Influence of new hydrophobic agent on the mechanical properties of modified cemented paste backfill

Cement-based materials is indispensable in the construction process, and the characteristics of cement mortar affect the quality and efficiency of construction obviously. Roof-contacted filling and dehydration in stope are two critical problems in mines in the process of mine filling, which has a very important influence on the strength of filling body. In order to enhance the work performance of cement paste backfill (CPB) and improve the work efficiency in field engineering, the mixed hydrophobic agent was mixed in the CPB slurry to improve the dewatering efficiency. The dewatering test device was designed by authors to test the dewatering efficiency of the CPB mixing different dosage of the hydrophobic agent. The rheological properties of the cement paste mixing with the hydrophobic agent were tested by the rheometer R/S plus to achieve the workability of the CPB. To analyze the influence mechanism of the hydrophobic agent on the dewatering efficiency of CPB, the density, shrinkage, water vapour permeability and capillary water absorption of the CPB specimens were measured. Considering the effect of the hydrophobic agent on the compressive strength of the hardened CPB, it can be concluded that the reasonable addition dosage of hydrophobic agent in CPB is 1% by weight.