再生粗骨料混凝土压缩徐变特性的研究

STUDY ON COMPRESSIVE CREEP PROPERTIES OF RECYCLED COARSE AGGREGATE CONCRETE

通过对再生粗骨料取代率为0%、50%、100%的混凝土试件进行徐变试验,研究再生粗骨料混凝土的徐变特性。结果表明:再生粗骨料混凝土的基本徐变和总徐变都随再生粗骨料取代率增大而增大,并且再生粗骨料取代率对再生粗骨料混凝土总徐变的影响大于对基本徐变的影响。基于试验结果,分析了徐变过程中的再生粗骨料、新砂浆、旧砂浆的相互作用机理,引入了新砂浆、旧砂浆与再生粗骨料混凝土徐变的关系计算模型,即修正的Neville徐变模型。利用该模型,计算了旧砂浆在再生粗骨料混凝土基本徐变和总徐变过程中的徐变量。基于ANSYS软件,建立了再生粗骨料混凝土的二维随机凸集料模型,以验证修正的Neville徐变计算模型的可靠性,并采用该有限元模型,分析再生粗骨料随机分布对再生粗骨料混凝土徐变的影响。最后,基于提出的修正Neville模型,建立了能够计算旧砂浆徐变、反映旧砂浆含量和性能的再生粗骨料混凝土徐变预测模型。

According to replacement rates of recycled coarse aggregate(RCA)of 0%,50%,100%,the compressive creep tests of recycled course aggreagte concrete were conducted.The creep properties of recycled coarse aggregate concrete(RAC)were studied.The experimental results indicated that both of the basic creep and total creep of RAC increased with the increase of replacement rates of RCA,and the effect of replacement rates on total creep of RAC was bigger than that of basic creep.Based on the experimental results,the interaction mechanism recycled coarse aggregate,the new mortar and old mortar in the creep process of RAC was studied,a creep calculation model reflecting the creep relation of new mortar,old mortar and RAC was introduced,which was the modified Neville creep model,and the creep of old mortar in the basic creep or the total creep process of RAC was calculated by the modified creep model.Based on software ANSYS,a two-dimensional random convex aggregate model of RAC was put forward to verify the reliability of the modified creep model.In addition,the influence of the random distribution of RCA on the creep of RAC was studied by the finite element model.Finally,a creep prediction model was constructed,which could be used to compute the creep of old mortar and RAC,and also reflect the content and properties of the old mortar in RAC based on the modified creep model.