Yīshēng yòng shúshígāo gěi tā dǎ le shígāo bēngdài.
The doctor used plaster of Paris to put a cast on him.
Tips
usage
熟 ('cooked / processed') marks it as the heat-treated form, contrasting with 生石膏 ('raw gypsum'). The 生/熟 distinction shows up across Chinese material vocabulary: 生铁 vs 熟铁, 生肉 vs 熟肉.