低温条件下水泥-粉煤灰复合胶凝体系早期强度的研究

Study on the early strength of fly ash-cement mixed system in the condition of low temperature

在固定水胶比的条件下研究了不同温度,不同粉煤灰掺量及亚硝酸钠的掺入对低温条件下水泥-粉煤灰复合胶凝体系早期强度的影响规律。研究结果表明:在5～-10℃范围内,随着温度的降低,胶凝材料的水化加速期出现不同程度的滞后,胶砂试件养护龄期为14 d时,0℃及0℃以下条件下养护的不同配合比的复合胶凝材料体系的抗压、抗折强度已基本接近,但仍低于5℃养护条件下同龄期同配合比的胶砂试件强度;在-5℃和-10℃两个养护温度下,随着粉煤灰掺量的增多,其胶砂试件的抗折、抗压强度均呈现不同程度的降低,但是粉煤灰掺量小于10%时,胶砂试件的抗折、抗压强度受温度影响较小,大于10%时,胶砂试件的抗折、抗压强度受温度影响较大;5℃养护条件下,亚硝酸钠的加入增加了同一配合比下胶砂试件的抗折强度,却降低了同一配合比下胶砂试件的抗压强度。

Under the condition of constant water-binder ratio, the infuence of different temperature （all below 5 ℃ ）, different mixing amount of fly ash and adding of NaNOz on early strength of composite cementitious material with cement and fly ash was studied.The results showed that： In the range of 5 ℃ to - 10 ℃, as the temperature went down, the accelerating period of hydration was delayed to varying degrees.When the curing age reached 14 days,the compressive strength and flexural strength of specimens cured in temperature no more than 0 ℃ was almost close,which was less than that of specimens cured in 5 ℃ with the same proportion of mixture.At curing temperature of-5 ℃ and -10 ℃, the compressive strength and flexural strength of specimens decreased to varying degrees when mixing amount of fly ash was increased.But when the mixing amount was below 10%, the influence of temperature on the compressive strength and fexural strength of specimens was relatively small, and vice versa.At curing temperature of 5 ℃ ,the adding of NaNO2 brought a growth to the flexural strength and a reduce to the compressive strength of specimens with the same water-binder ratio.