Biopolymers with viscosity-enhancing properties for concrete

Viscosity-enhancing admixtures (VEAs) derived from biological sources are polymers that have a high-molecular-weight, are water soluble, or form colloidal dispersions, and are used to increase the viscosity and cohesion of cement-based materials for the construction industry. Various types of concrete such as underwater, pumped, sprayed, and especially highly fluid materials such as self-consolidating concrete depend on the use of VEAs. The main biopolymers are cellulose derivatives and microbial polysaccharides. Other alternatives are plant gums and mucilage, which are low-cost renewable sources of VEAs for concrete technology applications. This chapter presents the chemical structure, modes of action, rheological properties, and influence on cement hydration of biopolymers commonly used as VEAs, as well as those with potential for future use as VEAs.