A mesoscale discrete model for mechanical performance of concrete damaged by coupled ASR and DEF
A mesoscale discrete model for mechanical performance of concrete damaged by coupled ASR and DEF
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DOI：
10.1016/j.engfracmech.2020.107055
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发表时间：
2020-06
影响因子：
5.4
通讯作者：
Yi Wang;P. Jiradilok;K. Nagai;S. Asamoto
中科院分区：
文献类型：
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作者：
Yi Wang;P. Jiradilok;K. Nagai;S. Asamoto
真实的混凝土结构可同时遭受碱-硅反应（ASR）和延迟钙矾石形成（DEF），导致混凝土膨胀和表面地图开裂。这种损坏会导致严重的耐久性问题。ASR和DEF各自的影响已经研究，但混凝土的开裂行为时，他们一起行动仍然不清楚。本文采用三维刚体弹簧模型（3D RBSM）模拟了混凝土在ASR和DEF耦合作用下的开裂和力学性能退化，并对ASR和DEF的不同组合进行了参数研究。在砂浆-骨料界面和砂浆单元中引入应变。由于限制效应，经受耦合膨胀的试样可能比仅其中一个劣化起作用时遭受更少的膨胀或开裂。该模型清楚地可视化的开裂过程和应力发展的程度耦合膨胀的增加。更重要的是，基于模拟结果，两种类型的膨胀的相互作用，揭示了相关的力学性能的退化与内部开裂行为。此外，所产生的应用程序的第二种类型的扩展的限制效果进行了定量研究。虽然刚度没有显著变化，但在某些情况下，当较大的裂纹在约束效应下闭合时，抗压强度随着膨胀而增加。这种耦合效应的研究很难通过实验进行定量分析，但这项工作表明，使用RBSM模拟是可能的。
Real concrete structures can suffer simultaneously from the alkali-silica reaction (ASR) and delayed ettringite formation (DEF), resulting in expansion of the concrete and surface map cracking. This damage can lead to serious durability problems. The respective effects of ASR and DEF have been studied, but the cracking behavior of concrete when they act together remains unclear. In this study, a three-dimensional rigid body spring model (3D RBSM) is used to simulate the cracking and mechanical property degradation of concrete under coupled ASR and DEF. A parametric study is conducted to understand various combinations of ASR and DEF. In line with previous studies by the authors on independent ASR/DEF damage, expansions caused by ASR and DEF are, respectively, introduced as strains at the mortar-aggregate interface and in mortar elements. Due to a confinement effect, specimens subjected to coupled expansion may suffer less expansion or cracking than when only one of the degradations is acting. The model clearly visualizes the cracking process and stress development as the degree of coupled expansion increases. More importantly, based on the simulated results, the interactions of the two types of expansion are revealed by correlating the degradation in mechanical properties with internal cracking behavior. Further, the confinement effect arising on application of the second type of expansion is quantitatively examined. While there is no significant change in stiffness, compressive strength in some cases increases with expansion as larger cracks close up under the confinement effect. This kind of investigation of coupled effects is difficult to quantitatively analyze through experimentation, but this work demonstrates that it is possible using RBSM simulations.