高温中与高温后混凝土的冲击力学特性

Impact Mechanical Properties of Concrete at and after Exposure to High Temperature

采用Ф100mm分离式霍普金森压杆(split Hopkinson pressure bar,SHPB)试验装置,结合高温电阻炉,分别对常温和200,400,600,800℃高温中和高温后的混凝土进行了冲击压缩试验,分析了高温和弹速对混凝土冲击力学特性的影响.结果表明:高温对混凝土冲击力学特性影响显著,600,400℃分别是高温中、高温后混凝土各项力学指标发生明显改变的转折温度,高温中、高温后混凝土的动态抗压强度、比能量吸收分别在600,400℃以后下降明显;水冷却将造成400℃以上高温的混凝土强度损失严重,这在消防过程中应引起注意;混凝土经400℃以上高温作用,虽然强度损失严重,但是在较高速率的冲击载荷作用下,仍表现出良好的抗冲击韧性,说明混凝土是一种耐高温、抗冲击性能优越的材料,这对于其在军事防护工程中的应用极为重要.

A 100-mm-diameter split Hopkinson pressure bar（SHPB） apparatus, coordinating with electric furnaces, was adopted to investigate the behavior of concrete at room temperature, at and after exposure to 200, 400, 600 and 800 ℃ under impact compressive loading, the effects of high temperature and projectile velocity on impact mechanical properties were studied. Results show that the effect of high temperature on impact mechanical properties is significant. The critical temperatures for significant change of mechanical properties of concrete at and after exposure to high temperature are 600 ℃, 400℃, above these tempera- tures, dynamic compressive strength and specific energy absorption of concrete decrease rapidly. For con- crete exposed to high temperature of above 400 ℃, cooling down by water results in serious strength re- duction, which should be paid attention in fire-fighting. Though the loss in strength of concrete at above 400 ℃ is severe, it still shows a nice anti-impact toughness under higher velocity impact loading. Above all, concrete is an excellent thermal-resistant and anti-impact material, which is very important to military defensive engineering structure.