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Characterization on Molecular Structure of Polycarboxylate Superplasticizer and Its Interaction with Cementitious Components

Author: JiYaJun
Tutor: WeiJiangXiong
School: South China University of Technology
Course: Materials Science
Keywords: Polycarboxylate Adsorption Supplementary cementitious material Rheology
CLC: TU528.042.2
Type: Master's thesis
Year: 2011
Downloads: 447
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Abstract

Superplasticizer has a high water reduction and excellent control of slump loss, etc., especially in environmental protection, and the molecular structure can be regulated, has become an important future direction of development of concrete superplasticizer, in modern concrete works Applications are also increasingly popular. With the development of modern concrete technology, auxiliary cementitious material in concrete applications are increasingly widespread, and a wide range of dosage increase. Ensuing in the concrete mix compatibility of various materials caused by the early work of concrete gradually highlight issues, especially a variety of gelling components and the compatibility of additives. Concrete at Early poor mobility, setting and hardening is not normal, superplasticizer gradually increased over doping issues. Although existing research has begun to pay attention admixtures and cement-based materials compatibility between the problem and the problem for a number of studies carried out, but due to the practical application of the molecular structure of admixtures for businesses confidential, and difficult to characterize, causing people to admixture with cement-based materials compatibility issues research, mainly from the perspective of hydration of cement admixtures to understand, process compatibility is the main method by replacing the additive type and use some retarding component to adjustment, while the additive molecular structure and bonding component matching relationship between lack of deep understanding. Therefore, the paper focuses on the molecular structure of polycarboxylate Characterization and supporting two aspects of the interaction cementitious materials research, in order to grasp the molecular structure of polycarboxylate superplasticizer admixture with different types of cementitious component interaction between the basic law and to guide the molecular structure of polycarboxylate regulation and optimization of concrete mix design. Infrared spectroscopy (IR), gel permeation chromatography (GPC) and nuclear magnetic resonance (NMR) their own advantages, determined by IR Polycarboxylate the basic molecular structure of a group, GPC to determine the molecular weight and distribution of the molecular structure, NMR determine the molecular structure of the relative proportions of groups. Integrated data three test methods, analysis and characterization proposed polycarboxylate molecular structure. Using the method designed by the molecular structure Polycarboxylate analyzed data obtained basically consistent with the synthetic polycarboxylate molecular structure conformation. By radical copolymerization method, carboxyl group is introduced in the molecular structure, a sulfonic acid group and PEO long side, synthesis of functional polycarboxylate. Examines the proportion of monomer, initiator and adding the amount of added time of synthesis conditions on polycarboxylate molecular structure. The results show that the molecular structure of superplasticizer can be designed and strong, with various groups as well as the overall structure of the molecular weight control determines the types of performance polycarboxylate. Studied with different molecular structural features Polycarboxylate cement hydration process based cementitious material impact, as well as cementitious material in the adsorption of different dispersion behavior; various cementitious materials on polycarboxylate superplasticizer adsorption capacity size relationship: cement gt; fly ash gt; slag, supporting the incorporation of cementitious materials can reduce the saturation point of polycarboxylate; through the slurry rheological behavior study found that slag slurry at a very low dosage of superplasticizer under changed greatly, easily lead to bleeding, and fly ash cement paste with good compatibility, according to the initial cement paste simulated pore solution of complementary cementitious materials slurry on the adsorption behavior of polycarboxylate study to clarify the application of the admixture appeared doped such problems.

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CLC: > Industrial Technology > Building Science > Building Materials > Non-metallic materials > Concrete and concrete products > General issues > Raw materials and auxiliary materials > Admixtures > Superplasticizer
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