高温对早龄期混凝土力学性能的影响

Effect of High Temperature on Mechanical Properties of Early Age Concrete

研究了掺10%粉煤灰和掺10%矿粉的早龄期(标准养护7,14,21,28 d)混凝土经历不同高温作用后质量烧失率和残余抗压强度的变化规律。结果表明:2种混凝土试件不同龄期的质量烧失率均随着温度(300,500,700℃)的升高而增大,并且相同龄期质量烧失率增长趋势相近;500℃高温时,掺粉煤灰混凝土试件14,21,28 d龄期的残余抗压强度分别降至常温时的92%,83%,63%,掺矿粉的混凝土试件分别降至常温时的89%,78%,62%;700℃高温时,2种试件残余抗压强度均降至常温时的30%~40%,基本丧失承载力。基于此给出了经受高温后早龄期混凝土残余抗压强度与温度的关系式,可供实际工程参考。

The change laws of mass ignition loss and residual compressive strength of early age concrete mixed with10% fly ash and 10% mineral powder(standard curing 7,14,21,28 d)under different high temperature actions werestudied. The results show that the mass ignition loss of two kinds of concrete specimens in different ages increases withthe increase of temperature(300,500,700 ℃)and the growth trend of mass ignition loss in the same age is similar. Athigh temperature of 500 ℃,the residual compressive strength of concrete specimens mixed with fly ash decreases to92%,83%,63% and that of concrete specimens mixed with mineral powder decreases to 89%,78%,62% respectivelyat the age of 14,21 and 28 d. At high temperature of 700 ℃,the residual compressive strength of the two specimensdecreases to 30%~40% of that at the normal temperature,and the bearing capacity is basically lost. Based on thisresult,the relationship between residual compressive strength and temperature of early age concrete after hightemperature action was given,which could be used for reference in practical engineering.