Blast Furnace Slag addition effects on Delayed Ettringite Formation in heat-cured mortars

Reducing expansion due to Delayed Ettringite Formation (DEF) is becoming an important issue that must be taken into account, when producing heat-cured concrete. Mineral additives used as partial cement replacement should help in achieving the desired aspect. Based on an ongoing experimental program, this research emphasizes on the effect of Blast Furnace Slag (BFS) on the expansion of cement mortars caused by DEF. For this purpose, mortar prisms in which Portland cement was replaced by BFS, with three different replacement levels (10,20 and 40%) and two finenesses degree (400 and 500 m2/kg) were tested in length change, dynamic elasticity modulus and compressive strength over more than 750 days. Results showed that the efficiency of blast furnace slag in controlling expansion related to DEF was conditioned by its levels of replacement.