Research on frost resistance of non-spontaneous combustion coal gangue aggregate concrete
In order to study the frost resistance durability of non-spontaneous combustion coal gangue aggregate concrete under different water-cement ratio and non-spontaneous combustion coal gangue coarse aggregate substitution rate,the influence of water-cement ratio and substitution rate on the frost resistance of non-spontaneous combustion coal gangue concrete is analyzed by testing the compressive strength,ultrasonic wave velocity,dynam-ic elastic modulus and quality of freeze-thawed non-spontaneous combustion coal gangue concrete;SEM was used to scan the in-terface between aggregate and mortar,and the micro damage mechanism of non-spontaneous combustion coal gangue aggregate concrete after freezing and thawing was analyzed.The results show that the water-cement ratio and the replacement rate of non-spontaneous combustion coal gangue coarse aggregate have a great influence on the properties of concrete after freeze-thaw cy-cle,the higher the water-cement ratio and the replacement rate of non-spontaneous combustion coal gangue coarse aggregate,the worse the frost resistance;when the number of freeze-thaw cycles reaches 100,the specimens with water-cement ratio higher than 0.45 and non-spontaneous combustion coal gangue coarse aggre-gate replacement rate higher than 50%have been seriously dam-aged,unable to test their compressive strength,and freeze-thaw shall be stopped;Ultrasonic specific dynamic elastic modulus is sensitive to the damage measurement of non-spontaneous com-bustion coal gangue concrete after freeze-thaw;with the increase of freeze-thaw times,the pores and micro cracks on the surface of coarse aggregate are increasing,and the change of non-spontane-ous combustion coal gangue coarse aggregate is more significant,indicating that the frost resistance of non-spontaneous combus-tion coal gangue concrete is worse than that of ordinary concrete.
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