再生混凝土抗折疲劳试验断面破坏形态分析

ANALYSIS OF CROSS-SECTIONAL FAILURE MODES OF RECYCLED AGGREGATE CONCRETE FLEXURAL FATIGUE TEST

根据不同再生骨料取代率的再生混凝土在反复荷载作用下的断面破坏形态,分析影响再生混凝土抗折强度、抗折疲劳寿命的材料因素。对再生骨料取代率为0、30%、50%、70%的再生混凝土进行抗折强度试验以及应力水平为0.6、0.7、0.8的抗折疲劳试验。断面破坏形式表明:随着再生骨料取代率的提高,再生混凝土抗折强度越来越小,疲劳寿命逐渐降低,断面的两种破坏形式(骨料与砂浆之间的黏结破坏、骨料断裂破坏)的面积均呈线性递减趋势。为降低试件中再生集料附近区域产生应力集中的几率,建议生产再生混凝土时采取提高再生骨料强度、优化再生骨料加工工艺、增强再生粗骨料与砂浆之间的黏结等措施。

Based on the recycled concrete（ different recycled aggregate replacement ratio） specimen＇s damage mode under repeated loads,the material factors which can influence recycled concrete flexural strength,flexural fatigue life can be analyzed. Recycled concrete specimens of 0,30%,50%,70% regeneration replacement-rate were poured,and flexural strength tests performed as well as the flexural fatigue test with stress level being 0. 6,0. 7,0. 8. Crosssectional failure morphology showed that with the increasing of recycled aggregate rate,recycled concrete＇s flexural strength became smaller,and the fatigue life decreased,the section area of two kinds of failure modes（ the bond failure between aggregate and mortar,aggregate fracture） showed a linear decreasing trend. To reduce the probability stress concentration around the recycled aggregate,it was recommended that the strength of recycled aggregate should be improved,recycled aggregate processing technology be optimized and the bonding between the recycled coarse aggregate and mortar be enhanced etc during the production of recycled concrete.