Performance enhancement and mechanism of pregelatinized starch–binding gypsum at high water–gypsum ratios

•A pregelatinized starch-binding gypsum was prepared to mimic the historic binders.•The gypsum strength is enhanced by pregelatinized starch-binding gypsum structure at high w/c ratios.•The contact points stress enhancement promotes macro strength enhancement.•Hydrogen bonding plays a key role in constructing the pregelatinized starch–binding gypsum structures.