Abstract: The loss rate of hardness of sand material is an important index of evaluating concrete durability. The manufactured sand for the dam concrete of Jinping-I hydropower station is made from Santan marble which caused disputes over the hardness test results among construction participants. The proprietor,test center,and supervision institutions have organized many comparative tests on this issue since the concrete pouring. By comprehensive analysis and summary,the Guidebook of Hardness Test Inspection for Santan Marble Manufactured Sand is formulated. By complying with the criteria,the hardness inspection results are consistent. This research has achieved practical effect.

Key words: marble, manufactured sand, hardness loss rate, comparative test, comprehensive analysis