Polymer Physics and Modeling of Polycarboxylaye-Based Superplasticizers in Concrete

Wang, Y. (Speaker)

Activity: Talk or presentationInvited talk

Description

Superplasticizers, also referred to as high-range water reducing admixtures (HRWRAs), are used to optimize the workability of fresh concrete without adding excess water. These molecules disperse the cement particles by altering their attractive forces with steric and/or electrostatic repulsions. In recent years, polycarboxylate-based (often abbreviated as PCE) superplasticizers have established themselves as crucial ingredients in modern concrete technology for greatly improving workability, strength, and durability of cement-based materials. From the point of view of polymer chemistry and physics, PCEs are comb-shaped copolymer polyelectrolytes, possessing a linear anionic backbone and charge-neutral side chains. The key to the success of PCE superplasticizers is that they can have a broad range of possible molecular structures. Structural variations can be placed on the length and monomer constituents of the polymer backbone and the side chains, grafting density of the side chains, distribution of the side chains along the backbone, as well as the linkage groups between the backbone and the side chains. Molecular structure greatly affects the performance of PCEs, and tailing molecular structures of PCEs enables the development of superplasticizers with optimized and cost-effective properties for a broad range of applications. However, achieving the optimal performance requires exploiting the many degrees of freedom in PCE structures and polymerization conditions, accompanied by numerous performance testing (e.g. in cement paste, mortar, and concrete conditions), which makes the traditional product development approach by trial-and-error both time-consuming and expensive. To overcome such challenges, it is necessary to establish the structure-property relations of PCE superplasticizers through integrations of experimental, theoretical, and computational approaches. In recent years the PCE community has devoted a massive effort to research in this direction. Many carefully designed and executed experiments have been reported; both polymer physics and computer modeling are getting increasingly involved not only in academia but also in the chemical admixture industry. This report presents a brief summary of those research activities. Emphasis will be placed on results from our on-going research work, including analytical theory, atomistic simulation, and coarse-grained modeling of PCE conformations in aqueous solution and at liquid/solid interfaces and their adsorption properties.
PeriodNov 2020
Event title14th International Seminar on Polymer Science and Technology (ISPST)
Event typeSeminar
LocationTehran, Iran, Islamic Republic of
Degree of RecognitionInternational