Effects of freeze and cyclic flexural load on mechanical evolution of filling layer self-compacting concrete

As one of the core components, high quality self-compacting concrete filling layer is of great importance to the long-term safe service of CRTS III type slab ballastless track. The present paper designed a freeze and flexural-loading coupling action testing system to investigate the mechanical characteristics of self-compacting concrete applied in filling layer (FLSCC), aiming at understanding the service behavior of filling layer under severe environment condition. The effects of temperature, cycle number and stress level on mechanical properties including flexural strength, dynamic elastic modulus and damping ratio of FLSCC were discussed. Results show that the freeze and cyclic load coupling action aggravates the deterioration of concrete compared to single cyclic load condition. FLSCC exhibits better resistance to freeze and cyclic load action than other three investigated concretes in term of flexural strength, dynamic elastic modulus and damping ratio. The flexural strength of FLSCC decreases with increasing cycle number stress level at low temperature (-20 degrees C) and the damage variable of FLSCC increases exponentially with cycle number. The outstanding resistance of FLSCC to freeze and cyclic load coupling action results from the excellent microstructure which can maintain its good deformation capacity and delay the damage propagation. (C) 2018 Published by Elsevier Ltd.