Novel designs of polycarboxylate superplasticizers for improving resistance in clay-contaminated concrete

• DOI: 10.1016/j.jiec.2017.06.031
• Publication Date: 2017-06-27T17:46:05Z
• Authors: Xiao Liu; Jianan Guan; Guanghong Lai; Yunsheng Zheng; Ziming Wang; Suping Cui; Mingzhang Lan; Huiqun Li
• Keywords: Superplasticizer

Abstract Certain clays attached around the aggregates contaminate the concrete and also greatly affect the concrete workability, the mechanism of which was investigated through calculating the volume change of solid and liquid phases of concrete mixture containing clay. To minimize this detrimental effect, two novel designs based on the transfer of theory and techniques from polymer science, i.e., molecular design of polycarboxylate superplasticizer (PCE), were proposed. The one was “intercalator” synthesized via Hofmann rearrangement and cationization, and the other was “star-shaped polycarboxylate superplasticizer (SPCE)” synthesized via a route of “core first and arm second”. The results of Infrared Spectroscopy (IR) and 1 H Nuclear Magnetic Resonance ( 1 H NMR) confirm the designed structures. The applications of these polymers in clay-contaminated cement paste and concrete were tested. The results showed that, the dispersing capacities of “Intercalator + Comb-shaped polycarboxylate superplasticizer (CPCE)” and SPCE were less affected by adding clay in both cement paste and concrete. Adsorption and X-ray diffraction (XRD) experiments revealed less harmful intercalation for SPCE and preferential occupation in the interlayer space of clay for intercalator to protect other workable PCEs. It is interesting that optimizing charge characteristic and “disassembling-assembling” molecular arrangement can contribute to excellent resistance towards clay. The aim of this study is to offer two promising alternatives, which attractively provide the theoretical basis and technological application in researching advanced materials in clay-contaminated concrete.