Setting Time
The time it takes cement paste to lose plasticity and harden. Measured as Initial Set (start of stiffening) and Final Set (no longer deformable).
Initial set must be ≥30 minutes for OPC; final set ≤600 minutes (IS 4031). Setting is controlled by gypsum content and influenced by temperature, water content, and admixtures.\n\nIn hot weather, setting accelerates — retarders may be required.
The chemical reaction between cement and water that produces hardened cementitious paste. Hydration generates heat and the binding C-S-H gel that gives concrete its strength.
The point at which cement paste begins to stiffen and lose plasticity. Marks the end of the workable period.
The point at which cement paste has fully hardened and can resist a defined indentation. After this, no further finishing or remixing is possible.
An admixture that delays the initial setting of concrete. Used in hot weather, long hauls, or large pours to extend the workability window.