A cement accelerator is an additive for use in concrete, mortar (construction mortar), plaster or screeds. La adición de un acelerador acelera el tiempo de fraguado y, por lo tanto, el tiempo de curado "Reticulación (química)") comienza antes.[1]​ Esto permite colocar hormigón en invierno con un riesgo reducido de daños por heladas.[2]​ El concreto se daña si no alcanza una resistencia de 500 libras por pulgada cuadrada (3,4 MPa) antes de congelar.[3]​.

Typical chemicals used today for acceleration are calcium nitrate (Ca(NO)), calcium nitrite (Ca(NO)), calcium formate (Ca(HCOO)), and aluminum compounds. Calcium chloride (CaCl) is the most effective and economical accelerator and was formerly very popular. However, chloride anions are very corrosive to the steel (pitting corrosion) of rebar. (rebars), so its use is no longer recommended[4]​ and, in many countries, it is prohibited. As local corrosion of a reinforcing bar can cause it to break, it can compromise the tensile strength of reinforced concrete and therefore the structural stability of a building. Thiocyanate compounds can also corrode reinforcement, but are safe at recommended doses. Sodium compounds could compromise long-term compressive strength[5]​ if used with alkali-reactive aggregates.[3]​.

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