Synthesis and characterization of a polycarboxylate superplasticizer modified by sodium hypophosphite

Abstract

A sodium hypophosphite (SHP) modified polycarboxylatesuperplasticizer (P-PCE) was synthesized successfully and the synthesis parameters were optimized through orthogonal experiment. Gel permeation chromatography (GPC), X-ray photoelectron spectroscopy (XPS), 31 P magic spinning nuclear magnetic resonance ( 31 P MAS NMR) spectroscopy and elemental analysis measurements were used to characterize the molecular structure of P-PCE. Effects of P-PCE on the dispersing performance of cement paste were systematically investigated via mini slump test. The results showed that P-PCE exhibited superior dispersing performance, more retarding hydration effect and better sulfate and clay tolerance than conventional PCE (C-PCE).Results showed that the maximum flow of cement paste could reach up to 305 mm, while that of the C-PCE was 285 mm.The maximum variation of adsorption of P-PCE was 9% and 15% in the presence of sulfate and clay, whereas that of C-PCE was 15% and 25%, respectively, leading to better sulfate and clay tolerance. These significant advantages could be ascribed to the high anion density and high calcium complexing capacity induced by introducingphosphinate group and phosphonate group into the molecular structure of P-PCE. The as-synthesized P-PCE can be used as a kind of high performance superplasticizer in concrete engineering.

Synthesis and Properties of a New Clay-resistant Polycarboxylic Acid Water Reducer Research

“…However, the current machine-made sand on the market often has the problem of unstable clay content. A large number of scholars at home and abroad have studied the effect of clay on the performance of the polycarboxylic acid water reducer (PCE) and found that the layered structure of clay easily makes the conventional PCE fail due to intercalation and adsorption into the layered structure of clay [4][5][6]. It is of great significance to develop a clay-resistant polycarboxylic acid water reducer that is not easily adsorbed to the layered structure of clay.…”