslinked polycarboxylate superplasticizer could effectively improve the fluidity of mortar and maintain its fluidity as well.…”

“…13,14 In practice, COO À ions are usually introduced as the anionic groups in polycarboxylate superplasticizers. [15][16][17][18] Crosslinked superplasticizers are a new type of water reducing agent, 6,[19][20][21] which have attracted the attention of researchers and have been in increasing demand for industrial applications. These superplasticizers are usually obtained via the copolymerization of crosslinkers, anionic acrylates that act as monomers, and polyethers that provide long side-chains.…”

Advances in Organic Rheology-Modifiers (Chemical Admixtures) and Their Effects on the Rheological Properties of Cement-Based Materials

“…At a fixed molecular weight, the surface-occupied area became smaller for star-shaped PCEs with an increase in arm numbers, resulting in an increase in the adsorption free energy. In addition, many papers have reported cross-linked PCEs with different cross-linking monomers [142][143][144][145][146][147] with varied numbers of double bonds. Some reports have shown that slight cross-linking can improve the adsorption and thus the initial flowability of cement paste.…”

Influence of Pentaerythritol Tetraacrylate Crosslinker on Polycarboxylate Superplasticizer Performance in Cementitious System

“…Etsuo et al controlled slump loss by introducing the diethylene glycol diacrylate as a crosslinking agent in PC copolymers [15]. Cai et al found that a crosslinked polycarboxylate superplasticizer could effectively improve the fluidity of mortar and maintain its fluidity as well [16]. Liu et al reported the synthesis of the CLPCs.…”