Synthesis and Properties of a Starch‐based Clay Tolerance Sacrificial Agent

Abstract

For improving the workability of clay‐containing cement paste superplasticized by polycarboxylate ether (PCE), a new starch‐based sacrificial agent is synthesized in the following two steps: first, the starch is sulfonated to obtain sulfonated starch (SS) with a strong steric effect, which is verified through its dispersion performance; then, SS is quaternized to obtain starch‐based sacrificial agent (SSB). The structure of SSB is characterized by FT‐IR and element analysis. Montmorillonite (MMT), as the most detrimental clay, strongly perturbs the dispersing power of conventional PCE. Therefore, the MMT‐tolerance property of SSB is tested. With the addition of 0.02 wt.% SSB, the fluidity of MMT‐containing cement paste is increased from 191.5 to 222 mm and the rheological property of MMT‐containing cement paste is improved by reducing the yield stress and the flow index (τ0 and n in Herschel‐Bulkley model). Adsorption experiments, DLS, and XRD are used for explaining SSB's clay‐tolerance mechanism. Adsorption experiments show that the cationic group enhanced the interaction between MMT and SSB; DLS and XRD demonstrated that SSB is adsorbed on MMT through electrostatic attraction and could hinder the interaction between PCE and MMT by its high steric effect.

Synergistic Effect of Polycarboxylate Superplasticiser and Protein Retarders in Cementitious Materials Containing Na- Montmorillonite: Effect of Addition Methods

“…As shown in the figure, regardless of the addition method, the higher substitution ratio led to the thinner thickness of adsorption of the PCE. This result was similar to Li’s results—that the thickness of adsorption layer increased with increasing Mmt content [ 67 ], which could be due to trapping the side chain of the PCEs within the interlayer of Mmt, leading to the suppressed steric repulsion of PCE [ 52 ]. However, it is not surprising that when the separate addition method is applied, the thickness of the adsorption layer is further increased, with thickest layer being observed by DA.…”

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

“…Modifying the molecular structure of PCE or compounding sacrificial agents can effectively improve the tolerance to clay minerals (Rana et al, 2019;Du, 2019;Liu, et al 2017;Qiu, 2021). Among these methods, structural modification of the PCE molecules can enhance the dispersion performance by changing the shape of PEO (polyethylene oxide) side chains and introducing functional groups, further improving the adaptability between the superplasticizers and clay (Quainoonet al, 2021;Qi et al, 2020;Li et al, 2021;. Fang (2022) synthesized a side chain hyperbranched polycarboxylate superplasticizer, breaking the traditional comb structure of the PCEs.…”