高炉镍铁渣和钢纤维改性混凝土的耐热性和热损伤规律

Heat Resistance and Thermal Damage Law of Blast Furnace Nickel-Iron Slag and Steel Fiber Modified Concrete

利用高炉镍铁渣和钢纤维对混凝土进行了改性,并通过强度试验及波速测试对改性混凝土在热循环后的力学特性和热损伤规律进行了研究。强度试验表明:热循环对改性混凝土的强度退化具有积累效果;适量的高炉镍铁渣和钢纤维可以提高混凝土的耐热性,但过多的钢纤维会降低混凝土的耐热性;其中钢纤维的最佳掺量为0.5%~1.0%(体积分数)。波速测试表明,随着热循环次数的增加混凝土中的超声波速不断降低,类似于强度变化规律。根据波速测试和强度试验结果建立了波速与强度之间的关系,并建立了一般化的损伤因子表达式。对比不同参数的损伤因子表明各个参数对热循环的敏感性为:波速>抗拉强度>抗压强度;对热循环损伤的改善效果为:钢纤维>高炉镍铁渣;低水灰比>高水灰比。

The concrete was modified with blast furnace nickel-iron slag and steel fiber,and then the mechanical properties and thermal damage law of the modified concrete after thermal cycling were studied through strength test and ultrasonic speed test.The strength test shows that thermal cycling has an accumulative effect on the strength degradation of the modified concrete.An appropriate amount of blast furnace nickel-iron slag and steel fiber improve the heat resistance of the concrete,but too much steel fiber will reduce the heat resistance of the concrete.The optimal amount of fiber is 0.5%(volume fraction)to 1.0%.The ultrasonic speed test shows that the ultrasonic speed in the concrete decreases continuously with the increase of the number of thermal cycles,similar to change law of compressive and tensile strength.According to the results of ultrasonic speed test and strength test,the relationship between ultrasonic speed and strength is established,and a generalized damage factor expression is established.Compared with the damage factors of different parameters,the results shows that the sensitivity of each parameter to thermal cycling is:wave velocity>tensile strength>compressive strength;the improvement effect on thermal cycling damage is:steel fiber>blast furnace nickel-iron slag;low water-cement ratio>high water-cement ratio.