循环荷载对煤矸石混凝土损伤试验研究

Experimental Study on Damage of Coal Gangue Concrete under Cyclic Load

为了研究煤矸石混凝土在疲劳荷载作用下的损伤特性,制作了煤矸石质量取代率分别为0、20%、40%、60%、80%、100%的混凝土试件,循环荷载取0.3 f c0和0.5 f c0,分别在循环加载2500次、5000次、7500次、10000次后测试其抗压强度和相对动弹性模量。结果表明:不同质量取代率的煤矸石混凝土在循环加载次数较少时,可致密内部结构,抗压强度不但无损而且性能还有所提升,煤矸石的质量取代率越高,混凝土抗压强度越小,达到最大值所需的循环次数越少,循环10000次煤矸石质量取代率40%的混凝土抗压强度开始出现损伤,且疲劳荷载越大,损伤越大;不同质量取代率的煤矸石混凝土在循环加载初期相对动弹性模量下降较快,后期逐渐趋于稳定,疲劳荷载越大,煤矸石质量取代率越高,损伤越严重,加速了结构内部微裂隙的扩展以及新孔隙的产生。

In order to study the damage characteristics of coal gangue concrete under fatigue loading,concrete specimens with mass substitution rates of 0,20%,40%,60%,80%and 100%coal gangue were prepared.The cyclic loads were 0.3 f c0 and 0.5 f c0.The compressive strength and relative dynamic modulus of concrete were tested after cyclic loading of 2500 times,5000 times,7500 times and 10000 times respectively.The results show that the gangue concrete with different mass substitution rates can compact the internal structure with less cyclic loading times.The compressive strength is not only non-destructive,but also improved.The higher the mass substitution rate of coal gangue,the smaller the compressive strength of concrete,the less the number of cycles needed to reach the maximum value.The compressive strength of concrete begins to damage when the mass replacement rate of coal gangue is about 40%and the cycles times is 10000.And the greater the fatigue load,the greater the damage.At the beginning of cyclic loading,the relative dynamic elastic modulus of gangue concrete with different mass substitution rate decreases rapidly,and then tends to be stable gradually.The larger the fatigue load,the higher the mass substitution rate of gangue and the more serious the damage,which accelerates the expansion of micro-cracks and the generation of new pore in the structure.