Modeling of early age behavior of blast furnace slag concrete based on micro-physical properties

A multi-scale system called DuCOM was enhanced to model behaviors of blast furnace slag (BFS) concrete. Tests on the strength and micro–hygro–physical properties of BFS concrete and Portland cement concrete were conducted. The current model was found to underestimate the strength of BFS concrete at later ages owing to underestimation of the water content inside C–S–H gel pores. To remedy this, enhanced modeling of porosity allowing proper simulation of the porosity of the BFS paste matrix and higher strength development at later ages is proposed. Furthermore, based on the enhanced porosity model, the moisture loss and pore size distribution of the BFS paste matrix were investigated. The pore size distribution was found to be coarser than the test at later ages in the model, resulting in overestimation of moisture loss. Hence, the pore size distribution was enhanced as well, allowing simulation of a finer pore structure of the BFS matrix. Finally, verifications showed that the enhanced model better predicts water desorption, moisture loss and drying shrinkage behaviors.