冻融循环作用下橡胶混凝土蠕变特性试验研究

Experimental Study on Creep Characteristics of Rubber Concrete under Freeze-thaw Cycles

橡胶混凝土(concrete with rubber aggregate,RC)具有较高的抗冻融性,但其在各种冻融条件下的长期蠕变行为尚不清楚,势必会影响橡胶混凝土在严寒地区的应用。以RC在冻融循环条件下的蠕变特性为对象,选取C40普通混凝土配比为试验基准,将等体积、粒径为3~6 mm橡胶颗粒代替中砂质量的10%配制了一种RC,在RC材料经历0、30、60、90、120、150次冻融循环试验后,进行单轴抗压、单轴蠕变、冻融后动弹性模量及扫描电子显微镜(scanning electron microscope,SEM)观察等试验。结果表明:相对于0次冻融循环条件下的RC,经历30~150次冻融循环作用后其抗压强度分别下降了6.51%~47%,质量损失率分别提高了6%~11.2%。随冻融循环次数的增加,RC蠕变破坏逐渐达到其临界值应力水平,冻融动弹性模量不断降低。经多次冻融循环后,RC试件蠕变应力低于峰值强度的50%时,判断结构是安全的。超过该临界值时,判别安全标准取决于其应力荷载及冻融循环次数。

Concrete with rubber aggregate(RC)has high freeze-thaw resistance,but its long-term creep behavior under various freeze-thaw conditions is still unclear,which can negatively influence its application in severe cold areas.Aiming at the creep characteristics of rubber concrete material under freeze-thaw cycles,the ratio of C40 ordinary concrete was selected as the test standard,and the rubber particles of equal volume and particle size of 3~6 mm were substituted for 10%of the mass of medium sand.A kind of RC was formulated.After the RC material undergone 0,30,60,90,120,150 freeze-thaw cycle tests,uniaxial compression,uniaxial creep,dynamic elastic modulus after freezing and thawing,and scanning electron microscope(SEM)were carried out observe and other tests.The results show that compared with the RC under the condition of 0 freeze-thaw cycles,the compressive strength after 30~150 freeze-thaw cycles decreased by 6.51%~47%,and the mass loss rate increases by 6%~11.2%.With the increase of the number of freeze-thaw cycles,RC creep damage gradually reaches its critical stress level,and the dynamic elastic modulus of freeze-thaw decreases continuously.After multiple freeze-thaw cycles,when the creep stress of the RC specimen is less than 50%of the peak strength,the structure is judged to be safe.When the critical value is exceeded,the judgment safety standard depends on the stress load and the number of freeze-thaw cycles.