Synthesis and characterization of pregelatinized starch modified C-S-H: Inspired by the historic binders

Abstract

• A pregelatinized starch modified C-S-H were prepared to mimic the historic binders. • The modification of pregelatinized starch on C-S-H is dependent on the Ca/Si ratio. • Some pregelatinized starch/C-S-H shows a special stacking nanostructure similar to shells. • Pregelatinized starch have the potential of healing the defects of C-S-H silicate chains. • Pregelatinized starch affect the percentage of stacking units and the nanomechanical properties. The historic starch-lime mixtures are characterized by the hybrid of organic substance and inorganic materials. Inspired by the features of historic binders, this paper presents a novel method by introducing the pregelatinized corn-starch into the stacking of C-S-H nanoparticles. The nanostructure and mechanical properties of the modified C-S-H were evaluated. The results show that the pregelatinized starch interacts with the C-S-H through hydrogen bonding and change the C-S-H silicates chains. The Ca/Si ratios highly determines the crystalline nanostructure and elastic modulus of pregelatinized starch/C-S-H particles. When the Ca/Si is 0.83 and the addition of pregelatinized starch is 0.1%, the pregelatinized starch/C-S-H particles shows a “shells” morphology, in which the rod-like C-S-H stacking with the pregelatinized starch as the “binder”. The pregelatinized starch also affects the percentage of stacking units with different nanomechanical property. This paper provides theorical and basic data for creating new green cementitious materials.