To simulate the early age behavior of concrete structures composed of young concrete, a finite element analysis (FEA) was implemented with the hydration based microplane model. Structural behaviors were investigated with concrete age for a massive concrete wall and slab. From FEA, it was found that surface cracking at early age occurred via different crack driving mechanisms. In the case of combined hydration heat and shrinkage, later surface cracking was produced by differential drying shrinkage. A numerical analysis performed with the hydration based microplane model successfully simulated the typical cracking patterns due to edge restraint in the concrete slab. (C) 2009 Elsevier Ltd. All rights reserved.