自燃煤矸石集料预处理对混凝土工作性及强度影响

自燃煤矸石集料的多孔性能决定了其吸水特性,其附加水及预湿时间对混凝土性能影响较大。通过对自燃煤矸砂+天然碎石、天然河砂+自燃煤矸石两种组合集料配制的混凝土进行试验研究,揭示附加水及预湿时间的变化对混凝土拌合物工作性及硬化强度的影响。结果表明:自燃煤矸砂按饱和吸水率的60%、自燃煤矸石按吸水率的80%加入附加水,拌合物可获得预拌混凝土大流动性的配制要求。自燃煤矸砂、煤矸石随着附加水的递增,混凝土7,28 d抗压和劈拉强度皆呈下降的趋势,抗压强度下降幅度较大;自燃煤矸石粗集料预湿时间越长其强度增长越好,但当预湿时间大于1 h,变化幅度很小。而自燃煤矸砂随预湿时间的递增,强度呈递减趋势。

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.