Impact of mixing design parameters on the performance and surface quality of self-compacting concrete filling layers

Construction quality, durability and service life of China Railway Track System III (CRTS III) is influenced by the performance of the self-compacting concrete (SCC) used for filling layer. In this paper, the effect of unit water consumption, sand ratio and water reducer components on working performance of SCC filling layer is studied by laboratory and field tests. Appropriate mix proportion parameters are obtained. The results indicate that unit water consumption can significantly improve the in-service performance of SCC. However, it is essential to consider both the dosage of water-reducing agents and the unit water consumption to ensure the stability of the mixture. Sand ratio of SCC is between 49% and 52% used for filling layer, which have excellent flowability and stability. It is recommended that the content of the defoamer should be 3/1 000, and the content of the air-entraining agent should be 5/1000. These research results will play an important role in improving the construction quality of SCC filling layer.