再生粗骨料预处理及再生混凝土徐变试验研究

采用预湿法、净浆裹石法和掺硅灰净浆裹石法对再生粗骨料进行预处理,然后制备再生混凝土.研究不同再生粗骨料取代率(质量分数)和不同再生粗骨料预处理法对再生混凝土徐变性能的影响.以普通混凝土徐变预测模型(ACI209模型)为基础,考虑再生粗骨料取代率、预处理法的影响,提出了再生混凝土徐变预测模型(修正ACI209模型).结果表明:加荷150d时,再生粗骨料取代率50%,100%的再生混凝土总徐变度较普通混凝土分别增加19%和53%;3种预处理方法对减小再生混凝土的徐变变形均有明显效果,能使加荷150d的再生混凝土徐变度降低11%到24%.修正ACI209模型对再生混凝土徐变的预测效果良好.

Experimental Study on Pretreatment of Recycled Coarse Aggregate and Creep Behavior of Recycled Aggregate Concrete

Three kinds of different pretreatment methods i.e. pre wet, steep liquor wrapped stone craft and incorporation of silica fume steep liquor wrapped stone craft were adopted to treat the recycled coarse aggregate(RCA) for the recycled aggregate concrete. The influences of replacement rates(by mass) and pretreatment methods of RCA on the creep behavior of recycled aggregate concrete were studied. Based on the creep prediction model(ACI209 model) of normal concrete(NC), the influences of replacement rates and pretreatment methods of RCA were considered by the creep prediction model of RAC(modified ACI209 model). The test results indicate that the specific total creeps of recycled aggregate concretes with 50% and 100% replacement rate of RCA increase by 19% and 53% respectively after loading 150d, compared to that of NC. The three pretreatment methods have obvious effects on the decrease of the creep of recycled aggregate concrete, which can reduce the specific creep of recycled aggregate concrete by 11% to 24%. The creep predictions of modified ACI209 model have good forecasts for the recycled aggregate concrete.