SusChEM: Development of Polymer-grafted Lignin Superplasticizers

Carnegie Mellon University, Pittsburgh PA

Investigators

Abstract

CBET - 1510600 PI: Washburn, Newell R. Hydraulic cement is a major contributor to global carbon dioxide emissions into the atmosphere. Low carbon dioxide cements are available but not widely used, because they are difficult to process. This project will develop a new superplasticizer that can be added to low-carbon dioxide hydraulic cement to improve the cement's processing characteristics while reducing carbon dioxide emissions. The new superplasticizer will be formulated using a process developed by the PI in which synthetic polymers are grafted onto lignin, a biopolymer derived from plants. Use of the new superplasticizer could reduce water use and improve the performance of low-carbon dioxide cements, both of which would reduce the environmental impact of construction. The project will test the hypothesis that the complexity of lignin chemistry will enable the superplasticizer to adsorb onto a broad range of low-carbon dioxide cements. The project will identify chemistry-structure-property relationships governing the dispersant properties of polymer-grafted lignin in tuning the rheological properties of cementitious suspensions. The project will compare lignin chemistries and grafting variables to determine how they affect aqueous suspension properties, examine the adsorption of polymer-grafted lignin on cement particles as a function of grafting variables and charge, and establish effects of polymer-grafted lignin on the hydration of low-carbon dioxide cements and the formation of high-strength cement phases.