PP纤维和钢筋对高温下C60HPC板热应变的影响

Effect of Polypropylene Fiber and Steel Bar on Thermal Strain of C60 High Performance Concrete Slab at High Temperature

关键词:  聚丙烯纤维  钢筋  高温  C60高性能混凝土板  热应变

Key words:  polypropylene（PP） fiber  steel bar  high temperature  C60 high performance concrete slab  thermal strain

摘要:

通过测试高温下掺与未掺聚丙烯（PP）纤维、有无钢筋网的C60高性能混凝土板内部不同深度处的温度和热应变变化，研究了PP纤维和钢筋网对C60高性能混凝土板高温变形性能的影响.结果表明：C60高性能混凝土板内部各深度处的温度随着加热时间的推移而升高，随着与受热面距离的增加而递减；与高温下未掺纤维但布置钢筋网的钢筋混凝土板升温速率相比，掺加PP纤维可降低钢筋混凝土板的升温速率；高温下混凝土板的热应变随着温度的升高而增大，在相同温度下，距混凝土板底部受热面50 mm处的热应变最大；与高温下未掺纤维但布置钢筋网的钢筋混凝土板热应变相比，掺加PP纤维可降低钢筋混凝土板的热应变，两者在距钢筋混凝土板底部受热面25、50、75 mm处所测的热应变最大差值分别为54、50、36 μm/m左右；距底部受热面25 mm时，钢筋混凝土板中钢筋周围混凝土的热应变明显小于无钢筋网混凝土板的热应变，表明钢筋和PP纤维均能降低混凝土在高温下的热应变，改善混凝土的变形性能.

Abstract:

The high temperature test of C60 high performance concrete slab mixed with or without polypropylene （PP） fiber and with or without steel mesh is carried out. By testing the temperature and thermal strain changes at different depths of the concrete slab under high temperature， the effect of PP fiber and steel mesh on the high temperature deformation performance of the concrete slab is studied. The results show that the temperature at each depth of the C60 high performance concrete slab increases with the passage of heating time， and decreases with the increase of the distance from the heating surface. Compared with the heating rate of the reinforced concrete slab without PP fiber at high temperature， adding PP fiber can reduce the heating rate of the reinforced concrete slab. The thermal strain of the concrete slab increases with the increase of the temperature at high temperature， and at the same temperature， the thermal strain is the largest at 50 mm from the bottom of the concrete slab. Compared with the thermal strain of reinforced concrete slab without PP fiber at high temperature， adding PP fiber can reduce the thermal strain of reinforced concrete slab， the maximum strain difference between the two measured at 25， 50， 75 mm from the bottom of the reinforced concrete slab are about 54，50，36 μm/m respectively. When the distance from the bottom is 25 mm， the thermal strain of the concrete around the steel bars under high temperature of the reinforced concrete slab is significantly less than that of the concrete without steel mesh， indicating that both steel bars and PP fibers can reduce the thermal strain of concrete and improve the deformation performance of concrete.