为了研究高温后混凝土强度变化规律,制作标准混凝土立方体试块,对试块加热到不同温度,空气中冷却后观察试块表观现象,然后进行加载试验,测试试块抗压强度.通过对比不同温度工况下混凝土试块的表观现象和抗压强度,发现高温会使试块颜色变白并且促使表面龟裂纹的产生和拓展.当温度处于200~300 ℃时,试块的抗压强度无明显变化,300 ℃后抗压强度逐渐降低,且温度越高下降得越快,当温度达800 ℃时抗压强度下降到常温时的30%.与常温相比,高温后试块轴心抗压破坏形态变化较大,"四角锥"现象不明显,随着受热温度的升高,劈落的碎块由整块剥落向粉碎性剥落过渡.%Standard concrete specimens were made and heated under different temperatures,and apparent phenomena of specimens were observed after cooling in air.The load tests of specimens were conducted to acquire compressive strength.It has been found that the high temperature can cause specimens to white color and result in turtle cracks by comparing phenomena and strength of specimens under different temperature conditions.When the temperature reached 200~300℃,the compressive strength of specimens changed unconspicuously.The compressive strength decreased when temperature was beyond 300℃.The higher the temperature was,the faster the strength decreased.When the temperature reached 800℃,the compressive strength changed to 30%.Compared with the concrete strength at room temperature,the compressive failure pattern of specimens after heating changed considerably.The appearance of "quadrangular pyramid" wasn''t obvious.As the heating temperature rose,the debris transformed from large pieces to crushing spalling.
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