THE EFFECTS OF PRETREATMENT OF SPONTANEOUS COMBUSTION GANGUE AGGREGATE ON THE WORKABILITY AND STRENGTH OF CONCRETE

The porous properties of spontaneous combustion gangue aggregate determine its water absorption properties，and the additional water and pre-wetting time have a greater influence on the performance of concrete． Through experimental study on the concrete prepared by two kinds of combined aggregates including the coal gangue sand + natural gravel and natural river sand + spontaneous combustion gangue，it was revealed the influence of change in additional water and pre-wetting time on the workability and hardening strength of concrete mixture． The results show that the concrete mixture can get the large liquidity configuration requirement of the premixed concrete while 60% and 80% additional water is added respectively to the coal gangue sand and the spontaneous combustion gangue． as the additional water of coal gangue sand and spontaneous combustion gangue increasing，the concrete compressive strength and splitting tensile strength are a downward trend at 7 d and 28 d，and the compressive strength decreased largely; as the pre-wetting time of the spontaneous combustion gangue coarse aggregate is longer，its strength growth is better，but when the pre-wetting time is greater than 1 h，the change is very small． While the prewetting time of the coal gangue sand increases，the intensity will show the tendency of decreasing．