掺合料高强混凝土早龄期拉伸徐变实验研究
发布时间：2018-11-03 07:20
【摘要】：对高强混凝土早龄期拉伸徐变特性的研究,能够为服役期高强混凝土的高精度应力解析及开裂预测提供重要参数。本研究应用团队自行设计的早龄期拉伸基本徐变实验方法,首先评价了掺合料高强混凝土的基本力学性能及自收缩特性,然后系统性地研究了恒定应力作用下加载龄期、应力强度比及掺合料种类对高强混凝土早龄期拉伸徐变的影响,进一步地研究了变应力作用下高强混凝土的早龄期拉伸基本徐变特性。本研究的主要结论包括:(1)各掺合料高强混凝土的早龄期弹性模量发展速率明显大于劈裂抗拉强度和抗压强度的发展速率。(2)粉煤灰抑制混凝土自收缩作用明显;而矿渣促进自收缩作用则非常明显;复掺组兼具了粉煤灰与矿渣的特点,自收缩的发展速率介于两者之间,且与基准组较为接近。(3)恒定应力作用下,加载龄期对于掺合料高强混凝土拉伸徐变的影响主要集中在3 d前,尤其是1 d和2 d龄期加载的混凝土比徐变值特别大。随着加载龄期的推移,各掺合料高强混凝土在不同应力强度比下的非线性徐变特征逐渐变成线性徐变特征。粉煤灰组只在1 d加载龄期的各应力强度比时表现对拉伸基本徐变明显地促进作用;矿渣组明显的抑制作用也主要表现在1 d加载龄期的各应力强度比时及2 d加载龄期0.2应力强度比情况下;复掺组在2 d加载龄期前对拉伸徐变总体表现为微弱的促进作用。(4)变应力作用下,粉煤灰组对拉伸基本徐变表现出促进作用;矿渣组明显地抑制拉伸基本徐变;复掺组的拉伸基本徐变与基准组较为接近。复掺组混凝土在变应力与恒定应力作用下的基本徐变差值最大,粉煤灰组次之,再其次是矿渣组,基准组的基本徐变差值最小。(5)变应力作用下的拉伸徐变实验同样可以用来判断混凝土早龄期是否具有线性徐变特征,且与恒定应力下的结论基本一致。
[Abstract]:The study of tensile creep characteristics of high strength concrete at early age can provide important parameters for high precision stress analysis and crack prediction of high strength concrete in service period. In this study, the basic mechanical properties and autogenous shrinkage properties of high strength concrete with admixtures were evaluated by using the basic creep test method of early age tension designed by the team, and then the loading age under constant stress was systematically studied. The effect of stress intensity ratio and admixtures on tensile creep of high strength concrete at early age is studied. The basic creep behavior of high strength concrete at early age is further studied. The main conclusions of this study are as follows: (1) the development rate of early age elastic modulus of high strength concrete with different admixtures is obviously higher than that of splitting tensile strength and compressive strength. (2) the effect of fly ash on self-shrinkage of concrete is obvious; The effect of slag on self-shrinkage is very obvious. The compound admixture group has the characteristics of fly ash and slag, and the development rate of autogenous shrinkage is between the two groups, and is close to that of the reference group. (3) under constant stress, The effect of loading age on tensile creep of high strength concrete with admixture is mainly before 3 days, especially the concrete loaded at 1 d and 2 d is more than creep value. With the development of loading age, the nonlinear creep characteristics of high strength concrete with various admixtures at different stress intensity ratios gradually become linear creep characteristics. In the fly ash group, the tensile creep was obviously promoted by the stress intensity ratio of 1 day loading period. The obvious inhibition effect of slag group was mainly under the stress intensity ratio of 1 day loading age and 0.2 stress intensity ratio of 2 days loading age. (4) under the action of changing stress, the fly ash group can promote the basic tensile creep, while the slag group obviously inhibits the tensile creep. The tensile creep of the compound group is close to that of the reference group. Under the action of variable stress and constant stress, the difference of basic creep of concrete with compound admixture is the largest, followed by fly ash group and slag group. (5) tensile creep test under variable stress can also be used to judge whether the early age of concrete has linear creep characteristics, and it is basically consistent with the conclusion under constant stress.
【学位授予单位】：浙江工业大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TU528.31
本文编号：2307094
[Abstract]:The study of tensile creep characteristics of high strength concrete at early age can provide important parameters for high precision stress analysis and crack prediction of high strength concrete in service period. In this study, the basic mechanical properties and autogenous shrinkage properties of high strength concrete with admixtures were evaluated by using the basic creep test method of early age tension designed by the team, and then the loading age under constant stress was systematically studied. The effect of stress intensity ratio and admixtures on tensile creep of high strength concrete at early age is studied. The basic creep behavior of high strength concrete at early age is further studied. The main conclusions of this study are as follows: (1) the development rate of early age elastic modulus of high strength concrete with different admixtures is obviously higher than that of splitting tensile strength and compressive strength. (2) the effect of fly ash on self-shrinkage of concrete is obvious; The effect of slag on self-shrinkage is very obvious. The compound admixture group has the characteristics of fly ash and slag, and the development rate of autogenous shrinkage is between the two groups, and is close to that of the reference group. (3) under constant stress, The effect of loading age on tensile creep of high strength concrete with admixture is mainly before 3 days, especially the concrete loaded at 1 d and 2 d is more than creep value. With the development of loading age, the nonlinear creep characteristics of high strength concrete with various admixtures at different stress intensity ratios gradually become linear creep characteristics. In the fly ash group, the tensile creep was obviously promoted by the stress intensity ratio of 1 day loading period. The obvious inhibition effect of slag group was mainly under the stress intensity ratio of 1 day loading age and 0.2 stress intensity ratio of 2 days loading age. (4) under the action of changing stress, the fly ash group can promote the basic tensile creep, while the slag group obviously inhibits the tensile creep. The tensile creep of the compound group is close to that of the reference group. Under the action of variable stress and constant stress, the difference of basic creep of concrete with compound admixture is the largest, followed by fly ash group and slag group. (5) tensile creep test under variable stress can also be used to judge whether the early age of concrete has linear creep characteristics, and it is basically consistent with the conclusion under constant stress.
【学位授予单位】：浙江工业大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TU528.31
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