Abstract: Through experiments on crushing value,water absorption,particle size distribution of spontaneous combustion gangue aggregate,and the compressive strength of concrete,the influence to compressive strength of shotcrete when gangue aggregate replaced natural aggregate and the alkaline mixing water is investigated.The experimental data is analyzed with use of SPSS software,showing that aggregate type has little influence on concrete strength,alkaline mixing water benefits to enhance 3 d and 28 d strength of gangue concrete,but has less impact on 1 d strength of gauge concrete and each age of stone concrete.According to SEM observation and analysis,gangues with feature of loose and porous structure,easy absorption and rough surface is in favor of the attachment of cement mortar,effectively reduces water-cement ratio at the interface under high mixing water and decrease the thickness of the interfacial transition zone that is unfavorable to the concrete strength.Alkaline mine water contributes to dissolve out active SiO₂ and Al₂O₃ in natural aggregate,and these active substance react with Ca(OH)₂ collected around interface and then produce gel which enhances the density of interfacial transition zone.

Key words: Gangue, Concrete, Aggregate, Interface, Strength