Synthesis of polycarboxylate superplasticizer modified by β‐cyclodextrin for possessing clay tolerance

Abstract

Polycarboxylate superplasticizer (PCE) is widely used in concrete, but the clay content in the aggregate is increasing at present, which seriously weakens the dispersing function of PCE. Therefore, in order to lower the sensitivity of PCE to the clay, β‐cyclodextrin (β‐CD) was used for synthesizing anti‐clay polycarboxylate superplasticizers (AC‐PCE). Firstly, the clay tolerance property of AC‐PCE was explored by the fluidity and rheological test; then, the PCE was mixed with montmorillonite (MMT), and interaction mechanism was studied. The results showed that compared with the conventional polycarboxylate superplasticizer (CO‐PCE), an increase of 19.5% and 14.9% was observed in the fluidity of cement paste and mortar for AC‐PCE, indicating that the sensitivity of AC‐PCE to the clay was lower than that of CO‐PCE. Both CO‐PCE and AC‐PCE were adsorpted on MMT. XRD results showed that intercalation adsorption had occurred for both CO‐PCE and AC‐PCE. N2 adsorption results showed that although AC‐PCE was also inserted into the interlayer of MMT, its adsorption amount was lower than that of CO‐PCE due to steric hindrance from β‐CD, which increased the sorption level of the AC‐PCE on the cement clinkers particles. Therefore, the clay tolerance of PCE was enhanced significantly by β‐CD.

Study on the dispersion performance and mechanism of polycarboxylate superplasticizer by the long side‐chain dicarboxyl terminated

“…In addition, the characteristic peaks of double-bonded carbons (C2 and C3) were observed to disappear in the 13 C NMR spectra of PCE-B and PCETA, indicating that the monomers were polymerized and the PCE was synthesized. 39,40 Molecular properties of the synthesized PCEs were measured using the GPC. Figure 3 shows the GPC spectrum of PCETA-4000, and Table 2 shows the molecular parameters of 4 kinds of PCEs prepared after optimizing the acid-ether ratio.…”

DFT study on the polyol sacrificial agents for improved clay tolerance of polycarboxylate superplasticizers

“…By establishing the adsorption models for non-ionic sacrificial agents with clay minerals and hydration products, the anti-clay performance and mechanism of different sacrificial agents will be explored from the perspective of adsorption energy, further investigating the influence of the interlayer spacing of montmorillonite on the competitive adsorption performance. This research would also help in the structural design of sacrificial agents, achieving the controllable regulation of the anti-clay performance based on the molecular structure differences for the sacrificial agent (Du, 2019;Qiu, 2021;Li et al, 2022;Tan et al, 2017).…”

Synthesis and properties of multi‐armed polycarboxylate superplasticizer modified by β‐cyclodextrin

“…16 β-CD and its derivatives have been widely combined into dendrimer, block or star copolymers, which can better interact with cement particles and other additives to form a stable dispersion system and improve the water reduction effect of concrete. 17,18 Therefore, it is worthwhile to study the introduction of β-CD into the molecular structure design of PCE.…”