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为研究磨细矿渣对混凝土徐变性能的影响,在(20±1)℃,相对湿度为(60±5)%的条件下测试了33%载荷水平下磨细矿渣等量取代水泥量分别为0,30%,50%和80%4种情况下混凝土的徐变度。结果表明:磨细矿渣掺量(质量分数,下同)为30%和50%时,磨细矿渣对混凝土徐变性能的影响不明显,当磨细矿渣掺量增加为80%时,混凝土抵抗徐变的能力大大下降,其1a的徐变度为不掺矿渣混凝土的1.74倍。通过扫描电镜二次电子成像观测,结合压汞法测试基体的孔隙率与孔径分布,对不同掺量下的磨细矿渣及水泥颗粒与基体的结合情况进行了分析研究。采用烧失量法测试水泥-矿渣体系中的非蒸发水量来表征水化产物数量,并基于纳米压痕技术测量了磨细矿渣与水泥颗粒的弹性模量,通过上述几种实验方法的联合观测分析,对磨细矿渣影响混凝土徐变性能的机理进行了详细研究。由于磨细矿渣颗粒的弹性模量略低于水泥颗粒,故不能通过“微集料效应”抑制混凝土的徐变。混凝土徐变性能受水泥及磨细矿渣颗粒与基体的界面结合状况的影响较大,当界面结合良好时,可忽略其对混凝土徐变的影响,混凝土的徐变度和体系的水化产物数量正相关;当界面结合不良时,其对抑制混凝土徐变的负面效应显著增强,徐变性能受到水化产物数量与界面结合情况的双重影响。
In order to study the influence of ground slag on the creep property of concrete, the equivalent amount of ground slag at 33% load level was tested under the condition of (20 ± 1) ℃ and relative humidity of (60 ± 5)% 0, 30%, 50% and 80% of the four cases of concrete creep. The results show that the effect of ground slag on the creep property of concrete is not obvious when the content of ground slag (mass fraction, the same below) is 30% and 50%. When the amount of ground slag is increased to 80%, the concrete resistance The ability to creep greatly decreased, the lacuna of 1a was 1.74 times that of slag-free concrete. The SEM and SEM were used to measure the porosity and pore size distribution of the matrix, and the combination of the ground slag and the cement particles with the matrix at different dosages was analyzed. The amount of non-evaporated water in the cement-slag system was measured by the loss on ignition method to quantify the amount of hydration products. Based on the nano-indentation technique, the elastic modulus of ground slag and cement particles was measured. Through the joint observation of the above experimental methods The mechanism of the effect of fine slag on concrete creep was studied in detail. Due to the slightly lower elastic modulus of finely ground slag particles than cement particles, creep of concrete can not be suppressed by the “micro-aggregate effect”. The creep properties of concrete are greatly influenced by the interface bonding between cement and ground slag particles and matrix. When the interface is well bonded, the influence of creep on concrete creep, the creep degree of concrete and the amount of hydration products When the interface is poorly bonded, its negative effect on the inhibition of concrete creep is obviously enhanced. The creep performance is affected by the quantity of hydration products and the interface combination.