加载龄期对机制砂自密实混凝土徐变性能影响

Influence of loading age on the creep properties of manufacture sand self-compacting concrete

【目的】机制砂代替天然砂配制自密实混凝土已成为工程建设的发展趋势,徐变是混凝土的固有特性,为研究加载龄期对机制砂自密实混凝土徐变性能的影响,【方法】对7 d、14 d、28 d三种不同加载龄期的混凝土试件进行了压缩徐变试验,探究了徐变随加载龄期的发展规律,并通过LINK3D非线性软件对不同加载龄期和石粉含量的混凝土徐变进行数值模拟,分析了加载龄期和石粉含量对机制砂自密实混凝土徐变的影响。【结果】结果表明:加载龄期增大会减小机制砂自密实混凝土的徐变,持荷250 d时,14 d、28 d加载龄期的徐变系数是7 d龄期的82.5%、71.5%;LINK3D可以较好地模拟混凝土的徐变试验,当石粉含量为5%时,填充效应的正作用使徐变变形减小,石粉含量大于10%时,随石粉含量增加徐变增大;模拟得到的不同加载龄期的单位徐变比在普通混凝土的范围内。【结论】机制砂中石粉含量宜在10%以内;当徐变对结构性能影响较大时,可增大养护龄期。

[Objective]Manufacture sand has become the development trend of engineering construction to replace natural sand in the preparation of self-compacting concrete,and creep is an inherent property of concrete.In order to study the influence of the loading age on the creep performance of manufacture sand self-compacting concrete,[Methods]compression creep tests are con-ducted on concrete specimens with different loading ages of 7 d,14 d and 28 d,which could investigate the development law of creep with loading age,and numerical simulations are performed by LINK3D non-linear software to analyze the influence of load-ing age and stone powder content on the creep of concrete.[Results]The results show that the increasing loading age decreases the creep of manufacture sand self-compacting concrete.When subjected to a load of 250 days,the creep coefficients for 14 d and 28 d ages are 82.5%and 71.5%of 7 d.LINK3D software enables better simulation of concrete creep tests.The positive effect of the filling effect reduces the creep deformation when the stone powder content is 5%,and increases with increasing stone powder content when the stone powder content is greater than 10%.The simulated creep ratios per unit at different loading ages are with-in the range of normal concrete.[Conclusion]The stone powder content of manufacture sand should be within 10%.It is possi-ble that increasing the curing age can reduce the influence of creep on structural performance.