SGM PLBHCGP 60 lb Instant Hydraulic Cement Gray 36 per Pallet. SGM Instant Hydraulic Cement is a mixture of Portland cement and special additives that permits underwater patching and general concrete repair work to be done instantly. It can be used wherever a quick setting caulking or plugging material is needed. To use, mix approximately three (3) parts SGM Instant Hydraulic Cement to one (1) part water or until the material becomes a dough-like consistency.