Synthesis and Properties of a Starch‐based Clay Tolerance Sacrificial Agent. (8th March 2021)

• Record Type: Journal Article
• Authors: Li, Bin; Gao, Ruijun; Wang, Ling
• Is Part Of: Stärke. Volume 73:Number 5/6(2021)
• Page Start: n/a
• Page End: n/a
• Publication Date: 2021-03-08
• Subjects: adsorption -- clays -- MMT‐containing cement paste -- steric effects -- sulfonated starch; Starch -- Periodicals; 572.566
• DOI: 10.1002/star.202000223
• Languages: English
• ISSNs: 0038-9056

Abstract

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 ( τ 0 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. Abstract : In this study, a novel type of clay‐tolerance sacrificial agent (SSB) is synthesized using starch, with the addition of SSB, the fluidity of MMT‐containing cement paste increased significantly. This innovation not only developed a new way to improve the compatibility between PCE and clay, promoting the development of cement admixture but also exploited new applications of starch in the field of construction materials.