高温后纳米SiO_(2)混凝土力学性能试验研究

Experimental Study on Mechanical Properties of Nano-SiO_(2) Concrete after High Temperature

火灾高温是引起混凝土损伤的重要原因之一,纳米混凝土常温下的力学性能与普通混凝土有较大差异,为研究纳米(纳米二氧化硅,以下简称NS)混凝土高温后的力学性能,采用高温电炉对不同NS掺量的混凝土试块进行了加热并选取不同冷却方式至室温,然后采用电液伺服机对其进行了抗压、劈裂抗拉加载试验.结果表明:随着温度的升高,混凝土的质量损失逐渐增加,抗压和劈裂抗拉强度不断降低.将NS加入混凝土中能增强混凝土的耐高温力学性能,相对于普通混凝土,相同受热温度下,NS混凝土的抗压和劈裂抗拉强度均有所提高,综合来看,NS掺量为1.0%~1.5%时最为适宜.冷却方式对混凝土的力学性能产生不同的影响,相同情况下,喷水冷却后混凝土的强度低于自然冷却后的强度,且400℃以上时,两者之间的差异更为明显.

High temperature is one of the important causes of concrete damage.The mechanical properties of nano concrete at room temperature are quite different from those of ordinary concrete.In order to study the mechanical properties of nano(nano-silica, hereinafter referred to as NS) concrete after high temperature, concrete specimes with different NS contents were heated by an electric furnace and cooled down to room temperature by different cooling methods, and then the compressive and splitting tensile tests were carried out with an electro-hydraulic servo machine.The results showed that with the increase of temperature, the mass loss of concrete increased gradually, and the compressive and splitting tensile strengths decreased continuously.Adding NS could enhance the high temperature resistance of concrete.Compressive strength and splitting tensile strength of the NS concrete significantly increased, compared with the ordinary concrete after exposure to a same high temperature.The optimal content of NS was in the range of 1.0% to 1.5%.The mechanical properties of concrete were affected by cooling methods of the specimens.Under the same conditions, the strength of concrete cooled by water was lower than that of the concrete cooled naturally in the air, and the difference between them were more obvious when the heating temperature was higher than 400℃.