EFFECT OF LOW PRESSURE ON THE PROPERTIES AND MICROSTRUCTURE OF ULTRA-HIGH PERFORMANCE CONCRETE

The properties of fresh concrete, the mechanical properties and microstructure of Ultra-High Performance Concrete (UHPC) with different admixtures were studied in Chengdu and Lhasa, for exploring the influence of low pressure on the performance of UHPC. The test results indicated that: The plateau low pressure environment can significantly reduce the dosage of the admixtures and improve the performance of fresh UHPC, but the compressive strength was significantly reduced at 28 d and 60 d. The porosity and average pore size of the UHPC under low pressure are relatively small, but the pore size of the UHPC above 10000 nm takes up a larger proportion. In addition, the low pressure environment on the plateau can also reduce the degree of hydration of the UHPC.