Experimental and numerical investigation for the cracking potential of self-compacting concrete (SCC) at early age

This study mainly investigates the cracking index of three different types of concrete (normal, flowing, and self-compacting) due to thermal stresses developed by the heat of hydration in mass concrete block. The hydration heat generated by ten different normal, flowing, and self-compacting concrete mixtures was measured using a semi-adiabatic calorimeter. The cement was replaced by fly ash in varied percentages (20%, 30%, and 40%) to develop normal, flowing, and self-compacting concretes with altering the percentage of fines and the doses of superplasticizer additive. The mechanical (tensile and compressive strength) and thermal properties (thermal conductivity, specific heat capacity and thermal resistivity) of the concrete mixes were measured. Using finite element modeling, the viscoelastic behavior of 2 × 2x2 m concrete block containing 40% fly ash in place of cement was simulated at an early age to predict thermal stresses and cracking indices. The combined experimental and numerical investigations revealed that the three self-compacting concrete mixtures with 20%, 30%, and 40% FA were susceptible to thermal cracking (cracking index > 1). However, the normal concrete with 40% FA has the lowest likelihood of cracking compared to flowing and self-compacting concrete with the same replacement level, due to its lower heat of hydration.