冷却方式对高温后再生混凝土力学性能的影响

Influences of Cooling Methods on Mechanical Properties of Recycled Aggregate Concrete after Exposure to High Temperature

为了研究冷却方式对高温后再生混凝土力学性能的影响,以再生粗骨料取代率、受热温度、冷却方式为参数,设计了111块再生混凝土立方体标准试块,进行高温后力学性能试验,考察了不同冷却方式下试块的表观变化、破坏形态以及性能指标,分析其残余强度影响规律,并给出了相应强度计算方法.结果表明:随着受热温度的升高,试块表面颜色变浅、裂缝增多、破损程度加重;质量烧失率增大,且其增大趋势在自然冷却条件下先快后慢,在喷水冷却条件下倾向于线性变化;试块残余强度随着温度的升高而逐渐降低,与自然冷却相比,喷水冷却后的残余强度呈现先高后低、再高再低的变化趋势;在试验基础上提出的不同冷却方式下残余强度计算公式计算结果与已有试验数据吻合良好.

To study the influence of cooling methods on mechanical properties of recycled aggregate concrete（RAC）after high temperature exposure,111 standard cubic blocks were prepared.Several parameters of recycled coarse aggregate replacement rate,high temperature and cooling methods were taken in consideration in compression test after high temperature.Through the test,the appearance,failure pattern and mechanical properties of RAC with various cooling methods were observed.Influence rule of residual strength was analyzed and its corresponding calculation formulas was also proposed.Test results indicate that RAC surface color becomes light as the temperature rises,cracks and flaking degree increase.Mass loss rate tends from fast to slow under the condition of natural cooling,and in the case of water cooling,tends to a linear change.With the increase of temperature,the residual strength of RAC decreases gradually.Compared with natural cooling,residual strength is high to low before the change trend of high to low under water cooling.Based on test results,the residual strength calculation formula under different cooling methods are proposed respectively,which can be in good agreement with existing test data.