Composite cementing material system of ultra-high performance concrete and application method thereof

The invention relates to the technical field of civil engineering materials, in particular to a composite cementing material system of ultra-high performance concrete and an application method thereof. The system is characterized in that the composite cementing material system comprises cement, an active mineral admixture and a chemical activator, the active mineral admixture comprises fly ash, mineral powder, silica fume and nano aluminum oxide, and the chemical activator is sodium sulfate; the molar ratio of calcium oxide to silicon oxide in the composite cementing material system is (0.8-0.91): 1. The composite cementing material system has the advantages that the specific ratio of calcium oxide to silicon oxide is utilized so that the cementing material can exert good chemical compaction effect; the hydration reaction of the cementing material can be enhanced through the chemical activator (sodium sulfate), the chemical compaction effect of the cementing material can be well provided, and the obtained con