干硬性混凝土低温力学性质试验研究

Experimental study on low temperature mechanical properties of dry hard concrete

为探究低温对干硬性混凝土力学性质的影响,以及干硬性混凝土在冻融作用下动弹性模量和质量变化规律,基于室内试验条件,对不同温度梯度(20℃、0℃、-10℃、-20℃、-30℃)下干硬性混凝土的力学参数(fcu、fts、ff、τi)进行测定,并与相同条件下普通混凝土测试结果进行对比,同时对干硬性混凝土进行0~300次冻融循环,测定其动弹性模量和质量变化。得到以下结论:干硬性混凝土和普通混凝土的fcu、fts、ff、τi随温度降低增大;随着冻融循环次数增大,干硬性混凝土的动弹性模量逐渐降低,F300次循环后,干硬性混凝土的动弹性模量下降到73.7%;冻融作用使干硬性混凝土内部结构造成破坏,裂缝的产生及闭合孔隙的打开使试件吸水,产生质量损失出现“负增长”现象。

In order to investigate the effect of low temperature on the mechanical properties of dry hard concrete and the variation of dynamic elastic modulus and quality of dry hard concrete under freeze-thaw cycle,the mechanical parameters of dry hard concrete under different temperature gradients( 20℃,0℃,-10℃,-20℃,-30℃) based on laboratory test conditions( fcu、fts、ff、τi) were measured and compared with the test results of ordinary concrete under the same conditions,and the dynamic elastic modulus and quality changes of dry hard concrete were determined by 0 ~ 300 freeze-thaw cycle. The following conclusions are obtained: The fcu,fts,ffand τiof dry hard concrete and ordinary concrete increase with the decrease of temperature,and with the increase of freeze-thaw cycle,the dynamic elastic modulus of dry hard concrete decreases gradually,and the dynamic elastic modulus of dry hard concrete drops to 73.7% after F300 secondary cycle. The freeze-thaw cycle effect causes the damage of the internal structure of dry hard concrete,the generation of cracks and the opening of closed pores make the sample suck water and produce the phenomenon of " negative growth" in the quality loss.