A cement system for use in treating lost circulation includes a slurry of cement, water and a super-absorbent polymer which absorbs free water in the slurry to form a gel - ore preferably a solid-like structure - when placed in the well, and which releases the absorbed water to the cement hydration reaction as the cement sets. The absorption of water causes the slurry to develop a solid-like structure. In one embodiment, the superabsorbent is polyacrylamide or modified crosslinked poly(meth)acrylate. Also presented is a method of treating lost circulation by pumping the above-mentioned cement system.