A new multi-scale approach to characterize concrete creep and its implications in long-term durability

一种新的多尺度方法来表征混凝土徐变及其对长期耐久性的影响

基本信息

批准号：
RGPIN-2016-06077
负责人：
Sorelli, Luca
金额：
$ 1.75万
依托单位：
Université Laval
依托单位国家：
加拿大
项目类别：
Discovery Grants Program - Individual
财政年份：
2018
资助国家：
加拿大
起止时间：
2018-01-01 至 2019-12-31
项目状态：
已结题

来源：
https://www.nserc-crsng.gc.ca/ase-oro/Details-Detailles_eng.asp?id=665627
关键词：
new multi scale approach characterize

项目摘要

A recent survey on 71 concrete bridges monitored over a period of about 20 years showed that the creep deflection increases incessantly and it overestimates by far the predictions of several national codes. A wake-up call was then launched stating that the current national design recommendations and codes “are not only theoretically obsolete, but also indefensible”. The proposed research program aims at better understanding and characterizing the long term creep of concrete, and finally, to enhance the current design methods for predicting the long term behavior. ***Estimating the long-term creep of concrete (e.g., 30-50 years) using short term creep tests (e.g., 3-12 months) has been an unavoidable crux in civil engineering. In this context, novel microindentation techniques have been provided a breakthrough solution as they allow characterizing the logarithmic nature of the long term creep in few minutes. From a design point of view, the modern model code fib 2010 has recently adopted a logarithmic function for predicting the long term creep. This is extremely appealing for the proposed research program which intends to develop micro-indentation techniques to rapidly estimate the parameters of such logarithmic function for predicting the long term creep of concrete. ***The specific objectives of this research program are: ***(1) At the microstructure level, to fully characterize and better understand the effect of the temperature and possible damage on the creep behaviour of a cement paste by means of microindentation tests; ***(2) Upscale the properties measured at the level of a cement paste to the concrete level; ***(3) To implement a numerical model for predicting the long term deformation of a structure at different environmental conditions (e.g., temperature) and with possible damage due to durability issues;***(4) To improve the current design methods on the prediction of the long term creep; ***(5) To develop an international network of excellence and train students in highly specialized competences.***This innovative research direction will provide outstanding contributions to civil engineering, such as: ***(i) Fostering the current understanding on the long term creep of concrete with emphasis on its dependence on temperature and damage; ***(ii) Developing of ultra-rapid microindentation techniques for characterizing the long term creep of cement paste; ***(iii) Developing engineering tools for better predicting the long term creep of a concrete structures, such as bridges; ***(iv) Contribution to enhanced design recommendations for better predicting the long term creep of concrete structures and assuring the desired durability of the future Canadian infrastructure. *****

最近对71个混凝土桥梁进行了一项调查，该调查在大约20年的时间内进行了监测，该调查表明，蠕变定义不断增加，到目前为止，它高估了几种国家代码的预测。然后发出了一个警钟，指出当前的国家设计建议和代码“不仅是理论上的过时，而且是无法辩护的”。拟议的研究计划旨在更好地理解和表征混凝土的长期蠕变，最后增强当前的设计方法来预测长期行为。 ***使用短期蠕变测试（例如3-12个月）估计混凝土的长期蠕变（例如30 - 50年）在土木工程中是不可避免的关键。在这种情况下，已经为新颖的微观识别技术提供了突破性的解决方案，因为它们允许在几分钟内表征长期蠕变的对数特性。从设计的角度来看，现代模型代码FIB 2010最近采用了对数功能来预测长期蠕变。对于拟议的研究计划而言，这是非常有吸引力的，该计划旨在开发微观识别技术，以快速估计这种对数功能的参数，以预测混凝土的长期蠕变。 ***该研究计划的具体目标是：***（1）在微结构水平上，以完全表征并更好地理解温度的影响以及通过微观调节测试的水泥酱蠕变行为的影响； ***（2）高档在水泥糊中测量的特性至混凝土水平； ***（3）实施一个数值模型，以预测不同环境条件下结构的长期变形（例如温度），并且由于耐用性问题而导致可能的损坏； ***（4）可以改善当前的设计方法，以预测长期蠕变的预测； ***（5）建立国际卓越网络并以高度专业的能力培训学生。 ***（ii）开发超优化显微识别技术，以表征水泥糊的长期蠕变； ***（iii）开发工程工具，以更好地预测混凝土结构的长期蠕变，例如桥梁； ***（iv）对增强设计建议的贡献，以更好地预测混凝土结构的长期蠕变并确保未来加拿大基础设施的期望耐用性。 *****